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Alaska Oil and Gas Conservation Commission

Alaska Department of Administration, Alaska Oil and Gas Conservation Commission
Administration >  AOGCC >  Statistical Reports >  Annual Pool Statistics - 2004 >  Prudhoe Bay Unit, Midnight Sun Oil Pool
AOGCC Pool Statistics
Prudhoe Bay Unit, Midnight Sun Oil Pool
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Operator: BP Exploration (Alaska) Inc.

Discovery Well: BP Exploration (Alaska) Inc.
  Prudhoe Bay Unit MDS E-100 (Sambuca No. 1)
  Permit #197-188
  API No. 50-029-22819-00-00
  Sec. 06, T11N, R14E, UM

Depth: 13,282' MD / 9,423' TVD

December 20, 1997
Status: Producing
Location: Central Arctic Slope Area Location Map Pool Location Map
Orders: Complete List

The Midnight Sun Oil Pool is located in and adjacent to the Prudhoe Bay Unit ("PBU").  It was discovered in 1997 by the Sambuca #1 exploratory well (later renamed PBU MDS E-100), and confirmed by the Midnight Sun #1 delineation well  (later renamed the PBU MDS E-101) in 1998.  This pool comprises an accumulation of oil and gas trapped within the Lower Cretaceous-aged Kuparuk River Formation ("Kuparuk") that correlate with the interval from 11,662’ and 11,805’measured depth (~8,000’ below sea level) in PBU MDS E-100.   The pool has low structural dip, good vertical permeability, contains a relatively large gas cap, and has gross sand thickness of about 110 feet. Free gas volume associated with the gas cap is estimated to range between 60 and 80 BSCF.  Total gas in place is estimated to be 100 to 130 BSCF.  Production from the pool began in October of 1998. 


Within the pool, the Kuparuk is complex, displaying rapid changes in thickness, sedimentary facies and local diagenetic cementation. At Midnight Sun, the Kuparuk is informally divided into lower and upper units. The lower Kuparuk unit is about 40’ thick, and is, in turn, subdivided into two lithologic intervals. The basal non-productive sandstone is discontinuous, ranging up to 5’ thick, and contains abundant glauconite and minor detrital shale. The overlying unit is continuous, very fine to fine grained, quartz-rich sandstone. Mean porosity and permeability in the reservoir-quality portions of the lower Kuparuk unit are 27.3% and 760 md, respectively. The upper unit ranges from 0’ to 70’ in thickness, and consists of poor to well sorted, glauconitic- and siderite-bearing sandstone interbedded with minor amounts of muddy siltstone. Changes in intergranular siderite cementation and compaction cause localized reductions in porosity and permeability.  In the upper unit,  mean porosity is 20.7% and mean permeability is 200 md. Structural and stratigraphic elements combine to trap this oil pool.  It is bounded to the N by the Sambuca fault, to the W by the Prudhoe Mid-Field Fault, to the S by the Prudhoe-bounding fault system, and to the E by an apparent stratigraphic pinch out. No oil-water contact has been observed, but heavy oil was encountered below a true vertical depth of 8,107’in PBU E-101. The areal extent of this heavy oil accumulation is uncertain. A gas-oil contact lies at 8,010’ true vertical depth subsea.  API gravity of the oil is about 25.5 degrees.

Strat Column

Orig. Oil in Place: 40 to 60 MMSTB (CO 452)
Orig. Gas in Place: 100 to 130 BSCF (CO 452)
Reserves: Primary:  6 to 8 MMBO; Primary + Secondary 16 to 23 MMSTB (CO 452)
Production: Prod Chart Prod Report Prod Data

  Oil (bbls) NGL (bbls) Gas (mcf) Water (bbls)
Cumulative 11,342,234
0 40,092,659 1,630,107
2001 Total 1,305,188 0 6,750,499 33,282
2002 Total 3,157,373 0 9,878,600 886,521
2003 Total 1,719,308 0 3,499,585 401,474
2004 Total 1,641,441 0 6,191,077 300,216
2003 Daily Rate 4,710 0 9,588 1,100
2004 Daily Rate 4,497 0 16,962 823
Change (%) -5% 0 77% -25%
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