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Summary. The control of fluid mobility has become increasingly important to steamflood applications for oil recovery. Most of the EOR projects in the U.S. use steamflooding techniques. The efficiency of these projects is often reduced because such effects as gravity override result in poor volumetric sweep through the reservoir. Additives can improve the efficiency of steamflooding, but screening tests must be performed for selection oil the most effective additive for individual applications. As potential additives, nine commercially available sulfonate surfactants were tested with the high-temperature/high-pressure foamability (HTHPF) test procedure. and eight (if these were tested with the mobility control (MC) procedure. These surfactants were evaluated at 250 and 425deg.F [121 and 218deg.C] in deionized water and in 1% added NaCl. A correlation trend was also found between foam stability measured by the HTHPF test and mobility reduction measured by the MC test. This trend was evident for more than one type of sulfonate at both temperatures an increase in temperature corresponded to a decrease in foam stability and mobility reduction. The dependence of- foam stability on the presence of added NaCl varied from surfactant to surfactant. Introduction Steamflooding is the most commercially successful F-OR method in use. About 80% of the oil currently produced by EOR in the U.S. is reported to be from steamflooding. The volumetric sweep efficiency of steam, however, is often lowered by such phenomena as gravity separation, viscous fingering. and reservoir heterogeneity. The literature contains considerable information about ways of improving volumetric sweep efficiency. One method that may prove to be effective is the use of foams generated in situ. Foams are used to reduce the mobility of steam in highly permeable, steam-swept zones created through gravity override. If the mobility of the steam can be reduced in those areas, migration of the steam zone to other less easily accessible regions in the reservoir will be improved. The properties of foams have been studied extensively. Previous investigations have included studies of foam quality, foam viscosity, foam flow patterns, surface tension, wetting ability, foam stability, foam morphology, foam rheology, and permeability-reduction proper-ties. Foam stability and permeability-reduction properties were studied in this research. To select and to test surfactants for steamflood applications, surfactants that can be foamed at high temperatures and high pressure must be identified. Some suitable surfactants have been identified by use of a high-pressure cell located inside an air bath. In that research, static and dynamic foam stabilities were determined. Half-life times were calculated on the basis of first-order kinetics. A similar test, used in our laboratory to identify potential foaming surfactants, is called the HTHPF test. Several investigations of foam mobilities in Porous media have also been reported. Although different procedures were used in each study, these procedures can be classified as two basic types: continuous injection of foaming surfactant (steady state) and slug injection of foaming surfactant (nonsteady state,). Studies that use the first type are cited in 6 through 9. and studies that use the second type in Refs. 10 through 15. The test used in this study is the second type and similar to that used by Sharnia et al, where the unconsolidated matrix is presaturated with surfactant solution. This test is referred to as the MC test. Today, engineers must base their selection of a surfactant for optimum use in a steamflood field operation on a surfactant for optory tests designed to characterize all the properties of foaming surfactants. Little work has been done, however, to compare the results of the differently types of laboratory test with results of steam-flood applications for the same additives. In this paper. the results of the HTHPF test are compared with the results of the MC test for a given set of additives. This comparison represents the first step toward evaluating the effectiveness of laboratory screening tests. Experimental Equipment. Fig. 1 is a schematic of the HTHPF apparatus. The injection of N, is controlled with metering valves and pressure regulators to maintaining constant gas flow for foam generation. The N, passes through sintered stainless-steel spargers (7-um pore size) to generate the foam inside the pressure cells. The pressure cells are 500 mL in volume with 20-in. [51-cmi -long glass windows in front and back. The cells are rated to 700 psi 14.8 MPa] at 400deg.F [204deg.C). The N, is preheated before it enters the cells as it passes through tubing coils inside the oven. Fig. 2 is a schematic of the MC test apparatus. The core holder has an ID of 1.7 in. [4.4 cm] and is 36 in. [91 cm] long. Differential pressure across the entire core is measured throughout current experiments by a Validyne pressure transducer with a demodulator and strip-chart recorder. Surfactant Solutions. The solutions were prepared by dissolving, the surfactant as received from the suppliers into deionized water or 1 % NaCl solution to obtain a 1 wt% surfactant solution. Surfactant solutions with and without added NaCl were tested by the HTHPF procedure, and surfactant solutions without added NaCl were tested by the MC procedure. A variety of commercially available surfactants for steamflood applications were tested. The types tested and described in this report include alpha-olefin sulfonates (AOS's), alkyl-aryl sulfonates (AAS's), and ethoxy sulfonates (EOS's). All the surfactants were tested as received from the commercial suppliers. The concentration of active ingredients in weight percent is given in Table 1. Operating Procedures. HTHPF Test. The test operating, conditions were set at 650 psi 14.5 MPa] and -50 or 425deg.F [121 or 218deg.C]. The oven was allowed to equilibrate for 60 minutes after it reached the desired temperature. N2 was added through the sparger to generate a foam column. The height of this column was 4.7 in. [12 cm], except for measurements reported in Table 2 where the foam heights are specified. SPERE P. 543^

This revised edition of the "Environmental Regulations HandbooP. for Enhanced Oil Recovery" was prepared for the U.S. Department of Energy via contract through the National Institute for Petroleum and Energy Research. The contents of this handbook were assembled by Spears and Associates of Tuisa, Oklahoma. Environmental regulations that were extracted and summarized from every state included in this manual, were reviewed for accuracy and adequacy by a representative of each agency mentioned as the "Agency in Charge". Ali federal amended laws and regulations mentioned in the text are those currently in effect. However, the Clean Water Act which was amended i_L April, 1991, was not available as of this date (july 23, 1991). The project manager for this revision and the consultant who compiled the information contained herein, retain responsibility for any errors in judgement or fact.

CHAPTER2 DESCRIPTION OF THE RESOURCE The Department of Energy has defined Class 4 for the cost-shared oil recovery field demonstration program as strandplain/banier island reservoirs. This depositionally defied class of reservoirs represents a significant portion of the Nation's oil resource, as described in the DOE Tertiary O i l Recovery Information System (I'ORIS). The purpose of Chapter 2 is to present an overview of the reservoir, production, and geological characteristics of Class 4 reservoirs. Section 2.1 descriies the overall strandplain/banier island resource in the country based on an analysis of 330 Class 4 reservoirs listed in the TORIS database. Section 2.2 describes the general geological characteristics of strandplai4barrier island reservoirs based on a comprehensive review of the relevant geological literature. Section 2.3 presents an overview of the major Class 4 plays in the United States and includes summaries of the resource, reservoir, and production characteristics, as well as a summary of the recovery processes that have been used in these plays. The major plays are described in detail in Chapters 3 through 6. This facies, dong with the often overlying eolian facies, discussed below, constitutes the best reservoir rock associated with strandplainbarrier island systems.

Phone: (313) 994-1200 FAX: (313) 994-5824 Omnet: R.Onstott w e n t of Natural Resources, University of Michigan ABSTRACT when sea water freezes into sea ice, brine and pure ice are produced. Due to the effects of the expulsion of brine from the sea ice interior and the wicking action of snow and frost flowers deposited on the air-ice interface, brine may accumulate on the upper ice sheet surface. Brine is a concentrated solution of sea salts and water, hence is highly lossy and has a large dielectric constant. Sea ice which is several hours old transforms to a layer which, as a bulk dielectric constant, is considerably less than that of the sea water from which it was born. Questions arise as to the impact of the surface brine layer. Potentially, the air-ice interface the reflectivity and transmission characteristics of this upper most ice layer may be perturbed. The purpose of this work is to quantify the importance of a brine layer on an ice surface, the type of changes in the microwave signature which may occur, and the expected signal dynamics. predicted results are produced by the integration of an n-layer reflectivity model for use in determining the effective reflectivity of the air-brine-ice-water system, a sea-ice electrical-property model for predicting the ice sheet permittivity profile based on the temperature and salinity profile, an electrical-pmperty model for brine, and EM models based on Kirchoff methods to predict backscatter for a rough surface. T h w results are compared with in-situ observations conducted during the recent Office of Naval Research Accelerated Research Initiative of the Electromagnetics of Sea Ice. Model predictions and measured data extend the microwave and millimeter-wave (0.5 to 95 GHz) portion of the electromagnetic spectrum.