Roc Oil Says Wei-6-12S-1 Discovery Very Significant

Preliminary analysis of initial wireline log data indicates that the Wei-6-12S-1 exploration well, in Block 22/12 in the Beibu Gulf, offshore China, is a potentially significant oil discovery.

A gross interval of about 500 meters contains numerous separate reservoir sands which collectively represent approximately 100 meters of net oil pay with generally good reservoir characteristics. Overall individual sands range in thickness up to 25 meters.

The Block 22/12 Joint Venture is currently giving consideration to immediate appraisal.

A wireline logging program is being conducted, at a Total Depth of 2,535 meters below rotary table ("mBRT"), at the Wei-6-12S-1 exploration well in Block 22/12, in the Beibu Gulf, offshore China.

Preliminary analysis of the initial log data indicates that the gross reservoir interval targeted by the well - sands within the Weizhou Formation of Oligocene age - contains numerous oil-bearing sands. The top of the highest oil sand is at about 1,950 mBRT and the base of the lowest oil sand is at 2,450 mBRT. The intervening 500 meters is comprised of a gross sand-shale-silt sequence within which individual oil-bearing sands range up to 25 meters in thickness. The total collective net thickness of these oil sands is approximately 100 meters which substantially exceeds the Joint Venture's most likely pre-drill expectation. Consistent with such a thick net oil pay interval, reservoir characteristics vary in fine detail but generally the majority of the oil-bearing sands display good reservoir quality.

The Wei-6-12S prospect represents an unusual structural target: the area of structural closure is relatively small (about one sq km) but the vertical structural closure is considerable (up to 95 meters) and the gross prospective reservoir section is very thick (500 meters). The well, which was designed to penetrate most of the target sands about 30 meters down dip from the crest of the structure, is located in about 30 meters of water, approximately 3 km southwest of the 2002 Wei-6-12-1 oil discovery.

Commenting upon the discovery ROC's Chief Executive Dr John Doran stated that:

    "Anytime you get a 100 meters of good quality net oil pay, way beyond pre-drill expectations, you can be forgiven for being cautiously optimistic.
  • Prior to drilling the well ROC had two main technical concerns: trap integrity and the structure's relatively small areal closure. Subsequent to drilling we no longer have those concerns. The integrity of the trap is self evident and although the structure does have a limited areal extent, that factor is more than offset by the thickness of the multiple reservoir sand sequence.
  • It will take many weeks to collect and analyse all the data to the point where we can begin to offer detailed comments on field size and commercial implications. In the meantime, we can safely say that this well has delivered a handsome discovery that certainly merits further appraisal."

The Block 22/12 Joint Venture is comprised of Roc Oil as operator with 40%; Horizon Oil with 30%; Petsec Energy with 25% and Oil Australia with 5%. CNOOC is entitled to participate up to a 51% funding equity level in any commercial development within Block 22/12.

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