Study On Selecting Water Discharge And Gas Production Equipments For CBM Wells

Selecting water discharge and gas production equipments for CBM wells is regarded as the key technology in the exploitation of CBM, and is important factor of making continuous and steady operation in CBM wells. Research is processed combining to major technical national project, thematic of large oil and gas fields and CBM development, which is sub-project of optimization selecting technology of system equipments in CBM wells.In this paper, based on the reservoir-forming mechanism of CBM in China, the properties of every mining process in CBM wells were studied. The flowing law of fluid and prediction law of productivity were studied by applying Darcy seepage and non-darcy flow law. Calculating method of bottomhole flowing pressure in every phase was provided by setting up mathematical model and developing numerical solution method. Predicting maximum water production was provided by obtaining reliable water producing index and setting up equations. The relationship among various mining parameters and their impacts on the volume of produced water and gas were developed by analyzing them. At last, the analysis of dynamic and production system were completed which laid a foundation on selecting equipments for CBM wells.Process principle, technical features and adaptability of various pumping equipments were analyzed. Based on geological conditions, various production parameters and practical mining factors such as hole deviation, sand and pulverized coal production, comprehensive evaluation method of parameter quantization was setted up. Based on this method, main indexes of various pumping equipments were evaluated. Therefore, optimal selecting method of type was developed. The selection of optimum equipments was completed.The working theory and polished rod motion of beam pump in CBM wells were analyzed. Basic parameters of beam pump were determined, which included calculating horsehead load, drawing indicator diagram, selecting stroke and pumping speed and calculating torque of reducer following crank angles. Then mode, principle and calculation of balance were developed. At last, design and calculation of beam pump was completed which provided a basis for selecting the type of equipments for CBM wells.Based on estimating the maximum volume of water to be produced, pump diameter, stroke and pumping speed for typical equipments were determined. Rod string assemblage and dimension of tubing were designed based on pump depth and pumping parameters. The basic parameters of beam pump were calculated based on the selected pump diameter, stroke, pumping speed, rod string and tubing. At last, the type of pumping equipments and power plants was selected. The selection graphic of unit and pump type and the specification select table of sucker rod string and tubing were developed. At last, selection of water drainage and gas production equipments for the CBM wells was setted up.The paper aims at setting up the method of selecting water discharge and gas production equipments for CBM wells and parameter matching norm and guiding the systematic and scientific selection for special equipments, in order that the problems can be solved, such as large investment, not matching equipments and evacuation, the pump inspection period can be improved effectively, per-well production can be increased, and the development benefits of CBM can??romoted.