Gas-flood enhanced oil recovery

This chapter reports adsorption data for a number of surfactants suitable for mobility control foams in gas-flooding enhanced oil recovery. Surfactants suitable for foam-flooding in reservoirs containing high salinity and hardness brines are identified. The results of adsorption measurements performed with these surfactants are presented surfactant adsorption mechanisms are reviewed and the dependence of surfactant adsorption on temperature, brine salinity and hardness, surfactant type, rock type, wettability and the presence of an oil phase is discussed. The importance of surfactant adsorption to foam propagation in porous media is pointed out, and methods of minimizing surfactant adsorption are discussed. 

Bachu S. and Shaw J.C. C02 storage in oil and gas reservoirs in western Canada effect of aquifers, potential for C02-flood enhanced oil recovery and practical capacity. 

In principle, the combination of membranes for bulk removal of the carbon dioxide with amine units as polishing systems offers a low-cost alternative to all-amine plants for many streams. However, this approach has not been generally used because the savings in capital cost are largely offset by the increased complexity of the plant, which now contains two separation processes. The one exception has been in carbon dioxide flood enhanced oil-recovery projects [49,54], in which carbon dioxide is injected into an oil formation to lower the viscosity of the oil. Water, oil and gas are removed from the formation the carbon dioxide is separated from the gas produced and reinjected. In these projects,... 

A considerable percentage (40% - 85%) of hydrocarbons are typically not recovered through primary drive mechanisms, or by common supplementary recovery methods such as water flood and gas injection. This is particularly true of oil fields. Part of the oil that remains after primary development is recoverable through enhanced oil recovery (EOR) methods and can potentially slow down the decline period. Unfortunately the cost per barrel of most EOR methods is considerably higher than the cost of conventional recovery techniques, so the application of EOR is generally much more sensitive to oil price. 

Domestic petroleum, natural gas, and natural gas Hquids production has declined at a rate commensurate with the decrease in reserves (see Table 2). Consequently, the reserves/production ratio, expressed in years, remained relatively constant from about 1970 through 1992, at 9—11 years (16). Much of the production in the early 1990s is the result of enhanced oil recovery techniques water flooding, steam flooding, CO2 injection, and natural gas reinjection. 

Other Specialty Chemicals. In fuel-ceU technology, nickel oxide cathodes have been demonstrated for the conversion of synthesis gas and the generation of electricity (199) (see Fuel cells). Nickel salts have been proposed as additions to water-flood tertiary cmde-oil recovery systems (see Petroleum, ENHANCED oil recovery). The salt forms nickel sulfide, which is an oxidation catalyst for H2S, and provides corrosion protection for downweU equipment. Sulfur-containing nickel complexes have been used to limit the oxidative deterioration of solvent-refined mineral oils (200). 

The choice of a specific CO2 removal system depends on the overall ammonia plant design and process integration. Important considerations include CO2 sHp required, CO2 partial pressure in the synthesis gas, presence or lack of sulfur, process energy demands, investment cost, availabiUty of solvent, and CO2 recovery requirements. Carbon dioxide is normally recovered for use in the manufacture of urea, in the carbonated beverage industry, or for enhanced oil recovery by miscible flooding. 

Pressure Swing Adsorption. A number of processes based on Pressure Swing Adsorption (PSA) technology have been used in the production of carbon dioxide. In one version of the PSA process, CO2 is separated from CH using a multibed adsorption process (41). In this process both CH4 and CO2 are produced. The process requires the use of five adsorber vessels. Processes of this type can be used for producing CO2 from natural gas weUs, landfiU gas, or from oil weUs undergoing CO2 flooding for enhanced oil recovery (see Adsorption, gas separation). 

Enhanced oil-recovery processes include chemical and gas floods, steam, combustion, and electric heating. Gas floods, including immiscible and miscible processes, are usually defined by injected fluids (carbon dioxide, flue gas, nitrogen, or hydrocarbon). Steam projects involve cyclic steam (huff and puff) or steam drive. Combustion technologies can be subdivided into those that autoignite and those that require a heat source at injectors [521]. 

Although strictly not an acid-gas disposal method, miscible flooding using carbon dioxide is, in some situations, an economic method of enhanced oil recovery. It shares many characteristics with its disposal cousin, particularly the surface equipment. 

Many enhanced oil recovery processes use gas drives to displace trapped oil, ie. steam floods and CO2 floods. The sweep efficiency of these methods is often low because of the unfavorable mobility ratio of gas to oil. (The mobility of gas is much greater than the mobility of oil.) Therefore, gas tends to overide or finger through oil. 

Despite the massive drop of oil prices in the early 1980s, the crippling or elimination of several major oil companies, and the layoffs of thousands of talented employees, the oil industiy has managed to commercialize a major new kind of enhanced oil recovery (EOR). This type of EOR is gas-flooding , in which COj (or less often, some other fluid) is injected into an old field at a pressure of about 8 MPa or greater to produce oil that otherwise would not be recovered. 

Conventional (primary and secondary) recovery methods recover only a small fraction of the crude oil originally in place in a typical reservoir. The primary and secondary recovery techniques, which include pressure maintenance by gas injection and water flooding for improved recovery, leave approximately two-thirds of the original oil in the reservoir. As the conventional oil production of the United States continues to decline, enhanced oil recovery will play an important role in the utilization of our domestic resources. Conventional methods do not overcome the basic problems of oil being trapped within the rock pores and of the low mobility of the remaining oil. 

Schramm, E.E., Mannhardt, K., and Novosad, J.J. (1993) Selection of oil-tolerant foams for hydrocarbon miscible gas flooding, in Proceedings, 14th International Workshop and Symposium, International Energy Agency Collaborative Project on Enhanced Oil Recovery (ed E. Rieder), OMV Energie, Vienna, paper 18. 

Deposition in EOR Gas Flooding A Predictive Technique," SPE/DOE Paper 17376, SPE/DOE Enhanced Oil Recovery Symposium held in Tulsa, OK, pp. 617-625, April 17-20,1988. 

In the eastern and western portion of the Prudhoe Bay field the natural gas is also used for miscible flooding process. The heavier hydrocarbons are stripped from the natural gas and injected into the Prudhoe Bay Reservoir to achieve miscibility and thus enhance the oil recovery. Such an enhanced oil recovery process is certainly cost effective due to availability of natural gas. This is probably the lowest cost option for the North Slope gas utilization. 

On the same token, the North Slope gas can be effectively utilized for the enhanced oil recovery in the other North Slope oil fields. Plans for undertaking miscible flood in the Kuparuk River Field (Kuparuk Formation) similar to Prudhoe Bay are already underway. Lisburne and Endicott fields also show promise for the use of natural gas for future enhanced oil recovery. 

Cmc values are important in virtually all of the petroleum industry surfactant applications. For example, a number of improved or enhanced oil recovery processes involve the use of surfactants including micellar, alkali/surfactant/polymer (A/S/P) and gas (hydrocarbon, N2, CO2 or steam) flooding. In these processes, surfactant must usually be present at a concentration higher than the cmc because the greatest effect of the surfactant, whether in interfacial tension lowering [30] or in promoting foam stability [3J], is achieved when a significant concentration of micelles is present. The cmc is also of interest because at concentrations... 

Recently, Taber and co-workers [65] have published screening criteria for all enhanced oil recovery (EOR) methods and their applications and impact of oil prices. About 3% of the worldwide production now comes from EOR. There are relatively few chemical flooding projects in the world, and these projects contribute very little to worldwide EOR production when compared to steamflooding and gas injection. A LTPWF, as a secondary flood method, may drain the reservoir to a residual oil saturation in the range of 15-20% rather fast and this may have an impact on the economics of the process. Future researeh on chemical flooding should move in this direction. 

Coal-Tar Products Enhanced Oil Recovery Natural Gas Natural Gas Pipelines Oil Field Flooding Oil Fields... 

While geological sequestration will build generally on the totality of experience with fossil fuel extraction, it will be most directly built on current practice of CO2 injection for enhanced oil recovery (EOR). Conventional extraction methods typically leave substantial oil in place. This oil may be extracted using EOR. Carbon dioxide injection (or flooding in industry jargon) is particularly effective because, as an organic solvent, the CO2 acts to reduce the viscosity of the residual oil and in addition causes the oil to expand thus helping to free it from the porous rock in which it is embedded. Typical EOR floods operate at pressures above the critical point of CO2 so that fluid flow is facilitated by the absence of a liquid-gas interface. 

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