Abstract
AbstractThe correlation between the produced water cut and average water saturation around the perforation obtained from Cased-Hole Saturation Tool (CHST) measurements is evaluated in this paper. The motivation for this study is to enable significant financial savings which would accrue by the need for less CHST logging runs for effective Reservoir Fluids Management provided average water saturation can be quantified in terms of produced water cut, the water perforation coverage and the wellbore completion string parameters such as perforation thickness, and deviation angle.Average water saturation and perforation water coverage, was determined by analyzing CHST logs block by block obtained using CHST tools in two different petroleum provinces (Nigeria Joint Venture Area and North Sea Basin). For each well logged, well test data or Production Logging Tool data, wellbore deviation survey and the completion schematic were obtained. The datasets from each region were split in two categories – well shut-in for less than four months prior to CHST log measurements and wells shut-in for more than 4 months. Regression analysis was used to investigate the correlation between CHST log determined parameters and other flowing and static wellbore parameters for wells without any history of damage or complex water production mechanisms.The results obtained indicate that for wells in the Niger Delta with large perforation intervals (> 30 ft), produced water cut strongly correlates with average water saturation while for wells in the North Sea Basin with short perforation intervals (10 - 30ft) the average water saturation correlates strongly with both water cut and the perforation interval thickness. It was apparent that for the wells shut-in for periods exceeding four months no empirical relationships could be established. Heterogeneity in petrophysical property distribution and borehole reinvasion are suspected to be responsible for deviation from the correlation between produced water cut and average water saturation.
Published Version
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