A study on flow-rate stabilisation control for a dual-pump drilling fluid property measurement system

Abstract Drilling fluid rheology is important for wellbore cleaning, drilling efficiency and operational safety. In online pipe-viscometer measurements, pump pulsation and the non-Newtonian, time-varying behaviour of drilling fluids can cause actual flow deviations and fluctuations, thereby disturbing pressure-flow data and reducing the reliability of subsequent rheological parameter estimation. To address this issue, a dual-pump flow-stabilised measurement system was developed for drilling fluid testing under multiple operating conditions. The system integrates two diaphragm pumps, a pressure tank, a pipe measurement section, an ultrasonic flowmeter and pressure sensors to provide stable flow conditions over low-, medium- and high-shear-rate ranges. An improved Grey Wolf-optimised fuzzy PID controller was introduced to optimise the scaling factors of the fuzzy controller and enhance adaptability and robustness. Comparative experiments were conducted under small-pump, large-pump and dual-pump operating modes. The proposed controller achieved the best overall performance among the three control strategies tested. Under the small-pump condition, the RMSE and ITAE were reduced to 0.0104 and 0.0187, respectively; under the large-pump condition, they were reduced to 0.0187 and 0.0125; and under the dual-pump condition, the settling time was shortened to 0.5 s, with an ITAE of 0.0047. These results indicate that the proposed method improves flow response and flow stability, reduces the influence of flow deviations and fluctuations on pressure-flow data, and provides more reliable measurement conditions for subsequent rheological evaluation of drilling fluids.