Comprehensive Evaluation And Production Optimization Of Dewatering Gas Production Technology On The Tight Gas Production Well

Tight sandstone gas(hereinafter referred to as tight gas)has become one of the most important fields of unconventional gas exploration and development in the world,a prominent problem in the late stage of the tight gas reservoir is the gas well bottom fluid,will cause huge economic losses to gas fields.So analysing the wellbore fluid law,on the basis of building the suitable comprehensive evaluation and production optimization model for drainage and gas extraction is constructed,there is a great practical significance to optimize the gas extraction process technology.Aiming at production characteristics of tight gas,develop the basis of related research,on the basis of analyzing the seepage law of tight gas reservoir,a gas phase and water-phase capacity model is established to consider the effect of gas slip and stress sensitivity and starting pressure gradient.Starting from the research on the rules of wellbore fluid,using the method of both liquid critical velocity diagnose wellbore fluid,and based on previous theoretical and experimental research results,evaluate the commonly used 11 kinds of critical flow velocity calculation model,the evaluation results show that,for the vertical Wells,when the GWR is more than 1400 m~3/m~3,peng chao-yang model has the highest diagnosis accuracy;When the GWR is less than 1400 m~3/m~3,li min model has the highest diagnostic accuracy.For the directional well,Chen de-chun model is the best of all models.Eight commonly used two-phase pressure drop models are evaluated and optimized based on the analysis of 102 groups of gas well production data from home and abroad.The results show that,Hagedorn-Brown model and Gray model are recommended for gas wells with high GWR(>2441 m~3/m~3)and Beggs-Brill model is recommended for gas wells with low GWR(<2441 m~3/m~3).From the law of gas effusion and wellbore fluid distribution,and based on the principle of"U"type tube wellbore fluid pressure balance,the mechanism of gas-liquid two-phase flow in a wellbore is studied,and a model for calculating the fluid height of the wellbore is established,the example calculation results show that in 10 Wells,wellbore liquid fluid height calculation model established by the calculated values and measured values of the average absolute error is 39.67m and the average relative error is 12.71%,can meet the needs of engineering calculation,provides the basis for design and implementation of measures for production.Aiming at the characteristics of tight gas reservoir,drainage and gas extraction technology suitable for tight gas reservoirs is optimized,a comprehensive evaluation index system of drainage and gas extraction technology is established,an example of a tight gas well is used to evaluate the integral value of the drainage are 0.936,0.837,0.821 and 0.793,respectively.Therefore,it is recommended to select the drainage gas extraction process in the order of the optimal gas lift,followed by the eddy current tool,the third choice is the bubble row,and the fourth is the optimized string.It can provide the correct guidance for the optimization and investment decision of the tight gas well drainage.