Solid–Liquid Impurity Separation in Shale Gas Gathering and Transportation Systems: Method Development and Field Application

To address the critical challenges in shale gas development, including severe erosion and wear of gathering and transportation equipment as well as frequent compressor failures induced by sand-laden and liquid-bearing raw gas, along with the insufficient representativeness of solid–liquid impurity sampling and the poor applicability of existing separation performance evaluation methods, a closed-loop integrated sampling and detection prototype was developed. Numerical simulations were conducted to optimize the structural design and screen the performance of the swirl impeller. Furthermore, a sampling representativeness coefficient model was established to enable an accurate correction of sampling results under varying operating conditions. On this basis, a comprehensive evaluation methodology for solid–liquid impurity separation performance was proposed, incorporating both overall separation efficiency and classification efficiency, thereby forming a complete technical framework encompassing equipment development, data correction, laboratory calibration, and field evaluation. The results show that the deviations between the corrected value and the actual value at the high representative position are about 1.55% and 7.53%. The corrected field evaluation indicates that the two-stage separation system achieved overall solid- and liquid-phase removal efficiencies of approximately 99% and 96%, respectively, under the investigated operating conditions. These results represent model-corrected estimates based on field sampling data. This study fills the technological gap in solid–liquid two-phase sampling and separation efficiency evaluation for high-pressure, liquid-bearing raw gas gathering systems, providing both theoretical support and technical assurance for the optimization of separation processes and the safe and efficient operation of critical equipment in shale-gas-gathering and -transportation systems.