Natural gas associated

Natural gas is a naturally occurring mixture of light hydrocarbons accompanied by some non-hydrocarbon compounds. Non-associated natural gas is found in reservoirs containing no oil (dry wells). Associated gas, on the other hand, is present in contact with and/or dissolved in crude oil and is coproduced with it. The principal component of most... 

The South African government initiated the Mossgas project in the mid-1980s to investigate the conversion of gas and associated natural gas liquids into transportation fuel. This eventually led to the construction of the Mossgas gas-to-liquids plant (presently known as PetroSA) in Mossel Bay, South Africa. It was designed as a 33,000 barrels per day oil equivalent facility, with two thirds of the production being derived from Fischer-Tropsch synthesis and the remainder from associated gas liquids. This facility reached full commercial production in 1993 and was aimed at the production of transportation fuel only.50... 

Mexican Frasch sulfur output, like our own, will decline over the next 15 years. However, an estimate of Mexican recovered sulfur from oil and associated natural gas is 2-4 MMLT/Y by 1985 and... 

Traditional estimates of oil-associated natural gas reserves historically have rated the former Soviet Bloc as holding nearly 40% of the reserves, Iran about 14%, and the United States nearly 6%, with additional fairly high reserves in Qatar. Algeria, and Saudi Arabia. At one time. North America was attributed to have a 60-year supply, but with revisions in estimating procedures, coupled with increased efficiency in natural gas production and gas combustion efficiency, the future is now believed to be in terms of at... 

In general, SOCAR s production of both associated and non-associated natural gas will remain fairly until around 2010, when it will start to decline. 

The Azeri-Chirag-Guneshli reservoirs contain crude oil with a large volume of associated natural gas. The development of these reserves, have significant implications for the management of Azerbaijan s natural gas resources. 

Under the terms of the Gas Protocol, all ACG natural gas delivered to SOCAR has priority over all non-associated natural gas, including both Shakh Deniz and inports. This measure is designed to maximize continuing oil production, to the benefit of the partners and the Government, in the event of the loss of the ability to re-inject associated natural gas production offshore. The management of this requirement effectively, implies a need for significant planning and investment. 

Figure 8.32 A typical membrane/amine plant for the treatment of associated natural gas produced in carbon dioxide/enhanced oil projects. The membrane permeate gas is often used as a fuel for the amine absorption plant...

Natural gas is the gaseous mixture associated with petroleum reservoirs and is predominantly methane but does contain other combustible hydrocarbon compounds as well as non-hydrocarbon compounds (Table 2.3 Speight, 1999). In fact, associated natural gas is believed to be the most economical form of ethane. 

Thus there is nonassociated natural gas, which is found in reservoirs in which there is no, or at best only minimal amounts of, petroleum. Nonassociated gas is usually richer in methane but is markedly leaner in terms of the higher-molecular-weight hydrocarbons and condensate. Conversely, there is also associated natural gas dissolved natural gas) that occurs either as free gas or as gas in solution in the petroleum. The gas that occurs as a solution with the crude petroleum is dissolved gas, whereas the gas that exists in contact with the crude petroleum (gas cap) is associated g 5. Associated gas is usually leaner in methane than the nonassociated gas but is richer in the higher-molecular-weight constituents. 

Table 3.2. Composition of Associated Natural Gas From a Petroleum Well (adapted from Speight, 1999)...

Hgure 1 Typical chromatogram of associated natural gas using thermal conductivity (TCD upper curve) and flame ionization (FID lower cunre) detection. (From IP 345/80, courtesy of the Institute of Petroleum.)... 

Institute of Petroleum. Standard Methods for Analysis and Testing of Petroleum and Related Products. Published annually by J Wiley on behalf of the Institute of Petroleum, London. Method IP 345/80 Determination of composition of associated natural gas - gas chromatography method. Method AX/87 Determination of oxygenates in gasoline - gas chromatography method. 

Some general assumptions have been made in this context concerning the future use of oil and non-associated natural gas for electricity production, in the major oil-exporting countries a case can be made for nuclear power from the national economics point of view, and in most... 

Qatar Petroleum s NGL-3 plant Gas Sweetening Facility treats 1020 mmscfd of Non-associated Natural gas containing approx. 0.6 % H2S and 2.4 % C02 in two trains of Acid gas removal units (AGRU) using aqueous Methyl Di-Ethanolamine (MDEA) solution absorbent. Recovered Acid gas is processed in a single train Sulphur Reeovery Unit (SRU) with two catalytie conversion stages. 

Coal, Lignite, Peat Natural Gas Associated Natural Gas Oil Shale Tar Sands Crude Oil Bbmass... 

To prepare gas for evacuation it is necessary to separate the gas and liquid phases and extract or inhibit any components in the gas which are likely to cause pipeline corrosion or blockage. Components which can cause difficulties are water vapour (corrosion, hydrates), heavy hydrocarbons (2-phase flow or wax deposition in pipelines), and contaminants such as carbon dioxide (corrosion) and hydrogen sulphide (corrosion, toxicity). In the case of associated gas, if there is no gas market, gas may have to be flared or re-injected. If significant volumes of associated gas are available it may be worthwhile to extract natural gas liquids (NGLs) before flaring or reinjection. Gas may also have to be treated for gas lifting or for use as a fuel. 

The composition of natural gas varies oonsiderably from lean non-associated gas which is predominantly methane to rich associated gas containing significant proportion of natural gas liquids. Natural gas liquids (NGLs) are those components remaining once methane and all non-hydrocarbon components have been removed, i.e. (Cg-C ). 

In most of the rest of the world the olefins industry was originally based on naphtha feedstocks. Naphtha is the dominant olefins feedstock in Europe and Asia. In the middle 1980s several large olefins complexes were budt outside of the United States based on gas Hquids feedstocks, most notable in western Canada, Saudi Arabia, and Scotiand. In each case the driving force was the production of natural gas, perhaps associated with cmde oil production, which was in excess of energy demands. 

Orfice Metering of Natural Gas and Other Kelated Hydrocarbons, ANSI/API 2530, AGA report No. 3, American Gas Association, Arlington, Va., 1985. FluidMeters—TheirTheoy and Application, 6th ed., American Society of Mechanical Engineers, New York, 1971. 

There is an inherent economic penalty associated with producing Hquids from either natural gas or soHd coal feedstock. Synthetic Hquid fuels technologies are generally not economically competitive with cmde oil processing in the absence of extraneous influences such as price supports or regulations. 

Associated gas free natural gas in immediate contact, but not in solution, with cmde oil in the reservoir. 

In 1991, there were approximately 418 sulfur production plants associated with oil and gas production in operation throughout the world. Approximately 86% of these plants were based on the Claus process, and there were 118 Claus units operating in natural gas processing faciHties (11). 

Neir Directions Natural Gas Energy, Natural Gas Council (American Gas Association, Independent Petroleum Association of America, Interstate Natural Gas Association of America, Natural Gas Supply Association), 1992. 

The main commercial source of methane, ethane, and propane is natural gas, which is found ia many areas of the world ia porous reservoirs they are associated either with cmde oil (associated gas) or ia gas reservoirs ia which no oil is present (nonassociated gas). These gases are basic raw materials for the organic chemical industry as well as sources of energy. The composition of natural gas varies widely but the principal hydrocarbon usually is methane (see Gas, natural). Compositions of typical natural gases are Hsted ia Table 2. 

As indicated in Table 4, large-scale recovery of natural gas Hquid (NGL) occurs in relatively few countries. This recovery is almost always associated with the production of ethylene (qv) by thermal cracking. Some propane also is used for cracking, but most of it is used as LPG, which usually contains butanes as well. Propane and ethane also are produced in significant amounts as by-products, along with methane, in various refinery processes, eg, catalytic cracking, cmde distillation, etc (see Petroleum). They either are burned as refinery fuel or are processed to produce LPG and/or cracking feedstock for ethylene production. 

Butanes are naturally occurring alkane hydrocarbons that are produced primarily in association with natural gas processing and certain refinery operations such as catalytic cracking and catalytic reforming. The term butanes includes the two stmctural isomers, / -butane [106-97-8] CH2CH2CH2CH2, and isobutane [79-28-9], (CH2)2CHCH2 (2-methylpropane). 

Plants in the United States are basicaHy iodine producers and must extract the solutions from deep (between 2000- and 3000-m) weUs. The depleted solutions are reinjected for environmental reasons and maintain the pressure of the exploitation area. In Japan, on the other hand, iodine is mainly a by-product of natural gas production, and the weUs are less deep (about 1500 m). Depleted solutions are often discarded into the ocean. Costs associated with deep weUs are relatively high, reaching 1.7 to 2.0 x 10 in the United States and up to ca 0.7 x 10 in Japan. 

Methods in Development. The U.S. Department of Energy (DOE) and the American Gas Association (AGA) have sponsored the development of more efficient gasification processes, but as of this writing the plentihil supply of iaexpensive natural gas has precluded commercialization. 

The nameplate capacity of worldwide methanol plants is given by country in Table 2 (27). A significant portion of this capacity is based on natural gas feedstock. Percent utilization is expected to remain in the low 90s through the mid-1990s. A principal portion of this added capacity is expected to continue to come from offshore sources where natural gas, often associated with cmde oil production, is valued inexpensively. This has resulted in the emergence of a substantial international trade in methanol. In these cases, the cost of transportation is a relatively larger portion of the total cost of production than it is for domestic plants. 

A large use of molecular sieves ia the natural gas industry is LPG sweetening, in which H2S and other sulfur compounds are removed. Sweetening and dehydration are combined in one unit and the problem associated with the disposal of caustic wastes from Hquid treating systems is eliminated. The regeneration medium is typically natural gas. Commercial plants are processing from as Htde as ca 30 m /d (200 bbl/d) to over 8000 m /d (50,000 bbl/d). 

If possible comparisons are focused on energy systems, nuclear power safety is also estimated to be superior to all electricity generation methods except for natural gas (30). Figure 3 is a plot of that comparison in terms of estimated total deaths to workers and the pubHc and includes deaths associated with secondary processes in the entire fuel cycle. The poorer safety record of the alternatives to nuclear power can be attributed to fataUties in transportation, where comparatively enormous amounts of fossil fuel transport are involved. Continuous or daily refueling of fossil fuel plants is required as compared to refueling a nuclear plant from a few tmckloads only once over a period of one to two years. This disadvantage appHes to solar and wind as well because of the necessary assumption that their backup power in periods of no or Httie wind or sun is from fossil-fuel generation. Now death or serious injury has resulted from radiation exposure from commercial nuclear power plants in the United States (31). 

In the 1980s, however, the prices of oil and natural gas reversed their upward trends. Natural gas discoveries, both on-shore and off-shore, have considerably iacreased the world s energy supply and oil discoveries, many with associated gas, contributed more feedstock potential for ammonia production. 

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