Overview: EOR/IOR (January 2006)

Abstract

Papers in this feature discuss the incremental oil production from three field projects that use three different enhancement technologies: biotechnology, or microbial enhanced oil recovery (MEOR); miscible gas; and mobility-control polymer. Petro-Tech Peruana S.A. reported an impressive improvement after inoculating two pair of production wells in different offshore fields. Both fields contained a paraffinic crude oil that, when treated by conventional wellbore-cleanup technologies, simply maintained oil-production rates. Biotreating the producers resulted in improved oil rates, and subsequent radial inoculation further enhanced oil rates, approximately doubling the pre-MEOR rates. A peripheral, downdip, high-pressure gas-injection project in the RKF field in Algeria also is impressive. The paper discusses the discovery, development, and operation of a miscible-gas-cycling project in a fluvial complex of carboniferous reservoirs of low-permeability, high-clay-content formation containing asphaltic crude oil and salt-saturated water. During 8 of the 9 years of operation, production was maintained at approximately 20,000 B/D. A tracer study to quantify well conductivity and help identify preferential flow was implemented early in the gas-injection phase. Additional laboratory studies to support continued numerical simulation were performed, with the objective of continued studies being to define and select options that would improve oil recovery as gas injection continues. Three mobility-control pilot projects in Brazil complete the trio of papers. Four polymer pilot projects were started in 1997, 1999, and 2001 in the Carmopolis, Buracica, and Canto do Amaro fields, respectively. Mobility ratios ranging from 2 to 12 for water displacing crude oil provide a motive to implement the different mobility-control-polymer pilot floods. Injectivity changes and differences in interwell tracer studies are reported. Oil production increased, and declining water/oil ratios are discussed for each pilot and for well patterns within each pilot. These projects emphasize the importance of an ongoing evaluation and study of an EOR flood to maintain oil production and maximize oil recovery. Continual monitoring of project performance and reaction to what is happening in the field, making adjustments as necessary, and learning from performance are essential for successful expansion as well as for continued operation. EOR/IOR additional reading available at the SPE eLibrary: www.spe.org SPE 94139 "Application of Tracer Technology for Optimizing RKF Miscible-Gas-Injection Recovery—Field Case," by H. Cubillos, SPE, Cepsa, et al. SPE 94808 "Twenty Years of Steam Injection in Heavy-Oil Fields" by J.C. de Souza, Petrobras, et al. SPE 93100 "Sorption of Surfactant Used in CO2 Flooding Onto Five Minerals and Three Porous Media," by R.B. Grigg, SPE, New Mexico Recovery Research Center, et al. SPE 93241 "Gasflood Flow-Pattern Evaluation: Mesozoic Chiapas-Tabasco Basin Field Revisited," by M. Mercado, Pemex, et al.