Numerical Well Testing Theory And Application Research On Fractured-vuggy Gas Reservoirs

Fractured-vuggy carbonate gas reservoirs play an important role in the distribution of gas filed in the world.Based on the numerical reservoir simulation technology,the numerical well test interpretation technology provides a more accurate method in well testing of Fractured-vuggy carbonate gas reservoirs.Based on the detailed research of articles about well testing of fractured-vuggy carbonate gas reservoirs and the method of numerical well testing analysis,PEBI grid is chosen in the spatial dispersion of reservoir region.Mathematical model of well test interpretation for single-phase of homogeneous carbonate gas reservoirs,mathematical model of well test interpretation for single-phase of-dual medium carbonate gas reservoirs and mathematical model of well test interpretation for single-phase of triple medium carbonate gas reservoirs are established on consideration of wellbore storage coefficient,skin factor and boundary property.Finite volume method is used to discrete the well testing model,and then,the log-log curves of bottom hole pressure and pressure derivative are plotted.The effect of complicated boundaries and interfering wells are also considered in this article.Results of the research suggest that:1)Combined with the reservoir characteristics of Gaoshiti dengying group gas reservoir,it is determined that there are three kinds of seepage models.2)Three mathematical model of well test interpretation are established,and the typical well testing curve are obtained.(1)in homogeneous carbonate reservoirs,the wellbore storage coefficient and skin factor affect the early stage of well testing curve.Permeability affects the height of straight line on the well testing curve.The bigger permeability,the lower the straight line it is.(2)In pore-fracture based carbonate gas reservoirs,storativity ratio and inter-porosity flow coefficient are the two basic characters of pore-fracture based carbonate reservoirs.The storativity ratio reflects the percentage of-the matrix reserve in the total system.It reflects the time of-inter-flow stage.The fewer fluid in matrix,the shorter time of inter-flow stage it is,if there are few fluids in matrix,the well testing curve will turn into homogeneous reservoir character.The better connectivity between matrix and fracture,the earlier inter-flow stage it is.(3)In pore-fracture-vuggy based carbonate gas reservoirs,The storativity ratio of the inner zone reflects the percentage of the matrix reserve in the total system.The storativity ratio of the outer zone reflects the percentage of the fracture reserve in the total system.It reflects the time of inter-flow stage.The interporosity flow coefficient of the inner zone reflects the turbulence intensity between the fracture system and the matrix systc,n.The interporosity flow coefficient of the outer zone reflects the turbulence intensity between the fracture system and the vuggy system.The better connectivity between matrix and fracture and vuggy,the earlier inter-flow stage it is.In addition,based on the models mentioned above,well test interpretation program for carbonate reservoirs is developed.The real well test data is analyzed by the program and satisfactory result is achieved.