Abstract
Abstract Production logging in high GOR horizontal wells still exhibits difficulties due to multi-phase, complicated flow regimes in undulating long well bores. Accurate diagnosis of gas entries is important for the understanding of the well performance, reservoir dynamics, characterization and if possible, for shut-off remedial action. In this paper, a case study is presented in a horizontal well with high GOR where oil production decreased significantly due to gas entries. The example horizontal well is located in Saudi Arabian Lower Cretaceous carbonate reservoir that has gas cap and relatively weak aquifer. Although the horizontal well is placed away from the gas cap, increase in GOR was observed after two years of production time. Since GOR increased to over 5000 SCF/STB by then, an integrated production logging tool was utilized to detect gas entries and determine flow profile. Results showed that the gas entries were detected from the high sides of the well and the majority of the gas was entering from the heel section over 500 ft of interval. Gas hold up in the well bore was determined from gas sensor tool in real time and pulsed neutron tool, providing high confidence. All the sensors exhibited coherent measurements, yielding confident and conclusive results for the gas entries. Image logs and permeability determinations identified the presence of different facies with high permeability over the interrelated entry intervals, supporting the calculated flow profile. The results, observed difficulties and recommendations are discussed for improvements. A single well fine grid numerical reservoir simulation model was also developed to assess impact of remedial action plans.
Published Version
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