Research On Productivity Evaluation Of Fractured Horizontal Wells In Tight Gas Reservoirs

Up to now, countries over the world have an increasing need for energy. Scholars and specialists from all over the world pay more and more attention to the development of tight gas reservoirs. Low permeability gas reservoirs have huge reserves and have a large potential in development. Because of the low natural production, we must use multi-stage fractured horizontal well technology to improve economic flow. Thus, productivity evaluation is much important for analyzing hydraulic fracturing performance. In this thesis, we research productivity evaluation method on multi-stage fractured horizontal well in tight gas reservoir as follow:(1) At first, we investigate and survey well test analysis, productivity evaluation methods multi-stage fractured horizontal well technologies and reservoir percolation mechanics.(2) Based on reservoir percolation mechanics and reservoir engineering, we make use of Warren-Root model and dual medium gas reservoir percolation theory to derivate the modern well test model of multi-stage fractured horizontal well with upper and lower boundary closed and the lateral boundary infinite, which considers effect of wellbore storage, skin effect and the effect of natural fracture.(3) We use some math approach such as Laplace transform, Stehfest numerical inversion, point source method and Duhamel method to solve this model and calculate pressure response by Matlab.(4) Further more, we use the modern well test model to derivate gas productivity index of tight gas reservoir. Based on the well test and gas productivity index, we build the evaluation system of tight gas reservoir's productivity with multi-stage fractured horizontal well.(5) In addition, we optimize fracture system based on our productivity evaluation system to verify the correctness and effectiveness combining modern well test curves and gas productivity index curves.