Addax Petroleum Corporation has completed its 2006 exploration and appraisal campaign on the Okwok field discovery in OML67 with encouraging results. The Corporation acquired a 40 per cent participating interest in the Okwok field in June of this year from Oriental Energy Resources Limited and commenced the exploration and appraisal program immediately thereafter. Addax Petroleum is the technical adviser and Oriental is the operator for the Okwok field joint venture.
Commenting on the 2006 Okwok exploration and appraisal campaign, Jean Claude Gandur, President and Chief Executive Officer of Addax Petroleum said; “I am delighted that our joint venture with Oriental under Nigeria’s Marginal Field program has proceeded so well. Our 2006 objectives for the Okwok field were to explore and appraise the two main fault blocks on the structure, to confirm the nature of the oil present and to flow test the wells. I am pleased that these objectives have been achieved; the Okwok field contains medium to light crude oil and the reservoir is of high quality. Following these encouraging results, we are now updating our geological models to evaluate our future appraisal strategy and potential fast-track development plans.”
The Okwok field is located south of and adjacent to OML123, Addax Petroleum’s largest producing property, in a water depth of approximately 50 meters and comprises three major fault block compartments, named Blocks 1, 2 and 3. Block 1 was drilled by well Okwok-1 in 1967 and Block 2 by well Okwok-2 in 1968, both by a previous operator, whereas Block 3 had not been drilled prior to the recent campaign. Both earlier wells had discovered hydrocarbons but had not been flow tested.
The Okwok 2006 exploration and appraisal campaign by Addax Petroleum and Oriental commenced when the GlobalSantaFe High Island IX jack-up drilling rig arrived on location in early July and concluded in late October. The campaign comprised the drilling of wells Okwok-4A and Okwok-4AST1 in Block 2 and Okwok-7A and Okwok-8A in Block 3. The objectives of the campaign were to appraise Block 2, explore Block 3 and to conduct flow tests to establish the oil properties and reservoir conditions in both blocks. The primary reservoir objective in the Okwok field is the stacked “Lower D” sandstone sequence of Upper Pliocene/Lower Pleistocene age which, at Okwok, occurs at depths between 3,000 and 4,000 feet subsea.
For Block 2, Okwok-4A was drilled approximately 1.3 kilometres west of Okwok-2 to appraise the areal extent of the fault block’s oil accumulations. Okwok-4A encountered 14 feet of net oil pay in its primary target in the Lower D sequence which was thinner than anticipated but which also encouraged the drilling of a sidetrack down-dip. Okwok-4AST1 was drilled as the sidetrack to Okwok-4A targeting a more sand-prone area and encountered 95 feet of net oil pay in two intervals within the Lower D sequence. A drill stem test was attempted but was curtailed due to a rupture of the sand exclusion screen which caused excessive sand production into the well. The test produced at a rate of approximately 400 barrels per day of light 32 degree API gravity oil. The true flow potential of the well was not reached because of sand control problems during the test, however, the Corporation was pleased with the high quality of the oil tested and will use the knowledge gained regarding the reservoir conditions in future appraisal efforts.
Following the appraisal of Block 2, the High Island IX was moved to explore Block 3 and spudded Okwok-7A. However, Okwok-7A was abandoned prematurely because of mechanical difficulties after encountering hydrocarbons and abnormally high pressures while drilling in the Lower D sequence. The Okwok-8A well was spudded immediately thereafter, was drilled successfully and encountered 97 feet of net oil pay in two sandstone intervals in the Lower D sequence. As a precaution against the excessive sand production experienced in Okwok-4AST1, Okwok-8A was gravel packed prior to testing. The well was flow tested at a maximum rate of 1,220 barrels per day of medium 26 degree API gravity oil on a 32/64” choke. Both the Okwok-4AST1 and Okwok-8 wells are currently suspended for potential tie-back to production facilities.
Addax Petroleum and Oriental are now in the process of incorporating the well data, oil properties and flow test data from this exploration and appraisal campaign into existing geological and engineering models. The new information will be used to evaluate the 2007 Okwok work programme which the Corporation anticipates will include further appraisal drilling and potentially fast-track development planning. Should additional appraisal efforts prove successful, the Okwok field is likely to be developed through the OML123 FPSO 12 kilometres to the north and first commercial oil production could commence as early as 2008.