Abstract

The COSH Process (COSH is the acronym of Combustion Override Split-production Horizontal-well) was conceived based on experience gained from a number of successful gravity drainage processes and the less fortunate fireflood process. Typical combustion operational problems such as early oxygen breakthrough, severe sanding and gas locking of downhole pumps are minimized by using an innovative well arrangement to segregate and control the fluid flows. This process is perceived to work very well in a wide variety of reservoirs, ranging from oil sands to conventional bottom water reservoirs.

In February 1994, a joint ADOE/Industry COSH Process Development Task Force consisting of 18 industry, government and research member companies was formed to assess the commercial development potential of COSH in Western Canada. The performance and economics of six high potential field applications, including Athabasca McMurray tar sands, Provost McLaren channel sand, undeveloped Cold Lake Clearwater oil sands, Battrum Roseray, Bellshill Lake Blairmore sand and cyclic steam stimulated Cold Lake Clearwater oil sands, were studied. This paper compares the results of this study and outlines the major technical issues identified by the Task Force.

Introduction

Pilot results from Alberta Department of Energy's (formerly AOSTRA) steam injection projects such as Underground Test Facility (UTF), Kearl Lake and GLISP indicate that gravity drainage is a very favorable recovery mechanism in thermal recovery. The benefits are particularly evident at the UTF Pilot where the Steam Assisted Gravity Drainage process (SAGD) is employed. While SAGD is technically sound, efficient and robust, its applicability could be influenced by a number of economic and resource factors such as natural gas price, fresh water supply, water disposal capacity, etc.

In 1990, investigations were carried out at ADOE to broaden the application of the gravity drainage mechanisms. The COSH Process was conceived as a result of this exercise. Instead of generating steam on surface, compressed air would be injected into the reservoir to generate steam and heat in-situ. Preliminary simulation and economic analyses indicated that the process was very promising. Since the air compression process is more energy efficient and requires less water, the COSH Process could be applicable in a wider variety of field types. In 1994, a joint AOSRD/Industry Task Force was initiated to assess this process. This paper provides a summary of the results obtained.

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