| Carbonate oil and gas resources have the huge potential of exploitation, it’s very significant for worldwide nations to develop economy successfully. With the complicate geological structure functions, in generally, carbonate fractured vuggy reservoirs indicate fractured porous media and fractured vuggy media, reservoir structure has the feature of high heterogeneity. Taking Gaoshiti-Moxi Sinian fractured vuggy gas reservoir for example, because of the existence of vuggy and fractures, gas reservoir has the characteristic of heterogeneity. Therefore, This paper is funded by CNPC with the project of "Study on the Special Seepage Law in Sinian Carbonate Gas Reservoir by Experiments" and conducts the research on the characteristics of fluid flow in fractured vuggy gas reservoir, it’s of significance to guide this type of gas reservoir to exploit scientifically and rationally.In this paper, physical simulation method is applied to conduct experiments with field reservoir full-diameter cores and artificial fractured vuggy cores. Experiments at room conditions consist of single gas flow tests and gas-water relative permeability tests by using matrix cores, fractured porous cores and fractured vuggy cores, and it is necessary to contrast and analyze gas flow law in different kinds of reservoirs by using experiment results. At the same time, the influence of high temperature and high pressure on the volume and solubility of natural gas and formation water are taken into account, and gas-water relative permeability test procedure and method are established to specifically study the change relationships of gas-water relative permeability curves between fracture-vuggy horizontal connection and fracture-vuggy vertical connection.Research results indicate that (1) gas flow in dry matrix cores exists slippage effect, Darcy flow effect and high-speed non-Darcy flow effect, matrix cores with water saturations have threshold pressure effect, and water saturations have influence on non-Darcy seepage features;(2) fractured porous cores and fractured vuggy cores are only dominated by Darcy flow effect and high-speed non-Darcy flow effect, the existence of vuggy is good for gas seepage;(3) at room conditions, compared with matrix cores, the gas-water relative permeability curves of fractured porous cores have larger irreducible water saturation, the seepage ability of gas-water two phase decreases; compared with fractured porous cores, the gas-water relative permeability curves of fractured vuggy cores remove to the right, and gas phase relative permeability increases at the irreducible water saturation;(4) compared with fracture-vuggy horizontal connection, the irreducible water saturation decreases when fractured vuggy is connected vertically, gas phase relative permeability increases at the irreducible water saturation, equal permeability point removes to the right;(5) at high temperature and high pressure conditions, when comparing with gas-water relative permeability curves at room conditions, they have lower irreducible water saturation and larger two-phase seepage zone, the seepage ability of gas-water two phase is enhanced. |
