Puguang Gas Field Stress Calculation Method For The Study

Gas reservoirs with high hydrogen sulfide content, as a kind of unconventional reservoir, are widespread in China, including Zhaolan Village Gas Field in Bohai Bay Basin, Luojia Gas Field of Shengli Oil Field, Feixianguan Formation of Dukou River Gas Field, Feixianguan Formation of Luojiazhai Gas Field, Feixianguan Formation of Puguang Gas Field, and Jialingjiang Formation of Wolonghe Gas Field in Szechwan Basin. On the one hand, the natural gas produced in these fields is rather poisonous and extremely corrosive due to their high hydrogen sulfide content. On the other hand, the numerous individual payzones in vertical and strong heterogeneity of reservoir make the development of Sour-gas reservoirs dramatically more painful and challengeable. Take for instance the Puguang Gas Field. It has a number of distinctive characteristics, say, strong heterogeneity, having edge and bottom water and nonuniform distribution of different wells.This paper, through vast literature research, firstly establishes formulae to calculate the bottom hole pressure of dry gas wells on the basis of conservation of energy. Then it achieves a final algorithmic method, after improving and solving these formulae, to acquire an accurate bottom hole pressure. Finally, through revising the compressibility factor of natural gas while taking the feature of high H2S content into account, it successfully work out the pressure of bottom hole in Puguang Gas Field.There are a variety of methods to obtain the strata pressure of sour gas reservoirs. This paper mainly applies several methods, of the systematical well test, combination of material balance and deliverability equation, pressure build-up test, and pressure draw-down test, to achieve this objective. Systematical well testing method requires the data of productivity test, meanwhile, the method combining material balance and deliverability equation, with a rather wide application scope, could acquire the stratum pressure change merely based on production data. Then, by fitting the pressure and production data of testing, it could not only guarantee the reliability of outcome but also figure out the productivity factors (A and B) and reserves, unfortunately the pressure draw-down testing might be infeasible for conventional gas reservoirs, since it is impossible to keep the production rate constant during test. After that, the pressure build-up testing could work out the formation parameter. In the meantime, it applies Saphir, a well testing analysis software developed by KAPPA company, French, to analyze the well testing data of P104-1and P3011-5with appropriate models. The results indicates that this method could attain precise formation parameters conveniently and expeditiously.