Vuggy Carbonate Reservoir In The Percolation Theory And Transient Testing

In company with our country's increasing energy demand, the exploration and development of unconventional reservoirs became more and more important. Because of its large reserve volume and high productivity, naturally fractured vuggy carbonate reservoirs are signified to our national petroleum strategy. Be different with conventional clastic reservoirs, the most outstanding problem of carbonate reservoirs are extreme heterogeneity and the various scales of fracture and vuggy fabric. All these made a great deal of difficulty in the development of carbonate reservoirs. As an efficient method of apprehending the reservoir' s dynamic character and flowing regulation, well testing is the sticking point that not only reflect the ultimate evaluated foreground of reservoirs but also direct the further development. So in order to provide the technique support for calculating the characteristic parameter of reservoirs and appraising the productivity, it is essential to carry on the percolation mechanism and well testing research of naturally fractured vuggy carbonate reservoirs.Based on the extensively research in the past, this paper started with the primary double-porosity model and investigated the percolation mechanism of naturally fractured vuggy carbonate reservoirs detailedly. According to property of secondary porosity and the difference of interporosity flowing manner, we classified these kinds of reservoirs into normal triple-porosity single-permeability,nested triple-porosity single-permeability, triple-porosity dual-permeability and quadruple-porosity reservoirs. For each reservoir we have built corresponding pressure-transient model. The analytical solutions are given under different outer boundary conditions of infinite> circular closed and constant pressure. Analysis of each model's type-curve is also discussed. All of the models are taken the effect of wellbore storage and skin into account except the double-porosity single-permeability model.Innovates of this paper are as follows:(1) Established three kind of mathematical models to describe the productive variation of naturally fractured vuggy carbonate reservoirs. The sensitivity analysis of potential decline curve and cumulative production curve under the condition of circular closed outer boundary are also discussed.