Rate-Transient Analysis of a Constant-Bottomhole-Pressure Multihorizontal Well Pad with a Semianalytical Single-Phase Method

SummaryBecause of readily available production data, rate-transient analysis (RTA) is an important method to predict productivity and reserves, and for reservoir and completion characterization in unconventional reservoirs. In addition, multihorizontal well pads are a common development method for unconventional reservoirs. Close well spacing between multifractured horizontal wells (MFHWs) in the multiwell pads makes interference from adjacent MFHWs especially significant. For RTA of production data from multihorizontal well pads, the influence of adjacent MFHWs cannot be ignored. In this work, we propose a semianalytic RTA model for the multihorizontal well pad with arbitrary multiple MFHW properties and starting-production times. Combining Laplace transformation and finite-difference analysis, we obtained a general solution of a multiwell mathematical model to use in RTA. Our model is applicable to cases of multiple MFHWs with different bottomhole pressures (BHPs), varying hydraulic-fracture properties, and different starting-production times. In the solutions, we observe bilinear flow, linear flow, transition flow, and multi-MFHW flow. Rate-normalized pressure (RNP) and its derivative are also affected by multi-MFHW flow. Two case studies revealed that the negative effect of interwell interference on the parent-well productivity is closely related to the pressure distribution caused by the production of child wells.