A new oil resourceConocoPhillips applies to AOGCC for rules for Kuparuk Moraine oil pool ALAN BAILEY Petroleum News
ConocoPhillips has applied to the Alaska Oil and Gas Conservation commission for the approval of pool rules for a new oil development in the Moraine oil pool, in the northwestern part of the Kuparuk River unit. In its application the company says that it plans initial development from the existing onshore 3S drill site, with produced fluids to be commingled with other Kuparuk production for processing in a Kuparuk central processing facility. Additional development may take place from one or more new drill sites, the company says.
ConocoPhillips spokeswoman Natalie Lowman told Petroleum News in an April 7 email that the company is currently evaluating the commerciality of the Moraine deposit and the applicability of various development scenarios.
The proposed development involves turbidites of the upper and lower Moraine members of the Torok formation, in the relatively shallow Brookian rock sequence. Turbidites are rocks consisting of sandstone layers and channels, laid down as a consequence of periodic submarine sand flows in an ancient marine basin. The Moraine oil pool lies at depths between 4,940 feet and 6,190 feet below the surface.
The 3S drill site was originally developed to support the Palm satellite field, which came on line in 2003, producing from the Kuparuk C4 interval below the Moraine. The Palm No. 1 well penetrates the Moraine and provides a type section for the Moraine reservoir.
Layered reservoir ConocoPhillips says that reservoir sands within the Moraine members vary in thickness from less than a few inches to a few feet, with the sand grains typically being very fine grained to fine grained, but with rare occurrences of medium sands. The porosity ranges from 15 to 30 percent. Oil is trapped in the sands as a consequence of mudstone layers between the sand bodies, although the strata lie in a broad anticline that has contributed to the trapping mechanism.
The company anticipates the Moraine development requiring the drilling of horizontal wells through the reservoir rocks, with staged hydraulic fracturing used to stimulate oil production in the highly laminated reservoir. Well bores may extend horizontally as far as 20,000 feet from the 3S drill site location. Well lengths within the reservoir will range from 3,000 to 8,000 feet, in alternating rows of production and injector wells. The company anticipates using waterflood as the primary method for maximizing oil recovery, although the injection of lean gas or miscible gas injectant may be needed at some stage. The first injector/producer well pair drilled will enable testing of the fluid communications through the reservoir, the company told AOGCC. Gas lift will enhance well productivity.
Sand continuity Turbidite rock sequences of the type involved in the Moraine oil pool tend to be compartmentalized. But tests from existing wells indicate lateral reservoir sand continuity of 1,000 to 2,000 feet, ConocoPhillips says. A high initial water saturation does present an initial risk to production - this risk will be addressed through the potential application of water-alternating-gas injection techniques.
For the development from the 3S drill site and one additional site, ConocoPhillips estimates original oil in place to be somewhere in the range of 200 million to 800 million barrels. With an anticipated recovery factor in the range of 10 to 40 percent, oil recovery may range from 20 million to 320 million barrels from the two sites.
Encountered in 1965 According to information provided in ConocoPhillips’ pool rules application, the Moraine reservoir was first encountered in 1965 by Sinclair Oil Corp., when drilling the Colville No. 1 well, targeting a deeper horizon. Tests of the reservoir by Texaco in the 1980s, using the Colville Delta No. 2 and No. 3 wells resulted in insignificant oil flow rates, although fracture stimulation of the No. 3 well upped the rate to modest levels. ARCO Alaska, ConocoPhillips’ predecessor company, evaluated the reservoir in the 1990s using the Kalubik No. 1 and No. 2 wells - unstimulated flow from the No. 1 well showed minimal oil production.
Between 2010 and 2012 Pioneer Natural Resources drilled and completed three production wells in the upper Moraine member in the Oooguruk unit, to the immediate northwest of the Kuparuk unit. Those wells achieved initial production rates of 350 to 600 barrels of oil per day.
Then, in 2013, ConocoPhillips hydraulically stimulated the upper Moraine member from the 3S-19 well, a well that targeted the Kuparuk C-sands but which presumably penetrated the Moraine. That test resulted in a flow rate of 250 to 300 barrels per day from the Moraine reservoir. In 2015 the Moraine No. 1 well further evaluated the characteristics of the reservoir. Also in 2015, ConocoPhillips drilled the 3S-620 well, with a 4,200-foot lateral through the Moraine reservoir, using an eight-stage hydraulic fracturing program to achieve a production rate of 1,575 barrels of oil per day - there was a relatively high rate of water production along with the oil.
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