Abstract:
Real-time and accurate calculation of gas extraction pipeline networks is essential for ensuring the sound and efficient operation of gas extraction systems. However, the determination of negative-pressure distribution at individual nodes and the accurate assessment of gas extraction compliance remain challenging. To achieve accurate gas extraction compliance assessment, a high-precision real-time pipeline-network calculation method and a compliance analysis method based on the calculated data are proposed. To address noise interference and systematic deviations in monitoring data, a data reconciliation model integrating adaptive Kalman filtering with mass-flow conservation is developed for the high-accuracy preprocessing of monitored gas extraction flow data. Dynamic boundary constraints at pumping stations and drilling sites, together with internal sensor constraints, are incorporated into a binary gas-mixture flow model under multiple constraints. An improved Newton method is employed to efficiently determine the network-wide flow rate, gas concentration, and nodal pressure. A coal seam parameter inversion and gas extraction compliance assessment model is established, through which the coal seam permeability coefficient is inversely determined, compliance indicators are calculated, and the time required to achieve compliance is predicted based on the pipeline-network calculation results. Field experiments are conducted to verify the reliability of the proposed pipeline-network calculation and compliance prediction methods. The results show that, compared with four conventional solution methods, the improved Newton method incorporating Kalman filtering and mass-conservation-based data reconciliation effectively overcomes the difficulties of poor convergence and excessive computational time encountered by conventional methods. The relative errors in the calculated flow rate, pressure, and gas concentration are 5.168%,
1.0697%, and
2.8049%, respectively, indicating that reliable data are provided for subsequent gas extraction compliance assessment. Good agreement with field observations is obtained for both the inverted coal seam permeability coefficient and the gas extraction compliance assessment results. High accuracy is also achieved in predicting the time required for compliance, and gas extraction compliance is achieved within the predicted period. The results are of great significance for improving gas extraction efficiency and provide a mathematical modeling basis and key algorithmic support for the intelligent control and optimization of gas extraction systems.