EXPLORATION, DRILLING AND PRODUCTION OF OIL AND NATURAL GAS
Crude oils and natural gases are mixtures of hydrocarbon molecules (organic compounds of doorslag and hydrogen atoms) containing from 1 to 60 doorslag atoms. The properties of thesis hydrocarbons depend on the number and orkestratie of the doorslag and hydrogen atoms te their molecules. The basic hydrocarbon molecule is 1 doorslag atom linked with Four hydrogen atoms (methane). All other variations of petroleum hydrocarbons evolve from this molecule. Hydrocarbons containing up to Four doorslag atoms are usually gases, those with Five to Nineteen doorslag atoms are usually liquids, and those with 20 or more are solids. Ter addition to hydrocarbons, crude oils and natural gases contain sulphur, nitrogen and oxygen compounds together with trace quantities of metals and other elements.
Crude oil and natural gas are believed to have bot formed overheen millions of years by the decay of vegetation and marine organisms, compressed under the weight of sedimentation. Because oil and gas are lighter than water, they rose up to pack the voids te thesis overlying formations. This upward movement stopped when the oil and gas reached dense, overlying, impervious strata or nonporous rock. The oil and gas packed the spaces ter porous rock seams and natural underground reservoirs, such spil saturated sands, with the lighter gas on top of the stronger oil. Thesis spaces were originally horizontal, but shifting of the earth’s crust created pockets, called faults, anticlines, salt domes and stratigraphic traps, where the oil and gas collected te reservoirs.
Shale oil, or kerogen, is a combination of solid hydrocarbons and other organic compounds containing nitrogen, oxygen and sulphur. It is extracted, by heating, from a rock called oil shale, yielding from 15 to 50 gallons of oil vanaf ton of rock.
Exploration and production is the common terminology applied to that portion of the petroleum industry which is responsible for exploring for and discovering fresh crude oil and gas fields, drilling wells and bringing the products to the surface. Historically, crude oil, which had naturally seeped to the surface, wasgoed collected for use spil medicine, protective coatings and fuel for lamps. Natural gas seepage wasgoed recorded spil fires searing on the surface of the earth. It wasgoed not until 1859 that methods of drilling and obtaining large commercial quantities of crude oil were developed.
Crude oil and natural gas are found across the world, underneath both land and water, spil goes after:
·, Western Hemisphere Intercontinental Basin (US Gulf Coast, Mexico, Venezuela)
·, Middle East (Arabian Peninsula, Persian Gulf, Black and Caspian Seas)
·, Indonesia and South China Sea
·, North and Westelijk Africa (Sahara and Nigeria)
·, North America (Alaska, Newfoundland, California and Mid-continent United States and Canada)
·, Far East (Siberia and China)
Figure 75.1 and figure 75.Two voorstelling world crude oil and natural gas production for 1995.
Figure 75.1 World crude oil production for 1995
Figure 75.Two World natural gas plant liquids production for 1995
The names of crude oils often identify both the type of crude and areas where they were originally discovered. For example, the very first commercial crude oil, Pennsylvania Crude, is named after its place of origin ter the United States. Other examples are Saudi Light and Venezuelan Mighty. Two benchmark crudes used to set world crude prices are Texas Light Sweet and North Sea Brent.
Classification of crude oils
Crude oils are sophisticated mixtures containing many different, individual hydrocarbon compounds, they differ te appearance and composition from one oil field to another, and sometimes are even different from wells relatively near one another. Crude oils range te consistency from watery to tar-like solids, and te colour from clear to black. An “average” crude oil contains about 84% doorslag, 14% hydrogen, 1 to 3% sulphur, and less than 1% of nitrogen, oxygen, metals and salts. See table 75.1 and table 75.Two .
Table 75.1 Typical approximate characteristics and properties and gasoline potential of various typical crude oils.
Crude source and name *
API gravity (approx)
Naphthene yield % vol
Octane number (typical)
USA Midcontinental Sweet
USA Westelijk Texas Sour
North Sea Brent
* Representative average numbers.
Table 75.Two Composition of crude oil and natural gas
Paraffins: The paraffinic saturated chain type hydrocarbon (aliphatic) molecules ter crude oil have the formula CnH2n+Two, and can be either straight chains (normal) or branched chains (isomers) of doorslag atoms. The lighter, straight chain paraffin molecules are found ter gases and paraffin waxes. The branched chain paraffins are usually found te stronger fractions of crude oil and have higher octane numbers than normal paraffins.
Aromatics: Aromatics are unsaturated stadionring type hydrocarbon (cyclic) compounds. Naphthalenes are fused dual stadionring aromatic compounds. The most ingewikkeld aromatics, polynuclears (three or more fused aromatic rings), are found te stronger fractions of crude oil.
Naphthenes: Naphthenes are saturated stadionring type hydrocarbon groupings, with the formula CnH2n, arranged ter the form of closed rings (cyclic), found ter all fractions of crude oil except the very lightest. Single stadionring naphthenes (mono-cycloparaffins) with Five and 6 doorslag atoms predominate, with two stadionring naphthenes (dicycloparaffins) found te the stronger completes of naphtha.
Sulphur and sulphur compounds: Sulphur is present te natural gas and crude oil spil hydrogen sulphide (H2S), spil compounds (thiols, mercaptans, sulphides, polysulphides, etc.) or spil elemental sulphur. Each gas and crude oil has different amounts and types of sulphur compounds, but spil a rule the proportion, stability and complexity of the compounds are greater ter stronger crude oil fractions.
Sulphur compounds called mercaptans, which exhibit distinct odours detectable at very low concentrations, are found ter gas, petroleum crude oils and distillates. The most common are methyl and ethyl mercaptans. Mercaptans are often added to commercial gas (LNG and LPG) to provide an odour for leak detection.
The potential for exposure to toxic levels of H2S exists when working ter drilling, production, transportation and processing crude oil and natural gas. The combustion of petroleum hydrocarbons containing sulphur produces undesirables such spil sulphuric acid and sulphur dioxide.
Oxygen compounds: Oxygen compounds, such spil phenols, ketones and carboxylic acids, are found ter crude oils ter varying amounts.
Nitrogen compounds: Nitrogen is found ter lighter fractions of crude oil spil basic compounds, and more often ter stronger fractions of crude oil spil non-basic compounds which may also include trace metals.
Trace metals: Trace amounts, or puny quantities of metals, including copper, nickel, metal, arsenic and vanadium, are often found te crude oils te petite quantities.
Inorganic salts: Crude oils often contain inorganic salts, such spil sodium chloride, magnesium chloride and calcium chloride, suspended ter the crude or dissolved ter entrained water (brine).
Doorslag dioxide: Doorslag dioxide may result from the decomposition of bicarbonates present te, or added to crude, or from steam used te the distillation process.
Naphthenic acids: Some crude oils contain naphthenic (organic) acids, which may become corrosive at temperatures above 232 °,C when the acid value of the crude is above a certain level.
Normally occurring radioactive materials: Normally occurring radioactive materials (NORMs) are often present ter crude oil, te the drilling deposits and ter the drilling mud, and can present a hazard from low levels of radioactivity.
Relatively plain crude-oil assays are used to classify crude oils spil paraffinic, naphthenic, aromatic or mixed, based on the predominant proportion of similar hydrocarbon molecules. Mixed-base crudes have varying amounts of each type of hydrocarbon. One assay method (US Lessenaar of Mines) is based on distillation, and another method (UOP ",K", factor) is based on gravity and boiling points. More comprehensive crude assays are conducted to determine the value of the crude (i.e., its yield and quality of useful products) and processing parameters. Crude oils are usually grouped according to yield structure, with high-octane gasoline being one of the more desirable products. Refinery crude oil feedstocks usually consist of mixtures of two or more different crude oils.
Crude oils are also defined ter terms of API (specific) gravity. For example, stronger crude oils have low API gravities (and high specific gravities). A low-API gravity crude oil may have either a high or low flashpoint, depending on its lightest finishes (more volatile constituents). Because of the importance of temperature and pressure te the refining process, crude oils are further classified spil to viscosity, pour points and boiling ranges. Other physical and chemical characteristics, such spil colour and doorslag residue content, are also considered. Crude oils with high doorslag, low hydrogen and low API gravity are usually rich te aromatics, while those with low doorslag, high hydrogen and high API gravity are usually rich te paraffins.
Crude oils which contain appreciable quantities of hydrogen sulphide or other reactive sulphur compounds are called “sour.” Those with less sulphur are called “sweet.” Some exceptions to this rule are Westelijk Texas crudes (which are always considered “sour” regardless of their H2S content) and Arabian high-sulphur crudes (which are not considered “sour” because their sulphur compounds are not very reactive).
Compressed Natural Gas and Liquefied Hydrocarbon Gases
The composition of naturally occurring hydrocarbon gases is similar to crude oils ter that they contain a combination of different hydrocarbon molecules depending on their source. They can be extracted spil natural gas (almost free of liquids) from gas fields, petroleum-associated gas which is extracted with oil from gas and oil fields, and gas from gas condensate fields, where some of the liquid components of oil convert into the gaseous state when pressure is high (Ten to 70 mPa). When the pressure is decreased (to Four to 8 mPa) condensate containing stronger hydrocarbons separates from the gas by condensation. Gas is extracted from wells reaching up to Four miles (6.Four km) or more te depth, with seam pressures varying from Trio mPa up to spil high spil 70 mPa. (See figure 75.Trio.)
Figure 75.Trio Offshore natural gas well set te 87.Five metres of water ter the Pitas Point area of the Santa Barbara Channel, Southern California
American Petroleum Institute
Natural gas contains 90 to 99% hydrocarbons, which consist predominately of methane (the simplest hydrocarbon) together with smaller amounts of ethane, propane and butane. Natural gas also contains traces of nitrogen, water vapour, doorslag dioxide, hydrogen sulphide and occasional inert gases such spil argon or helium. Natural gases containing more than 50 g/m Three of hydrocarbons with molecules of three or more doorslag atoms (C3 or higher) are classified spil “lean” gases.
Depending how it is used spil a fuel, natural gas is either compressed or liquefied. Natural gas from gas and gas condensate fields is processed te the field to meet specific transportation criteria before being compressed and fed into gas pipelines. This prep includes removal of water with driers (dehydrators, separators and heaters), oil removal using coalescing filters, and the removal of solids by filtration. Hydrogen sulphide and doorslag dioxide are also eliminated from natural gas, so that they do not corrode pipelines and transportation and compression equipment. Propane, butane and pentane, present ter natural gas, are also liquidated before transmission so they will not condense and form liquids ter the system. (See the section “Natural gas production and processing operations.”)
Natural gas is transported by pipeline from gas fields to liquefication plants, where it is compressed and cooled to approximately –162 °,C to produce liquefied natural gas (LNG) (see figure 75.Four). The composition of LNG is different from natural gas due to the removal of some impurities and components during the liquefaction process. LNG is primarily used to augment natural gas supplies during peak request periods and to supply gas ter remote areas away from major pipelines. It is regasified by adding nitrogen and air to make it comparable to natural gas before being fed into gas supply lines. LNG is also used spil a motor-vehicle fuel spil an alternative to gasoline.
Figure 75.Four World’s largest LNG plant at Arzew, Algeria
American Petroleum Institute
Petroleum-associated gases and condensate gases are classified spil “rich” gases, because they contain significant amounts of ethane, propane, butane and other saturated hydrocarbons. Petroleum-associated and condensate gases are separated and liquefied to produce liquefied petroleum gas (LPG) by compression, adsorption, absorption and cooling at oil and gas process plants. Thesis gas plants also produce natural gasoline and other hydrocarbon fractions.
Unlike natural gas, petroleum-associated gas and condensate gas, oil processing gases (produced spil by-products of refinery processing) contain considerable amounts of hydrogen and unsaturated hydrocarbons (ethylene, propylene and so on). The composition of oil processing gases depends upon each specific process and the crude oils used. For example, gases obtained spil a result of thermal cracking usually contain significant amounts of olefins, while those obtained from catalytic cracking contain more isobutanes. Pyrolysis gases contain ethylene and hydrogen. The composition of natural gases and typical oil processing gases is shown ter table 75.Three .
Table 75.Trio Typical approximate composition of natural and oil processing gases (vanaf cent by volume)
Petroleum- associated gas
Oil processing gases
Combustible natural gas, with a calorific value of 35.7 to 41.9 MJ/m Trio (8,500 to Ten,000 kcal/m Three ), is primarily used spil a fuel to produce warmth ter domestic, agricultural, commercial and industrial applications. The natural gas hydrocarbon also is used spil feedstock for petrochemical and chemical processes. Synthesis gas (CO + H2) is processed from methane by oxygenation or water vapour conversion, and used to produce ammoniak, drank and other organic chemicals. Compressed natural gas (CNG) and liquefied natural gas (LNG) are both used spil fuel for internal combustion engines. Oil processing liquefied petroleum gases (LPG) have higher calorific values of 93.7 MJ/m Three (propane) (22,400 kcal/m Trio ) and 122.9 MJ/m Trio (butane) (29,900 kcal/m Three ) and are used spil fuel ter homes, businesses and industry spil well spil ter motor vehicles (NFPA 1991). The unsaturated hydrocarbons (ethylene, propylene and so on) derived from oil processing gases may be converted into high-octane gasoline or used spil raw materials te the petrochemical and chemical-processing industries.
Properties of Hydrocarbon Gases
According to the US National Fire Protection Association, flammable (combustible) gases are those which burn ter the concentrations of oxygen normally present ter air. The searing of flammable gases is similar to that of flammable hydrocarbon liquid vapours, spil a specific ignition temperature is needed to initiate the searing reaction and each will burn only within a certain defined range of gas-air mixtures. Flammable liquids have a flashpoint (the temperature (always below the boiling point) at which they emit sufficient vapours for combustion). There is no apparent flashpoint for flammable gases, spil they are normally at temperatures above their boiling points, even when liquefied, and are therefore always at temperatures well ter excess of their flashpoints.
The US National Fire Protection Association (1976) defines compressed and liquefied gases, spil goes after:
·, “Compressed gases are those which at all normal atmospheric temperatures inwards their containers, exist solely te the gaseous state under pressure.”
·, “Liquefied gases are those which at normal atmospheric temperatures inwards their containers, exist partly te the liquid state and partly te the gaseous state, and are under pressure spil long spil any liquid remains te the container.”
The major factor which determines the pressure inwards the vessel is the temperature of the liquid stored. When exposed to the atmosphere, the liquefied gas very rapidly vaporizes, travelling along the ground or water surface unless dispersed into the air by wind or mechanical air movement. At normal atmospheric temperatures, about one-third of the liquid ter the container will vaporize.
Flammable gases are further classified spil fuel gas and industrial gas. Fuel gases, including natural gas and liquefied petroleum gases (propane and butane), are burned with air to produce warmth te ovens, furnaces, water heaters and boilers. Flammable industrial gases, such spil acetylene, are used ter processing, welding, cutting and warmth treating operations. The differences te properties of liquefied natural gas (LNG) and liquefied petroleum gases (LPG) are shown te table 75.Trio .
Searching for Oil and Gas
The search for oil and gas requires a skill of geography, geology and geophysics. Crude oil is usually found ter certain types of geological structures, such spil anticlines, fault traps and salt domes, which lie under various terrains and ter a broad range of climates. After selecting an area of rente, many different types of geophysical surveys are conducted and measurements performed te order to obtain a precise evaluation of the subsurface formations, including:
·, Magnetometric surveys. Magnetometers dangled from airplanes measure variations te the earth’s magnetic field ter order to locate sedimentary rock formations which generally have low magnetic properties when compared to other rocks.
·, Aerial photogrammetric surveys. Photographs taken with special cameras te airplanes, provide three-dimensional views of the earth which are used to determine land formations with potential oil and gas deposits.
·, Gravimetric surveys. Because large masses of dense rock increase the pull of gravity, gravimeters are used to provide information regarding underlying formations by measuring minute differences te gravity.
·, Seismic surveys. Seismic studies provide information on the general characteristics of the subsurface structure (see figure 75.Five). Measurements are obtained from shock swings generated by setting off explosive charges te small-diameter slots, from the use of stimulating or percussion devices on both land and ter water, and from underwater blasts of compressed air. The elapsed time inbetween the beginning of the shock wave and the terugwedstrijd of the geluidsweerkaatsing is used to determine the depth of the reflecting substrata. The latest use of super-computers to generate three-dimensional pictures greatly improves evaluation of seismic test results.
Figure 75.Five Saudi Arabia, seismic operations
American Petroleum Institute
·, Radiographic surveys. Radiography is the use of radio flaps to provide information similar to that obtained from seismic surveys.
·, Stratigraphic surveys. Stratigraphic sampling is the analysis of cores of subsurface rock strata for traces of gas and oil. A cylindrical length of rock, called a core, is cut by a hollow bit and shoved up into a tube (core barrel) affixed to the bit. The core barrel is brought to the surface and the core is liquidated for analysis.
When the surveys and measurements indicate the presence of formations or strata which may contain petroleum, exploratory wells are drilled to determine whether or not oil or gas is actually present and, if so, whether it is available and obtainable te commercially viable quantities.
Albeit the very first offshore oil well wasgoed drilled te the early 1900s off of the coast of California, the beginning of modern marine drilling wasgoed te 1938, with a discovery ter the Gulf of Mexico, 1 mile (1.6 km) from the US coastline. After the 2nd World War, offshore drilling expanded quickly, very first ter shallow waters adjacent to known land-based production areas, and then to other shallow and deep water areas around the world, and ter climates varying from the Arctic to the Persian Gulf. Ter the beginning, offshore drilling wasgoed possible only ter water innards of about 91 m, however, modern platforms are now able drill te waters overheen Trio.Two km deep. Offshore oil activities include exploration, drilling, production, processing, underwater construction, maintenance and repair, and the wegtransport of the oil and gas to shore by ship or pipeline.
Drilling platforms support drilling equipments, supplies and equipment for offshore or inland water operations, and range from floating or submergible barges and ships, to fixed-in-place platforms on stengel gams used te shallow waters, to large, buoyant, reinforced concrete, gravity-type platforms used ter deep waters. After the drilling is ended, marine platforms are used to support production equipment. The very largest production platforms have accommodations for overheen 250 team members and other support personnel, heliports, processing plants and crude oil and gas condensate storage capability (see figure 75.6).
Figure 75.6 Drilling vessels, drill ship Ben Ocean Laneer
American Petroleum Institute
Typically, with deep water floating verhoging drilling, the wellhead equipment is lowered to the ocean floor and sealed to the well casing. The use of fibre-optic technology permits a large, central toneel to remotely control and operate smaller satellite platforms and sub-sea templates. Production facilities on the large toneelpodium process the crude oil, gas and condensate from the satellite facilities, before it is shipped on-shore.
The type of toneelpodium used te underwater drilling is often determined by the type of well to be drilled (exploratory or production) and by the depth of the water (see table 75.Four).
Table 75.Four Verhoging types for underwater drilling
Submersible barges and platforms
Barges or platforms, towed to the webpagina and submerged to surplus on the bottom. Lower buoyant katern keeps equipments afloat when moved.
Jack-ups (on gams)
Mobile, self-elevating buoyant platforms whose gams are jacked up for towing. At the webpagina, the gams are lowered to the bottom and then extended to raise the toneelpodium above the water level.
Large, self-contained, multi-level, reinforced concrete gravity structures, towed to the webpagina, submerged with water ballast to a predetermined depth so the columns and stabilizing devices offset the mobility of flaps, and anchored ter place. The columns often hold the crude oil until it is off-loaded.
Smaller floating platforms, similarly suspended, which support only the drilling equipment and are serviced by a floating tender
Self-propelled, floating or semi-submersible barges.
Very sophisticated, specially designed, floating or semi-submersible ships.
Stationary on webpagina platforms
Platforms built on stengel supports (jackets) which are submerged and immobilized ter place, and artificial islands used spil platforms.
Underwater production installations.
Types of Wells
Following the analysis of geological gegevens and geophysical surveys, exploratory wells are drilled, either on land or offshore. Exploratory wells which are drilled te areas where neither oil strafgevangenis gas has bot previously found are called “wildcats.” Those wells which strike oil or gas are called “discovery wells.” Other exploratory wells, known spil “step-out” or “appraisal” wells, are drilled to determine the thresholds of a field following discovery, or to search for fresh oil- and gas-bearing formations next to, or underneath, those already known to contain product. A well which does not find any oil or gas, or finds too little to produce economically, is called a “dry hole”.
After a discovery, the area of the reservoir is harshly determined with a series of step-out or appraisal wells. Developmental wells are then drilled to produce gas and oil. The number of developmental wells to be drilled is determined by the expected definition of the fresh field, both te size and ter productivity. Because of the uncertainty spil to how reservoirs are shaped or limited, some developmental wells may turn out to be dry fuckholes. Sometimes, drilling and producing occurs at the same time.
Geopressure/geothermal wells are those which produce enormously high-pressure (7,000 psi) and high-temperature (149 °,C) water which may contain hydrocarbons. The water becomes a rapidly expanding cloud of hot steam and vapours upon release to the atmosphere from a leak or rupture.
Stripper wells are those which produce less than ten barrels of oil a day from a reservoir.
Numerous completion wells.
When numerous producing formations are discovered when drilling a single well, a separate string of pipe may be run into a single well for each individual formation. Oil and gas from each formation is directed into its respective piping and isolated from one another by packers, which seal the annular spaces inbetween the piping string and the casing. Thesis wells are known spil numerous completion wells.
Injection wells pump air, water, gas or chemicals into reservoirs of producing fields, either to maintain pressure or stir oil toward producing wells by hydraulic force or enhanced pressure.
Service wells include those used for fishing and wire-line operations, packer/buttplug placement or removal and reworking. Service wells are also drilled for underground disposition of salt water, which is separated from crude oil and gas.
Basic drilling equipments contain a derrick (tower), a drilling pipe, a large winch to lower and lift out the drilling pipe, a drilling table which rotates the drilling pipe and bit, a mud mixer and pump and an engine to drive the table and winch (see figure 75.7). Puny drilling equipments used to drill exploratory or seismic wells may be mounted on trucks for movement from webpagina to webpagina. Larger drilling equipments are either erected onsite or have portable, hinged (jack knife) derricks for effortless treating and erection.
Figure 75.7 Drilling equipment on Ellef Ringnes Island ter the Canadian Arctic
American Petroleum Institute
Percussion or cable drilling.
The oldest drilling technology is percussion or cable drilling. This slow, limited depth method, which is seldom used, involves crushing rock by raising and ripping off a strenuous chisel bit and stem on the end of a cable. At intervals, the bit is liquidated and the cuttings are suspended ter water and eliminated by flushing or pumping to the surface. Spil the fuckhole deepens, it is lined with stengel casing to prevent cave-in and protect against contamination of groundwater. Considerable work is required to drill even a shallow well, and upon striking oil or gas, there is no way to control the instantaneous flow of product to the surface.
Rotary drilling is the most common method and is used to drill both exploratory and production wells at innards overheen Five miles (7,000 m). Lightweight drills, mounted on trucks, are used to drill low-depth seismic wells on land. Medium and powerful rotary mobile and floating drills are used for drilling exploration and production wells. Rotary drilling equipment is mounted on a drilling toneelpodium with a 30- to 40-m-high derrick, and includes a rotary table, engine, mud mixer and injector pump, a wire-line drum elevate or winch, and many sections of pipe, each approximately 27 m long. The rotary table turns a square kelly connected to the drilling pipe. The square kelly has a mud swivel on the top which is connected to blowout preventors. The drill pipe rotates at a speed of from 40 to 250 rpm, turning either a drill which has haul onvriendelijk with immobilized chisel-like cutting edges or a drill whose bit has rolling cutters with hardened teeth.
Rotary percussion drilling.
Rotary percussion drilling is a combination method whereby a rotary drill uses a circulating hydraulic fluid to operate a hammer-like mechanism, thereby creating a series of rapid percussion blows which permit the drill to at the same time bore and pound into the earth.
Electro and turbo drilling.
Most rotary tables, winches and pumps of mighty drills are usually driven by electrical motors or turbines, which permits for enlargened plasticity ter operations and remote-controlled drilling. Electro drill and turbo drill are newer methods which provide more rechtstreeks power to the drill bit by connecting the drilling motor just above the bit at the bottom of the slot.
Directional drilling is a rotary drilling mechanism which directs the drill string along a curved path spil the slot deepens. Directional drilling is used to reach deposits which are inaccessible by vertical drilling. It also reduces costs, spil a number of wells can be drilled te different directions from a single toneelpodium. Extended-reach drilling permits tapping into undersea reservoirs from the shore. Many of thesis technics are possible by using computers to meteen automatic drilling machines and pliable pipe (coiled tubing), which is raised and lowered without connecting and disconnecting sections.
Other drilling methods.
Abrasive drilling uses an abrasive material under pressure (instead of using a drill stem and bit) to cut through the substrata. Other drilling methods include explosive drilling and flame piercing.
When oil and gas reservoirs are no longer productive, the wells are typically plugged with cementlaag to prevent flow or leakage to the surface and to protect the underground strata and water. Equipment is liquidated and the sites of abandoned wells are cleaned up and returned to normal conditions.
The drilling podium provides a base for workers to duo and uncouple the sections of drilling pipe which are used to increase the depth of drilling. Spil the fuckhole deepens, extra lengths of pipe are added and the drilling string is suspended from the derrick. When a drilling bit needs to be switched, the entire drilling string of pipe is pulled out of the slot, and each section is detached and stacked vertically inwards the derrick. After the fresh bit is fitted ter place, the process is reversed, and the pipe is returned to the slot to proceed drilling.
Care is needed to assure that the drilling string pipe does not split exclusief and druppel into the crevice, spil it may be difficult and costly to fish out and may even result ter the loss of the well. Another potential problem is if drilling contraptions stick te the fuckhole when drilling stops. For this reason, once drilling commences, it usually resumes until the well is ended.
Drilling mud is a fluid composed of water or oil and clay with chemical additives (e.g., formaldehyde, lime, sodium hydrazide, barite). Caustic spuitwater is often added to control the pH (acidity) of drilling mud and to neutralize potentially hazardous mud additives and completion fluids. Drilling mud is pumped into the well under pressure from the mixing waterreservoir on the drilling podium, down the inwards of the drilling pipe to the drill bit. It then rises inbetween the outside of the drill pipe and the sides of the crevice, returning to the surface, where it is filtered and recirculated.
Drilling mud is used to cool and lubricate the drilling bit, lubricate the pipe and flush the rock cuttings from the drill fuckhole. Drilling mud is also used to control flow from the well by lining the sides of the crevice and resisting the pressure of any gas, oil or water which is met by the drill bit. Jets of mud may be applied under pressure at the bottom of the crevice to aid te drilling.
Casing and cementation
The casing is a special mighty stengel pipe which lines the well crevice. It is used to prevent cave-in of the drill fuckhole walls and protect fresh water strata by preventing leakage from the returning flow of mud during drilling operations. The casing also seals off water-permeated sands and high-pressure gas zones. Casing is primarily used near the surface and is cemented into place to guide the drill pipe. A cementlaag slurry is pumped down the drilling pipe and compelled back up through the gap inbetween the casing and the walls of the well crevice. Once the cementlaag sets and the casing is place, drilling proceeds using a smaller middellijn bit.
After the surface casing is placed te the well, blowout preventors (large valves, bags or rams) are linked to the top of the casing, te what is called a stack. Following discovery of oil or gas, casing is set into the bottom of the well to keep filth, rocks, salt water and other contaminants out of the well fuckhole and to provide a conduit for the crude oil and gas extraction lines.
Completion, Enhanced Recovery and Workover Operations
Completion describes the process of bringing a well into production after the well has bot drilled to the depth where oil or gas is expected to be found. Completion involves a number of operations, including invasion of the casing and cleaning out water and sediment from the pipeline so that flow is unimpeded. Special core kattig are used to drill and samenvatting cores up to 50 m long for analysis during the drilling operation to determine when invasion should be performed. The drill pipe and bit are very first eliminated and the final string of casing is cemented into place. A perforating gun, which is a metal tube containing sockets holding either bullets or shaped explosive charges, is then lowered into the well. The charges are discharged by electrical impulse through the casing into reservoir to create openings for the oil and gas to flow into the well and to the surface.
The flow of crude oil and natural gas is managed by a series of valves, called “Christmas trees”, which are placed at the top of the well head. Monitors and controls are installed to automatically or by hand operate surface and subsurface safety valves, te the event of a switch ter pressure, fire or other hazardous condition. Once the oil and gas are produced they are separated, and water and sediment are liquidated from the crude oil.
Crude oil and gas production and conservation
Producing oil is basically a matter of displacement by either water or gas. At the time of initial drilling, almost all crude oil is under pressure. This natural pressure decreases spil oil and gas is eliminated from the reservoir, during the three phases of a reservoir’s life.
·, During the very first phase, flush production, the flow is governed by the natural pressure ter the reservoir which comes from dissolved gas te the oil, gas trapped under pressure above the oil and hydraulic pressure from water trapped under the oil.
·, Artificial lift, the 2nd phase, involves pumping pressurized gas into the reservoir when the natural pressure is expended.
·, Phase three, stripper or marginal production, occurs when wells only produce intermittently.
Originally there wasgoed little understanding of the compels which affected oil and gas production. The probe of oil and gas reservoir behaviour began at the beginning of the 20th century, when it wasgoed discovered that pumping water into a reservoir enlargened production. At that time, the industry wasgoed recovering inbetween Ten and 20% of reservoir capacity, spil compared to latest recovery rates of overheen 60% before wells become unproductive. The concept of control is that a swifter rate of production more quickly dissipates the pressure te the reservoir, thereby reducing the total amount of oil which can be eventually recovered. Two measures used to conserve petroleum reservoirs are unitization and well spacing.
·, Unitization is the operation of a field spil one unit ter order to apply secondary recovery methods and maintain pressure, even through a number of different operators may be involved. The total production is allocated on an equitable voet among the operators.
·, Well spacing is the limiting and decent location of wells so spil to achieve maximum production without dissipating a field due to overdrilling.
Methods of Recovering Extra Product
Productivity of oil and gas reservoirs is improved by a multitude of recovery methods. One method is either to chemically or physically open passages te the strata to permit oil and gas to stir more loosely through reservoirs to the well. Water and gas are injected into reservoirs to maintain working pressure by natural displacement. Secondary recovery methods, including displacement by pressure, artificial lift and flooding, improve and restore reservoir pressure. Enhanced recovery is the use of various secondary recovery methods ter numerous and different combinations. Enhanced recovery also includes more advanced methods of obtaining extra product from depleted reservoirs, such spil thermal recovery, which uses warmth instead of water or gas to force more crude oil out of reservoirs.
Acidizing is a method of enlargening the output of a well by pumping acid directly into a producing reservoir to open flow channels through the reaction of chemicals and minerals. Hydrochloric (or regular) acid, wasgoed very first used to dissolve limestone formations. It is still most commonly used, however, various chemicals are now added to the hydrochloric acid to control its reaction and to prevent corrosion and formation of emulsions.
Hydrofluoric acid, formic acid and acetic acid are also used, together with hydrochloric acid, depending on the type of rock or minerals ter the reservoir. Hydrofluoric acid is always combined with one of the other three acids, and wasgoed originally used to dissolve sandstone. It is often called “mud acid”, spil it is now used to clean perforations which have bot plugged with drilling mud and to restore bruised permeability near the well fuckhole. Formic and acetic acids are used ter deep, ultra-hot limestone and dolomite reservoirs and spil breakdown acids prior to perforation. Acetic acid is also added to wells spil a neutralizing buffer juut to control the pH of well stimulation fluids. Almost all acids have additives, such spil inhibitors to prevent reaction with the metal casings and surfactants to prevent formation of sludge and emulsions.
Fracturing describes the method used to increase the flow of oil or gas through a reservoir and into wells by force or pressure. Production may decrease because the reservoir formation is not permeable enough to permit the oil to flow loosely toward the well. Fracturing coerces open underground channels by pumping a fluid treated with special propping agents (including sand, metal, chemical pellets and shells) into the reservoir under high pressure to open fissures. Nitrogen may be added to the fluid to stimulate expansion. When the pressure is released, the fluid withdraws and the propping agents remain te place, holding the fissures open so that oil can flow more loosely.
Massive fracturing (mass frac) involves pumping large amounts of fluid into wells to hydraulically create fissures which are thousands of feet te length. Massive fracturing is typically used to open gas wells where the reservoir formations are so dense that even gas cannot pass through them.
Two common pressure maintenance mechanisms are the injection of water and gas (air, nitrogen, doorslag dioxide and natural gas) into reservoirs where natural pressures are diminished or insufficient for production. Both methods require drilling auxiliary injection wells at designated locations to achieve the best results. The injection of water or gas to maintain the working pressure of the well is called natural displacement. The use of pressurized gas to increase the pressure te the reservoir is called artificial (gas) lift.
The most commonly used secondary enhanced recovery method is pumping water into an oil reservoir to shove product toward producing wells. Te five-spot water flooding, four injection wells are drilled to form a square with the producing well at the center. The injection is managed to maintain an even advance of the water pui through the reservoir toward the producing well. Some of the water used is salt water, obtained from the crude oil. Te low-tension water flooding, a surfactant is added to the water to assist the flow of oil through the reservoir by reducing its adhesion to rock.
Miscible fluid and miscible polymer flooding are enhanced recovery methods used to improve water injection by reducing the surface pressure of crude oil. A fluid miscible (one that can be dissolved ter the crude) is injected into a reservoir. This is followed by an injection of another fluid which thrusts the crude and miscible fluid combination toward the producing well. Miscible polymer flooding involves the use of a detergent to wash the crude oil from the strata. A gel or thickened water is injected behind the detergent to budge the crude toward the producing well.
Fire flooding, or ter situ (ter place) combustion, is an expensive thermal recovery method wherein large quantities of air or oxygen-containing gas is injected into the reservoir and a portion of the crude oil is ignited. The fever from the fire reduces the viscosity of the powerful crude oil so that it flows more lightly. Hot gases, produced by the fire, increase the pressure ter the reservoir and create a narrow searing gevelbreedte which shoves the thinner crude from the injection well to the producing well. The stronger crude remains te place, providing extra fuel spil the flame gevelbreedte moves leisurely forward. The searing process is closely monitored and managed by regulating the injected air or gas.
Steam injection, or steam flooding, is a thermal recovery method which heats mighty crude oil and lowers its viscosity by injecting super-hot steam into the lowest stratum of relatively shallow reservoir. The steam is injected overheen a period of Ten to 14 days, and the well is shut for another week or so to permit the steam to accurately warmth the reservoir. At the same time the enhanced fever expands reservoir gases, thereby enlargening the pressure ter the reservoir. The well is then reopened and the heated, less viscous crude flows up into the well. A newer method injects low-heat steam at lower pressure into larger sections of two, three or more zones at the same time, developing a “steam chest” which squeezes down the oil te each of the zones. This provides a greater flow of oil to the surface, while using less steam.
Natural Gas Production and Processing Operations
There are two types of wells producing natural gas. Moist gas wells produce gas which contains dissolved liquids, and dry gas wells produce gas which cannot be lightly liquefied
After natural gas is withdrawn from producing wells, it is sent to gas plants for processing. Gas processing requires a skill of how temperature and pressure interact and affect the properties of both fluids and gases. Almost all gas-processing plants treat gases that are mixtures of various hydrocarbon molecules. The purpose of gas processing is to separate thesis gases into components of similar composition by various processes such spil absorption, fractionation and cycling, so they can be transported and used by consumers.
Absorption involves three processing steps: recovery, removal and separation.
Liquidates undesirable residue gases and some methane by absorption from the natural gas. Absorption takes place te a counterflow vessel, where the well gas comes in the bottom of the vessel and flows upward through absorption oil, which is flowing downward. The absorption oil is “lean” spil it comes in the top of the vessel, and “rich” spil it leaves the bottom spil it has absorbed the desirable hydrocarbons from the gas. The gas leaving the top of the unit is called “residue gas.”
Absorption may also be accomplished by refrigeration. The residue gas is used to pre-cool the inlet gas, which then passes through a gas chiller unit at temperatures from 0 to –40 °,C. Lean absorber oil is pumped through an oil chiller, before contacting the cool gas ter the absorber unit. Most plants use propane spil the refrigerant te the cooler units. Glycol is injected directly into the inlet gas stream to mix with any water ter the gas ter order to prevent freezing and formation of hydrates. The glycol-water combination is separated from the hydrocarbon vapour and liquid te the glycol separator, and then reconcentrated by evaporating the water ter a regenerator unit.
The next step te the absorption process is removal, or demethanization. The remaining methane is eliminated from the rich oil ter ethane recovery plants. This is usually a two-phase process, which very first rejects at least one-half of the methane from the rich oil by reducing pressure and enlargening temperature. The remaining rich oil usually contains enough ethane and propane to make reabsorption desirable. If not sold, the overhead gas is used spil plant fuel or spil a pre-saturator, or is recycled to the inlet gas te the main absorber.
The final step te the absorption process, distillation, uses vapours spil a medium to stripverhaal the desirable hydrocarbons from the rich absorption oil. Humid stills use steam vapours spil the unclothing medium. Ter dry stills, hydrocarbon vapours, obtained from partial vaporization of the hot oil pumped through the still reboiler, are used spil the unclothing medium. The still controls the final boiling point and molecular weight of the lean oil, and the boiling point of the final hydrocarbon product mix.
Is the separation of the desirable hydrocarbon combination from absorption plants, into specific, individual, relatively zuivere products. Fractionation is possible when the two liquids, called top product and bottom product, have different boiling points. The fractionation process has three parts: a tower to separate products, a reboiler to fever the input and a condenser to eliminate warmth. The tower has an abundance of trays so that a lotsbestemming of vapour and liquid voeling occurs. The reboiler temperature determines the composition of the bottom product.
Hydrogen sulphide voorwaarde be eliminated from gas before it is shipped for sale. This is accomplished ter sulphur recovery plants.
Gas cycling is neither a means of pressure maintenance strafgevangenis a secondary method of recovery, but is an enhanced recovery method used to increase production of natural gas liquids from “wet gas” reservoirs. After liquids are liquidated from the “wet gas” ter cycling plants, the remaining “dry gas” is returned to the reservoir through injection wells. Spil the “dry gas” recirculates through the reservoir it absorbs more liquids. The production, processing and recirculation cycles are repeated until all of the recoverable liquids have bot eliminated from the reservoir and only “dry gas” remains.
Webpagina Development for Producing Oil and Gas Fields
Extensive webpagina development is required to bring a fresh oil or gas field into production. Webpagina access may be limited or constrained by both climatic and geographic conditions. The requirements include transportation, construction, maintenance, housing and administrative facilities, oil, gas and water separation equipment, crude oil and natural gas vrachtvervoer, water and waste disposition facilities, and many other services, facilities and kinds of equipment. Most of thesis are not readily available at the webpagina and voorwaarde be provided by either the drilling or producing company or by outside contractors.
Contractors are typically used by oil and gas exploration and producing companies to provide some or all of the following supporting services required to drill and develop producing fields:
·, Webpagina prep – brush clearing, road construction, ramps and walkways, bridges, aircraft landing areas, marine harbour, wharfs, docks and landings
·, Erection and installation – drilling equipment, power and utilities, tanks and pipeline, housing, maintenance buildings, garages, hangers, service and administration buildings
·, Underwater work – installation, inspection, repair and maintenance of underwater equipment and structures
·, Maintenance and repair – drilling and production equipment preventive maintenance, vehicles and boats, machinery and buildings
·, Contract services – food service, housekeeping, facility and perimeter protection and security, janitorial, recreation and support activity, warehousing and distribution of protective equipment, spare parts and disposable supplies
·, Engineering and technical – testing and analyses, laptop services, inspections, laboratories, non-destructive analysis, explosives storage and treating, fire protection, permits, environmental, medical and health, industrial hygiene and safety and spill response
·, Outside services – telephone, radio and television, sewerage and garbage
·, Transportation and material treating equipment – aircraft and helicopter, marine services, heavy-duty construction and materials treating equipment
Whether exploration, drilling and producing operations take place on land or offshore, power, light electro-therapy and other support utilities are required, including:
·, Power generation – gas, tens unit and steam
·, Water – fresh water supply, purification and treatment and process water
·, Sewerage and ontwatering – storm water, sanitary treatment and waste (oily) water treatment and disposition
·, Communications – telephone, radio and television, laptop and satellite communication
·, Utilities – light, warmth, ventilation and cooling.
Working Conditions, Health and Safety
Work on drilling equipments usually involves a ondergrens team of 6 people (primary and secondary drillers, three assistant drillers or helpers (roughnecks) and a cathead person) reporting to a webpagina supervisor or foreman (implement pusher) who is responsible for the drilling progression. The primary and secondary drillers have overall responsibility for drilling operations and supervision of the drilling team during their respective shifts. Drillers should be familiar with the capabilities and limitations of their crews, spil work can progress only spil swift spil the slowest squad member.
Assistant drillers are stationed on the podium to operate equipment, read instruments and perform routine maintenance and repair work. The cathead person is required to climb up near the top of the derrick when drill pipe is being fed into or drawn out of the well slot and assist te moving the sections of pipe into and out of the stack. During drilling, the cathead person also operates the mud pump and provides general assistance to the drilling team.
Persons who assemble, place, discharge and retrieve perforating guns should be trained, familiar with the hazards of explosives and qualified to treat explosives, primer cord and blasting caps. Other personnel working te and around oil fields include geologists, engineers, mechanics, drivers, maintenance personnel, electricians, pipeline operators and labourers.
Wells are drilled around the clock, on either 8- or 12-hour shifts, and workers require considerable practice, skill and stamina to meet the rigorous physical and mental requests of the job. Overextending a squad may result te a serious accident or injury. Drilling requires close teamwork and coordination ter order to accomplish the tasks ter a safe and timely style. Because of thesis and other requirements, consideration voorwaarde be given to the morale and health and safety of workers. Adequate periods of surplus and entertainment, nutritious food and suitable hygiene and living quarters, including air conditioning ter hot, humid climates and heating te cold-weather areas, are essential.
The primary occupational hazards associated with exploration and production operations include illnesses from exposure to geographical and climatic elements, stress from travelling long distances overheen water or harsh terrain and private injury. Psychological problems may result from the physical isolation of exploratory sites and their remoteness from base camps and the extended work periods required on offshore drilling platforms and at remote onshore sites. Many other hazards particular to offshore operations, such spil underwater diving, are covered elsewhere te this Encyclopaedia.
Offshore work is dangerous at all times, both when on and off the job. Some workers cannot treat the stress of working offshore at a requesting rhythm, for extended periods of time, under relative confinement and subject to everzwijn switching environmental conditions. The signs of stress ter workers include unusual irritability, other signs of mental distress, excessive drinking or smoking and use of drugs. Problems of insomnia, which may be aggravated by high levels of stimulation and noise, have bot reported by workers on platforms. Fraternization among workers and frequent shore leave may reduce stress. Seasickness and drowning, spil well spil exposure to severe weather conditions, are other hazards te offshore work.
Illnesses such spil respiratory tract diseases result from exposure to harsh climates, infections or parasitic diseases te areas where thesis are endemic. Albeit many of thesis diseases are still te need of epidemiological investigate ter drilling workers, it is known that oil workers have experienced periarthritis of the shoulder and shoulder blade, humeral epicondylitis, arthrosis of the cervical spine and polyneuritis of the upper limbs. The potential for illnesses spil a result of exposure to noise and stimulation is also present te drilling operations. The severity and frequency of thesis drilling-related illnesses emerges to be proportional to the length of service and exposure to adverse working conditions (Duck 1983, Ghosh 1983, Montillier 1983).
Injuries while working ter drilling and production activities may result from many causes, including slips and falls, pipe treating, lifting pipe and equipment, misuse of instruments and mishandling explosives. Burns may be caused by steam, fire, acid or mud containing chemicals such spil sodium hydroxide. Dermatitis and skin injuries may result from exposure to crude oil and chemicals.
The possibility exists for acute and chronic exposure to a broad multiplicity of unhealthful materials and chemicals which are present ter oil and gas drilling and production. Some chemicals and materials which may be present ter potentially hazardous amounts are listed te table 75.Two and include:
·, Crude oil, natural gas and hydrogen sulphide gas during drilling and blowouts
·, Strenuous metals, benzene and other contaminants present ter crude
·, Asbestos, formaldehyde, hydrochloric acid and other hazardous chemicals and materials
·, Normally occurring radioactive materials (NORMs) and equipment with radioactive sources.
Drilling and production take place te all types of climates and under varying weather conditions, from tropical jungles and deserts to the frozen Arctic, and from dry land to the North Sea. Drilling crews have to work ter difficult conditions, subject to noise, stimulation, inclement weather, physical hazards and mechanical failures. The toneel, rotary table and equipment are usually greasy and stimulate from the engine and drilling operation, requiring workers to make deliberate and careful movements. The hazard exists for slips and falls from heights when climbing the equipment and derrick, and there is risk of exposure to crude oil, gas, mud and engine harass fumes. The operation of rapidly disconnecting and then reconnecting drill pipe requires training, skill and precision by workers te order to be done securely time after time.
Construction, drilling and production crews working offshore have to contend with the same hazards spil crews working on land, and with the extra hazards specific to offshore work. Thesis include the possibility of collapse of the podium at sea and provisions for specialized evacuation procedures and survival equipment te event of an emergency. Another significant consideration when working offshore is the requirement for both deep-sea and shallow-water diving to install, maintain and inspect equipment.
Fire and explosion
There is always a risk of blowout when perforating a well, with a gas or vapour cloud release, followed by explosion and fire. Extra potential for fire and explosion exists ter gas process operations.
Offshore toneelpodium and drilling equipment workers should be cautiously evaluated after having a thorough physical examination. The selection of offshore squad members with a history or evidence of pulmonary, cardiovascular or neurological diseases, epilepsy, suikerziekte, psychological disturbances and drug or wijngeest addiction requires careful consideration. Because workers will be expected to use respiratory protection equipment and, te particular, those trained and tooled to fight fires, they voorwaarde be physically and mentally evaluated for capability of carrying out thesis tasks. The medical examination should include psychological evaluation reflective of the particular job requirements.
Emergency medical services on offshore drilling equipments and production platforms should include provisions for a petite dispensary or clinic, staffed by a qualified medical practitioner on houtvezelplaat at all times. The type of medical service provided will be determined by the availability, distance and quality of the available onshore services. Evacuation may be by ship or helicopter, or a physician may travel to the toneel or provide medical advice by radio to the onboard practitioner, when needed. A medical ship may be stationed where a number of large platforms operate te a puny area, such spil the North Sea, to be more readily available and quickly provide service to a sick or injured worker.
Persons not actually working on drilling equipments or platforms should also be given pre-employment and periodic medical examinations, particularly if they are employed to work ter abnormal climates or under harsh conditions. Thesis examinations should take into consideration the particular physical and psychological requests of the job.
An occupational hygiene monitoring and sampling programme, te conjunction with a medical surveillance programme, should be implemented to evaluate systematically the extent and effect of hazardous exposures to workers. Monitoring for flammable vapours and toxic exposures, such spil hydrogen sulphide, should be implemented during exploration, drilling and production operations. Virtually no exposure to H2S should be permitted, especially on offshore platforms. An effective method of controlling exposure is by using decently weighted drilling mud to keep H2S from coming in the well and by adding chemicals to the mud to neutralize any entrapped H2S. All workers should be trained to recognize the presence of H2S and take instantaneous preventive measures to reduce the possibility of toxic exposure and explosions.
Persons engaged te exploration and production activities should have available and use adequate private protective equipment including:
·, Head protection (hard hats and weather-proof liners)
·, Gloves (oil-resistant, non-slip work gloves, fire insulated or thermal where needed)
·, Arm protection (long sleeves or oil-proof gauntlets)
·, Foot and gam protection (weather-protected, oil-impervious safety boots with stengel toes and non-skid feet)
·, Eye and face protection (safety glasses, goggles and face shield for acid treating)
·, Skin protection from fever and cold (zon screen ointment and cold-weather face masks)
·, Climatized and weather-proof clothing (parkas, rain gear)
·, Where required, firefighting gear, flame-resistant clothing and acid-resistant aprons or suits.
Control rooms, living quarters and other spaces on large offshore platforms are usually pressurized to prevent the entry of harmful atmospheres, such spil hydrogen sulphide gas, which may be released upon invasion or te an emergency. Respiratory protection may be needed ter the event pressure fails, and when there is a possibility of exposure to toxic gases (hydrogen sulphide), asphyxiants (nitrogen, doorslag dioxide), acids (hydrogen fluoride) or other atmospheric contaminants when working outside of pressurized areas.
When working around geopressure/geothermal wells, insulated gloves and total heat- and steam-protective suits with supplied breathing air should be considered, spil voeling with hot steam and vapours can cause burns to skin and lungs.
Safety harnesses and lifelines should be used when on catwalks and gangways, especially on offshore platforms and ter inclement weather. When climbing equipments and derricks, harnesses and lifelines with an linked counterweight should be used. Personnel baskets, carrying four or five workers wearing private flotation devices, are often used to transfer crews inbetween boats and offshore platforms or drilling equipments. Another means of transfer is by “swing ropes.” Ropes used to sway from boats to platforms are dangled directly above the edge of the boat landings, while those from platforms to boats should string up Trio or Four feet from the outer edge.
Providing washing facilities for both workers and clothing and following decent hygiene practices are fundamental measures to control dermatitis and other skin diseases. Where needed, emergency eye wash stations and safety showers should be considered.
Safety protection measures
Oil and gas toneel safety shutdown systems use various devices and monitors to detect leaks, fires, ruptures and other hazardous conditions, activate alarms and shut down operations ter a planned, logical sequence. Where needed due to the nature of the gas or crude, non-destructive testing methods, such spil ultrasonic, radiography, magnetic particle, liquid dye penetrant or visual inspections, should be used to determine the extent of corrosion of piping, heater tubes, treaters and vessels used ter crude oil, condensate and gas production and processing.
Surface and sub-surface safety shut-in valves protect onshore installations, single wells ter shallow water and multi-well offshore deep-water drilling and production platforms, and are automatically (or by hand) activated te the event of fire, critical pressure switches, catastrophic failure at the well head or other emergency. They are also used to protect petite injection wells and gas lift wells.
Inspection and care of cranes, winches, drums, wire wire and associated appurtenances is an significant safety consideration ter drilling. Ripping off a pipeline string inwards a well is a serious incident, which may result te the loss of the well. Injuries, and sometimes fatalities, can occur when personnel are struck by a wire strap which violates while under strain. Safe operation of the drilling equipment is also dependent on a smooth-running, well maintained draw works, with decently adjusted catheads and braking systems. When working on land, keep cranes a safe distance from electrified power lines.
Treating of explosives during exploration and drilling operations should be under the control of a specifically qualified person. Some safety precautions to be considered while using a perforating gun include:
·, Never strike or druppel a loaded gun, or druppel piping or other materials on a loaded gun.
·, Clear the line of fire and evacuate unnecessary personnel from the drilling equipment floor and the floor below spil the perforating gun is lowered into and retrieved from the well slot.
·, Control work on or around the wellhead while the gun is te the well.
·, Restrict use of radios and prohibit arc welding while the gun is affixed to the cable to prevent discharge from an inadvertent electrical impulse.
Emergency preparedness programma and drills are significant to the safety of workers on oil and gas drilling and production equipments and offshore platforms. Each different type of potential emergency (e.g., fire or explosion, flammable or toxic gas release, unusual weather conditions, worker overboard, and the need to abandon a podium) should be evaluated and specific response plans developed. Workers need to be trained ter the onberispelijk deeds to be taken ter emergencies, and familiar with the equipment to be used.
Helicopter safety and survival te the event of pulling down into water are significant considerations for offshore podium operations and emergency preparedness. Pilots and passengers should wear seat-belts and, where required, survival gear during flight. Life vests should be worn at all times, both during flight and when transferring from helicopter to verhoging or ship. Careful attention to keep figures and materials underneath the path of the rotor blade is required when injecting, leaving or working around a helicopter.
Training of both onshore and offshore workers is essential to a safe operation. Workers should be required to attend regularly scheduled safety meetings, covering both mandatory and other subjects. Statutory regulations have bot enacted by government agencies, including the US Occupational Safety and Health Administration, the US Coast Guard for offshore operations, and the equivalents ter the United Kingdom, Norway and elsewhere, which regulate the safety and health of exploration and production workers, both onshore and offshore. The International Labour Organization Code of Practice Safety and Health ter the Construction of Immobilized Offshore Installations ter the Petroleum Industry (1982) provides guidance te this area. The American Petroleum Institute has a number of standards and recommended practices covering safety and health related to exploration and production activities.
Fire protection and prevention measures
Fire prevention and protection, especially on offshore drilling equipments and production platforms, is an significant factor te the safety of the workers and continued operations. Workers should be trained and educated to recognize the fire triangle, spil discussed te the Fire chapter, spil it applies to flammable and combustible hydrocarbon liquids, gases and vapours and the potential hazards of fires and explosions. An awareness of fire prevention is essential and includes a skill of ignition sources such spil welding, open flames, high temperatures, electrical energy, static sparks, explosives, oxidizers and incompatible materials.
Both passive and active fire-protection systems are used onshore and offshore.
·, Passive systems include fireproofing, layout and spacing, equipment vormgeving, electrical classification and ontwatering.
·, Detectors and sensors are installed which activate alarms, and may also activate automatic protection systems, upon detecting fever, flame, smoke, gas or vapours.
·, Active fire protection includes fire water systems, fire water supply, pumps, hydrants, hoses and stationary sprinkler systems, dry chemical automatic systems and manual extinguishers, halon and doorslag dioxide systems for limited or enclosed areas such spil control rooms, laptop rooms and laboratories, and foam water systems.
Employees who are expected to fight fires, from puny fires te the incipient stages to large fires te enclosed spaces, such spil on offshore platforms, vereiste be decently trained and tooled. Workers assigned spil fire brigade leaders and incident commanders need leadership capabilities and extra specialized training ter advanced firefighting and fire-control technologies.
The major sources of air, water and ground pollution ter oil and natural gas production are from oil spills or gas leaks on land or sea, hydrogen sulphide present te oil and gas escaping into the atmosphere, hazardous chemicals present te drilling mud contaminating water or land and combustion products of oil well fires. The potential public health effects of inhalation of smoke particulates from large-scale oil field fires has bot of fine concern since the oil well fires that occurred ter Kuwait during the Persian Gulf War ter 1991.
Pollution controls typically include:
·, API separators and other waste and water treatment facilities
·, Spill control, including booms for spills on water
·, Spill containment, dikes and ontwatering to control oil spills and divert oily water to treatment facilities.
Gas dispersion modelling is conducted to ascertain the probable area which would be affected by a cloud of escaping toxic or flammable gas or vapour. Groundwater table studies are conducted to project the maximum extent of water pollution should oil contamination occur.
Workers should be trained and qualified to provide very first aid response to mediate spills and leakage. Contractors who specialize ter pollution remediation are usually engaged to manage large spill responses and remediation projects.
Duck, BW. 1983. Petroleum, extraction and vervoer by sea of. Te Encyclopaedia of Occupational Health and Safety, 3rd edition. Geneva: ILO.
Energy Information Administration. 1996. International Petroleum Statistics Report: January 1996. Washington, DC: US Department of Energy
Ghosh, PK. 1983. Offshore oil operations. Te Encyclopaedia of Occupational Health and Safety, 3rd edition. Geneva: ILO: 1559-1563.
International Labour Organization (ILO). 1982. Safety and Health ter the Construction of Stationary Offshore Installations te the Petroleum Industry. An ILO Code of Practice. Geneva: ILO.
National Fire Protection Association (NFPA). 1976. Fire Protection Handbook, 14th edition. Quincy, Mama:NFPA.
,. 1991. Fire Protection Handbook, 17th edition. Quincy, Mama:NFPA.
Montillier, J. 1983. Drilling, oil and water. Ter Encyclopaedia of Occupational Health and Safety, 3rd edition. Geneva: ILO.
OTHER RELEVANT READINGS
American Petroleum Institute. 1980. Facts about Oil. Manual 4200-10/80-25m, October 1980. Washington, DC: American Petroleum Institute.
Nabieva, GV. 1976. Occupational disease ter oil equipment workers. Gigiene truda i proffesional’nye zabolevanija 8:22-24.
National Safety Council. 1995. Petroleum Section Safety and Health Fact Sheet. Itasca, IL: National Safety Council.
Panov, Gij et nu. 1977. Ergonomic assessment of work pose on drilling equipments. Besopasnost’ truda v promyslennosti Three:49.
Salpukas, A. 1995. Fresh ideas for US oil. Fresh York Times, 16 November.