Rate-transient analysis for estimating the linear flow parameters of communicating wells using the dynamic drainage area (DDA) concept

Abstract

Development of unconventional reservoirs using multi-fractured horizontal wells (MFHWs) has led to closer well and hydraulic fracture spacing. Tighter placement of MFHWs has consequently led to increased instances of well interference, particularly through hydraulic fractures. In addition to possible problems posed for development, fracture communication that persists during production complicates rate-transient analysis (RTA) because models/methods for RTA have mostly been developed for single-well analysis. Availability of RTA methods specifically developed for communicating wells can reduce errors associated with hydraulic fracture and reservoir characterization and can lead to improved decision making.A semi-analytical method for history matching MFHWs communicating through hydraulic fractures has recently been developed using the dynamic drainage area (DDA) concept. In the current work, the DDA concept is employed to develop a new straight-line analysis (SLA) method for the transient linear flow regime that can be applied to two communicating MFHWs. The change in the drainage area of a single well due to communication challenges the use of the DDA concept. However, when the second well comes on production, reinitialization of the calculations for the first well helps to facilitate the implementation of the DDA concept.The new DDA-corrected RTA (SLA) method for communicating wells is verified against the results of numerical simulation. Several synthetic cases are generated using numerical simulation to verify the accuracy of the developed method using various reservoir/fracture properties. The new method applied to the simulated cases allows the fracture half-length (xf) to be estimated within 10% of simulation model input. The DDA-corrected RTA method has also been applied to a field dataset, previously analyzed by the authors using the DDA approach to history match well production data. This dataset consists of six wells, drilled into two separate reservoir layers (three wells per layer) and from two adjacent pads, which exhibit strong well-pair communication. For this dataset, the calculated linear flow parameters for these wells are compared. The results demonstrate that there is a difference between the linear flow parameters of wells completed in the upper layer and lower layers, which could be attributed to either differences in effective fracture area or permeability.This new approach can help practitioners quickly and accurately estimate reservoir and fracture properties in these scenarios. The method can therefore be used to improve hydraulic fracture design, well forecasting and development planning where persistent well communication through hydraulic fractures is occurring.