Flooding for enhanced oil recovery

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). 

The usefulness of xanthan in polymer flooding for enhanced oil recovery is based on its ability to yield large increase in viscosity at low polymer concentrations under high-temperature and high salinity conditions. This important property of xanthan is determined both by its molecular weight and by the conformation adopted in solution (1). 

PetH-rri. [Toho Chem. Industry] Surfactants complex fix use in water flooding for enhanced oil recovery. 

Uses Interfadal tension reducing agent for use In alkaline surfactant polymer flooding for enhanced oil recovery... 

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. 

Figure 3.29 Illustrations of changes occurring in physical properties and other phenomena in the region of the optimal salinity for enhanced oil recovery using surfactant flooding. From Sharma [235]. Copyright 1991, Plenum Press.

Future production of surfactin from potato process effluents will be used in core floods to characterize further its potential application as an agent for enhanced oil recovery. 

The micelles present also help to solubilize the released oil droplets hence, this process is sometimes referred to as micellar flooding. The emulsions can be formulated to have moderately high viscosities that help to achieve a more uniform displacement front in the reservoir this uniform front gives improved sweep efficiency. Thus, a number of factors can be adjusted when using a microemulsion system for enhanced oil recovery. These are discussed in detail in Chapter 7. 

The physicochemical aspects of micro- and macroemulsions have been discussed in relation to enhanced oil recovery processes. The interfacial parameters (e.g. interfacial tension, interfacial viscosity, interfacial charge, contact angle, etc.) responsible for enhanced oil recovery by chemical flooding are described. In oil/brine/surfactant/alcohol systems, a middle phase microemulsion in equilibrium with excess oil and brine forms in a narrow salinity range. The salinity at which equal volumes of brine and oil are solubilized in the middel phase microemulsion is termed as the optimal salinity. The optimal salinity of the system can be shifted to a desired value hy varying the concentration and structure of alcohol. 

Dodiflood Brands. [HoechstAG] Ether sulfonates, ether carboxylates anionic surfactants for enhanced oil recovery and miooemulsion flooding. 

These theories were tested by several authors, and many exceptions were found (69, 73-75). Thus, in foam-flooding systems for enhanced oil recovery, Schramm and Novosad (76) and Manlowe and Radke (77) did not find a correlation between E, S, and the effect of oil on foam stability. Hence, the classical spreading—entering theory is not consistent with many experimental findings. 

Several attempts have been made to use aqueous foams for mobility control of steam-flooding in enhanced oil recovery (99—101). The application of foam is, however, seriously hindered by the extreme conditions of the process. The temperature can be as high as 80—300 °C, and the pressure can be 60—4000 psi, which is not common in other foam applications. The oil saturation in the porous media can be higher than 15% (44), and several authors (100—102) found that crude oil is generally detrimental to the foam. Thus, the foam stability in these conditions is a limiting factor in the success of foam flooding. 

A number of laboratory investigations were made into different aspects of consumption of sodium hydroxide and sodium orthosilicate in alkaline flooding of petroleum reservoirs for enhanced oil recovery. One investigation studied the role of reversible adsorption and of chemical reaction v en petroleum reservoir sands are contacted with alkaline solutiais. Another investigation studied the effect of flow rate on caustic consumption by means of a series of flow experiments through reservoir sand packs. A third series of high rate flow experiments studied changing alkaline consumption with time. 

Surfactants can be employed in different forms in enhanced oil recovery processes. The emulsions and foams have been also used in combination with other oil recovery processes. Surfactant flooding for improving oil recovery is described as follows ... 

In addition to reducing the proportion of oil used for energy (1973 49% 1984 41%), other measures must be applied to maintain a steady supply of oil for the long term. It has been shown that for each 1% Increase in drilling yield, an increased in supply of 1.7 years results. 7 one of the most important methods for enhancing oil recovery is the use of methods like polymer flooding. 

Solubility. Solubility in the primary process solvent is a mandatory criteria which is easily met in most extraction processes conducted in water. But, new applications such as polymeric viscosifiers for supercritical carbon dioxide flooding in enhanced oil recovery present enormous solubility problems for candidate polymers. If the polymer must remain soluble in secondary fluids encountered during the extraction process, then solubility requirements on the polymer will span large ranges of solvent pH, solvent-and-other-solute activity, and solvent polarity. 

In chemical flooding processes for enhanced oil recovery, alkaline chemicals can be useful for hardness ion suppression or removal, reaction with acidic crude oils to generate surface-active species, reduction in surfactant adsorption on reservoir rock surfaces, changes in interfacial phase properties, mobility control and increased sweep efficiency, oil wettability reversal and increased emulsification. 

The proceedings cover six major areas of research related to chemical flooding processes for enhanced oil recovery, namely, 1) Fundamental aspects of the oil displacement process, 2) Microstructure of surfactant systems, 3) Emulsion rheology and oil displacement mechanisms, 4) Wettability and oil displacement mechanisms, 5) Adsorption, clays and chemical loss mechanisms, and 6) Polymer rheology and surfactant-polymer interactions. This book also includes two invited review papers, namely, "Research on Enhanced Oil Recovery Past, Present and Future," and "Formation and Properties of Micelles and Microemulsions" by Professor J. J. Taber and Professor H. F. Eicke respectively. 

Foam Flooding. In enhanced oil recovery, the process in which a foam is made to flow through an underground reservoir. The foam, which may be either generated on the surface and injected or generated in situ, is used to increase the drive fluid viscosity and improve its sweep efficiency. In refinery distillation and fractionation towers, the occurrence of foams which can carry fiquid into regions of the towers intended for vapour. 

Fathi, Z. and Ramirez, W. F., Optimal Injection Policies for Enhanced Oil Recovery Part 2—Surfactant Flooding. Soc. Pet. Engr. Journal 30, No. 4, 333-342 (June 1984).. 

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