Development and Performance Verification of a High-Temperature High-Pressure Impact Force Acquisition Sub for Drilling Jar

To address the difficulty in accurately evaluating the instantaneous impact force magnitude and unsticking effectiveness of drilling jars during jarring and unsticking operations in deep and ultra-deep wells, an impact force acquisition sub suitable for high-temperature high-pressure environments in ultra-deep wells was developed with a ϕ121.0 mm drilling jar as an example. Its main functional components included resistance strain gauges, an integrated circuit board, a battery component, a shock-absorbing device, a temperature sensor, and a pressure sensor. The sub has a total length of 1 100.0 mm, an outer diameter of 127.0 mm, a rated operating temperature of 150 °C, and a compressive strength of 75 MPa, with resistance strain gauges employed as the sensing elements. During service, the sub can automatically switch between high- and low-frequency acquisition modes through the coordinated triggering of temperature, pressure, and acceleration sensors, thereby meeting the impact force acquisition requirements in long-term downhole operating environments. Through finite element strength check, simulated well tests, and surface bench tests, the strength reliability, sealing integrity, and acquisition stability of the sub under high-temperature high-pressure conditions were validated. It can accurately capture axial load fluctuations in the drill string during jarring and unsticking, providing a direct and reliable measurement means for quantitatively evaluating the jarring performance of drilling jars.