CO2 Foam Field Verification Pilot Test at EVGSAU: Phase II—Foam Injection Design and Operating Plan

Abstract

SPE Members Abstract The East Vacuum Grayburg San Andres Unit (EVGSAU) operated by Phillips Petroleum, is the site selected for a comprehensive evaluation of the use of foam for improving the sweep efficiency of a CO2 flood. The four-year project is jointly funded by the EVGSAU Working Interest Owners (WIO), the U.S. Department of Energy (DOE), and the State of New Mexico. The Petroleum Recovery Research Center (PRRC), a division of the New Mexico Institute of Mining and Technology (NMIMT), is providing laboratory and research support for the project. A Joint Project Advisory Team (JPAT) composed of technical representatives from numerous major oil companies, PRRC, and DOE provides input, review and guidance for the project. This paper is the second in a series of papers detailing various aspects of the CO2 Foam Field Verification Pilot test at EVGSAU. An earlier paper summarized the project plans and detailed the laboratory work leading to the selection of a surfactant for the field trial. This paper presents:an overview of the operating plan for the project,details of the foam injection schedule and design criteria, anda discussion of the data collection program and performance criteria to be used in evaluating successful application of foam for mobility control in the EVGSAU CO2 project. Specific items discussed in the foam injection design include the determination of surfactant volume and concentration, selection of the surfactant-alternating-gas (SAG) injection sequence for foam generation, field facilities, operations during foam injection, and contingency plans. An extensive data collection program for the project is discussed including production testing, injection well pressure and rate monitoring, injection profiles, production well logging, observation well logging program, and both gas and water phase tracer programs. Introduction The EVGSAU, located about 15 miles northwest of Hobbs in Lea County is the site of the first full-scale miscible carbon dioxide injection project in the state of New Mexico. CO2 injection at EVGSAU began in September, 1985. The CO2 project area covers 5000 acres developed using an 80-acre inverted nine-spot flood pattern. The total CO2 injection rate is about 30 MMcf/D. A water-alternating-gas (WAG) ratio of 2:1 (time basis) is used in the project, resulting in about one-third of the project area being on CO2 injection at any one time. In any given area, a WAG cycle consists of about four months of CO2 injection followed by eight months of water injection. This results in approximately 1.5 to 2% hydrocarbon pore volume (HCPV) CO2 injection and 3 to 4% HCPV brine injection per WAG cycle. The project is currently in the seventh WAG cycle. The tertiary oil response at EVGSAU to date has been very favorable. As shown in Figure 1, the waterflood decline established prior to CO2 injection has been arrested, and oil production has held approximately constant near the current 9000 BOPD Unit total for the past six years. P. 115^

Foam Field Tests: State of the Art and Critical Review

“…This test, a four-year project started late 1989 andjointly funded by the US DOE, the state of New Mexico and the field owners, has been well documented [20][21][22][23][24][25].…”

“…The objective of this test is to divert injected CO 2 from highpermeability zones and reduce breakthrough at the producers. Only near-well effects were expected due to surfactant adsorption [21], despite injection of a sacrificial slug. Rapid foamer solution slugs alternating with gas caused an increase in injection pressure, showing foain generation.…”

Understanding aqueous foam with novel CO2-soluble surfactants for controlling CO2 vertical sweep in sandstone reservoirs

“…Carbon dioxide (CO 2 ) foams in porous media with aqueous soluble surfactants have been widely studied in connection with their application in enhanced oil recovery (EOR) (Lee and Heller 1988;Du et al 2007). These experimental and theoretical studies have contributed to the success of several field foam applications (Patzek 1996), especially for carbonate reservoirs (Hoefner et al 1995;Stevens 1995). Unfortunately, field experiences have shown that conventional foams with only aqueous soluble surfactants have some important limitations.…”

Polymer Foam Flow in Porous Media under Different Injection Modes

“…Shan, et al [1] given an optimal foam-injection strategy in homogeneous reservoirs with a variety of foam models by using simulation. Stevens, et al [2] presented an overview of the operating plan for CO 2 foam injection and the details of the CO 2 foam injection schedule and design criteria in the East Vacuum Grayburg San Andres Unit. Hou, et al [3] compared three main injection modes, including co-injection of gas and solution, alternative injection of gas and solution, and direct injection of foam and pointed that the direct injection of foam was the most effective mode and the alternative injection of gas and solution is the poorest.…”