Combination Gas and Water Injection Project - Leduc D-3 Pool

Abstract

Abstract The oil zone in the Leduc D-3 Pool is sandwiched between an extensiveoverlying gas cap and a large underlying aquifer. It is therefore free to moveto higher or lower elevations within the reef, in response to any imbalancebetween gas cap expansion and water influx. Recent studies have shown that itwill be necessary to control the movement of both the gas-oil and oil-watercontacts relative to well completion intervals for optimum recovery andperformance. The field has been unitized and both gas and water are beinginjected to achieve this objective. The results of a detailed engineering studyare being used to control injection ratios and pool performance. Introduction The discovery, geology, development and performance of the Leduc D-3 Poolhave been discussed in the past. Only a brief chronological summary of poolhistory will be given here to provide a basis for this review of reservoirengineering studies. The reservoir was discovered in 1947 about 12 milessouthwest of Edmonton. Early development was spread over a period of severalyears with a total of 535 wells being drilled to 5300 feet on 40-acre spacing.At least four separate pools have been defined as shown in Figure1. Thesubject of this paper is the "Main Reservoir", which covers almost 90 per centof the developed acreage. Its properties are summarized in Table 1. It was in 1948 that Atlantic No. 3, drilling on the eastern edge of thepool, blew wild for six months. The uncontrolled production of oil and gas-capgas during this period resulted in a sharp decline of 50 psi in reservoirpressure. An estimated 28 billion cubic feet of gas was produced withapproximately a million barrels of oil, most of which was salvaged in earthenpits.