Experimental Simulation And Mining Application Of Multi - Layer Mining In Tight Sandstone Gas Reservoir

Although China is rich in terrestrial facies tight sandstone gas resource, the reservoir sand body is characterized by multi-superimposed in longitudinal, poor continuity in transverse, small scale and strong heterogeneity. Moreover, high resistivity water layer is coexistent with high and low resistivity gas reservoir, gas layer and water layer are difficult to be distinguished. Gas reservoir commingling production has already become an effective way to improve gas well production and increase economic benefits. So, making clear that multilayer interference, each layer supplying ability and water output mechanism in commingling gas wells is of great significance for efficient development of tight sandstone gas reservoir.This article focuses on tight sandstone in Sulige gas field. By means of advanced core analysis. Further clear multi-scale geological characteristics of tight sandstone. Design and carry out tight sandstone sample series-parallel experiments. Preliminarily reveal water output mechanism in multilayer gas wells. Analyse the test and production data of typical gas wells. Verify the reliability of experimental equipment and result. Discuss technical countermeasures of developing multilayer tight sandstone gas reservoir.Further clear multi-scale geological characteristics of tight sandstone. Sulige tight sandstone reservoirs have geological characteristics of low porosity, low permeability, strong imhomogeneity, high capillary pressure. On the basis of gas supply and petrophysical property, Sulige gas field has been divided into three categories which include class I high-TK(principal production formation), class Ⅱ mid-TK(potential production formation) and classⅢ low-TK(assistant gas supply).Design and carry out series experiments for permeability tight sandstone sample, and evaluate the gas supply ability for the configuration relationship of different permeability level tight sandstone. If gas source is the relatively low permeability zone, the greater the permeability differential is. the faster the gas well production declines in its early exploitation; If gas source is the relatively medium or high permeability zone, there is no significant effect on permeability differential; The greater the permeability differential level in the tight sandstone layer is, the greater the production contribution difference is."TK low (source) and TK high (collection) series" mode can fully use the relatively high and low permeability reservoir, and the matrix transfer efficiency determines the supply capacity of the reservoir.Develop an analog evaluation device to monitor gas supply ability under the condition of multilayer test,’Design and carry out tight sandstone sample parallel experiments, reappear multi gas layer commingling production "backflow" phenomenon. According to the assemble of electromagnetic valve, mass flowmeter, pressure sensor and the switch on the control panel, It has achieved to monitor each layer’s pressure changes and production contribution feature; Simulate and monitor the gas flux, the pressure, and the gas ratio in each layer under different back pressure. and pressure depletion experiments recurrence that multilayer commingled production "backward" phenomenon and the influence of back pressure to flow backward time. When back pressure is equal, the greater the permeability differential, the greater the gas flow backward, the longer started to flow backward; When Permeability differential is equal, the greater the back pressure, the shorter the time started to flow backward."Parallel" simulation experiments preliminarily reveal water output mechanism in multilayer gas wells."Parallel" experiments simulate the process of formation water and condensate water output during commingled production with different permeability reservoir. Formation water desalination or condensate water output from gas layer under multilayer test can lead to the phenomenon of high resistance layer water production; Compared with desalination formation water, water output earlier in formation water flooding gas sample, higher water phase permeability and formation water is easier to produce.Analyse the test and production data of typical gas wells, Verify the reliability of experimental equipment and result. And discuss technical countermeasures of developing multilayer tight sandstone gas reservoir. Suggestion is to deepen reservoir evaluation theory, optimize gas well type and location, reasonable production proration, select the optimal timing of commingled production, in order to enhance single gas well recovery and improve well production.