The Lectotype And Optimal Design Of Dewatering Gas Production Equipments For CBM Wells

The lectotype and design of dewatering gas production equipment, is regarded as the keytechnology in CBM exploitation, and half the battle of making safe and scientific, continuousand stable production. Combined with the programme “Research on High EfficientDewatering Gas Production Technology for CBM Wells on LiuLin Demonstration Area (No.2011ZX05062-004)”, which is the sub-topics of major national oil and gas projects “Large Oiland Gas Fields Development”, research is conducted in this paper around the optimization&selecting of dewatering gas production equipment, discharge of coal powder in suckerrod-tube, sucker rod design and anti-eccentric wear study.First, by analysing the Characteristic and adaptability of common CBM dewatering gasproduction equipment, the multi-level fuzzy comprehensive evaluation system and dynamicevaluation functions are established based on factors such as exploitative conditions,underground engineering conditions, economic input, etc. The weights of index system arecalculated by application of AHP method, which can quantify the status and role of index onthe overall project. The best one is found by dynamic comprehensive comparative analysisand evaluation on CBM dewatering gas production equipment.Then, the kinematics and mechanical analysis of beam-pumping unit is made based onthe model of four-bar linkage. And the optimization design model of beam-rod-pump systemis established combined with the special requirements of beam-rod-pump system used forCBM wells. A reasonable one is selected according to the power and load capacity of themotor. The new design method of sucker rod, which combining the API method andWilnowsk method and contraposing the working conditions and actual mechanical behaviorof that on CBM wells, is reached so that its working life can be extended.At the same time, the discharge condition of coal powder in wellbore is analyzed to reasonably design the operating parameters of beam-pumping unit. And the rod tubecombination is optimized to discharge the most coal powder of wellbore up to ground, whichcan effectively solve problems such as stuck pump, buried pump, and coal reservoir damagecaused by coal powder, ensure the continuous and stable operation of CBM wells.Finally, the expert system of lectotype and optimal design of CBM dewatering gasproduction equipment, is developed with VB software, in which functions such as theevaluation and optimization of CBM dewatering gas production equipment, the selection anddesign of beam-pumping unit, the analysis of coal powder discharge from wellbore up toground, and the anti-eccentric wear design of sucker rod, are integrated. This system makesthe automation of lectotype and designs (of CBM dewatering gas production equipment)come true. Through the verification and comparison of on-site usage, it is found that, by usingthe system to design and analyze, the check period of sucker pump can be extended by morethan25%, and the problem that sucker rod eccentric wear, fracture, and trip can be bettersolved, which is of great significance to improve the cycle of failure-free operation.