Pressure Transient Testing and Fluid Profiling using Wireline Formation Tester Helps Optimizing Completion Strategies: Pakistan Tal Block Case Study

Abstract

ABSTRACTWell testing is very challenging especially in northern parts of Pakistan, as there are complex lithologies and multiple formations encountered in a single well. These formations include both fractured carbonates and sandstones. In addition, lower matrix porosities make it more difficult and time consuming as it can take several weeks to months to test multiple formations individually using a casedhole drillstem test (DST). These tests impact the overall well cost due to the extended rig time required and production loss. Extended buildups are a huge concern that must be kept in consideration due to the high rig-time requirement.This paper describes the application of a wireline formation tester (WFT) for interval pressure transient testing (IPTT), which is also referred to as a mini-DST, to estimate flow regimes and reservoir properties along with vertical pressure profiling, fluid identification, and sampling. This technique was applied at two of the exploratory wells in TAL block. There, WFT was deployed with a single probe and straddle packers to achieve the desired results across four potential reservoirs. Vertical pressure profiles across the prospective formations were acquired using the single probe; this was followed by a mini-DST using straddle packers to test zone by zone for fluid type, collect samples, and record pressure buildups. Real-time pressure derivatives were monitored to optimize the buildup time at each station depth. This integrated IPTT gave necessary reservoir information in a very short span of time. It saved significant amount of time and costs, especially rig costs and entire well testing cost giving valuable information for completion strategy.