Using Formation-Testing-While-Drilling Pressures to Optimize a Middle East Carbonate Reservoir Drilling Program

摘要

Formation-testing-while-drilling (FTWD) technology was introduced in 2002 and has been used primarily for applications similar to wireline formation testers (WFT). These applications include accurate formation pressures, gradient analysis, formation connectivity, differential depletion, and flow barrier detections. A largely untapped application for FTWD is drilling optimization. The testing practices for drilling optimization are somewhat different than those used for typical WFT applications. In these cases, it is desirable to obtain pressures as soon as possible; and real-time test results are paramount. Combined with other downhole drilling information, such as vibration, torque, and weight-on-bit, drilling parameters can be adjusted to improve the rate of penetration (ROP) and make adjustments to the wellbore stability model in real-time. This paper reviews a Middle East case study in a carbonate gas reservoir. In part of this field, the reservoir pressure was uncertain due to possible communication with a high-pressure lower interval. Therefore, establishing the actual formation pressure was a priority. By monitoring the FTWD pressure tests in real-time, it was possible to verify the quality and validity of each test. Then, the test data was used to change mud parameters gradually. A composite log clearly indicates how decreasing annular pressures resulted in an increase in ROP. The method of testing and real-time monitoring results are reviewed and compared with high-resolution memory data from the FTWD tool. Comparison validated the real-time test data. Conclusions are drawn concerning drilling applications and how such test data can be utilized to improve the drilling process.