A High-Pressure Dry-Gas Miscible Displacement SchemeSimulation and Economics

Abstract

Summary To develop an enhanced recovery scheme for theCardium E pool, the feasibility of waterflooding andgas injection was examined. A compositional modelwas developed to account for mass transfer andchanges in composition of this undersaturated, highly volatile oil system. High-pressure dry-gasinjection was desirable to achieve a high degree ofmiscibility. Introduction The Caroline Cardium E pool, discovered in June1974, is approximately 65 km (40 miles) southwest ofRed Deer, Alta. (Fig. 1). The discovery well was theHudson's Bay Oil and Gas (HBOG) 10–16–34–06W5, which was followed by the drilling of five additionalwells in the Bearberry Cardium A pool(T34, R06W5). The existence of a 23-km (14-mile) northwestextension of this Cardium trend was proved by thedrilling of the Pacific et al. Ricinus 10–22–36–08W5 inAug. 1975 and subsequently confirmed by the Pacificet al. Ricinus 11-28-35-07W5 in Jan. 1976. The arealextension involving T36, R08; T35, R07;and part ofT36, RO7 will be referred in this study as the areaoperated by Pacific Petroleums Ltd. The oil reservoirin these wells initially was referred to as the CardiumU pool. In Aug. 1976, an application was filed with theAlberta Energy Resources Conservation Board(ERCB)** requesting a special 130-ha (320-acre)spacing unit comprising either the northern orsouthern half of the section. This request was basedmainly on the marginal economics for developingthis thin-pay, narrow-type reservoir. It was approvedby the ERCB in an order prescribing drilling spacingunits in the Caroline area that became effectiveNov. 1, 1976. On this basis, the well allowable wasapproximately 9 m3/d (58 STB/D). By Dec. 1976, a total of 13 wells had been drilled inthe Pacific-operated area. At that time, based onpressure data and reservoir fluid analysis, Pacific pressure data and reservoir fluid analysis, Pacific filed an application requesting that the RicinusCardium E pool and the Bearberry Cardium A poolbe coalesced into the Caroline Cardium E pool.The ERCB's approval to this matter was given inFeb. 1977.1 As of June 1979, a total of 34 wells hadbeen drilled in the Pacific-operated area. To develop an optimum enhanced recovery schemefor the Caroline Cardium E pool in the Pacific-operatedarea, the feasibility of a waterflooding andhigh-pressure dry-gas miscible displacement schemeshave been examined in this study. A number ofpapers have emphasized the field application of papers have emphasized the field application of high-pressure dry-gas or vaporizing gas miscibledisplacement. It has been shown that a miscibledisplacement of oil with dry gas can be accomplishedif the oil is rich enough in the intermediatecomponents (C through C). The reservoir fluid fromthe Cardium E pool, being a highly volatile oil, appears to be amenable to undergo miscibledisplacement under high-pressure dry-gas injectionand involving multiple-contact miscibility of the gaswith the reservoir oil. JPT P. 359