Research Of Residual Gas Of Low-permeability Sandstone

Xinchang field locates in the middle of Chuanxi sag, Sichuan basin. This field is a large, far source, clastic gas field which is made up of many gas stacked reservoirs(include shallow, middle, deep reservoirs) in vertical. The reservoirs are of many types, the reservoirs' distribution is complex, so it is very difficult to recover. Peng-er gas reservoir was discovered by 1992, which is one of the main reservoirs of Xinchang field. This reservoir is a mesotype shallow full-contained gas field, which is formed by 5 gas stacked formations in vertical. The buried depth is from 900m to 1200m, average porosity is 11.83%, average effective permeability is 0.28 X 10~-3 u m2. So this reservoir belongs to low permeability gas reservoir. Peng-er gas reservoir is on the declining stage of low pressure and low production.It is geologic basis for the research of the law of the distribution of residual gas to carry on elaborate description of Peng-er gas field. During the research, we carry on elaborate formation structure research and top structure of gas-contained sandstone research by adopted a set of technics which mainly consist of elaborate seism scaling and seism inversion technic constrainted by wells, integrate well drilling and log data; and then we carry on integrated geological research include sedimentary facies, diagenesis, physical property of socks, pore structure and gas pool production trends. Finally, we elaborately describe the geological character and production trends of Peng-er gas pool.On the condition of reservoir elaborate description and amplitude attribute data of 3D seism, we put up reservoir geological modeling. Double Calculate reserves by using volumetric method. And then classify that to three grades- high grade reserves, common reserves and hard producing reserves, compile distribution ichnography of the three reserves of every member.On the basis of geological modeling and double reserve calculation, we carry on numerical simulation by using the soft of ECLIPSE, elaborately numerical simulate the 5 members in Peng-er gas pool by using 3D gas-water two phases black-oil model. The matching ratio of gas wells' history matching is 88.5%, which reach a high level. The distribution of reserves of residual gas is described by press of gas reservoirs and reserves abundance in this gas pool.The research result is that the distribution of reserves of residual gas has 3 types, that is type of uncontrolled by well pattern, exploited by halves and exploiting. Based on these, we can enhance the recovery degree of residual reserves by using the method of infilled well pattern, massive hydraulic fracturing and so on.During the whole research, we firstly use modern high and new-technology industries such as the elaborate seismic scaling, seismic layer inversion technic restricted by wells, geological modeling technic using 3D seismic amplitude attribute data, and numerical simulation by using 3D gas-water two phases black-oil model for the research of residual gas of low-permeability sandstone gas field. The research result is exciting.