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Alaska Oil and Gas Conservation Commission

Alaska Department of Administration, Alaska Oil and Gas Conservation Commission
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AOGCC Pool Statistics
Kuparuk River Unit, Tabasco Oil Pool
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Operator: ConocoPhillips Alaska, Inc.
Index Map
Discovery Well: ARCO Alaska, Inc.
  Kuparuk River Unit 2T-02
  Permit No. 186-141
  API No. 50-103-20072-00-00
  Sec. 1, T11N, R08E, UM

Depth: 8,890’ MD / 6,107' TVD

October 18, 1986

Status: Producing
Location: Central Arctic Slope Area Location Map Pool Location Map DNR Unit Map
Orders: List of Orders Summary - Annotated References  
Summary:

The Tabasco Oil Pool is one of the satellite pools that have been discovered and developed utilizing Kuparuk River Unit (“KRU”) infrastructure. The pool was discovered in 1986 during development drilling of the underlying Kuparuk River Oil Pool from the KRU 2T-Pad. The Tabasco Sandstone underlies part of the southern and western KRU. Producible hydrocarbons were encountered in the Tabasco Sandstone between 3,352’ to 3,599’ measured depth (“MD”) in the KRU 2T-201 well. The Tabasco pool lies at approximately 3,000’ true vertical depth subsea (TVDSS) , about 300’ to 400’ below the West Sak sands. Regular production began in April of 1998 from the 2T-Pad. Production peaked in May 1999 at an average of 7,913 barrels of oil per day (BOPD). For the first six months of 2011, the pool averaged 1,725 BOPD with a water cut of 88 percent.


Geology:

The Tabasco Sandstone is an informal member of the Late Cretaceous-aged (Campanian) Schrader Bluff Formation. It was deposited near a shelf margin as a prograding sequence of deltaic to near shore marine sediments. The sandstone is discontinuously distributed over a broad region, with sand thickness generally most significant along the shelf margin. Large-scale slumping and erosion are common. Two lithologies are present: a discontinuous thin-bedded sandstone facies with shale interbeds and an overlying amalgamated sandstone facies. The thin-bedded sandstone facies is more widespread; its gross interval thickness is about 80’ to 400’. The amalgamated sandstone facies ranges in thickness between 45’ to 350’ thick. The transition between the two facies is abrupt. Porosity ranges from 17 to 22% and averages 20%. Log water saturation ranges from 17 to 60%, with 20 to 25% representative of the 2T-Pad area. Pressure transient permeability ranges from 3 to 100 darcies.

The Tabasco structure is a monocline, dipping east to northeast and striking north to northwest in the western portion of the KRU and east to southeast in the southern portion. The hydrocarbon-trapping mechanism is a combination of stratigraphic and structural elements. The Tabasco accumulation is cut by a series of north-south and east-west normal faults, with throws typically ranging between 10’ to 50’ and maximum throws to 100’.

Oil distribution appears to be controlled by the stratigraphic distribution of reservoir sands. Tabasco oil has an API gravity of 16 degrees, and it is highly viscous (253 centipoise). No definitive oil-water contacts have been delineated within pool. A small gas cap of about 32 acres occurs in the 2T-201 area, with the gas-oil contact at 2,915’ TVDSS. This gas cap is not expected to have a major impact on reservoir performance.

 

  Strat Column Type Log
Production: Prod Chart          
  Oil (bbls) NGL (bbls) Gas (mcf) Water (bbls)
Cumulative 16,961,227 0 2,786,066 71,332,800
2005 Total
1,530,992 0 344,791 8,183,195
2006 Total
1,433,161 0 336,291 7,402,947
2007 Total
1,063,136 0 366,014 5,680,607
2008 Total
1,155,442 0 119,170 7,660,176
2009 Total
710,929 0 94,554 5,981,975
2010 Total
755,433 0 100,251 5,062,363
2011 Total
587,064 0 92,519 5,196,944
2007 Rate (b/d)
2,913 0 1,003 15,563
2008 Rate (b/d)
3,166 0 326 20,987
2009 Rate (b/d)
1,948 0 259 16,389
2010 Rate (b/d)
2,070 0 275 13,869
2011 Rate (b/d) 1,608 0 253 14,238
2008 Change (%)
9 0 -67 35
2009 Change (%)
-38 0 -21 -22
2010 Change (%)
6 0 6 -15
2011 Change (%)
-22 0 -8 3

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