New type curves for analyzing horizontal well with multiple fractures in shale gas reservoirs

摘要

To produce economically from most shale gas plays, horizontal wells (cased or openhole) with multiple fractures are the most popular choice for completing the wells. A number of well-performance behaviors can be seen for these wells depending on reservoir behavior and induced hydraulic-fracture geometry. In this paper, conceptual models for well/reservoir/hydraulic fracture combinations are first presented. Next, we discuss the impact of various reservoir types/induced hydraulic-fracture geometries upon the sequence of flow-regimes that could be encountered for shale gas reservoirs. In addition, we develop and present new sets of dimensionless type-curves for one of the conceptual models. The newly developed type curves in this study yield more unique results than those presented previously. With these dimensionless type curves, the early linear flow (early-time half slope) and boundary-dominated flow (late-time unit slope) fall on top of each other and the transition between these two regimes depends on the geometry of the reservoir and completion. Using the type curves as a guide, we then present the flow regimes that are expected for different values of horizontal well length, number of fractures, length of the fractures and spacing between horizontal wells. We also present a new method for evaluating the contribution from the outer reservoir (beyond the fracture length). Finally, using the characteristics of new dimensionless parameters and the new type-curve set, we present a simple and practical procedure for long-term forecasting in multi-fractured horizontal wells.