Hemi Springs — South Prudhoe Bay

On-shore, Western North Slope


  • Key Features
    • Borders the Prudhoe Bay Unit
    • Numerous HC Tests & Shows: Hemi Spr. #1: (CCPPQ) many 500+ BOPD tests in Kuparuk C Sand (26-35 API); 21 barrels oil in Sadlerochit (27 API); apparent O/W contact in Schrader Bluff. Hemi Spr. #3-9-11: (susp. until ’07) SWC oil in Sagavanirktok. Hemi Spr. Unit #3: minor live oil in mudstone fractures near LCU. Hemi Spr. Sag R. #1: SWC oil shows above LCU. Burglin #33-1: (susp.) O/W contact in Schrader Bluff; gas in Kuparuk C; oil in Ivishak conventional core (24-16 API).
    • Shale Oil: The project borders Great Bear Petroleum Leasehold and is within 10 miles of GBP proposed well. TAPS crosses the project and the Dalton Highway is within 1 mile.
  • Leases
    • ADL 391544, 391545   (6/30/2017)
    • ADL 391750, 391757, 391758, 391759, 391766, 391767   (4/30/2018)
    • ADL 391768, 391774, 391775, 381776, 391777, 391778   (4/30/2018)
    • Tract 976, Tract 996   (Apparent High Bid in NS Sale 2011; ?/?/2022)


Geologic Summary by: D. T. Gross (3/13/2012)


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The Donkel/Cade Hemi Springs – South Prudhoe Project is comprised of 14 leases totaling 35,733 acres with an additional two 2560-acre tracts obtained in the North Slope Areawide 2011W lease sale upon which Mr. Donkel and Dr. Cade were the apparent high bidders (approx. 40,853 acres grand total). The entirety of this acreage is spread along the southwestern border of the Prudhoe Bay Unit and wraps around the western and southern sides of the Arctic Fortitude Unit (Alaskan Crude). Two now-dissolved units are worthy of mention in that the Rockflour Unit (ENI) was formed immediately to the west and the location of the NE Storms Unit (Pioneer Natural Resources Alaska) is entirely overlain by the Donkel/Cade Sale 2010 leases.

Recent leasing activity has been very aggressive in the Hemi Springs – South Prudhoe area. In the 2011 North Slope Sale, Repsol E&P USA bid $475,000 on seven tracts immediately west of the project area, losing the northeastern tract to a Donkel/Cade bid of $71,680. On the project’s southern border, Great Bear Petroleum acquired a 500,000+ acre position for $8 million in the 2010 lease sale. GBP added to their position in the December 2011 sale by spending $2.9 million to acquire the 45,600 acres that were previously held by ENI. In the same sale, Royale Energy Inc. spent $2.7 million to acquire 100,480 aces in two groups. Both companies are pursuing a nonconventional shale oil play in the three major source rocks of the Colville Basin. The Cretaceous Hue Shale, the Lower Jurassic Kingak, and the Triassic Shublik are all thermally mature in the area, but the initial target will be the Shublik at depths of 9,000’ to 11,000’. Great Bear announced their intention to drill four of six proposed well locations along the Dalton Highway in 2012 and has future plans of using at least 20 rigs year-round to drill 200 wells a year. They expect their production rates to reach 200,000 barrels per day by 2020 and to have a peak rate of 600,000 barrels per day by 2056.

The key well of the Hemi Springs – South Prudhoe Project is the ARCO Hemi Springs State #1 well, one of three drilled in the defunct Hemi Springs Unit. It was directionally drilled in 1984 to a depth of 10,937’ (10,370’ TVD) from a surface location in the extreme southeast corner of a ConocoPhillips/Pioneer lease but the well’s bottomhole location is 648’ inside of a Donkel/Cade lease (ADL391544). The well was originally Certified Capable of Producing in Paying Quantities in June 1984 and ARCO requested an extension of its suspended status as recently as March, 1995, citing its productive potential. Only now is ConocoPhillips proposing to permanently plug and abandon the well by September, 2012. The Lower Cretaceous Kuparuk C Sand earned the well its CCPPQ designation when it yielded oil and gas at rates in excess of 500 BOPD (26 to 35 API gravity) and up to 1.9 MMCFGPD in several tests at depths between 7,190’ and 7,220’ MD. The well encountered oil and gas in several intervals above the Kuparuk with the U. Cretaceous Schrader Bluff Sand having an apparent oil-water contact at ~4,200’ SS. (This is consistent with those from nearby wells: -4,120’ SS in the Rock Flour #1 well to the west and -
4,133’ SS in the suspended Burglin #33-1 well to the east). Below the Kuparuk, the L. Triassic Sadlerochit yielded 21 barrels of 27 API oil and 25 barrels of gas cut mud between 9,538’ and 9,578 MD. The State #1 reached T.D. in its secondary objective of the Penn-Mississippian Lisburne Formation but found it to be wet.

Despite its lackluster test result in the Hemi Springs State #1 well, the Sadlerochit/Ivishak should not be written off as an exploration target in the Hemi Springs – South Prudhoe Project area. The aforementioned suspended Burglin #33-1 well to the east in the Arctic Fortitude Unit also had an inconclusive test of this horizon. Published structure maps of the Prudhoe Bay Field illustrate the strong role of fauting in defining its Sadlerochit/Ivishak oil accumulations. Other mapping indicates the existence of a fault-controlled high immediately to the south of the State #1 well, leaving the possibility that the well encountered the Sadlerochit/Ivishak near its oil-water contact. Though the Sadlerochit/Ivishak officially tested wet at 9,011’ TVD (-8,891 SS) in the State #1, (despite recovering 21 barrels of 27 API oil in one test), this horizon is a prolific producer in the adjacent Prudhoe Bay Field. Nine miles to the east-northeast of the State #1, the Mobil/Sohio Hurl State 5-10-13 well had two production tests in Sadlerochit sands. The interval from -8,887’ to -9,005’ SS flowed clean 24 API oil at a rate of 1,980 barrels per day with medium gas flows. Two miles further east, the Placid PB State No. 1 had DST’s in the Sadlerochit that yielded 23 API oil at a maximum rate of 2,030 barrels per day (-8,888-920’ SS and -8,936-86’ SS ). Continuing east another mile, the Getty State No. 1 reported the Top Sadlerochit at -8,873’ SS with an oil-water contact at -9,011 SS. Taken collectively, this lends strong support to the proposition that the Hemi Springs State #1 well encountered the Sadlerocht/Ivishak at or near its oil-water contact.

ARCO Alaska followed up the Hemi Springs State #1 discovery the next year with another well. The Hemi Springs Unit #3 was drilled in April, 1985 and reached a depth of 10,059’ MD (TVD) in a location presently four miles southwest of the Berglin #33-1 well and less than one half mile south of the Donkel/Cade acreage. ARCO’s objective was oil in the Kuparuk River Formation and they cut seven conventional cores continuously through the interval above and below the Lower Cretaceous Unconformity (8,567-833’ MD). Unfortunately the interval contained only mudstones, but minor live oil was noted in the fractures. The well was plugged and abandoned due to the lack of economic hydrocarbons. (Today, it is generally accepted that Kuparuk “C” Sands are only well developed in this area on the downthrown side of faults). A year earlier, similar results had been encountered in the HG&G Hemi Springs Sag River #1 well that had been drilled 5 1⁄2 miles due east of the Hemi Springs Unit #3 location. (The HG&G well now lies one mile east of the Donkel/Cade project boundary). The well failed to find hydrocarbons in paying quantities but SWC’s just above the LCU recovered shales that displayed dull to bright oil staining, white to yellow fluorescence, and some fast bleeding.

Drilling activity returned to the Hemi Springs – South Prudhoe Project area when Pioneer formed the above mentioned NE Storms Unit and drilled the Hailstorm #1 well in 2006. The well was drilled to a depth of 9,840’ MD (9,804’ TVD) and reached its Ivishak target at 9,601’ MD (9,563’ TVD; -9,474’ SS). The well encountered drilling problems when it reached the top of the Kingak Formation (8,397’ MD), losing a fish in the hole that required a sidetrack to be drilled. The well was plugged and abandoned after taking only a RCI pressure test of 3,717 psi in the Ivishak at 9,607’ MD (9,571’ TVD). Pioneer dissolved the unit without pursuing a second planned well that would have been located several miles west-northwest of the Hailstorm #1. It appears that trapping mechanism of Pioneer’s play at the NE Storms Unit involved the southeastward extension of a well-established fault system that would cut NW-SE across the unit (and the present Donkel/Cade acreage). These faults are part of a system that is shown to trap oil and gas accumulations on its faults’ northern sides in the official AOGCC Prudhoe Bay Field structure map of the Top Sadlerochit. The unsuccessful Hailstorm #1 well may well have been drilled directly into a major fault or very near to it. The Arco Hemi Springs State #1 well, with its test of 21 barrels of 27 API oil in the Sadlerochit/Ivishak, is located on the downthrown, south side of this fault. Pioneer’s undrilled second well location would have been located in a similar structural position, approximately six miles southeast of the Hemi Springs State #1 well, and remains an untested prospect on the Donkel/Cade acreage.