Vol. 28, No.13 Week of March 26, 2023
Providing coverage of Alaska and northern Canada's oil and gas industry

Another step forward

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Another step forward Oil Search files Pikka Nanushuk pool rules, estimates 592-868 million barrels

Kristen Nelson

Petroleum News

As Oil Search continues to move toward production at its Pikka unit on the North Slope, the company has applied to the Alaska Oil and Gas Conservation Commission for pool rules for the Nanushuk oil pool at Pikka.

Oil Search (Alaska) LLC, the Pikka unit operator, a subsidiary of Santos Ltd., submitted the March 6 pool rules application on behalf of itself and Repsol E&P USA LLC, the other working interest owner.

The company said that prior to beginning injection it will apply to AOGCC for an area injection order to authorize water-alternating-gas, WAG, for the proposed Nanushuk oil pool.

Oil Search said the area proposed for the Nanushuk pool rules coincides with the Pikka unit boundary.

“The Nanushuk Oil Reservoir does extend outside the unit boundary to the south and to the west of the Pikka Unit into leases operated by ConocoPhillips Alaska,” Oil Search said, with the extent of the Nanushuk “proven by recent delineation wells drilled in those areas as well as recent seismic interpretations.”

The Nanushuk Oil Pool is the accumulation between measured depths of 3,892 and 5,166 feet or 3,785 feet true vertical depth subsea and 4,985 feet TVDSS in the Qugruk 3 well, the company said.

The Pikka working interest owners plan to form a separate participating area for Nanushuk oil within the unit, Oil Search said, but “the intent of the pool rules and AIO (area injection order) application will be to align development strategies and minimize waste across the Pikka Unit boundary and any future expansion acreage.”

Project development

The final investment decision for the project was made in the third quarter of 2022, followed by pool rules submission in the first quarter of 2023 with drilling operations slated to begin in the second quarter of 2023, facilities installation to begin in 2023 and first oil production targeted for the second quarter of 2026, Oil Search said.

Out of more than 20 known penetrations of the Nanushuk, there is flow test data from six wells and Nanushuk core from four wells. Wells and associated sidetracks important to delineation of the Nanushuk within Pikka are the Qugruk 3, Qugruk 3A, Qugruk 7, Qugruk 301, Qugruk 8, Qugruk 9, Qugruk 9A, Fiord 2, Fiord 3, Pikka B and Pikka C.

Within the Pikka unit, some 15 miles long and 3 miles wide, the company said “Nanushuk fluid samples were collected from nine wellbores and Alpine fluid samples were collected from two wellbores.”

Initial development will be only from the Nanushuk oil pool.

Phased development

Oil Search said the Nanushuk oil pool development will be “completed in discrete phases to apply knowledge gained from previous phases and improve recovery.”

Most wells will have lengths of 3,000 to 8,000 feet within the reservoir.

The current development plan for the project includes the Nanushuk Processing Facility or NPF; Nanushuk phase 1 drill site B and future drill sites A and C; the Nanushuk Operations Pad; infield pipelines, import and export pipelines; infield and access roads; and a tie-in pad at ConocoPhillips’ Central Processing Facility 2. A new seawater treatment pad will be built at Oliktok Point.

Multiphase fluids will be processed at the NPF and sales oil exported to Kuparuk Transportation common carrier pipeline for delivery to the trans-Alaska pipeline.

“The produced water separated at the NPF will initially be disposed into the Ivishak disposal zone and then after sufficient volume is available, will be delivered to the drill sites and injected into the producing formation,” Oil Search said.

Produced gas will be compressed and dehydrated at the NPF and used as fuel gas and for injection. “Fuel gas may be imported from outside the Pikka Unit to preserve indigenous gas for enhanced oil recovery injection,” the company said.

Nanushuk injection wells will be water alternating gas, or WAG, injection wells.


Oil Search said the decision to begin development from the Nanushuk B gravel drill site was based on the ability “to target the NOP from that surface location and due to the ability to use infrastructure already established to process and transport oil to Pump Station #1.”

The initial drill site and others that are part of the full development plan will be “unmanned and require minimal operator presence for daily operations,” with data gathering and routing done remotely from the main field control room, the company said.

Drill sites are designed for 40-50 wells on 20-foot centers, with 44 wells planned initially for the Nanushuk B drill site.

Facilities at the NDB drill site will include: gas lift, water injection and gas injection lateral piping and headers; multiphase metering; production heating and chemical injection equipment; and instrumentation, control and communication equipment.

Production from drill sites will be separated into wet oil, gas and water streams at the NPF.

“Gas separated from oil in the separation train is processed and compressed primarily for artificial lift and reinjection,” the company said. Produced water separated from the stream will be disposed of or reinjected into the reservoir for pressure maintenance and waterflood, with seawater injection pumps used for injecting seawater into the reservoir for pressure maintenance and waterflood.

OOIP, recovery estimates

Original oil in place, OOIP, is estimated in a range from 2,297 million to 2,814 million barrels “for the development planned from the NDB (Nanushuk drill site B) and additional drill sites,” Oil Search said.

“The crude oil viscosity and initial pressure requires adoption of a secondary recovery mechanism to obtain an economic production profile,” the company said. “WAG injection will be implemented as the main improved recovery process as it has been widely used on the North Slope with consistent success.”

Primary recovery is estimated to recover less than 7% of the OOIP, 161 million to 253 million barrels.

Primary recovery plus waterflood is estimated to recover 23%, 532 million to 718 million barrels.

By adding gas injection - miscible or immiscible - recovery is estimated to total 26-29%, 592 million to 868 million barrels.

“Resource recovery for floods is heavily dependent on injection throughput, waterflood recovery efficiency, and gas injection recovery efficiency,” the company said.

Oil Search said development of the Nanushuk oil pool is expected to use horizontal wells, with initial producer to injector spacing of 1,800 feet and adjustment possible based on long-term production from initial wells.

Lateral reach will be as far as 31,000 feet from current drill site locations, the company said, and may reach farther depending on the location of any additional drill sites and available technologies.

“Unlike more typical multi-zone or multi-layer fields on the North Slope, the NOP represents a single hydrocarbon accumulation. Production from a single pool minimizes profile modifications and well work will focus on maintenance within an existing wellbore (paraffin/scale removal) that does not require a sundry,” Oil Search said in discussing well work operations and necessary AOGCC approvals for those operations.

The commission has scheduled a public hearing for April 18 at 10 a.m. at its Anchorage offices. The call-in information is 907-202-7104 conference ID: 665 332 079#.

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