South Yukon Gold

On-shore, Western North Slope

  • Key Features
    • Sourdough Discovery lies 6 miles from both projects and has reported reserves of 100 MMBO in the Lower Tertiary.
    • Yukon Gold Discovery lies midway between the projects and has reported reserves of 120 MMBO in two Canning Formation sands.
    • South Yukon Gold borders ANWR.
  • Leases
    • ADL 391715, 391716, 391717   (4/30/2018)
    • ADL 392099   (?/?/2022)

Geologic Summary by: D. T. Gross (3/22/2012)

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The South Yukon Gold Project is comprised of three leases totaling 10,313 acres and one tract of 2,560 acres acquired in the NS 2011W Sale, giving a project total of approximately 12,873 acres. The project is located adjacent to the ANWR Area 1002 on the western banks of the Canning River and derives its name from its proximity to the 120 MMBO Yukon Gold oil discovery. The project acreage lies six miles south of the 300 MBO 9 TCFG Point Thomson Unit, 8 miles southwest of the 100 MMBO Sourdough discovery, and 13 miles southeast of the 60+ MMBO Badami Unit.

The Yukon Gold oil discovery was made in 1994 when BP Exploration drilled the Yukon Gold #1 well one mile due north of the project acreage to a depth of 12,800’ MD (12,667’ TVD). The entire well was drilled in strata that interfingered the Tertiary Sagavanirktok Formation and the time-equivalent Canning Formation, first encountered at 5,164 MD. The Staines Tongue of the Sagavanirktok was found from 8,195’ to 9,340’ MD and the well reached total depth while still in the Lower Canning Formation. In 1995, the DNR granted extended confidentiality to the well’s data due to its location proximal to the ANWR border and the presence of hydrocarbons in two intervals. Though depths of these intervals were never precisely identified by BP in public reports, in which one interval was described as a topset delta front and the other as a bottomset turbidite, some clues to their location can be found in the well’s logging and coring history. BP ran only minimal logging suites above 11,605’ MD where they set 7” casing, indicating that their primary target was in the L. Canning Formation or possibly deeper in the Cretaceous (not reached). Two conventional cores were taken which had strata that appeared to have been deposited in a deepwater environment. Core # 1 (12,136-46’ MD) returned mudstone with sandstone laminae and Core #2 (12,330-86’ MD) was a contorted siltstone with sandstone laminae. Unfortunately, neither core had any significant hydrocarbon shows. Surprisingly, only seven sidewall cores were taken with three clustered around 11,680’ MD and four around 12,250’ MD. The four SWC’s taken in the interval from 12,249’ to 12,253’MD had oil saturations of 35% to 46%, supporting the idea that the two hydrocarbon intervals described by BP were located near this depth. The Yukon Gold #1 well information was released when the lease upon which it was drilled expired in March, 2001and presently Savant holds a three-lease position that includes the well location. In the December NS 2011W Sale, Savant exceeded a Donkel/Cade bid by $3.05 per acre to become the apparent high bidder on the tract immediately north of the well and just east of the North Yukon Gold Project acreage.

The Point Thomson Field was discovered in 1977 by Exxon which encountered hydrocarbons in the L. Cretaceous Thomson sandstone and the Tertiary Flaxman turbidites. Early in 2009, ExxonMobil drilled two Point Thomson wells, the PTU-15 and PTU-16, as part of its $1.3 billion development project for the field and plans to begin production of gas condensate as early as year-end 2015 (subject to pipeline completion). At least five wells will be used in a cycling project that involves bringing gas to the surface, collecting the condensate, and then injecting the dry gas back down into the reservoir. To bring this production to market, ExxonMobil recently announced the plans for a 22-mile pipeline to connect Point Thomson to the Badami Field and PTE Pipeline, LLC has applied to the DNR for permission to lay this common carrier pipeline. Construction was slated to begin in 2011 and to be completed by 2014 but was delayed by a year due to permitting issues, which have been resolved. Presently, the liquid production potential at the Point Thomson Field is only 10,000 barrels per day of gas condensate, leaving an excess capacity in the planned pipeline of 60,000 barrels per day. Additional production may come from Sourdough, a Lower Tertiary turbidite oil discovery (6 miles northest of the project) that was made by Chevron and BP in the southeastern corner of the Point Thomson Unit. Their 1997 announcement placed its reserves at 100 MMBO and it has been suggested that this reservoir may extend eastward under ANWR Area 1002.

The Badami Field was discovered in 1990 by Conoco when their Badami #1 well drilled to 13,595’ MD (12,911’ TVD) and had a drillstem test of over 4,000 BOPD from Brookian turbidite sands (Tertiary). These pay sands were encountered between 9,500’ and 11,500’ MD and were described as being very fine-to-fine grained and moderately sorted with porosities of 15-21%, permeabilities of 1-400 md, and oil gravity of 21-30 degrees API. Original recoverable reserves in these turbidites were placed at 120 MMBO, but were reduced to 60 MMBO after subsequent drilling and production showed that the reservoir sands are complex, consisting of 61 identified fans laid down during seven depositional events. The field was shut-in in 2007 when production dropped to 1,300 BOPD from six straighthole wells. In 2008, Savant (90%) and ASRC (10%) formed a deal with BP in which Savant would drill one new development well (#B1-18A horizontal sidetrack) and one exploration well (Red Wolf #B1-38). The exploration well found oil in its primary objective (Kekiktuk Formation) and in a shallower secondary objective (Late Cretaceous Killian sands). Despite a reserve estimate of 45 MMBO for the Kekiktuk accumulation found in the #B1-38 well, the Killian horizon was selected to be part of the re-start production which included the new #B1-18A redevelopment well and four previous producers. Savant projected that the combined production from all six wells would eventually be more than 4,000 BOPD. (The November, 2011 daily production stood at just over 1,000 BOPD.) Presently, Savant has a workover rig operating on the #B1-21 well which will move next to the #B1-16 well. They have also recently obtained a rig in order to drill the Red Wolf #2 well, a 12,000’ straighthole test of the Kekiktuk Formation on the northwestern side of the unit and outside of the Badami Sands PA.

The area south of the Badami and Point Thomson units has been extensively leased in the past and two attempts to drill and develop this acreage have reached the unitization stage. Three miles due west of the South Yukon Gold Project, the Slugger Unit was formed in April of 2001 and contained 79,508 acres within 14 leases. BP Exploration Alaska’s primary objective in the unit was the Lower Cretaceous Kemik Sandstone. The play was based upon seismic data that showed dipping reflectors above basement that were interpreted to be siliciclastic units of the Kekiktuk Conglomerate (Mississippian) or carbonates of the Lisburne Group (Carboniferous). These in turn were eroded by the Lower Cretaceous Unconformity and formed sites for the deposition of the coarse-grained Kemik sandstone. BP presented technical information to the DNR that suggested a four-way structural closure and they estimated Slugger’s reserves at 280 MMBO (in place). The terms of the unit approval required that BP drill two wells within the unit, the first by May of 2003 and the second a year thereafter, and that these wells must penetrate and evaluate the Kemik. Due to the failure to replace a partner who opted out of the drilling program, no wells were drilled and this resulted in the termination of the unit in May of 2003.

The acreage of South Yukon Gold Project’s northernmost tract (ADL 392099) was previously included in the eastern quadrant of the Greater Bullen Unit, proposed by Brooks Range Petroleum Corporation in March, 2011. These 68 leases covering 200,179 acres would have incorporated the old Slugger acreage along with leases to its north, up to and between the Badami and Point Thomson units’ boundaries. It appears that the Greater Bullen Unit’s primary target was sandstone deposited upon the Lower Cretaceous Unconformity similar to the Point Thomson sand and the Kemik Sandstone, the untested objective of the Slugger unit. Other targets may have been the older Mississippian Kekiktuk Conglomerate or younger Tertiary turbidite sands, both productive in the Badami Unit. In October of 2011, BRPC abandoned its unitization efforts at Greater Bullen and relinquished all of its leases with 2012 expiration dates. In the December NS 2011W Sale, ConocoPhillips captured 20 tracts (approx. 51,200 acres) that lie 6 miles west of the South Yukon Gold Project and that incorporate what was the northern portion of Slugger and the west-central portion of Greater Bullen units.

Aside from the Yukon Gold #1 well, there are two other key wells related to the South Yukon Gold Project. Four miles west of the project area, Union Oil of California drilled the E. de K. Leffingwell #1 well in 1984 to a total depth of 14,824’ MD (14,041’ TVD). The well evaluated the strata down to basement, but no hydrocarbons were encountered. The top of the Cretaceous Colville Group was reached at 5,267’ MD, the L. Cretaceous Kongakut Formation (Pebble Shale/Kemik Sandstone) at 13,630’ MD, the Carboniferous Endicott Group at 13,974’ MD, and basement argillite at 14,720’ MD. It appears that the Tertiary Sagavanirktok Formation was the primary objective in that two conventional cores were cut in it; Core #1 returned shale (4,296- 356’MD) and Core #2 returned sandstone (4,583-612’MD). A secondary target may have been the pre-Mississippian in that Core #3 was taken at total depth in the basement argillite (14,794- 824’ MD).

Four mile southwest of the South Yukon Gold Project, Exxon drilled the Alaska State #J-1 well in 1984 to a depth of 13,652’ MD (TVD). The well encountered intertongued Sagavanirktok Formation and Canning Formation with mudlog shows of spotted stains and fluorescence noted from 8,860’ to 13,200’ MD and with solid stains and fluorescence below this down to 13,270’ MD. Two conventional cores were cut in the Sagavanirktok; Core #1 returned siltstone (12,310- 41’ MD) and Core #2 returned sandstone with siltstone (12,668-704’ MD). Neither core had hydrocarbon shows and no formation tests were made in the well. In 1986, the DNR granted extended confidentiality to the Alaska State #J-1 data citing the well “contained significant information relating to the valuation of unleased acreage within ANWR”. This information was release when the lease containing the well expired in 1994.