Well Test Analysis Of Horizontal Wells And Acid Pressure Horizontal Wells In Carbonate Reservoirs

Carbonate reservoirs play a very important role in the world’s gas and oil resources, and the statistical data shows40percent of the236giant oilfields belong to carbonate oil reservoirs. The main mining method of carbonate resource is to adopt horizontal and acid fractured lateral well technique. Based on a great amount of literature about carbonate reservoir well test analysis, this paper investiages carbonate horizontal and acid fractured horizontal well test. We set dual medium and triple-medium well test analysis models in order to capture the character of carbonate reservoir. Applying semi-analytical method, we obtained the solution in Laplace domain, and with the help of computer programming, the typical curve can be easily plotted with Stehfest algorithm and different regimes can be identified then. The main ideas carried out from this research are the following:1) According to the different combination of natural fracture、cave and matrix in carbonate reservoir, this paper devide this type of reservoir into two model for research: dual-medium model and triple-medium model.2) Set up the dual-medium reservior well analysis model of horizontal and acid fractured horizontal (considering infinite conductivity and finite conductivity fracture) well with two parallel planes sealed both on top and bottom; apply point-source function method for analysis solution, then draft the typical curve with the aid of programming. Identify the flow regimes base on the typical curve, and deeply analyze the effect of sensitive factor, such as storability ratio and inter-porosity flow coefficient on the pseudo-pressure responses.3) Model triple-medium parallel planes sealed oil reservoir by consider the seepage type are triporate-uniphase parallel flow and triporate-uniphase step-by-step flow; establish infinite-conductivity and finite-conductivity fissure flow model for acid fractured horizontal wells. Realize the typical curve with the aid of programming techniques and identify the flow regimes on the basis of typical curve, then analyze the sensitive factor.4) Utilize the horizontal recovery pressure data from X carbonate oil field in Xinjiang province for well-test interpretation, which can verify the rationality and validity of the model presented by this article.