A novel slab source function has been formulated and successfully applied to accurately evaluate performance of a horizontal well with multiple fractures in a tight formation.A semi-analytical method is then applied to solve the newly formulated mathematical model by discretizing the fracture into small segments,each of which is treated as a slab source,assuming that there exists unsteady flow between the adjacent segments.The newly developed function has been validated with numerical solution obtained from a reservoir simulator and then extended its application to a field case.The pressure response together with its corresponding derivative type curves has been reproduced to examine effects of number of stages, fracture conductivity,and fracture dimension under various penetration conditions.The fracture conduc- tivity is found to mainly influence early-stage bilinear/linear flow regime,while a smaller conductivity will force more fluid to enter the toe of the fracture than its heel.Penetrating ratio will impose a significant impact on the pressure response at the early stage,forcing the bilinear/linear flow to the radial flow.
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