Showing papers on "Natural gas published in 1980"

A Laboratory Study of Low-Permeability Gas Sands

Abstract: To help moderate or reverse the persistent decline in US gas reserves, the industry is expanding its exploration and development efforts to include fields with permeabilities in the microdarcy range; however, the design of stimulation treatments to achieve commercial rates of production from such low-permeability rocks demands a more accurate means of determining their flow properties. Laboratory tests designed to develop correlations for predicting a reservoir's in situ permeability from routine core-analysis data have shown that the routine permeability values of tight gas sands are often more than 100 times greater than permeabilities under actual reservoir conditions because of the great relief of stress, absence of connate water, and increased gas slippage. The correlations developed can account for these three separate effects and produce a closer estimate of the reservoir's in situ effective gas permeability.

Power conversion system utilizing reversible energy of liquefied natural gas

Abstract: A power conversion system comprising a combination of a liquefied natural gas vaporizing plant and a fuel burning power generating facility is disclosed. The liquefied natural gas vaporizing plant utilizes the cryogenic capacity of the liquefied natural gas to produce liquid air which is pumped to a high pressure by a liquid air pump. The liquid air is then brought into a heat exchanging relationship with air drawn into the vaporizing plant so that the high pressure liquid air is converted to high pressure gaseous air. The high pressure gaseous air which represents recovered reversible energy of the liquefied natural gas is fed into a combustion chamber of the fuel burning power generating plant. Since the power generating facility requires no significant output of power to drive a compressor to compress ambient air prior to its entry into the combustion chamber, the power generating facility is operated at a high efficiency.

Transient Flow In Naturally Fractured Reservoirs And Its Application To Devonian Gas Shales

Abstract: Devonian shale gas reservoirs typically are characterized by a low storage, high flow-capacity natural fracture system fed by a high storage, low flow-capacity rock matrix. In this study analytical solutions are developed to analyze the basic fractured reservoir parameters that control well productivity. These parameters include fractured system porosity and permeability, matrix porosity and permeability, and matrix size. It is shown that the conventional well test method does not usually work for fractured Devonian shale gas reservoirs. For most cases, the semi-log plot of the drawdown then buildup data does not show 2 parallel straight lines with a vertical separation. Numerical solutions also are used to include the Klinkenberg effect and desorption in the shale matrix. 18 references.

Effect of partial gas/brine saturation on ultrasonic absorption in sandstone

Abstract: Ultrasonic compressional wave velocities and absorption have been measured for Berea sandstone as a function of different nitrogen gas and brine saturations at 103.3-bar net confining pressure. The results of this experiment show larger absorption for partially gas/brine-saturated sandstone than for either complete gas or complete brine saturations. These results are in agreement with suggestions made by some early experimenters and with recently reported resonance data on Vycor glass and ultrasonic measurements on Berea sandstone. These results suggest the possible use of sonic logging as a means of detecting bypassed gas production in older hydrocarbon producing wells.

Eastern Green River Basin: A Developing Giant Gas Supply from Deep, Overpressured Upper Cretaceous Sandstones

Abstract: During the past 4 years, a previously unexplored 3,000-sq mi (7,800 sq km) overpressured area in the eastern Green River basin has developed into a major gas province which should ultimately produce more than 20 Tcf. Production is from lenticular sandstones in the Upper Cretaceous Lewis Shale and Mesaverde Group. Abnormally high pressure gradients of 0.5 to 0.86 psi/ft are caused by the generation of natural gas from coals and carbonaceous shales in the Mesaverde Group and perhaps from other source rocks such as the marine Lewis and Cody Shales. Because cumulative gas generation from coals increases approximately exponentially with increases in temperature and depth, the largest volumes of gas and the highest pressures should have been generated in the deepest parts of th basin. The deepest rocks (15,000 to 20,000 ft; 4,600 to 6,100 m) are sparsely explored but may prove to be the most productive parts of the overpressured area for the following reasons. (1) Higher pressures result in more gas in the available pore space. (2) Sufficient gas should have been generated at these depths to fill all available pore space in Mesaverde and Lewis sandstones, and to reduce water saturation to an immobile minimum. More total pay should thus be expected than in shallower areas where water production is a common problem. (3) Higher pore-fluid pressures increase the ease with which natural fracturing of rock units can occur and more fracturing should enhance reservoir performance. (4) Younger sandstones in the Upper Cretaceous Lance and Paleocene Fort Union Formations are also overpressured in the deepest basin areas because of gas generation from associated coals and carbonaceous shales. These formations should contain significant gas accumulations.

Method of and system for refrigerating a fluid to be cooled down to a low temperature

Abstract: A process of and an apparatus for saving energy in a method of liquefying a natural gas by cooling same with the vapor from a liquid coolant sub-cooled after expansion thereof in the liquid condition, the vapor simultaneously sub-cooling the liquefied coolant, the process consisting in expanding the sub-cooled high-pressure liquid coolant in a hydraulic turbine providing mechanical power possibly for driving a rotary machine.

Biogenic and Thermogenic Origins of Natural Gas in Cook Inlet Basin, Alaska

Abstract: Two types of natural gas occurrences are present in the Cook Inlet basin. The major reserves (1.8 x 10/sup 11/m/sup 3/) occur in shallow (less than 2300 m), nonassociated dry gas fields that contain methane with ..delta.. /sup 13/C in the range of -63 t -56 per mil. These gas fields are in sandstones interbedded with coals of the Sterling and Beluga Formations; the gas fields are interpreted as biogenic in origin. Lesser reserves (1.1 x 10/sup 10/ m/sup 3/) of natural gas are associated with oil in the deeper Hemlock Conglomerate at the base of the Tertiary section; associated gas contains methane with ..delta.. /sup 13/C of about -46 per mil. The gases associated with oil in the Hemlock Conglomerate are thermogenic in origin.

Method of treating natural gas to obtain a methane rich fuel gas

Abstract: A method for the recovery of a methane-rich natural gas from a natural gas containing, apart from methane, also hydrogen sulfide, carbondioxide, higher hydrocarbons and, in most cases, organosulfur compounds. According to the invention a hydrocarbon fraction of C4 hydrocarbons and higher is naturally removed from the natural gas which is then subjected to a selective scrubbing for the removal of hydrogen sulfide with a regeneratable extraction, of scrubbing liquid. Next a C3 fraction is removed, the remaining gas being scrubbed with a second regeneratable washing agent, for the removal of carbondioxide to leave the methane-rich gas.

Production of methanol

Abstract: In the production of methanol from a methane-containing gaseous feedstock such as natural gas by steam reforming the gas and treating the reformate to produce methanol by inter-reaction of the hydrogen and oxides of carbon in the reformate, the use of part of the feedstock to fire the reformer is avoided by immersing the reformer reactor tubes in a fluidized bed heated by the combustion of a low grade, solid, fossil-based fuel such as coal, lignite, oil shale or asphaltic residues from oil refining. By pressurizing the fluidized bed, all the power requirements of the process can be obtained by expansion of the flue gas, which can also provide the CO 2 balance for the methanol synthesis, and a compressor can be omitted.

Fuel Gas Purification with Permselective Membranes

Abstract: Production of fuel gas from biomass and recovery of flared gas from landfills, oil fields, coal mines, is hampered by the high cost of gas purification for the removal of C02 and H2S. Membranes offer a potentially simple and attractive technique for on-site gas purification. Two membrane approaches have been considered for fuel gas purification-polymer films and facilitated transport-each with its own unique advantages. Polymer films can be made extremely thin (<500A), and thus have high gas throughput and a very low membrane area requirement. Ultrathin polymer membranes have been found to be extremely attractive for purification of gas produced from waste or in remote site applications. Of particular interest is biogas produced from anaerobic digestion of sewage, municipal waste, agricultural waste, and landfills. Membrane purification is expected to cost less than half of that for conventional scrubbing processes. Additionally, the gas is purified and dried at the same time. Laboratory tests co...

Gas storage and transmission systems

Abstract: Liquefiable gases such as associated natural gas may be liquified, stored in the liquid form and re-vaporized by cooling a pressurized first liquified gas stream by indirect heat exchange with a first stream of a refrigerant, such as liquid nitrogen, to form a second liquified gas stream whose temperature is less than its initial boiling point at ambient pressure and a first warmed refrigerant stream. The second liquified gas stream is passed to a vessel wherein the liquified gas is stored. When the gas is required the second liquified gas is removed from the storage vessel and warmed by indirect heat with a second warmed refrigerant stream, to form a third liquified gas stream and said first refrigerant stream. The warmed refrigerant stream is also in indirect heat exchange with said first warmed refrigerant stream and after heating comprises second warmed refrigerant stream. Thereafter, the third liquified gas stream is vaporized.

A method for producing a methane-lean synthesis gas from petroleum coke

Abstract: A methane-lean synthesis gas is produced from the steam gasification of petroleum coke in a fiuidized bed at temperatures of between 650 and 790°C and pressures of between 1.75 and 14 kg/cm² using a potassium or sodium salt to catalyze the steam-gasififation reaction. The synthesis gas produced contains less than about 3 volume % methane and less than 40% volume of steam. Because of its low methane content the gas may be used to produce methanol or a high purity product gas containing substantially only hydrogen and carbon dioxide which, in turn, may be scrubbed to pro­ duce a gas containing at least 95 volume % hydrogen. If the methane lean gas produced from the gasification reactor con­ tains nitrogen, e.g. when air is used to combust the coke to maintain the temperature of the fluidized bed, then the methane lean gas may be used to produce high purity ammonia.

Process for producing hydrogen and sulphur from hydrogen sulphide

Abstract: A process is provided for the production of hydrogen and sulphur from a gas containing hydrogen sulphide. Such a process comprises passing the gas through a cracking zone at a temperature of from about 850° C. to 1600° C., cooling the cracked gas to a temperature of from about 110° C. to 150° C., and separating the condensed elemental sulphur. The uncracked hydrogen sulphide is separated and returned to the cracking zone; the remaining gas is withdrawn as hydrogen-rich gas.

Method and system for producing and transporting natural gas

Abstract: Natural gas taken from a gas well is loaded continuously and at a preselected, generally uniform rate into a movable separate pressure vessel means until such is filled with a discrete batch of natural gas at a pressure in excess of 800 psia, whereupon it is replaced with another separate pressure vessel means, with no interruption of gas flow. The filled, movable vessel means is then transported to an off-loading terminal. Well shock is thus controlled, and maximum natural gas recovery obtained. A generally uniform flow rate is obtained by a regulating valve, when well head pressure exceeds about 800 psia, and by a compressor when the well head pressure is below such value.

Unconventional gas hydrate seals may trap gas off southeast US. [North Carolina, South Carolina]

Abstract: Seismic profiles have indicated to the US Geological Survey that an unconventional seal, created by gas hydrates that form in near-bottom sediments, may provide gas traps in continental slopes and rises offshore North and South Carolina. The most frequently cited evidence for the presence of gas hydrate in ocean sediments is the observation of a seismic reflection event that occurs about 1/2 s below and parallel with the seafloor. If gas-hydrate traps do exist, they will occur at very shallow sub-bottom depths of about 1600 ft (500m). Exploration of such traps will probably take place in the federally controlled Blake Ridge area off the coast of South Carolina where seismic data suggest a high incidence of gas hydrates. However, drilling through the gas-hydrate-cemented layer may require new engineering techniques for sealing the casing.

Utilization of the Cold by LNG Vaporization With Closed-Cycle Gas Turbine

Abstract: In the course of the world-wide efforts to save energy, the utilization of cold in connection with the regasification of liquefied natural gas gains more and more importance. The aim is the partial recovery of the energy consumed in liquefaction. There are particular advantages when using the closed-cycle gas turbine, in which the energy of the liquefied natural gas is transformed to electrical energy with a very high efficiency. The paper deals with the optimization, design, and operational behavior of such a plant. 7 refs.

Production of reducing gas for furnace injection

Abstract: A process for producing a reducing gas for a direct reduction or blast furnace which comprises partially oxidizing oil and/or coal and/or coke in the presence of air to produce a gas stream containing hydrogen and nitrogen together with other gases, treating the gas stream to remove substantially all gases other than hydrogen and nitrogen, drying the gas stream if there is water present, subjecting the gas stream to a separation stage, e.g. in a cryogenic separator, to separate a hydrogen-rich gas stream and a nitrogen-rich gas stream, heating the hydrogen-rich gas stream and injecting it into the furnace. In the case of a direct reduction furnace the gas stream may be obtained by partial oxidation of coal and/or oil. In the case of the blast furnace the reducing gas may be derived from the top gas in addition or as an alternative to partial oxidation of coal and/or oil.

Furnace with protective atmosphere for heating metals

Abstract: A furnace for the heat-treatment of metallic articles with a protective atmosphere such as a reductive gas mainly consisting of H 2 , CO, N 2 . Said protective atmospheric gas is made from LPG, LNG, urban gas and other raw natural gases which have been supplied into the furnace directly from their sources by heating them by heating elements within the furnace and simultaneously converting them by a plurality of catalytic means extending along said heating elements.

Chemical and Isotopic Evidence of the Origins of Natural Gases in Offshore Gulf of Mexico

Abstract: The chemical and isotopic composition of natural gases from 55 fields in the offshore Gulf of Mexico province has been analyzed. The gases display a trend of more positive 13C1, values (-70 to -35 (permil)) with increasing depth and age of producing reservoir. The mechanisms responsible for this fractionation are biognic enrichment of 12C1, thermal cracking, and mixing. Separate trends are present in Texas and Louisiana which suggest a higher geothermal gradient or different type of organic matter in offshore Texas. There is considerable scatter along the general trend because gases generated from deeper, thermally mature source rocks have commonly migrated to shallower immature reservoirs. The province is primarily a gas-producing region for three reasons. Many gas fields, particularly those of Pleistocene age, are of apparent biogenic origin. This gas is characterized by enrichment of the light isotope 12C in methane (13C1, more negative than -55) and by large amounts of methane (C1/C1-5> 0.99). Miocene gas accumulations in the western part of the province are either the result of early stages of thermal cracking of liquid hydrocarbons because of a higher geothermal gradient, or a different type of organic matter from which the hydrocarbons were derived. This gas is wetter than biogenic gas (C1/C1-5> 0.94) and isotopically heavy (13C1 more positive than -40). Many gas fields in reservoirs of all ages are the result of"separation-migration" in which the gas phase was physically segregated from a petroleum accumulation. These gases are similar in composition to gas associated with petroleum.

Method for removal of hydrogen sulfide from sour gas streams

Abstract: A cost effective and environmentally acceptable method for removal of hydrogen sulfide from sour gas streams associated with source materials such as geothermal and petrochemical energy sources. The method comprises the steps of scrubbing inert, non-combustible components such as carbon dioxide from the sour gas, flowing the remaining combustible gas for further processing including compression, cryogenic liquifaction, and expansion to segregate hydrogen sulfide and gaseous components having a similar critical temperature from "clean" combustible gaseous components. The hydrogen sulfide and gaseous components of similar critical temperatures are then disposed of by ignition in a heat exchanger and fluidized bed scrub, converting hydrogen sulfide to sulfur dioxide which is scrubbed from the exhaust before release to the atmosphere. The clean combustible gaseous components are combusted and utilized to drive generators thereby providing a net energy output for the inventive abatement scheme.

Process for controlling nitrogen oxides in exhaust gases and apparatus therefor

Abstract: In a process and an apparatus for controlling oxides of nitrogen in exhaust gases from combustion equipment by decomposing the oxides, in the presence of oxygen, with ammonia blown into the equipment and associated ducting at temperatures within the range from 700° to 1300° C., a catalyst assembly is arranged, with the catalytic surfaces of the component units substantially in parallel to the direction of exhaust gas flow, in a region where the temperature of the gas after the decomposing treatment is between 300° and 500° C., and the gas after the decomposing treatment is caused to pass through the catalyst assembly to decompose residual nitrogen oxides and ammonia in the gas to innocuous substances. An additional supply of ammonia, in an amount from 0.5 to 1.5 times equivalent (in molar ratio) to the amount of nitrogen oxides in moles in the gas is introduced into the space immediately upstream of the catalyst assembly, thereby to accelerate the decomposition of the oxides in the gas to make it harmless.

Process for reconcentrating moist glycol

Abstract: Reconcentration of moist glycol, which has been used to dry natural gas, by heating the moist glycol with flue gas from a reboiler and by thereafter stripping water from the moist glycol with the dried flue gas or with a hydrocarbon gas by-product of the natural gas being dried.

A Natural Gas Flow Model under Uncertainty in Demand

Abstract: Storage and purchasing policies that minimize expected shortages of natural gas in the service area supplied by a single natural gas utility are developed. The problem is formulated and solved using a multiperiod linear programming model. The model takes into consideration the variability of weather conditions and its effects on the demand for natural gas. Forecasts of future weather conditions are updated several times during the model planning period. Also, the optimal flows of natural gas are determined at the time that the forecasts are updated. The optimal storage quantities at the beginning of each time period and the consequences of contracting for additional storage facilities on the natural gas shortage are derived by using the model. The natural gas planning strategy is to plan natural gas flows based on forecasted future demand. The optimal flows should be recalculated for future time periods at several computational stages of the model, honoring the orders placed during previous time periods.

Geology of Bangladesh Gas Fields

Abstract: All the gas fields are located in and near the frontal fold belt of the Indoburman Ranges in the eastern part of Bangladesh. The gas is confined in the crests of the anticlines and the sand reservoirs are mainly of Miocene age. The traditional method of correlation on the basis of lithological criteria alone of the Neogene deltaic foredeep sequences of the Bengal Basin from Assam to southern Chittagong Hill Tracts is untenable and this long standing problem can be resolved with the help of palynology. Results of isotope analyses of gases of Bangladesh gas fields indicate that the natural gas is derived from marine source rocks and was generated well within the “oil window” of maturation. Geochemical data known so far suggest that the marine source rocks of the present natural gas are of Paleogene or even older age. The total recoverable reserve of natural gas is estimated to be 10.0 trillion cubic feet. Since the gas fields are not adequately explored, the true extent of the reservoirs is not precisely known. The gas is essentially methane, practically sulphur free, and has a high calorific value. It is used in fertilizer and power plants as well as in industrial, commercial and domestic sectors.

Shallow, Low-Permeability Reservoirs of Northern Great Plains--Assessment of Their Natural Gas Resources

Abstract: Major resources of natural gas are entrapped in low-permeability, low-pressure reservoirs at depths less than 4,000 ft (1,200 m) in the northern Great Plains. This shallow gas is the product of the immature stage of hydrocarbon generation and is referred to as biogenic gas. Prospective low-permeability, gas-bearing reservoirs range in age from late Early to Late Cretaceous and include most of the section from the base of the Mowry Shale to the top of the Judith River Formation. For detailed examination, the potential reservoir section was divided into five intervals represented by one or more formations and their correlatives. The intervals selected correspond to (1) Mowry Shale, (2) Belle Fourche Shale and Greenhorn Formation, (3) Carlile Shale, (4) Niobrara and Telegrap Creek Formations and Eagle Sandstone, and (5) Claggett Shale and Judith River Formation and their equivalents. Within each interval, several different facies are developed. The following facies were identified and mapped for each interval: nonmarine rocks, coastal sandstones, shelf sandstones, siltstones, shales, and chalks. Two types of shelf sandstone were differentiated but generally not mapped separately because of lack of well log control. The "sand ridge" type has reservoir properties comparable to coastal sandstones and occurs as isolated tongues as much as 75 ft (23 m) thick. The second type of shelf sandstone is in beds commonly less than 1 in. (3 cm) thick which are interbedded with shale and contain a high content of allogenic silt- and clay-size material. It is impossible to differentiate these individual beds on conventional well logs. The siltstone and shale facies are grouped to ether because conventional logs cannot distinguish between these two rock types, particularly when they are interbedded. For future evaluation of natural gas resources from low-permeability reservoirs, it will be necessary to differentiate between the siltstone and shale facies and to identify individual beds, particularly very thin ones, within the shelf sandstone facies. Each facies contains distinct reservoir types, some of which are low in permeability. The most promising low-permeability reservoirs are developed in the shelf sandstone, siltstone, and chalk facies. Reservoirs within these facies are particularly attractive because they are enveloped by thick sequences of shale which serve as both a source and a seal for the gas. When naturally fractured, these shales also may be low-productivity gas reservoirs similar to the Devonian shales of the Appalachian basin. In addition, facies with low-permeability reservoirs are present over most of the study area when maps for all of the intervals are combined. Natural gas is produced from low-permeability reservoirs in the northern Great Plains in the southern part of western Canada. Established production covers an area of approximately 8,000 sq mi (20,700 sq km) where reported recoverable reserves average as much as 2 Bcf sq mi. Using these reserve data as an analog, the United States portion may contain resources of natural gas in excess of 100 Tcf. The volume of recoverable gas in the United States will depend on the development of improved recovery technology and higher gas prices relative to costs.

Vertical borehole design and completion practices used to remove methane gas from mineable coalbeds

Abstract: Coalbed gas drainage from the surface in advance of mining has long been the goal of researchers in mine safety. Bureau of Mines efforts to achieve this goal started about 1965 with the initiation of an applied research program designed to test drilling, completion, and production techniques for vertical boreholes. Under this program, over 100 boreholes were completed in 16 different coalbeds. The field methods derived from these tests, together with a basic understanding of the coalbed reservoir, represent an available technology applicable to any gas drainage program whether designed primarily for mine safety or for gas recovery, or both.

System for generation of electricity by utilization of heat exchange between liquefied natural gas and intermediate heat medium

Abstract: A system for generation of electricity which comprises warming an intermediate heat exchange medium, cooled and liquefied as the result of having been used for warming LNG to vaporize, with water or sea water to vaporize, introducing the vaporized intermediate heat medium into a turbine equipped with an electric power generator for driving and using again the intermediate heat medium discharged from the turbine for warming LNG to vaporize while the intermediate heat medium discharged from the turbine is contacted with the condensed liquid of the intermediate heat medium with intervention of a packing material.

Potential New Sources of Natural Gas

Abstract: Natural gas continues to be one of the major sources of energy produced and used in the U.S. Declining gas reserves and curtailment of supplies have reemphasized the major influence this energy source has on the U.S. economy. The U.S. DOE is investigating several options for increasing the supply, including a program for unconventional gas recovery (UGR). Four UGR projects currently are being assessed: western tight gas sands, geopressured reservoirs, Devonian shales, and methane from coalbeds. Both the Devonian shale and methane-fromcoalbeds projects are paramount in this assessment, since they underlie a large section of the U.S. The eastern (Devonian) shales contain a vast, essentially tmexplored volume of natural gas. This area could represent new gas recovery from approximately 250,000 sq miles throughout the U.S. Studies by the government and industry have been focused on shale characterization to determine the magnitude of potential gas reserves and technology development needed to improve current state-of-theart stimulation techniques. The initial R&D results have shown promise and point out the technology needed for successful development. The goal of the methane-from-coalbeds project is