Oil recovery tests

Inlet oil concentration. Oil recovery tests were run in 10% NaCI solution with laboratory sparged and dispersed gas cells. 

Tables 2 and 3 show the results of the foam-enhanced oil recovery tests for the constant pressure and the constant flow rate experiments respectively. The foam-enhanced oil recovery results from both sets of experiments are similar in that the recovery efficiency and gas bteakthrough time increased in the same order C 2 0S, AOS and C AOS.

To determine the effect of the properties of liquids on oil recovery, tests were carried out using low viscosity products. In this case a gassed kerosene served as the liquid. Its gas content was the same as the gas content of the crude oil. According to the results, only 37% of the kerosene by volume has been displaced from the reservoir model although the kerosene viscosity under the conditions of the experiment was 100 times smaller than the viscosity of the crude oil. The rate of pressure reduction had no effect on oil recovery from the bed. 

Abstract. Numerous single-phase flow and oil recovery tests were carried out in unconsolidated silica sands using C14 tagged hydrolyzed polyacrylamide solutions. The polymer retention data from these flow tests are compared to the adsorption data obtained from static adsorption tests. 

During oil recovery tests a commercial refined oil was used, diluted with kerosene to 9 cp at room temperature. 

I. Oil recovery tests at irreducible water saturation. Before each oil recovery test, the permeability of the sandpack to brine was determined. Next, oil was pumped through the sandpack until irreducible water saturation was reached. The total volume of displaced brine was determined volumetrically. A regular brineflood was carried out in the oil saturated sandpack. After the brineflood, the sandpacks were resaturated with oil. The polymerflood was carried out in the resaturated sandpack. 

The curves in Figure 25 demonstrate that in all oil recovery tests, mechanical... 

Figure 26 shows the percent polymer retention as a function of cummulative produced water in a few oil recovery tests in the low permeability sand. It is noteworthy... 

Fig. 26. The effect of salinity on the rate of polymer recovery in selected oil recovery tests.

Fig. 28. The polymer retention as a percent of injected polymer in selected oil recovery tests.

Fig. 30. Distribution of retained polymer in sandpacks after completion of oil recovery tests.

Including a surfactant in the caustic formulation (surfactant-enhanced alkaline flooding) can increase optimal salinity of a saline alkaline formulation. This can reduce iaterfacial tension and increase oil recovery (255,257,258). Encouraging field test results have been reported (259). Both nonionic and anionic surfactants have been evaluated in this appHcation (260,261). 

Micellar/polymer (MP) chemical enhanced oil recovery systems have demonstrated the greatest potential of all of the recovery systems under study (170) and equivalent oil recovery for mahogany and first-intent petroleum sulfonates has been shown (171). Many somewhat different sulfonate, ie, slug, formulations, slug sizes (pore volumes), and recovery design systems were employed. Most of these field tests were deemed technically successful, but uneconomical based on prevailing oil market prices (172,173). 

Acrylamide—polymer/Ct(III)catboxylate gel technology has been developed and field tested in Wyoming s Big Horn Basin (211,212). These gels economically enhance oil recovery from wells that suffer fracture conformance problems. The Cr(III) gel technology was successful in both sandstone and carbonate formations, and was insensitive to H2S, high saline, and hard waters (212). 

There are several other applications where significant gains could be made through the use of supercomputer simulations of detailed physical models. Reservoir simulations was one of the first areas where the value of supercomputing was recognized by Industrial companies. It Is only possible to measure a few properties of Interest to enhanced oil recovery. Furthermore, field tests are extremely expensive, and the monetary... 

To develop improved alkali-surfactant flooding methods, several different injection strategies were tested for recovering heavy oils. Oil recovery was compared for four different injection strategies [641] ... 

Micellar flooding is a promising tertiary oil-recovery method, perhaps the only method that has been shown to be successful in the field for depleted light oil reservoirs. As a tertiary recovery method, the micellar flooding process has desirable features of several chemical methods (e.g., miscible-type displacement) and is less susceptible to some of the drawbacks of chemical methods, such as adsorption. It has been shown that a suitable preflush can considerably curtail the surfactant loss to the rock matrix. In addition, the use of multiple micellar solutions, selected on the basis of phase behavior, can increase oil recovery with respect to the amount of surfactant, in comparison with a single solution. Laboratory tests showed that oil recovery-to-slug volume ratios as high as 15 can be achieved [439]. 

The state of the art in chemical oil recovery has been reviewed [1732]. More than two thirds of the original oil remains unrecovered in an oil reservoir after primary and secondary recovery methods have been exhausted. Many chemically based oil-recovery methods have been proposed and tested in the laboratory and field. Indeed, chemical oil-recovery methods offer a real challenge in view of their success in the laboratory and lack of success in the field. The problem lies in the inadequacy of laboratory experiments and the limited knowledge of reservoir characteristics. Field test performances of polymer, alkaline, and micellar flooding methods have been examined for nearly 50 field tests. The oil-recovery performance of micellar floods is the highest, followed by polymer floods. Alkaline floods have been largely unsuccessful. The reasons underlying success or failure are examined in the literature [1732]. 

Surfactants have been widely used to reduce the interfacial tension between oil and soil, thus enhancing the efficiency of rinsing oil from soil. Numerous environmentally safe and relatively inexpensive surfactants are commercially available. Table 18.6 lists some surfactants and their chemical properties.74 The data in Table 18.6 are based on laboratory experimentation therefore, before selection, further field testing on their performance is recommended. The Texas Research Institute75 demonstrated that a mixture of anionic and nonionic surfactants resulted in contaminant recovery of up to 40%. A laboratory study showed that crude oil recovery was increased from less than 1% to 86%, and PCB recovery was increased from less than 1% to 68% when soil columns were flushed with an aqueous surfactant solution.74-76... 

This decline in the price of oil has resulted in major changes in the types of enhanced oil recovery (EOR) being studied in the laboratory and field tested. Steam injection and injection of miscible gases, primarily remain of great interest due to the... 

Recent research and field tests have focused on the use of relatively low concentrations or volumes of chemicals as additives to other oil recovery processes. Of particular interest is the use of surfactants as CO (184) and steam mobility control agents (foam). Also combinations of older EOR processes such as surfactant enhanced alkaline flooding and alkaline-surfactant-polymer flooding have been the subjects of recent interest. Older technologies polymer flooding (185,186) and micellar flooding (187-189) have been the subject of recent reviews. In 1988 84 commercial products polymers, surfactants, and other additives, were listed as being marketed by 19 companies for various enhanced oil recovery applications (190). 

This multitude of properties the polymer must possess dictate that better polymer performance will be obtained from materials with complicated structures. Such polymers are complex polymers l) random copolymers, 2) block copolymers, 3) graft copolymers, 4) micellizing copolymers, and 5) network copolymers. There has been a dramatic increase in the past decade in the number and complexity of these copolymers and a sizable number of these new products have been made from natural products. The synthesis, analysis, and testing of lignin and starch, natural product copolymers, with particular emphasis on graft copolymers designed for enhanced oil recovery, will be presented. 

The present study investigates the adsorption and trapping of polymer molecules in flow experiments through unconsolidated oil field sands. Static tests on both oil sand and Ottawa sand indicates that mineralogy plays a major role in the observed behavior. Effect of a surfactant slug on polymer-rock interaction is also reported. Corroborative studies have also been conducted to study the anomalous pressure behavior and high tertiary oil recovery in surfactant dilute-polymer systems(ll,12). 

The works of various investigators such as Gogarty and Tosch (1), Healy and Reed (2), and Davis and Jones (2), have shown that the micellar flooding process can be used effectively to mobilize residual oil in watered-out light oil reservoirs. Many field tests conducted in the U.S. have further proved its effectiveness. However, the economics of the process remain unattractive for implementing the process for tertiary oil recovery. 

By the addition of other liquid reservoirs, e.g. for water and crude oils, and replacement of the capillary test unit by a sand pack, the effectiveness of the same foams for enhanced oil recovery at reservoir temperatures and pressures will be investigated. 

McCormick, C.L., et al. "Development of Laboratory Screening Tests to Predict Polymer Performance in Enhanced Oil Recovery (I). Shear Degradation, Viscosity, and Electrolyte Studies," prepared for DOE under contract No. EF-77-S-05-5603, 1977. 

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