Is Jarring Effective? Design and Testing of High-Frequency Jarring Force Measurement Sub for High-Temperature, High-Pressure Ultradeep Wells

Summary Proper use of drilling jars can effectively minimize nonproductive time resulting from pipe-sticking incidents during drilling operations. Due to factors such as temperature, friction, and viscous resistance, the jarring performance of drilling jars is generally poor during jarring operations in ultradeep wells. Existing theories and downhole tools are unable to accurately assess and measure the jarring performance of drilling jars. To address this issue, we designed and developed a high-frequency jarring force measurement sub capable of operating under downhole high-temperature and high-pressure (HTHP) conditions. The tool is characterized by a high sampling rate, high structural strength, strong vibration resistance, a wide measurement range, and stable operational performance, and it can be installed directly below the drilling jar as part of the bottomhole assembly. Finite element analysis indicates that the measurement sub remains structurally safe under rated loads. Combined with high-temperature bench testing and field experiments, the results demonstrate that the measurement sub can accurately capture instantaneous impact loads, axial acceleration, and downhole temperature and pressure during continuous jarring operations, with actual test results showing a relative error of less than 1%. This provides a direct and reliable technical means for quantitatively evaluating the jarring performance of drilling jars under ultradeep well conditions. The findings offer essential data support and experimental evidence for subsequent structural optimization of drilling jars, refinement of jarring operating parameters, and improvement of operational procedures.