Theoretical And Applied Research Tower Unstable Gas Condensate Well Test Analysis

Condensate gas reservoir is a kind of special reservoirs.It is different of dry gas reservoirs. And it also unlike conventional dissolved gas drive reservoir. As the exploitation of condensate gas reservoirs, the pressure constantly declined.The fluid would appeared different seepage characteristic in the porous medium:(1)single phase flowing;(2) two-zone compound model of oil and gas coexistence but only gas flowing;(3)three-zone compound model of existence oil and gas flowing;(4)four-zone compound model of high-speed flowing effect;(5)only existing oil and gas two-phase but only near the well regional is two-phase flowing;(6) oil-gas two-phase flowing in the whole model formation.Gas condensate system is a very complex physical chemistry system. It may encounter extremely difficult problems during the study of physical-chemical properties, or the seepage law.Even established a basic differential equation of the seepage flow process, the differential equation would be too complex to solve.These force to seek simple methods to sidestep the difficult.Based on the deeper understanding of condensate gas reservoir seepage flowing characteristic, and the condensate gas reservoir development for different stages of the seepage flowing mechanism, this paper takes compound model to analyze condensate gas reservoirs.This paper derived the differential equation of condensate oil-gas seepage. And the equation is of highly non-linear. In order to linear the equation, this paper introduces the pseudo pressure functions to obtain the equation, which is similar to the equation when there is only single flowing in the formation. Based on the linearization of condensate oil-gas flow equation according to different geological conditions, this paper established the three-zone compound model, four-zone compound model and model of two-phase flowing and solved these models.At the same time this paper conducted a series of sensitivity analysis of typical curves of transient pressure testing.And derived condensate equivalent calculation formula to deal with the production of gas condensate well.Then gave examples of such compound well testing model in the practical application to demonstrate that we can use compound model to deal with condensate gas reservoirs.Finally, this paper proposed some suggest about the analysis of condensate gas well testing, and pointed out the direction that well testing analysis of condensate gas reservoirs need to study in the future.