Optimal FE Acquisition in a Complex Carbonate Reservoir: a Case Study onthe Karachaganak Field, Kazakhstan

摘要

The Karachaganak Field is an oil and gas condensatereservoir in northwest Kazakhstan. This field covers anarea of 280 square kilometres, with a hydrocarboncolumn extending over 1 km in thickness - from thePermian pinnacle reefs down into the Carboniferousand Upper Devonian platform carbonates. Discoveredin 1979, this field now has over 230 wells, with datafrom these wells showing a very heterogeneousreservoir that is difficult to characterize. The currentFormation Evaluation (FE) database contains a mix ofolder vintage wells (Former Soviet Union logs, cores,well tests) and new wells with recently acquired core,logs, production logs and well tests. WithKarachaganak nearing full-field development, aninvestigation is underway to determine the optimal FEacquisition necessary to evaluate the reservoir. A recentwell, consisting of a 45 degree main bore and a lateralsidetrack, was chosen as a test well to run a variety ofwireline and LWD logs. In addition to logging, over250m of core was taken in the 45 degree portion of themain bore. The LWD string run in the 8 ?” main borewas the most complex ever run in Kazakhstan, with thefull suite of standard logs (Gamma Ray, resistivity,neutron, and density), full-waveform sonic, magneticresonance and formation pressure tester. The pipeconveyed logs also contained a full suite of datacomparable to that run on LWD (minus the magneticresonance). Image logs and formation pressures wereobtained from both LWD and wireline tools. All of thisdata was thoroughly evaluated and integrated with coreanalyses results. Based on this evaluation, an optimalFE acquisition strategy has been developed for futurewells. Examples from this test well, showing log-coreintegration, along with LWD-to-wireline comparisonswill be presented as part of this paper.