A Study Of Water-blocking Experiment And Productivity Evaluation Of Complex Well In Low Permeability Fractured Gas Reservoirs With Water

Its geologic features and fluid flow characteristics through porous media are so complex that conventionally classical percolation laws are not suitable for low permeability fractured gas reservoirs with water any more. Large numbers of experimental studies and gas field applications have prove that nonlinear gas flow through porous media happens in low permeability fractured gas reservoirs. These types of reservoirs have strongly suffered from Klinkenberge effect, non-Darcy flow, startup pressure difference and water blocking as damage mechanism when the encroaching fluid of drilling, fracturing and completion invades these gas reservoirs.On the basis of the domestic and abroad literature researches, as an example of the Jiawu1 low permeability fractured gas reservoir with water in Baoyuan gas field, a series of water blocking experiments using representative core material and complex well deliverability evaluation have been conducted and a field-scale simulation have been used to characterize the reservoir-aquifer system and forecast future performance. Productivity formulas of horizontal well used to predict the productivity of conventional horizontal well have been developed in gas reservoirs with closed bottom and top boundaries and with supply boundaries. In addition, Analytical method and numerical simulation method was applied to study the seepage mechanism of complex horizontal well.The acquired achievements are as follows: Water blocking experimental method and process in low permeability fractured gas reservoirs with water have successful been set up. Its gas-water relative permeability curve and water-drive-gas efficiency were determined and its water-blocking mechanism was analyzed. By using conformal transformation method, productivity formulas of horizontal well, taking effects of non-Darcy flow and water-blocking effect into account, have successful been developed. We used these formulas to predict well BP1 deliverability and analyze influences of water-blocking effect, non-Darcy flow effect and variation in water saturation on BP1 complex horizontal gas well productivity. By simplifying and decompounding snaky well in Baoyuan fractured gas reservoir, the basic structure of snaky well comes into being. Our in-housing gas-water two-phase numerical simulator are used to study fluid flow mechanism through porous media of snaky well. Using the reservoir simulator IMEX, a field-scale simulation have been carried out in Baoyuan low permeability fractured gas reservoir with water. Base on good history match, influences that water invasion, water blocking and gravity effect on gas-yielding well interval and complex well productivity were analyzed. Plentiful off-take strategies complex wells are demonstrated and the field-scale simulation gives reasonable further development plan.