Angun Point

Off-shore, Eastern North Slope

  • Key Features
    • Niguanak High East Flank
    • ANWR: USGS study that assigned 10.3 BBO reserves to ANWR identified 2 distinct plays over the project area.
      • External references:
    • Oil Seep at Angun Point (1 mile)
    • Jago R. KIC Well is 18 miles to the northwest.
    • Water Depths ± 35’
  • Leases
    • ADL 391371   (8/31/19)

Geologic Summary by: D. T. Gross / D. W. Brizzolara (4/24/12)

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The Angun Point Project lease is comprised of 3,659 acres located in Alaska State Waters at depths of ± 35’ and borders the eastern side of the ANWR 1002 Area. One of the key attributes of the lease is its proximity to the Angun Point oil seep and surficial oil impregnated sands. The project lies 16 miles from an onshore 92,000-acre leasehold held by Chevron and BP from the Arctic Slope Regional Corporation (ASRC). This ASRC leasehold contains the only exploration well drilled in ANWR, the 1986 Jago River KIC #1 (15,193’ MD), which is 17 miles northwest of the project acreage. The data from this well has been held confidential for over 25 years, known only to Chevron, BP, and the State of Alaska. As a result, the USGS assessments of the 1002 Area petroleum potential were made without this well data and some speculate that this severely reduced the USGS reserve estimates for the area. A year after the KIC #1 well, Tenneco began drilling the Aurora #1 well in Federal waters just beyond the Alaska three-mile-limit line and 14 miles northwest of the Angun Point project. The 18,325’ MD well was 6 miles ENE of KIC #1 and had minor gas shows in the Tertiary Brookian sands. An Alaska DNR geologist noted that the sand equivalent to the Cretaceous Kuparuk “C” was 178’ thick and relatively tight, “but all the interesting sands ... were pretty deep”.

The geology of the Angun Point region is very complex but offers several potentially enticing opportunities. The subsurface is complicated by thrust and fold geology that has been active since the late Cretaceous. The Basal Eocene Unconformity (BEU) is a significant truncating event in this region. The BEU truncates the local thrust and fold features and serves as a surface of deposition for contemporaneous and post‐unconformity erosion. These localized pods of deposition develop on the back limb of thrust sheets and have been referred to as “piggy‐back” accumulations. Hydrocarbon charge is expected to be from lower Cretaceous and/or lower Tertiary mudstones and shales, the same source that provides the charge for the onshore oil seep at Angun Point. The basal Eocene “piggyback” sandstones would be a primary exploration target. Below the BEU, the geology becomes highly uncertain. Stratiform Paleocene seismic reflectors are present and may represent deposition coeval with the onshore Sabbath Creek section that outcrops north of the eastern Brooks Range mountain front. It has been hypothesized that these deposits prograde to the north/northeast in the direction of the Angun Point Project lease and that reservoir parameters may have “cleaned‐up” as deposition transitioned from deltaic to shallow marine facies. Beneath the Paleocene, the geology enters into an even greater unknown. There are indications of a possible lower Cretaceous section which could hold the equivalent of the Kemik or Point Thomson sands. Deeper yet lies the potential of a yet undiscovered Ellesmerian section (Sadlerochit, Lisburne, Kekiktuk Formations). Such geology may be present beneath the project area but would likely be at depths greater than 14,000 feet.

A 1998 USGS report on the petroleum potential of the ANWR 1002 Area calculated that 10.3 BBO of reserves were contained in ten plays in this area and the adjacent State of Alaska Waters. The Angun Point lease overlies two of these plays: 1) The Thin Skinned Thrust Belt, Tertiary Brookian strata trapped in northwest trending folds formed by Paleocene to Miocene thrusting; and 2) The Niguanak-Aurora Play, domes formed by pre-Brookian imbrecated thrusts of Franklinian rocks including Devonian clastics.