Research Of Calculation Method Of Single Well Controlled Reserves And Excavating Potential Scheme Of Residual Gas In D1 Low Permeability Gas Reservoir

Natural gas has the characteristics of high burning calorific value,high utilization efficiency and high economic value.The production of low permeability gas reservoir is growing,and it has become an important part of natural gas production in China and the world.At the same time,the calculation of gas reserves is very important in the process of gas reservoir development,it is very important for the accurate evaluation of gas reservoir,the formulation of the development scheme and the matching of the later numerical simulation.Due to poor physical property,the formation pressure of low permeability gas reservoir falls fast,and the production entered the decline period fastly.At this time,researching on residual gas exploitation on the basis of studying the distribution of residual gas is important to increase the recovery degree of gas reservoir.D1 gas reservoir is located in the southwest of D gas field,its formation can be divided into three large layers,between which there is no layer deficiency.The formation of DI block has the low porosity,low permeability and strong heterogeneity.There are also special flow phenomena such as actuating pressure gradient,stress sensitivity and so on,and its lateral variation is obvious,it is the lithologic closed gas reservoir and physical property of the reservoir is poor.There are 52 gas wells in D1 block.D1 gas reservoirs began to start production in early 2005,the production of each single well is low.At the beginning of the February 2016,production has entered the decline stage.Deliverability of D1 has also been declining.At the same time,average formation pressure,tubing pressure and casing pressure has declined drastically,there is a high loss in formation energy.The main contents of this paper are as follows:(1)We have used the existing calculation method to calculate the single well reserves of each gas、well in block D1.We have calculated reserves of 52 single wells by material balance method and modern production decline analysis method.We have used RTA gas reservoir dynamic analysis software to calculate the reserves in modern production decline analysis method.(2)A new calculation method of single well controll reserves in low permeability gas reservoir considering actuating pressure gradient and stress sensitivity have been established.There are some special flow characteristics such as actuating pressure gradient and stress sensitivity in low permeability gas reservoir,whose influence of calculation results of single well controlled reserves in low permeability gas reservoir can’t be ignored.By example,we can get the conclusion that actuating pressure gradient and stress sensitivity can make the results of’dynamic reserves lower.(3)We have researched the geological and engineering factors which affect the low permeability gas reservoir development.We have established numerical simulation model of vertical and horizontal wells in low permeability gas reservoir and research the factors which affect low permeability gas reservoir development,such as actuating pressure gradient,stress sensitivity,formation thickness and perforation layer number by numerical simulation method.(4)We have researched distribution of residual gas and measures of excavating potential of residual gas in D1 block.We have done the reserve matching and production history matching work for the numerical simulation model of D1 block(including whole area and single well matching).On this basis,we have researched the distribution of residual gas in D1 block and put forward the corresponding scheme of excavating potential of residual gas in the light of different types of residual gas distribution.This paper have deduced the calculation method of reserves considering actuating pressure gradient and stress sensitivity and do an example analysis.And then,this paper have researched the residual gas distribution and measures to excavate potential of residual gas by numerical simulation.There is a certain theoretical and practical application value for determining single well dynamic reserves and make measures to excavate potential of residual gas in realistic low permeability gas reservoir.