Abnormal High-pressure Condensate Gas Reservoir Material Balance And The Law Of Diminishing Of The New Method

Based on the rock mechanics, the equilibrium phase change theory of the hydrocarbon and oil-gas field development theory, combining experiment with theoretical research, this paper constructs two models in the abnormally high pressure gas condensate reservoir. One is the reserves calculation mode, by means of material balance principle. The other is the production decline model. What's more, the case calculation proves the models are proper and practical.The abnormally high pressure gas condensate reservoir is different form the conventional gas condensate reservoir in two respects.Firstly, the rock in these reservoirs is deformable when exploited and the fluid pressure drops as the fluid is produced, then the stress loading on the rock is increased, that results in deforming the rock, reducing the pore volume and changing the pore configuration. Therefore, the rock deformation causes two results. On one hand, it supply driving energy; on the other hand, the permeability in the formation is cut down.Secondly, in some abnormally high pressure gas condensate reservoirs, there are a lot of water vapor. If the water vapor is neglected, the error of the reserves calculation is obvious. So all the factors must be considered when we computing the reserves in the way of material balance in abnormally high pressure gas condensate reservoirs. Otherwise, the original gas in place will be overestimated. In addition, the reduce of permeability has an effect on the well productivity and decline law, and the performance prediction will be deviated if using conventional method. It is necessary to build the production decline model which considers the effect of the abnormally high pressure on the rock and fluid character.On the foundation of the experiment and theory research, emphasizing on the effect of the abnormally high pressure on the petrophysics and fluid physical property, the paper makes the material balance model and the production decline model, both inabnormally high pressure gas condensate reservoirs. The former considers the compressibility of the rock, expansion of connate water, the effect of saturated vapor and the phase change; the latter thinks over the effect of the change of the pore volume and the high pressure on the physical property of the formation fluid. Finally, testing and verifying the theoretical model using cases, and obtaining practical results and suggests.