Case History and Appraisal of the West Buffalo Red River Unit High-Pressure Air Injection Project

Abstract

AbstractThe West Buffalo Red River Unit (WBRRU) project is one of the three High-Pressure Air Injection (HPAI) projects in the Buffalo Field. It produces from the Red River reservoirs, which are deep (~8,400 ft), thin (~15 ft), hot (215 °F), low permeability (~10 md) carbonates. The unit comprising 4,560 acres with 15 producing wells was formed in July 1987 and began air injection operations four months later.Before unitization the oil production was declining steadily but the response to air injection has resulted in a significant production increase over its historical decline. While unit production in July 1987 was 200 BOPD, a peak production rate of 500 BOPD was achieved in January 1990 with 15 producing wells, after the injection of 2 BSCF of air. As of December 2006 about 23 BSCF of air had been injected, for a cumulative oil production of 2.3 MMSTB since the beginning of injection.This paper reviews the production and economic performance of the WBRRU high-pressure air injection project to date. The production performance analysis includes estimates of incremental oil recovery due to air injection using conventional decline curve analysis, the expected ultimate recovery using the volume-burned method, and a discussion on how air utilization has changed over time. A detailed economic evaluation is carried out using different economic yardsticks such as net present value and incremental rate of return. A discussion on the impact of oil price on the economic profitability of the project is presented as wells as an estimate of the minimum oil price required for attractive economic results.To date, the HPAI project in WBRRU continues to be a technical and economic success. In year 2005 old vertical producers were re-entered to drill horizontal laterals and take advantage of the great reservoir response to injection.