The Hiswah-4 well was drilled with a vertical wellbore to a depth of 1276 meters in order to evaluate the oil-bearing Saar Formation. This vertical hole was used to gather reservoir data including two separate 9 meter cores. Independent petrophysical analysis has determined that Hiswah-4 intersected approximately 60 meters of gross 35 degrees API gravity oil pay and 20 meters of gross natural gas pay, over a total 80 meter gross interval, with average porosity of 16 percent. Cores cut from the Saar oil column show good oil staining within micro-fractured, high-energy carbonate grainstones which were comparable to the Hiswah-3 reservoir.
Hiswah-4 production tests were conducted over the open hole, horizontal well section with an electric submersible pump which cleaned the well up quickly and established flow rates of up to 1,200 barrels of oil per day and 400 Mcf per day of natural gas over several hours. The test was terminated when the pump failed due to a contractor's surface electrical control panel failure. Subsequent to termination of the test, oil continued to flow without artificial lift, at rates of up to 1,098 barrels oil per day before the well was successfully controlled by injecting 1,100 barrels of kill fluid into the well bore, then the downhole equipment was retrieved.
The test was then continued using a different contractor with new downhole and surface equipment. During the clean-up only 20% of the kill fluid was recovered and the well flowed at a reduced sustained flow rate averaging 380 barrels of oil per day and 600 Mcf per day of natural gas with no formation water, for 48 hours. Preliminary evaluation indicates that the reduced flow rate may be due to well bore damage which occurred between the time the kill fluid was injected and removal of the downhole equipment at the end of the initial test period. Upon completion of the evaluation, remedial workover operations will follow to rectify the damage and prepare the well for future production.
The production test and geological reservoir data at Hiswah-4 confirms that the reservoir is a contiguous, single oil accumulation. Hiswah-4 is the second of several horizontal appraisal wells planned for the Hiswah oil pool. The drilling rig is currently being moved to the Hiswah-5 well location, approximately 700 meters northwest of the Hiswah-4 well.
Calvalley Petroleum is the operator of Block 9 in Yemen.
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