Productivity Evaluation Of Strong Interlayer Heterogeneity And Low Permeability Tight Sandstone Gas Reservoirs

The Linxing gas field on the eastern margin of the Ordos Basin is composed of multiple layers of tight sandstone gas reservoirs.The reservoirs have large differences in permeability and complex pressure systems.The characteristics of tight low pressure in gas reservoir 8 and abnormally low pressure in relatively high permeability of He 2 gas reservoir.How to evaluate and reduce interlayer interference in multi-layer combined mining is the key to the economic and effective development of such gas fields.In view of this problem,the paper takes Linxing gas field as the research object.First,starting from the analysis of gas reservoir characteristics,the compact sandstone gas reservoir in the west of Linxing includes pore structure characteristics,reservoir physical properties,pressure systems and fluid properties Analysis.On this basis,the strength of the inter-layer heterogeneity is evaluated,the causes of inter-layer interference that may occur in multi-layer co-production are studied,and a method for evaluating the strength of inter-layer interference is developed.Then,by designing a multi-layer combined mining simulation experiment,selecting the core core of the Linxing Gas Field for experiments,and studying the changes in the layered gas production during multilayer combined mining,it was found that inter-layer interference will occur in the initial stage of mining,and back-irrigation will occur.Change the production rate,study the variation law of back-irrigation time,and simulate the frequent switch well operation during construction to study the variation law of reservoir pressure.Next,establish a multi-layer combined production mechanism model,select formation parameters in the west of Linxing,use numerical simulation software to simulate the actual development of the gas reservoir,and explore interlayer interference and backfill time affected by reservoir pressure,skin coefficient,and reservoir permeability.Of water,production and reservoir thickness.A mathematical model of multi-layer combined gas reservoirs without considering interlayer flow is established,and the wellbore pressure expression and multi-layer gas for single-layer production of circular closed boundary gas reservoirs are derived with consideration of wellbore storage effects and skin effects.Lagrangian spatial solution of stratified gas production in reservoirs.Through calculation,analyze the relationship between formation coefficient,storage capacity coefficient and formation pressure on multi-layer combined production and layered gas production,interlayer interference and back-irrigation time.Finally,the above research results are used to evaluate the development method of a production well in Linxing block,and the feasibility of its joint mining development is obtained.,Divide the mining strata of Linxing block,determine the reservoirs with similar physical properties and weak heterogeneity,and allocate the production reasonably in accordance with the production period of stable production period and economic requirements,and provide guidance suggestions for on-site mining.