Phillips Petroleum Co. unit Phillips China Inc. has drilled and tested its third successful well on Bozhong Block 11/05 in China's Bohai Bay, confirming what appears to be a major oil discovery.
The find follows the drilling of discovery well PL 19-3-1 and appraisal well PL 19-3-2, which were completed earlier this year (OGJ, July 19, 1999, p. 36). A third well, PL 19-3-3, was drilled above target zone and subsequently plugged and abandoned.
Phillips acquired the right to explore the 2.3 million-acre block in 1994 when it signed a petroleum exploration and development contract with China National Offshore Oil Corp. (CNOOC). Phillips holds a 100% participating interest, but CNOOC maintains the right to participate with a 51% interest in any development on the block.
Well PL 19-3-4 was drilled on a large, 6 mile anticline about 135 miles from Tanggu and 80 miles from Dalian in 85-90 ft of water (see map, p. 34).
Drilled on the northern portion of discovery area PL 19-3, the well confirmed for Phillips a significant amount of oil reserves: "Based on the results of the first three wells, the northern portion of this field is estimated to contain 400 million bbl of potentially recoverable reserves," said Kirby Hedrick, Phillips executive vice-president, upstream. "We are extremely encouraged by these results and plan to turn our attention now to the as-yet unexplored southern end of the field."
Program details
Drilled to 6,084 ft TD, PL 19-3-4 encountered a gross pay interval of more than 886 ft. About 290 ft of net pay was in the Minghuazhen and Guantao formations. The new well confirmed the same pay interval as PL 19-3-1 and was drilled in an untested fault block about 1.5 miles north of and 1,000 ft lower on the structure than the discovery well. Oil-water contact with PL 19-3-4 was 92 ft deeper than the discovery well.
Two limited drillstem tests were conducted on the latest well, under natural flow and without artificial lift. During the first test, PL 19-3-4 produced 850 b/d of 20° gravity oil with a gas-oil ratio of 120 scf/bbl. The second test yielded production of 190 b/d of 18° gravity oil with a gas-oil ratio of 190 scf/bbl.
Phillips's program calls for deploying two rigs to drill four additional appraisal wells before yearend to delineate the productive area of this large feature.
Due to the shallow water depth of these wells, Phillips expects facility and drilling costs to be relatively low. The company intends to jointly initiate commercialization studies with CNOOC, as the latest successful well is close to existing CNOOC production facilities.
Phillips has drilled three previous discovery wells in other prospect areas on Bozhong 11/05 Block. All were subsequently plugged and abandoned. These were: BZ 22-2-1, a subcommercial gas-condensate discovery; and PL 14-3-1 and BZ 36-2-1, both new field discoveries drilled in 1997.
Phillips plans an aggressive drilling program for other prospect areas on Bozhong 11/05 Block; it is slated to begin in early 2000. One of the two rigs being used to appraise discovery area PL 19-3 will be utilized for further drilling in these other areas.
