Numerical simulation study on the bottom-water invasion in the carbonate gas reservoir with high angle fractures and high permeability zones

Abstract

Numerical simulation of carbonate gas reservoir with bottom-water is still a challenging issue, due to the presence of nature conductive fractures. When the water invades into the gas well, the permeability of gas phase decreases sharply. The high angle fractures and high permeability zones have a serious impact on the production performance of the gas wells. The characteristic of the water invasion was unpredictable in conventional dynamic analysis. In fractured carbonate reservoir, the geometric shapes of the angled fracture are difficult to be described using commercial numerical simulation software. The method that calculating the pseudo relative permeability of the grid block containing high angle fracture was utilized in this paper. Through this method, the rapid water advancement in the conductive fracture was accurately tracked without modifying the grid geometry, and the influence of the conductive fracture to the water breakthrough phenomenon was studied by using the IMEX module in CMG.  The results show that the water invasion intensity depends on the conductivity of fracture, and the higher the conductivity is, the shorter the water breakthrough time is. The breakthrough time of water is affected by the angle of the fracture, the relative horizontal distance, the length of the fracture, the production rate and the type of water invasion. According to the characteristic curve, the type of water invasion can be quickly distinguished, which provides a basis for further study on the enhanced recovery of the fractured carbonate gas reservoir with water.