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Pikka injection order approved
AOGCC authorizes underground injection of fluids for enhanced oil recovery and oil storage purposes in the Nanushuk Kay Cashman Petroleum News
On Aug. 21, the Alaska Oil and Gas Conservation Commission said that on April 16, and amended June 11, Oil Search (Alaska) LLC (OSA), a subsidiary of Santos Ltd, as operator of the Pikka Unit requested an order authorizing underground injection of fluids for enhanced oil recovery and oil storage purposes in the area covered by the Nanushuk Oil Pool (NOP).
AOGCC scheduled a public hearing on the application for June 4.
Testimony was received from representatives of OSA. But no public comments on the application were received.
After the hearing OSA decided to expand the affected part of the proposed area injection order to match the extent of the NOP as it was defined in Conservation Order 807.
On June 11, OSA submitted an amended application to expand the proposed Affected Area in its initial application to coincide with the pool extents for the NOP. The proposed expansion required notifications of parties that were not required to be noticed based on the proposed area in the original application. As such, AOGCC tentatively scheduled an additional public hearing for July 18.
On June 12, AOGCC published notice of that hearing. No public comments on the amended application or requests to hold the additional tentatively scheduled hearing were received.
As AOGCC had sufficient information to make a decision on the amended application, the additional hearing was vacated and the area injection order for Pikka was approved on Aug. 21.
Who and where The surface landowners in the NOP area are Kuukpik Corp., the state of Alaska, Katherine Brown, Jim T. Allen and the estate of Helen E. Tukle.
Subsurface owners of the NOP are the Alaska Department of Natural Resources and the Arctic Slope Regional Corp.
OSA and Repsol E&P USA LLC are the working interest owners of the leased acreage within the Affected Area.
OSA is operator of all the leased acreage in the Affected Area. The company proposed that the Affected Area encompass the entirety of the Pikka Unit, which lies between the Colville River Unit to the west, the Kuparuk River, Oooguruk, and Quokka units to the east, the Beaufort Sea to the north and non-unitized state lands to the south. The unit lies mostly onshore on the North Slope of Alaska but also extends onto state submerged lands in the Beaufort Sea.
More than 20 wells AOGCC's findings in regard to exploration and delineation history were that OSA, along with predecessor operators Repsol and Armstrong Energy LLC., have conducted significant exploration activity in the project area. More than 20 wells have penetrated the Nanushuk Formation in the acreage and six of these had successful flow tests and four collected cores from the Nanushuk Formation.
Key wells used to define the NOP include the Qugruk-3, Qugruk-3A, Qugruk-7, Qugruk-301, Qugruk-8, Qugruk-9, Qugruk-9A, Fiord-2, Fiord-3, Pikka B and Pikka C.
Deltaic shelf deposits that were time-equivalent to the shale-dominated Torok Formation sediments were deposited in deeper water.
The NOP is the accumulation of hydrocarbons common to and correlating with that portion of the Nanushuk Formation shown on the Qugruk 3 reference log between 3,892 and 5,166 feet measured depth, which is equivalent to 3,785 and 4,985 feet true vertical depth below mean sea level (also termed true vertical feet sub-sea, or TVDSS).
OSA's informally named "Nanushuk 3" sandstone interval will be OSA's primary development target, but towards the western edge of the NOP the underlying Nanushuk 2 interval becomes more prevalent, and it may also be a development target.
EOR operation Enhanced recovery operations within the NOP will employ a horizontal well line drive pattern with a water alternating gas or rich gas flood, to enhance oil recovery from the reservoir.
Due to the highly laminated nature of the reservoir, all the wells (including the injectors) will be hydraulically fracture stimulated to enhance productivity and improve vertical injection sweep.
Additionally, to remove potentially damaging fracturing gel and confirm rate capacity, frac flowbacks will be conducted; and accompanying oil production from the wells will be re-injected into the reservoir prior to startup to prevent waste. Only pre-production test fluids recovered beyond the initial load recovery will be re-injected, with volumes and injection pressures being tracked to ensure fracture gradients are not exceeded.
The storage operation will involve re-injection of NOP crude oil, solution gas and minor amounts of water recovered from well tests prior to facility startup.
Seawater with alternating gas-injection is likely for enhanced recovery injection into the NOP. After water-breakthrough, individual well patterns may be swapped to produced water.
Injection history at the Colville River Unit has demonstrated the compatibility of both produced water and seawater in Brookian age reservoirs, specifically the Nanushuk Formation at the Qannik pool, over the past 10+ years.
No issues are expected with injection of either seawater or produced water/gas into the Nanushuk. Liquid injection rates between 2,000 and 10,000 barrels per day and gas rates between 3 and 15 million standard cubic feet per day are expected at each injection well drilled for the project and will be managed to achieve and maintain a voidage replacement ratio of one.
Pool to be affected The Nanushuk reservoir is a thick accumulation of deltaic shoreface deposits and is the up dip topset equivalent of the deeper water Torok Formation.
The Torok and Nanushuk formations are the lower portion of the Brookian sequence and are Lower Cretaceous in age.
The development of the NOP in the Pikka Unit contemplates the drilling of long horizontal wells across a number of different order clinoforms.
Conclusions In its conclusions, AOGCC said an area injection order is necessary for the development of the NOP to allow for enhanced oil recovery injection operations and the storage of fluids produced during well cleanup prior to the Pikka Unit processing facilities being brought online. (Santos most recently said Pikka Phase 1 would come online in the first half of 2026.)
Reservoir simulation results show that a primary recovery enhanced by waterflood and water alternating gas injection maximizes ultimate recovery from the NOP.
Further, AOGCC concluded that reservoir voidage will be targeted to maintain a replacement ratio of approximately 1:1.
Maintaining the sand face injection pressure gradient at or below 0.80 psi per foot as OSA plans to do will prevent fractures from forming or propagating in the confining intervals.
AOGCC concluded that an aquifer exemption is not required because water from the injection interval has a salinity of approximately 17,000 ppm.
Waivers to the packer setting depth requirements for injection wells contained in 20 AAC 25.412(b) are common in projects with high angle wells, as are being drilled for the development of the NOP and are appropriate in this situation.
Therefore, AOGCC authorized the underground injection of fluids for pressure maintenance, enhanced recovery, and storage purposes at Pikka.
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