Horizontal Well Cyclic Combustion, Wabasca Air Injection Pilot
Authors: Thornton B. , Hassan D. , Eubank J. 
Published: March 2010

Amoco Canada Petroleum Co. Ltd. and Alberta Department of Energy (Oil Sands & Research Division) are currently testing a novel combustion-related heavy oil recovery scheme utilizing horizontal wells in a thin pay horizon in the Wabasca area. The pilot is located approximately 250 km north of Edmonton, Alberta, at the south end of the Wabasca oil sands deposit. Primary production utilizing horizontal wells has proven economic in the area but the expected recovery is only 5 – 10%. The combustion pilot utilizes a central horizontal air injection well with two outside producing horizontal wells. This is a unique system in that it is the first time a horizontal well has been used as an air injector. All three horizontal wells were initially placed on primary production. The central horizontal injection well was then preheated with steam and ignited with air. Once air injection was terminated, production commenced from the two outside horizontal wells. Production response to date has been favourable in this first cycle due to the reservoir repressurization that has occurred. This enhanced oil recovery process may allow industry to economically extend the production of thin pay reservoirs beyond primary depletion.

Introduction

The Wabasca In Situ Horizontal Combustion Project is located approximately 250 km north of Edmonton, Alberta, at the south end of the Wabasca oil sands deposit as shown in Figure 1. The main oil bearing formation is the Wabiskaw ‘A’ sand with an average reservoir thickness of 5 m. The API gravity of the oil is 14 ° and the viscosity is between 5,000 - 10,000 cp at a reservoir temperature of 15 °C. Other reservoir parameters are shown in Figure 2. Amoco Canada holds approximately 60 sections of oil sands leases in the immediate pilot area. The first two primary horizontal wells were drilled in 1988. Currently, Amoco has a total of 12 horizontal wells which have been drilled for primary production. Primary recovery with horizontal wells is economic but is only estimated to produce 5 – 10% of the original oil in place.

Amoco Canada has initiated a cyclic combustion pilot utilizing three horizontal wells (see Figure 2). There is a central horizontal injection well flanked on either side by horizontal producing wells. After a period of primary production from all three wells, the injection well was preheated with steam, then ignited with air. Initial production results from the flank wells in the first cycle have yielded promising results to date, due to the reservoir repressurization that has occurred.

The results and conclusions reported in this paper are based on pilot operations to December 1994.

History

Vertical wells in the Wabasca area have been unsuccessful both from a primary and enhanced oil recovery perspective. Primary production rates have been low (on the order of 1 to 2 m3/d) and cyclic steaming, electrical wellbore heating and conventional fireflooding have failed to yield commercially viable results. Since 1988, Amoco Canada and CS Resources (which is the other major operator in the area) have been pursuing horizontal well primary production as a means of economic reservoir development.