Study Of JS₂ Gas Reservoir Modeling In Shaximiao Formation In Xinchang Gas Field, Sichuan, China

Establishing fine reservoir geological model is not only the final result of gas reservoir description, but also the basis for developing reservoir efficiently. JS₂ gas reservoir is a typical tight sandstone reservoir in Upper Shaximiao formation which is one of the main exploration targets in Xinchang gas field in west Sichuan depression, and it has been in the period of stable production. Not well improved development well network in this reservoir leads to a lower reserves producing level while the high gas producing rate is bad for improving the degree of reserves recovery, however.Considering the geologic characteristics, stochastic modeling technique is used to establish the geologic model of JS₂ gas reservoir including tectonic, strata, and reservoir parameters (porosity, permeability and water saturation) of zone JS₂¹, JS₂^2-1, JS₂^2-2, JS₂^3-1, JS₂^3-2 and JS₂⁴. This model is proved to be good in this paper. Based on the modeling, the results of classifying proved reserves have shown that the major productive formation JS₂² and JS₂⁴ has the characteristics of better physical properties, higher reserve-grade, better producing performance, and higher reserves producing level than formation JS₂¹ and JS₂³. Wells in high reserve-grade well field usually have good outputs, which means the gas zones and well field with better physical properties should be given the priority to allocate the developing adjustment wells. According to the earlier research results, combined production performance data, this paper considers that, JS₂² and JS₂⁴ has the characteristics of good physical properties, high remaining reserves in first and second category based on the proven classification, so that they should be the favorable target zones in adjustment of reservoir development scheme, on the other hand, JS₂¹ and JS₂³ have the potentiality of being put into development by adopting old-well-upward-return development method or separate-layer fracturing with multilayer commingled production method.Sand body and reservoir parameters dimensional distribution of JS₂ gas reservoir have become clearer than ever before through this research, which also provide a reliable basis for the reserves (especially for the remaining reserves) distribution pattern study, prolonging stable production period of gas wells, enhancing oil recovery, and etc, in further research.