Gas Reservoir Prediction Study

Performance prediction is the compass for seeking the optimum development plan for a gas reservoir so that the reservoir is developed rationally and efficiently. The material balance method and numerical simulation are the most widespread methods used in performance prediction of a gas reservoir. The material balance method is simple. It neglects the complexity of fluids' flow through porous media in the formation, and it needs a few data. Numerical simulation regards the heterogeneity of the formation, but its function is very powerful. This paper studies the performance of gas reservoirs by these two methods. Studies are made as follows: On the base of the material balance theory, by combining the deliverability equations of gas wells with the theories about wellbore hydromechanics, performance prediction models are built respectively for constant-volume gas reservoirs and water drive ones and abnormally pressured ones; The whole period of gas production is divided into the constant-gas-production-rate period and the constant-wellhead-pressure period, and the performance prediction methods for the both periods are studied; The models used to predict the real performance of the existing gas wells are built, and the models used to predict the average performance of all the existing production wells are also built; The theory about performance prediction for gas reservoirs by numerical simulation is introduced, and the mathematical model of the compositional simulation is studied deeply; The software for performance prediction by the material balance method is programmed, and the performance of different types of gas reservoirs is predicted by the software, and researches are done emphatically about how the gas recovery rate and the given minimum of wellhead flowing pressure affect the performance of constant-volume gas reservoirs; The performance of WenAn 23 Fault-Block Condensate Gas Reservoir locating in HeBei province is predicted by GEM compositional model, and studies are made about how the rate of gas recovery and the acid fracturing measure affect the performance of the gas reservoir and about how theperformance is affected by the gas production rate raised periodically in every winter. This study will help make a more reasonable development plan for a gas reservoir, and it will contribute to exploiting a gas reservoir more rationally and more efficiently.