Providing coverage of Alaska and northern Canada's oil and gas industry
May 2019

Vol. 24, No.19 Week of May 12, 2019

Brooks Range applies for injection order

Company plans water injection as the primary technique for enhanced oil recovery from the Mustang field on the North Slope

Alan Bailey

Petroleum News

Brooks Range Petroleum Corp. has applied to the Alaska Oil and Gas Conservation Commission for an area injection order that would authorize the injection of fluids into the Kuparuk oil pool in the Southern Miluveach unit, as part of the development of the Mustang oil field, on the North Slope. Brooks Range plans to start up the Mustang field this year. According to the AOGGC application, fluids injected for reservoir pressure maintenance and enhanced oil recovery would primarily consist of seawater and produced water, but with gas also being injected. Waterflood would be the primary reservoir pressure maintenance and enhanced recovery technique. Brooks Range is constructing a pipeline to ship seawater for injection from the seawater system in the neighboring Kuparuk River field, operated by ConocoPhillips.

Kuparuk A and C sands

According to the application, the Kuparuk oil pool in the Southern Miluveach unit occupies a continuation of the Cretaceous age Kuparuk A and Kuparuk C sands from the adjacent Kuparuk River unit. Brooks Range anticipates the drilling of 10 horizontal production wells and up to 11 horizontal injection wells as part of the initial development of the Mustang field, the application says. Some production wells may be hydraulically fractured to improve production and ultimate oil recovery.

Most of the development wells will trend north-south, parallel to a pattern of geologic faults that intersect the reservoir. Horizontal sections of wells may be up to 6,000 feet in length, with production wells alternating with injection wells. Some further infill drilling may be needed to maximize recovery.

Modeling of the reservoir performance indicates that at some stage it may be necessary to follow water flooding with the use of gas or a mixture of gas and natural gas liquids, to further improve oil recovery, the application says. Gas would come from the Mustang field processing facilities.

Variable thickness

The application says that the Kuparuk oil pool lies in the A and C sands, within the depth interval 6,008 feet and 6,090 feet in the Tarn 1A well - the sands range in thickness from zero to 80 feet in the development area. The Kuparuk A sand consists of a relatively fine-grained shallow marine sandstone overlain by the coarser grained Kuparuk C sands. The Kuparuk A, with its fine grain size, is generally less permeable than the Kuparuk C. Both sands have porosities of around 22%.

The oil trap is formed by a major geologic structure called the Colville Anticline. Oil is sealed in the Kuparuk sands by the overlying Kalubik shale, an extensive thick shale found in the region. Another impervious shale, the Miluveach, underlies the sands.

Starting small and growing

Although Brooks Range had originally planned to start up the Mustang field using permanent production facilities with a capacity of 15,000 barrels per day of oil, the vagaries of the oil price in recent years have caused the company to scale back the startup to the use of a small temporary facility, with production potentially ramping up to 6,000 bpd by the end of this year. Then, as revenue from the production comes in, the company anticipates scaling up the field towards a full development.

Brooks Range plans to start oil production at Mustang soon from a single well, the North Tarn 1A well. According to the company’s latest plan of operations, the company also plans to drill a lateral sidetrack from a partially completed well, the Mustang 1 well, and to complete the perforation and stimulation of the SMU M-02 well. Development will then proceed this year with the drilling of additional wells.

Following the initial use of the SMU M-02 for testing the performance of the well reservoir, this well will be converted to an injection well. Prior to the conversion of this well, any gas produced and not used as fuel gas for field facilities will be flared. Brooks Range has obtained an air quality permit from the Alaska Department of Environmental Conservation that allows the flaring of a certain amount of gas.

Presumably, as field development proceeds, water injection will begin. Maximum injection rates are estimated at 6,000 bpd of water and 6 million cubic feet per day of gas, the injection order application says.

Brooks Range will be the first small, independent operator to see an oil field through from discovery to production on the North Slope.

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