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Low Permeability Gas Reservoirs And Gas Condensate Percolation Mechanism In Porous Media

Posted on:2006-03-26Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y W JiangFull Text:PDF
GTID:1110360182456103Subject:Mineral prospecting and exploration
Abstract/Summary:PDF Full Text Request
Gas condensate fields are parts and parcels in the development of the gas field in China, the development of the gas condensate fields are lay store by the petroleum industry. Gas condensate fields are kinds of exceptive and complicated gas field; they assume key economic value because they both produce natural gas and condensate oil; the appearance of retrograde condensation because of the declining of the formation pressure during the development of those fields can make the development of this fields difficult , and because of it ,it is difficulty to improve the percent recovery of condensate oil.The conventional development fashions for the gas condensate fields mainly are natural depletion and cyclic gas injection: using the method of gas injection require know clearly about the formation and need more investment, so this method is used few in our country; although a good deal of condensate oil is loss in the formation because of the appearance of retrograde condensation by the method of natural depletion, it is the main development method in China because of the lower investment and lower perception level abut the formation . This paper closely researches the natural depletion mechanism for gas condensate fields and the factors affecting the effectiveness of developing the gas condensate fields by natural depletion with the help of the core experiments; tests the critical flow saturation of condensate oil in porous medium, condensate oil saturation during the depletion and the real relative permeability curves ; with two types of relative permeability curves, simulates and forecasts the results of experiments by CMG. The research shows that the percent recovery of natural gas and condensate oil in core experiments are larger than one in PVT experiments; the real relative permeability curves have a significant effect on the percent recovery;. retrograded condensate oil of lower condensate oil system can not second evaporate reciprocally in low permeability cores.In gas and condensate gas reservoir, the content of the irreducible water has great importance to the calculation of reserve and the percolation of formation fluid. Home the research about this field is seldom. In the process of the research, this paper analyses firstly analyses mobile water in low permeability cores with NMR(nuclear magnetic resonance) experiment, gas-flooding-water experiment and centrifuging experiment and construe the reason that wells produce water in low permeability gas reservoir when the initial water saturation is lower than the irreducible water saturation. The research shows that the pressure has great effect on the content of irreducible water; in lower pressure, the content of irreducible water is lower in highpermeability cores, but in higher pressure, the content of irreducible water is lower in lower permeability cores. The dynamic experiment of gas-flooding-water shows that the irreducible water content is not a definite value ,it is sensitive to the flooding speed ; the irreducible water content reduces with the rising of the flooding speed . In the process of production, this phenomenon leads to the rise of the produce and the improvement of the permeability in lower permeability gas reservoir. The tested the irreducible water content by NMR is higher than the tested value by centrifugation experiment. The tested pore by NMR is lower than that tested by conventional analysis method; the higher the pore tested by NMR ,the lower mobile fluid saturation. Suggest that it should consider fluid factor when evaluating the reservoir quality and exploitative potentiality of lower permeability gas reservoir.
Keywords/Search Tags:gas reservoir, condensate gas reservoirs, low permeability, depletion, critical flow saturation, relative permeability curves, irreducible water
PDF Full Text Request
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