Dynamic Reserve Calculation And Productivity Evaluation Of JLS Feixianguan Formation Low Permeability Gas Reservoir

The proportion of natural gas in the energy consumption structure is increasing.At present,most of the natural gas reservoirs found in China belong to medium or low permeability reservoirs,this paper investigates a large number of domestic and foreign Research results,evaluates the water invasion status of JLS gas reservoir combining with static geological and production data,calculates the reserves,evaluates the gas well productivity and analyses the factors affecting the gas well productivity.so as to comprehensively and thoroughly understand the gas reservoir development performance and put forward suggestions.The main work and research achievements in this paper are as follows:(1)The geological and development characteristics of JLS gas reservoir are analyzed in depth,which lays a solid technical foundation for later research.(2)Evaluating and studying the present situation of water invasion in gas reservoirs,it is concluded that water invasion has occurred in gas reservoir of JLS,and the cumulative water invasion is 8.2466 x 104m3.The formation energy of gas reservoir is supplemented by water invasion,but the water invasion interface has not yet broken through the bottom of production wells.The gas production and water production are stable.At present,water invasion does not have a greater impact on gas well productivity.(3)The reserves of JLS gas reservoir are evaluated.A mathematical model of theoretical extreme value of gas reservoir reserves based on the principle of material balance method is established.The gas reservoir reserves are comprehensively evaluated by the calculation results of material balance method,cumulative production method,water drive curve method and pressure drop curve characteristic analysis method.the dynamic gas reservoir reserves are determined to be 3.8939*108m3.(4)The productivity of production wells in JLS gas reservoir is analyzed and evaluated.This paper establishes a gas well productivity evaluation model considering the influence of multiple factors.The actual gas well data are used to verify and analyze.The error between the calculation results of the new model and the actual well test results is small,which can be used in the actual gas well productivity evaluation research.Then the productivity of LI 6 well is evaluated comprehensively by using binomial formula,one-point formula,exponential formula and new model,and the productivity of gas well is determined to be 5.628*l04m3/d.(5)Using the gas well productivity evaluation model established in this paper,the effects of geological factors and fracturing parameters on gas well productivity are analyzed and studied.In terms of geological factors,starting pressure gradient and stress sensitive effect will reduce the open flow rate of fractured gas wells;slipping effect will make the open flow rate of fractured gas wells increase slightly;when considering the starting pressure gradient,gas slipping effect and stress sensitivity of reservoir rocks comprehensively,The productivity of gas wells is obviously lower than that without consideration.In terms of fracturing parameters,the longer the fracture half-length,the greater the conductivity and the larger the open flow rate of gas wells.The increase of fracture half-length and fracture conductivity will not lead to a linear increase in productivity,on the contrary,the productivity increase will gradually decrease.