Development of methods for controlling premature oxygen breakthrough during fireflooding. Final report, June 2, 1989-October 1, 1990.

摘要

The overall objective of this study was to characterize the reservoir mechanisms that cause premature oxygen breakthrough, and develop practical tools for controlling it. The focus was on those conditions most likely to be encountered in moderate-depth to deep reservoirs; candidates included gas override, high-permeability steaks, and water underlie. Mitigation measures were selected based on due consideration of the cost of implementing them and their potential application to a wide range of specific problems. An overriding consideration was practicality for field use. This report details the results of Phase I which consisted primarily of characterizing the problem and selecting candidate mitigating measures suitable for simulation testing and modeling. Some of the design fabrication efforts that could be performed in parallel were also included. Based on the work performed in a linear tube system, the following preliminary conclusions can be drawn: Sodium chloride added as an injectant solute is effective in reducing the permeability of a sand pack by crystallizing in open spaces via thermal means. Crystallized sodium chloride can be dissolved by a solute within the sand pack and precipitated out of solution at a different area of the sand pack by thermal means. The amount of sodium chloride required to reduce the permeability of a specific area of the sand pack can be reduced by the addition of sodium silicate. Sodium silicate solution when acted upon by carbon dioxide will also reduce the permeability of the sand pack. These three systems (sodium chloride, sodium chloride and sodium silicate, sodium silicate and carbon dioxide) should be considered for further testing in a reservoir simulator prior to field application to determine their effectiveness and overall economics. 190 refs., 18 figs., 6 tabs.