Analysis of two phase transient pressure from permanent down-hole gauges (PDG)

• Main Author: Xu, Wenbin
• Other Authors: Zheng, Shiyi
• Published: Heriot-Watt University 2010
• Subjects: 622
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.547650

Currently many of the world’s mature fields have entered the middle-high water-cut period. At this stage, reservoir numerical simulation (RNS) becomes a powerful tool for reservoir management which allows the reservoir engineer to plan and evaluate future development options for the reservoir to carry out the ultimate goal of minimizing costs and maximizing economic returns. So the precision of RNS is crucial to the success of any development plan. A precise reservoir model, including a geological model and a fluid model, is the foundation of RNS. Hence, how to use all available history data (such as permanent down-hole gauges (PDG) data, production data, etc.) to calibrate a reservoir model is a huge challenge for reservoir management. In this thesis, the multiphase flow well testing problems encountered in reservoir management are studied. Based on analytical solutions, traditional multiphase flow well testing approaches are modified to make them suitable for special reservoirs. For non-uniform saturation reservoirs, some improved understandings of transient well testing have been synthetically developed. Before water breaks through, the transient pressure response in the transition zone of two phase flow systems is theoretically studied, and the results show that the pressure response in the transition zone is a function of the total effective mobility of the fluid. After water breaks through, the derivative of the bottom-hole pressure is a function of the integral of total mobility, which can be approximately replaced by the average total effective mobility. The trend of the BHP curve is controlled by the total mobility. For layered commingled reservoirs, the type curves of transient pressure data are obtained. According to these type curves, some improved understandings are developed. At the same time, the practicality of selective inflow performance methods (SIP) on field scale reservoir models is also discussed. Because of the limitation of analytical solutions, not all existing multiphase flow well testing approaches are fit for evaluating mature field cases. So based on numerical solutions, a new multiphase flow well testing procedure is developed. The overall conclusion to the work is that transient well test data or PDG data with multiphase flow effects should be used to improve the degree of accuracy of reservoir model and fulfill the ultimate goal of well testing of dynamic reservoir monitoring and management