Wells, high-pressure


Drilling and Field Development. The techniques for drilling hydrothermal weUs have been adapted from those in use in the oil and gas industry (7) (see Gas,natural Petroleum). Rotary drilling rigs are normally employed along with conventional drilling equipment such as steel casing, drilling lubricants, and casing cements. Drilling conditions encountered in geothermal areas are often more severe than those in oil fields, although, in some instances, soft sedimentary rock of the type common in oil and gas basins is encountered. Usually it is necessary to bore through extremely hard metamorphic or igneous rock, resulting in a slower drilling rate. Penetration rates of 5—13 cm/s (10—25 ft/h) are common, but frequently problems such as loss of circulation, caving, twist-off, and high pressure flow zones related to the rock formation cause intermptions. In addition, the temperatures encountered in drilling into hydrothermal reservoirs are usually considerably higher than those for oil and gas well drilling. Thus extra cooling procedures and special lubricant formulations must be employed. Moreover, geothermal drilling is subject to more stringent regulations than oil and gas drilling. The costs of drilling geothermal wells are from 2—4 times greater than those for oil and gas wells.  [c.264]

Electric Submersible Oil Well Pump Cable. These cables are rated up to 5 kV and are designed for highly corrosive oil wells that besides oil also contain brine and other harsh chemicals as well as gases under high pressure and high temperatures (6). Insulations can be based on polypropylene for low temperature wells or on ethylene—propylene mbber which is compounded with special ingredients in order to resist the environments of high temperature wells (Fig. 4).  [c.324]

Condensable Hquids also are recovered from high pressure gas reservoirs by retrograde condensation. In this process, the high pressure fluid from the reservoir produces a Hquid phase on isothermal expansion. As the pressure decreases isotherm ally the quantity of the Hquid phase increases to a maximum and then decreases to disappearance. In the production of natural gas Hquids from these high pressure wells, the well fluids are expanded to produce the optimum amount of Hquid. The Hquid phase then is separated from the gas for further processing. The gas phase is used as a raw material for one of the other recovery processes, as fuel, or is recompressed and returned to the formation.  [c.184]

Impingement risks for affected species seem more direct and identifiable than the indirect aspects of temperature change because these are more visible. The effects of impingement include long periods of futile swimming in screen wells, being held by water currents against the screen mesh (often resulting in suffocation through inabiUty to ventilate the giks), and physical injury from the rotating screen or high pressure water spray used to wash the screen. Beyond risks to individual fish are risks for populations of important species that could be seriously depleted by introducing a new form of chronic mortahty into the life cycle. Impingement acts selectively, affecting some species more than others, ie, generally schooling, pelagic fish.  [c.473]

Figure 1-1 is a block diagram of a production facility that is primarily designed to handle gas wells. The well flow stream may require heating prior to initial separation. Since most gas wells flow at high pressure, a  [c.1]

To produce electricity from a geothermal resource, wells are drilled into the reservoir, and as the hot, high-pressure water travels to Earth s surface, some of It vaporizes into steam as the pressure decreases. The hotter the original source, the greater the amount of dry steam produced. For dry-steam  [c.575]

Figure 2-56 shows a plot of the theoretical maximum overburden pressure and the theoretical minimum pressure as a function of depth. Also plotted are various bottomhole fluid pressures from actual wells drilled in the Gulf Coast region [33]. These experimentally obtained pressures are the measurements of the pressures in the fluids that result from a combination of rock overburden and the fluid hydraulic column to the surface. These data show the bottomhole fluid pressure extremes. The abnormally high pressures can be explained by the fact that the sedimentary basins in the Gulf Coast region are immature basins and are  [c.263]

After stabbing, start screwing the pipe together by hand or apply regular or power tubing tongs slowly. To prevent galling when making up connections in the field, the connections should be made up to a speed not to exceed 25 rpm. Power tubing tongs are recommended for high-pressure or condensate wells to ensure uniform makeup and tight Joints. Joints should be made up tight, approximately two turns beyond the hand-tight position, with care being taken not to gall the threads.  [c.1247]

A great number of specialized tools have evolved in drilling of oil and gas wells utilizing very different alloys specially suited for their service requirements. The main concern in designing the drilling equipment is controlling the high pressures and the ability to resist fractures. The fractures can be induced by low-temperature service of the surface equipment and fatigue failures of subsurface equipment.  [c.1257]

Once the liberated gas has overcome a critical gas saturation in the pores, below which it is immobile in the reservoir, it can either migrate to the crest of the reservoir under the influence of buoyancy forces, or move toward the producing wells under the influence of the hydrodynamic forces caused by the low pressure created at the producing well. In order to make use of the high compressibility of the gas, it is preferable that the gas forms a secondary gas cap and contributes to the drive energy. This can be encouraged by reducing the pressure sink at the producing wells (which means less production per  [c.186]

Compared to the solution gas drive case, the typical production profile for gas cap drive shows a much slower decline in reservoir pressure, due to the energy provided by the highly compressible gas cap, resulting in a more prolonged plateau and a slower decline. The producing GOR increases as the expanding gas cap approaches the producing wells, and gas is coned or cusped into the producers. Again, it is assumed that there is negligible aquifer movement, and water cut remains low (in the order of 10% at the end of field life). Typical recovery factors for gas cap drive are in the range 20 - 60%, influenced by the field dip and the gas cap size. A small gas cap would be 10% of the oil volume (at reservoir conditions), while a large gas cap would be upwards of 50% of the oil volume. Abandonment conditions are caused by very high producing GORs, or lack of reservoir  [c.189]

The skin term represents a pressure drop which most commonly arises due to formation damage around the wellbore. The damage is caused by the invasion of solids from the drilling mud or from the cementing of the casing. The solid particles partially block the pore space and cause a resistance to flow, giving rise to an undesirable pressure drop near the wellbore. This so called damage skin may be removed by backflushing the well at high rates, or by pumping a limited amount of acid into the well acidising) to dissolve the solids. Another common cause of skin is partial perforation of the casing across the reservoir which causes the fluid to converge as it approaches the wellbore, again giving rise to increased pressure drop near the wellbore. This component of skin is called geometric skin, and can be reduced by adding more perforations. At very high flowrates, the flow regime may switch from laminar to turbulent flow, giving rise to an extra pressure drop, due to turbulent skim, this is more common in gas wells, where the velocities are considerably higher than in oil wells.  [c.216]

The purpose of the well completion is to provide a safe conduit for fluid flow from the reservoir to the flowline. The perforations in the casing are typically achieved by running a perforating gun into the well on electrical wireline. The gun is loaded with a charge which, when detonated, fires a high velocity jet through the casing and on into the formation for a distance of around 15-30 cm. In this way communication between the wellbore and the reservoir is established. Wells are commonly perforated after the completion has been installed and pressure tested.  [c.227]

The Technology. Owiag to the large overpressure, geopressured wells flow freely iu high volumes. Production levels of 3000—5000 m /d (20,000—30,000 bbl/d) have been achieved iu some wells. At high flow rates, clogging of the pores near the wellbore can occur when the stmcture of the formation sand is disturbed by the turbulent flow, greatly reduciug the energy production capacity of the well. The high salinity of geopressured water leads to a spent fluid disposal problem. The most common solution is to pump the saline water down a nearby well iato a formation at a shallower depth than the geopressured resource. The formation of calcium carbonate scale creates significant operational difficulties iu utilising highly saline geopressured fluids. Scale inhibitors and the requirement for frequent removal of accumulated scale from piping and equipment can both add substantially to the maintenance cost of geopressured faciUties. In one proposed power plant design, the mechanical power is first utilized in a pressure-reduction turbine, then the hydrocarbon and aqueous fluids are separated, and the water is fed to the heat exchanger of a binary power plant. The gas is used to produce electricity through conventional technology or sold directly to off-site users.  [c.269]

The practical importance of the higher sulfanes relates to their formation in sour-gas wells from sulfur and hydrogen sulfide under pressure and their subsequent decomposition which causes well plugging (134). The formation of high sulfanes in the recovery of sulfur by the Claus process also may lead to persistance of traces of hydrogen sulfide in the sulfur thus produced (100). Quantitative deteanination of H2S and H2S in Claus process sulfur requires the use of a catalyst, eg, PbS, to accelerate the breakdown of H2S (135).  [c.137]

Oil well cements (78) are usually made from Pordand cement clinker and may also be blended cements. The American Petroleum Institute Specification for Materials and Testing for Well Cements API Specification 10) (78) includes requirements for nine classes of oil well cements. They are specially produced for cementing the steel casing of gas and oil wells to the walls of the bore-hole and to seal porous formations (79). Under these high temperature and pressure conditions ordinary Pordand cements would not dow propedy and would set prematurely. Oil well cements are more coarsely ground than normal, and contain special retarding admixtures.  [c.296]

UCG is started by drilling wells to serve as injection points for oxidant and steam as well as collection points for product gases. PermeabiUty of the coal seam is achieved by directional drilling, countercurrent combustion, electro-linking or hydrauHc fracturing. PermeabiUty is needed to provide a high rate of production with a minimum of pressure drop through the reaction zone. Low rank, ie, lignite and subbiturninous, coals crack and shrink during gasification, rendering the seams more permeable. The bituminous coals swell and plug gas channels unless carefully preconditioned with preliminary oxidation to avoid this.  [c.236]

The initial pressure in a reservoir is usually high enough to raise the oil to the surface. However, as production proceeds and the reservoir becomes depleted, the formation pressure falls and a new source of energy is required to maintain the flow of oil. A common practice is to inject either gas or water into the producing formation through special injection wells in order to maintain the pressure and move the oil toward the collection points in the producing wells. This procedure is called pressure maintenance or secondary recovei y. Its success depends on maintaining a stable front between the oil and the injected fluid so that the oil continues to arrive at the collecting wells before the injected fluid. To the extent that the gas or water passes around the oil, arrives at the producing wells, and becomes part of the product coming up to the surface, the process fails to achieve its full objective. This iind esirable outcome can occur, as noted above, when the mobility of the injected fluid exceeds that of the oil, as is the case for injected gas and for injected water with heavy oils. Gravity also can play a role in the success of secondary recovery depending on the geometry of the reservoir and the location of the injection and production wells.  [c.925]

The Resource. Geopressured resources consist of highly overpressured mixtures of hydrocarbons, predominantly methane, and water, in sedimentary formations (27). The potentially useflil energy in geopressured resources exists as three components fossil chemical from the methane, heat from the water, and mechanical from the high pressure of the fluid. Geopressured resources are generally found very deep in the earth at levels of 3600 to 6000 m or more. It is thought that these were formed when incompletely dewatered organic sediments were covered by layers of clay. Over time, the clay was converted from the smectite to the impervious iUite form, effectively isolating the sediments and setting the stage for the formation of a geopressured compartment (see Clays). Increa sing temperatures of the buried strata led to pressures above hydrostatic owing to aquathermal pressuring and the decomposition of the organic material into volatile low molecular weight compounds, particularly methane. The distinction between an oil or gas resource and a geopressured resource is somewhat arbitrary as some water and pressure are often encountered in petroleum (qv) deposits. It was estimated that in 1983 about 2% of the more than 50,000 oil and gas wells along the Texas Gulf coast were producing from geopressured reservoirs (28). In these operations, however, only the oil and gas were recovered.  [c.268]

The Technology. The basic technique for extracting energy from HDR was conceived and patented in the early 1970s (35). It is based on drilling and hydraulic fracturing technologies developed in the petroleum and geothermal industries. Eigure 10 shows an idealized HDR heat mine. The first step in constmcting a heat mine is to drill a well into sufficiently hot and impervious rock, with the exact depth of the well to be determined by local heat-flow and thermal conditions. Wells drilled for HDR appHcations are similar in many aspects to hydrothermal wells except that these wells are deeper and sometimes penetrate into a much greater depth of hard, crystalline rock. Eor this reason, specialized drilling and logging equipment which can withstand extended exposure to high temperatures is required. After the well has been completed, a segment of the bottom portion of the well is blocked off using a packer which provides pressure isolation. Water under high pressure is pumped through the packer and forced into joints in the surrounding rock body to form a reservoir consisting of a relatively small amount of water in a very large volume of rock. The extent of the reservoir region may be controlled by the pressure appHed via the injected fluid and the length of time the process is continued. The shape and orientation of the reservoir are functions of the natural jointing features of the host rock.  [c.270]

Pipelines or pipe lines are contiauous large-diameter piping systems, usually buried underground where feasible, through which gases, Hquids, or soHds suspended in fluids are transported over considerable distances. They are used to move water, wastes, minerals, chemicals, and industrial gases, but primarily cmde oil, petroleum products, and natural gas. In the oil and gas business, a pipeline system consists of a tmnMine, ie, the large-diameter, high pressure, long-distance portion of the piping system through which cmde oil is shipped to refineries, or natural gas and oil products, respectively, are transported to distribution points, and smaller low pressure gathering lines that transport oil or gas from wells to the tmnMine. Smaller lines used by natural gas distributors are not considered part of a gas pipeline system (see Gas, natural).  [c.45]

The polymers have been used in such aggressive environments as nuclear plant, oil and geothermal wells, chemical plant and high-pressure steam valves. One specific example announced in 1998 was for gas compressor line valve plates used in the collection, pressurisation and transportation of gases in chemical, petroleum and industrial process uses. Factors leading to the selection of PEEK as a replacement for metal in this application were the excellent corrosion resistance, strength, durability including wear resistance, high temperature stability, light weight and superior sealing characteristics. For similar reasons PEEK has replaced stainless steel in pumps for handling chemicals. In the car industry the combination of excellent thermal properties and excellent low-friction properties of bearing grades have led to use in such applications as bearing cages, gear support bearings, thrust washers, clutch seals, transmission parts, housings for tyre pressure sensors and valve spring discs. In the aircraft industry there is great interest as a result of the excellent fire properties and resistance to rain erosion of composites, whilst in general machinery and processing equipment the materials are used for rollers, guides, gears and reciprocating components. Parts for domestic irons and microwave ovens have been produced from PEEKK. Wire coverings are of interest because of the excellent fire properties, including absence of halogens, the resistance to radiation and the resistance to cut through round sharp comers, which helps miniaturisation. Filaments are used in filter cloths. Recent Japanese studies have indicated that PEEK is very suitable as a piping material for transporting ultra-pure material in microchip manufacture.  [c.606]

Often on high-pressure wells two chokes are installed in the llov.-line—one a positive choke and the other an adjustable choke. I Ik adjustable choke is used to control the flow rate. If it were to cut out. the positive choke then acts to restrict the flow out of the well and keep the well from damaging itself. Where there arc two chokes, it is good piping practice to separate the chokes by 10 pipe diameters to keep the jet nt flow formed by the first choke from cutting out the second choke. In practice this separation is not often done because of the expense of separating two chokes by a spool of pipe rated for well shut-in pressure. It is much less expensive to bolt the flanges of the two chokes together, No data has been collected to prove whether the separation of chokes is justi -tied from maintenance and safety considerations.  [c.462]

At one time, methane was widely used to produce acetylene (qv), by processes involving either electric arcs or partial oxidation. The so-called Reppe chemicals (ie, 1,4-butanediol and derivatives), once made solely from acetylene, can now be made from butane the outlook for continued acetylene demand from methane is poor. In 1993, in fact, acetylene production for chemicals was only about a third of that in 1970 (see Acetylene-DERIVED chemicals). Much interest has been shown in direct conversion of methane to higher hydrocarbons, notably ethylene. Development of such a process would allow utilization of natural gas from remote wells. Much gas is currently flared (burned) from such wells because the pipeline gathering systems needed for such gas tend to be prohibitively expensive. If the gas could be converted on-site to a condensable gas or pumpable Hquid, bringing those hydrocarbons to market would be faciHtated. In the early 1990s, partial oxidative coupling of methane to higher hydrocarbons (chiefly C2S) achieved by passing methane and an oxygen-containing gas over a basic oxide catalyst at high temperatures (600—700°C) and low pressures (<1 atm) has been the method of choice. However, despite enormous efforts, C2 yields higher than about 30% have not yet been realized. Direct methane conversion to other materials, such as methanol, has similarly not yielded commercially interesting results, mainly due to the extreme temperatures and very low throughput required for high selectivity to the desired products (7).  [c.400]

Desalination as currently practiced is driven almost entirely by the combustion of fossil fuels. These fuels are in finite supply they also pollute the air and contribute to global climate change. The whole character of human society in the 20th century in terms of its history, economics and politics has been shaped by energy obtained mostly from oil. Almost all oil produced to date is what is called conventional oil, which can be made to flow freely from wells (i.e. excluding oil from tar sands and shale). Of this vast resource, about 1600 billion barrels have so far been discovered, and just over 800 billion barrels had been used by the end of 1997. It is estimated that there may be a further 400 billion barrels of conventional oil yet to be found. With current annual global consumption of oil being approximately 25 billion barrels, and rising at 2 per cent per annum, the "business as usual" scenario would suggest that the remaining oil will be exhausted by 2050. The supply of oil will undoubtedly be boosted by an increase of supplies from unconventional sources, notably the tar sands and shale of Canada and the "Orinoco sludge" of Venezuela. This oil can only be extracted using high energy inputs, and at very high environmental costs. There will be strong political and international pressure against development of these resources, but, when world oil prices are high  [c.365]

In soniL fields, it may be necessary to provide heat during the early hie of the wells when flowing-tubing pressures are high and there is a high temperature drop across the choke. Later on, if the wells produce nuue liquid and the flowing-tubing pressure decreases, it may be necessary to cool the gas. Liquids retain the reservoir heat better and have less ot, i temperature drop associated with a given pressure drop than gas.  [c.3]

The use of large compressors is probably more prevalent in oil field facilities than in gas field facilities. Oil wells often require 1 Tee pressure and the gas that flashes off the oil in the separator must be compressed in a flash gas compressor. Often a g i lift system is nei help lift the oil to the surface. As described in Volume 1, a gas li pressor must compress not only the formation gas that is produce. . .. v,. r oil, but also the gas-lift gas that is recirculated down the well. Gas lift i npressors are chaiacterized by both high overall compressor ratios and 1 atively high throughputs.  [c.254]

Solids Some wells produce large amounts of sand and other soltds entrained in the fluid. Where solids are contained in the stream, suflicicnt velocity should be provided to assure they do not build up in the bottom of the pipe, causing higher than anticipated pressure drops or potciiiial areas for corrosion. However, if the velocity is too high, erosion m i. occur. (See Volume 1.)  [c.446]

Maxiniizing the lvalue of the reservoir requires that full reservoir dynamics be considered in drilling wells and in extracting oil. Gas and water must be recycled through the strategic placement of injection wells wells with high gas-oil or water-oil ratios must be closed or not drilled and the rate of oil production must be controlled to maintain underground pressure.  [c.961]


See pages that mention the term Wells, high-pressure : [c.1247]    [c.190]    [c.2261]    [c.317]    [c.254]    [c.715]   
Surface production operations Ч.2 (1999) -- [ c.462 ]