Abstract

Cold production is a primary recovery method used by producers in the Lloydminster area to improve recovery rates from heavy oil reservoirs by producing sand aggressively along with heavy oil. It improves oil production rates substantially through regions of increased permeability - wormholes. The process seems to key on the formation and flow of foamy oil into wormholes, as they grow into the reservoir. The wormholes provide significantly increased access to the reservoir. The area drained by a cold production well can be called its footprint. Identifying and mapping cold production footprints is useful in the planning and development of reservoir exploitation strategies for cold production pools. The cold production research group at the Alberta Research Council is constructing reservoir engineering tools, such as field scale numerical simulation models, that can be used to assess cold production footprints. The results generated by the tools will be illustrated with examples from an intensive study of a set of Edam cold production wells.

Introduction

Cold production is a method for enhancing primary production from heavy oil reservoirs. In the cold production process, sand is produced aggressively along with heavy oil. The process improves oil production rates substantially through regions of increased permeability - wormholes. It seems to key on the formation and flow of foamy oil into wormholes, as they grow into the reservoir. The wormholes provide significantly increased access to the reservoir.

The cold production process has been applied with commercial success by producers in the area surrounding Lloydminster. It emerged as a viable commercial technology for the recovery of heavy oil in the mid to late 1980s, with the adaptation of progressive cavity pumps for heavy oil lift operations. By the mid 1990s, cold production had become widespread throughout the Canadian heavy oil industry. Currently, it is established as one of the principal methods for recovering heavy oil from the Western Canadian Sedimentary Basin (WCSB). Production of heavy oil generated by cold production technology in western Canada is roughly 37,000 m3/day, from a producing well count of nearly 6,000, according to production figures for November 2001 (the most recent figures available at the time of writing). This is an unofficial estimate; no official production volumes for cold production have been assembled. The estimate was calculated for a current Alberta Research Council (ARC) internal study; production that could reasonably be attributed to the cold production process was determined from heavy oil sales volumes reported to the Alberta and Saskatchewan regulatory agencies(1). It forms a significant portion of the total production of heavy oil from western Canada (including net in situ bitumen production in Alberta) - approximately 140,000 m3/day according to official National Energy Board estimates for the same period(2).

The development of cold production as a successful commercial recovery technology has been field-driven. A substantial body of knowledge and expertise on cold production exploitation strategies and operating practices has been accumulated by Canadian heavy oil producers, through hard-won field experience.

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