A Novel Bidirectional Flow Electromagnetic Measurement System for Drilling Engineering

The prevailing advanced method for early overflow monitoring involves the comparison of the surface mud pump injection flow rate with the downhole annular return flow rate. Despite its widespread use, this indirect comparison method leaves room for enhancement, particularly in performance. Real-time monitoring of downhole bidirectional flow information near the drill bit presents a more direct and precise approach to early overflow detection. This article introduces a novel downhole bidirectional flow electromagnetic measurement system (BEMFS). Initially, an in-depth exploration is conducted into the measurement principles, the theoretical model's construction, and the weight function's solution related to the downhole BEMFS. Subsequently, through the finite element simulation software, the theoretical model of the downhole BEMFS and the theoretical model of the gas invasion system are verified, and the optimal structure design parameters of the excitation coil of the measurement system are obtained. Lastly, an experimental platform is established to conduct experimental testing on the BEMFS principle prototype. The experimental results show that the instantaneous flow measurement accuracy of the BEMFS principle prototype reaches 1.0 level, which can meet the needs of bidirectional flow measurement. This verifies that the feasibility of the BEMFS for gas invasion overflow monitoring is also validated.