Optimization Of Productivity Evaluation Methods Of Fractured Horizontal Wells In Low-permeability Tight Gas Reservoir

It is extremely difficult to develop low-permeability tight gas reservoirs.Atpresent, people mainly use fractured horizontal well to develop them at home andabroad. The productivity of fractured horizontal well is the key factor which candetermine whether unconventional gas reservoirs could be developed effectively.about how to evaluate and predict the productivity of fractured horizontal well, manypredecessors have made a lot of researches, but there are few methods to get gas wellproductivity for fractured horizontal well of low-permeability tight gas reservoirsquickly and effectively. Oil field deliverability test need quantity of money and time,beside that, it cannot adapt to large scale appliance to rate the productivity forfractured horizontal gas well of low-permeability tight gas reservoir in gas field. Atthe same time, some existing empirical formulas for horizontal deliverability haven’tbeen made a systemic analysis for their related factors, so their accuracy cannotsatisfy the appliance requirement in gas field.Basis on the predecessors’ research, this assay analyzes the mechanism of increasingproductivity and seepage characteristic for fractured horizontal well, then join idealmodel and numerical simulation to obtain a new method of predicting gas wells’productivity for fractured horizontal well of low-permeability tight gas reservoirquickly. This assay mainly gains several results as following.(1)make a research on increasing productivity mechanism、seepage characteristic andproduce characteristic for fractured horizontal well, which could be used as a basicfor low-permeability tight gas reservoir research later.(2)analyze and discuss the typical fractured horizontal well’s stable seepagemathematical model for gas reservoir. Besides this, analyze their applicability andpros and cons. Then use several of them to calculate fractured horizontal wells’productivity in gas field and make a contrast between them.(3)according to the geological characteristics of the low-permeability tight gasreservoirs in China, single well’s simulation model has been established. Then set aL16(45) orthogonal vector and simulate the processes of revision isochronal well test.Results of the simulation show that effective permeability and thickness of thereservoir are the most important parameters of all that will impact on the productivity of gas wells. At the same time, the results can be regressed to relationship equationsbetween binomial deliverability equations’ factors(A and B) and formation capacity.(4) use some statistical indicators to evaluate all these methods mentioned in thisassay, then find out that this new method derived in this assay is convenient operation,well-adopted, reliable result, economically and time saving. Especially, theseproductivity equations are suitable for field application.(5)analyze the results of orthogonal vector numerical simulation to make a conclusionof the relationship between formation parameters and fracture geometry parameters,then optimize the main parameters which affect the productivity of fracturedhorizontal well in low-permeability tight gas reservoirs.