Productivity And Development Strategy For Fractured Well In Low Permeability Reservoirs

Low permeability reservoir is an important part of unconventional resource which hasbecome the focus in oil development in recent years. Fractured well is a effective way for lowpermeability reservoirs. So the research on fractured well productivity and strategy aresignificant. In this paper, both vertical fractured well and multi-fractured well are studies.Based on the investigation on the recent study results, low permeability non-Darcy flowmechanism for low permeability reservoir was deeply investigated, and also verified byexperimental analysis. Result shows that non-Darcy flow model can simulate the actual flowmechanism in the reservoir when the flow velocity is low.The equipotential ellipse method has been carried on the analysis of fractured wellproductivity which shows that long fracture can effectively improve the productivity of asingle well compared with a vertical well; transient pressure behavior is analyzed throughestablished the well test model considering the different parameters including the single andthe double porous media. Results show that, considering the low velocity non Darcy flow hasa high pressure consumption than Darcy flow. The well test curve can be divided into thefollowing stages: early stage, transition stage, boundary effect stage which is influenced bythe wellbore storage effect, skin factor, fracture conductivity and the dual porosity model canbe divided into fracture linear flow, bilinear flow, interporosity flow, radial flow stage whichis affected by wellbore storage effect, fracture conductivity, inter-porosity flow factor,storativity ratio.According to the flow pattern in low velocity non-Darcy, a numerical simulationsoftware is developed considering the non-Darcy flow and the technical policy for longfracture and multi-stage fractured horizontal wells were studied.Numerical simulation software is verified by comparison with the Eclipse, and the localgrid refinement, nonlinear flow parameter, well-grid processing technology is speciallyexplained. The zero balance verification, symmetry verification with commercial softwaresimulation results verify the rationality of numerical simulation software. With the newdeveloped software the water injection pressure difference, pressure maintain level, oilproduction rate, injection-production ratio and other production parameters are optimized which can better guide the long-fractured well production; also, the multi-stage fracturedhorizontal wells are studies including fracture length, fracture spacing, fracture conductivity,different fracture length combinations which gives a perfect way for design of multi-stagefracturing wells.