Early development of the Delaware Basin Wolfcamp focused on exploration, lease holding, and operatorship capture. As a result of this early development strategy, many sections now possess a single horizontal well with an early vintage of completion technology. These standalone wells, referred to as "parent" wells, negatively affect the production performance of subsequently drilled "child" offset wells due to reservoir depletion effects. While the production degradation resulting from parent-child well interactions is well established empirically, generating accurate quantitative predictions remains challenging due to the complex nature of the physical processes involved. Attempts to develop predictive models to estimate the parent-child degradation effect have included numerical simulations and various machine learning techniques. Used individually, however, these approaches are subject to the following shortcomings: 1) machine learning techniques are hampered by scarce data, and 2) numerical simulations are too costly for evaluating the wide range of parameter configurations needed. In this work, we present a novel, hybrid approach that leverages the strengths of both machine learning techniques (extracting information from the available empirical data) and numerical simulations (providing physics-based theory). We analyzed a robust, well-distributed parent-child dataset using a combination of available empirical data and numerical simulation outputs, which was then utilized to develop a predictive machine learning model (comprising a multiple linear regression model and a simple neural network). This model has been successfully implemented in field developments to optimize child well placement and has produced improvements in performance predictions and net present value (NPV).
In the early stages of unconventional development of the Delaware Basin's Wolfcamp formation, practices of exploration, lease holding, and operatorship capture resulted in the completion of standalone wells in many sections across the basin. Subsequent offset wells drilled near these "parent" wells, called "child wells," have experienced disappointing production performance due to reservoir depletion by the parent wells. These child wells are distinguished from infill wells which do not interact with parent well depletion. This early development activity resulted in a large number of Wolfcamp parent-child well pairs distributed widely across the Delaware Basin (see Figure 1).