Abstract
A new method of objectively quantifying formation tester data quality has recently been developed with the aim of optimizing the generation of fluid gradients and contacts. This paper demonstrates how this new method of processing formation test data and integration with the open hole log data can be applied to improve job planning for sampling. By using data that have been quality controlled, sampling operations can be improved by using the optimal sampling tool configuration which can result in higher operational efficiencies with reduced rig time for complex logging and sampling operations. In this case study, formation tester objectives included establishing gradients and fluid contact points, determination of formation fluids and capturing representative samples over multiple horizons in a single 6 ⅛" wellbore. An additional factor which increased the complexity of this operation was the length and deviation of the wellbore, raising concerns about differential sticking due to the lengthy stationary sampling times required. The formation tester evaluation process was divided into two runs: wireline deployed pressure testing and drill pipe conveyed sampling. This culminated in successfully completing 22 pumpouts with 4 samples captured over 6 days without any incidents. The straddle packer was used 17 times in varying permeability formations and is considered to be the most number of inflations in the Middle East region.
The real-time formation tester data acquired were compared to the quality controlled data used for post processing analysis. The results were then used to identify the optimum procedures to be followed and future best practices. The lessons learned from the case study presented are used to demonstrate a quality control process with recently developed realtime methods for evaluating test quality. This allowed the data to be analyzed quickly and with confidence, enabling improved pumpout and sampling operation planning.
