Vol. 24, No 2 Week of January 13, 2019
Providing coverage of Alaska and northern Canada's oil and gas industry

Sourdough drilling

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First new well in eastern North Slope prospect in early 2020

Kay Cashman

Petroleum News

For years industry observers saw new drilling at the Sourdough oil prospect on state land next to the border of the Arctic National Wildlife Refuge as key to opening ANWR’s 1002 area to oil and gas exploration and development.

While the Trump administration recently took the first step by planning two ANWR 1002 lease sales, the first of which is expected to take place in October, it appears a new Sourdough well in the ExxonMobil-operated Point Thomson unit will follow early in the winter of 2020.

Per this issue’s lease report on page ______, Jade Energy’s newly approved agreement with Exxon on ADL 343112, the most southeasterly lease in Point Thomson, involves a commitment to drill on the lease, which contains the two 1990’s Sourdough wells. Geologists think Sourdough’s reservoir, estimated at 100 million recoverable barrels based on the two wells, stretches under the 1002 area.

The new drilling plan proposed for Point Thomson state of Alaska lease 343112 is spelled out in the two-year Point Thomson Unit 2018 Area F Plan of Development, submitted Dec. 21 to the Alaska Department of Natural Resources’ Division of Oil and Gas by Alaska-based Jade.

Although Oil and Gas Division Director Chantal Walsh formally told the unit working interest owners - Exxon, BP, ConocoPhillips, Colt and most recently Jade - in a letter that the POD “as submitted” does not meet the requirements set forth in regulation, that fact “in no way triggers the release of Area F acreage.” Dec. 21, she noted, “remains the date of submittal” for purposes of the Point Thomson Unit Settlement Agreement with the state, which dates back to March 29, 2012.

Proposed drilling

The plan of development turned in by Jade’s managing director Erik Opstad calls for targeting Brookian oil reserves, which was the kind of play found at the Sourdough prospect.

Within the Point Thomson unit, Brookian reservoirs are “generally interpreted as amalgamated lowstand channel fill and basin-floor fan deposits,” the plan said, pointing out that “typically” these reservoir sands are “predominantly” found onshore at depths between 11,000 feet and 12,000 feet true vertical depth, TVD.

New seismic 3-D data was acquired over the Sourdough area by Jade during the 2017-18 winter season, which the company is currently having evaluated, the plan said.

Jade is also “seeking to access additional seismic data and has engaged a well-known consultancy to assist interpreting that data.”

When that work is finished the company said it will select an “optimized” well location “to further evaluate the deliverability of the Brookian reservoir,” and further delineate “both the vertical and areal extent of the oil accumulation.”

The well will be drilled in the first quarter of 2020.

The well site, the plan said, will be accessed by an ice road and Jade is “involved in ongoing discussions” with Exxon to secure support from “existing unit infrastructure resources.”

Jade will gather data from the vertical pilot hole such as mechanical drilling parameters, LWD data, wireline logs, sidewall and conventional cores, VSP and check-shot information or drill stem test data, the plan said.

Such information will be “used to determine the suitability of the encountered stratigraphic reservoir section for horizontal well construction. Jade feels that that the deployment of horizontal production wells is a critical element in commercializing the Point Thomson unit Brookian opportunity in Area F, as well as its adjoining areas,” the plan said.

“Once a vertical pilot hole is drilled, the well will be plugged back and drilled at a high angle into the Brookian reservoir for completion and an extended production test. Production data gathered at this time would be used to analyze the economic viability of a field development program,” the plan said.

At the conclusion of this evaluation the well will be plugged and abandoned or suspended.

Upon completion of drilling and extended production testing, analysis of the data “would be integrated into the Jade 3D Brookian seismic model,” the plan said.

With those results in hand, a second plan of development will be prepared and submitted by Jade to DNR by Dec. 1, 2020.

Work done to date

As part of the development plan Jade outlined work done to date, noting the Brookian reservoir in Area F has been delineated and characterized by five wells that were drilled in and around the Point Thomson unit since the mid-1970s.

Three of the wells are in the northeast corner of the unit and were summarized as follows in the plan:

* Alaska State A-1 on ADL 047556 was drilled by Exxon and reached a 14,206-feet TVD in September 1975 and was plugged and abandoned. (That data is available to the public from the Alaska Oil and Gas Conservation Commission.)

* Alaska State A-2 is immediately adjacent to Alaska State A-1 and was drilled as a cutting’s disposal well by Exxon in 1995 to 2,364-feet TVD and was plugged and abandoned in March 2002.

* Exxon spud Alaska State G-2 from ADL 343110 and directionally drilled the well north to reach a bottom-hole at 14,340-feet TVD within ADL 343109 in August 1983. The well was subsequently plugged and abandoned, but AOGCC granted the well extended confidentiality.

The other two wells that characterize Point Thomson’s Brookian reservoir are Sourdough 2 and 3 and were summarized as follows in Jade’s plan:

* BP drilled Sourdough 2 to 12,562-feet TVD in March 1994 and the well was plugged and abandoned.

* Two years later, Sourdough 3 was drilled by BP reaching 12,475-feet TVD in March 1996. The well is suspended. AOGCC granted both wells extended confidentiality.

Vintage seismic

Various 3-D seismic surveys have been acquired and interpreted over acreage in Area F, including: Point Thomson 3-D in 1989, 70 square miles, with Exxon the operator; Yukon Gold 3-D in 1994, 95 square miles, with BP the operator; and Mammoth 3-D in 1997, 13 square miles.

“Generally speaking, the quality of all these data sets are good and they have been used by the working interest owners to gain a broad overview of the Point Thomson unit Brookian reservoir,” the plan said.

Jade has had “access to the Point Thomson 3D volume and has used that data set to help it characterize the Brookian opportunity at Point Thomson as well.”

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Sourdough & ANWR

Check out the following articles from past issues of Petroleum News in our online archive at to better understand the historical relationship between Point Thomson’s Sourdough discovery and opening the 1002 area to oil and gas exploration and development.

* Dec. 28, 1998: Lawyers or Drillers?

Exxon still … didn’t soften its position late last year when the U.S. Department of the Interior indicated it might be open to a “paper” oil and gas lease sale in ANWR, which would allow subsurface entry into the refuge via horizontal drilling through Sourdough/Point Thomson wells.

* May 28, 2001: State asks for production from Point Thomson unit next to ANWR by 2008

Unit operator ExxonMobil had proposed a commitment to development drilling within five years of expansion approval

* Jan. 12, 2003: Unlocking ANWR

Development of BP-discovered Sourdough field near refuge is key to opening the coastal plain, whether or not feds go after drainage royalties.

* April 27, 2008: Tapping ANWR from PTU

Rejection of Point Thomson unit plan confirms state’s interest in Sourdough oil discovery.

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