Optimization Design And Simulation Research Of CBM Drainage Specialized Pump

In the process of coalbed methane drainage and gas production, due to drainage disturbance and coal bed buckling failure during drilling, a part of pulverized coals and sand are carried to the well bore continuously. Due to its own gravity, the pulverized coals and sand would deposite to pump finally. Thus, it is hard to avoid such problems as stuck pump and buried pipe string, which will unquestionably shorten inspection cycle and service life of the pump. As a result, production efficiency of the coal-bed gas well will be seriously affected. Therefore, research on coal dust (sand) distribution law in the pump and completion of the specialized anti-clogging drainage pump are of great theoretical significence and pratical value.This paper discussed the generation mechanism of the pulverized coals in the process of drainage, analyzed the movement and distribution law of coal particles in a conventional pump and optimizing ordinary pump valve and plunger structure in order to design a new type of special CBM anti-clogging drainage pump. The main contents are as follows:Combined with coal bed methane reservoir characteristics and drainage characterize in different stages, the paper studied the generated mechanism of pulverized coals in coalbed methane wells, and analyed the influencing factors of stuck pump and buried pipe string within production process.On the basis of solid-liquid two-phase flow theory, by analyzing the different flow patterns in vertical tube, the force of the single-particle of pherical coal particle and settling velocity and distribution, a mesh model of ordinary pump barrel with the sucker rod annulus parts and fixed valve parts should be established; By using the FLUENT software to simulate flow field under different drainage intensities, the movement and distribution law of the volume fraction of5%of the coal particles was analyzed within the model.According to the distribution characteristics of pulverized coals in the pump, the ordinary pump structure was optimized to propose a CBM specialized anti-clogging drainage pump designing scheme, thus the specific parameters of the new type of pumpwas determined and its new structural design was completed. Therefore, a solid model was built by PRO/E software.Established finite element models of the key parts for a new type of drainage pump,calculated the pump barrel strength calculation and cone valve contact stress utilizing theANSYS software to ensure the strength reliability of the parts.Simulated flow field for the new type of pump fixed valve part by FLUENT software,and verified the rationality of the design to ensure the use reliability of CBM specializedanti-clogging drainage pump.Through this research, an effective way for CBM low-cost mining was found out, whichwill be benefit to boost the efficiency of the drainage system and optimize structure of CBMspecialized anti-clogging drainage pump. Thereby adaptive capacity of the drainage pump willbe promoted in actual working conditions.