Abstract

Murphy Oil Company Ltd., on behalf of working interest partners CS Resources and Liftlock Resources, has operated the Eyehill In-situ Combustion Pilot since 1980. In June of 1990, after nearly ten years of operation, air injection was suspended as continuing operational problems and significant operating losses eroded technical justification for maintaining air injection. The initial post-injection period (6–8 months) resulted in some of the best performance results seen to date at the pilot including a number of monthly production records. Some fireflood indicators have decreased, but remain apparent even two years following the cessation of air injection.

In February, 1992, Murphy drilled the first horizontal well along the SE boundary of the pilot. Initial production performance was well above expectations with evidence of combustion gases in the produced gas. Based on the success of the first well, two additional wells were drilled ill the summer of 1992, including one that passed through two of the fireflood patterns. The three horizontal wells all have varying levels of influence from the pilot corresponding to the placement of the horizontal wellbore relative to the project.

Introduction

The Eyehill Cummings sand pool is located roughly 100 km south of the city of Lloydminster (Figure 1), and has been producing heavy oil since its discovery in June, 1971. From 1971 to 1979, a total of 17 locations were drilled to delineate the pool resulting in 12 primary oil wells and 5 abandonments. The producing wells encountered anywhere from 5 to 18 m oil pay, in some cases with as much as 15 m water underlying the oil column. Although initial production rates in the order of 7 cubic metres of clean oil per day were encouraging, the high water/oil mobility ratio on wells associated with bottom water resulted in rapid increases in water cut and poor ultimate oil recoveries (less than 1% of the original oil-in-place based on a 16 ha drainage unit). On an areal basis, in excess of 50% of the interpreted resource was underlain by water (almost 70% on a volumetric basis). Thus, it became apparent early on that improved pool recoveries would require some form of enhanced oil recovery technique.

From 1980 to 1982, Murphy Oil Company Ltd., in cooperation with the Government of Saskatchewan and Energy, Mines, Resources in Ottawa, and along with working interest partners Canadian Reserve and Canada Cities Service initiated the Eyehill Thermal Project. A total of 16 producing wells and 9 air injectors were drilled to complete nine 8 ha inverted five-spot patterns (Figure 2) that would test the applicability of a dry in-situ combustion process in a bottom wet heavy oil reservoir.

From 1982 to 1986, air injection was supplied by two Ingersol Rand electric drive compressors injecting a total of 254 E 3 m3air per day into the 9 patterns. In 1986, the sudden drop in world oil prices had a devastating effect on project operating margins given heavy oil prices of less than $65/m3 and historical operating costs in the $120/ m3 range.

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