Transient behavior modeling of a multi-well horizontal pad in a reservoir with irregular boundary using boundary element method

Abstract The probability of well interference in reservoirs has greatly increased due to the introduction of offsetting wells. At the early stage of production, the well connectivity is mainly through the connected fractures, but the well interference is time-dependent. The connected fractures may not remain open during the whole period of production. Therefore, it becomes essential to identify different types of interference. In this study, a new transient model based on the boundary element method (BEM) is presented to efficiently evaluate the targeted well's behaviors with the offsetting well production interference in 2D and 3D bounded formations. The findings have shed light on the flow regions and factors that substantially influence the transient behaviors. We observed that the flow regions of the targeted well, a multiple fractured horizontal well (MFHW), have two prominent linear flows. The first linear flow presents the flow from the formation into the hydraulic fracture, while the second linear flow is dominated by the flow from the offsetting well into the targeted well. The well spacing is closely related to the behaviors during the second linear flow period, which offers the probability to evaluate the well spacing on the basis of transient behaviors. Properties and geometries of offsetting well have important impacts on the second linear flow and pseudo-radial flow with interference, which yields a mathematical formula for the relationship between the second pseudo-radial flow and 0.5 line. Sensitivity analysis also indicates that the first pseudo-radial flow could be replaced by the spherical or hemispherical flow in 3D domain. The introduction of offsetting wells will cause an increase of the pressure behaviors of the targeted well, as caused by formation heterogeneity. Results from the application indicate the existing depleted pressure areas could be the most likely cause for the well interference.