Improved Well Spacing Decision Using RTA: Workflow to Translate RTA Half-Length to Actual Depletion

Abstract

Abstract Rate Transient Analysis (RTA) is widely used in the industry to understand the Stimulated Reservoir Volume (SRV) of horizontal wells for forecasting and for comparing well performance. However, significant well interferences are observed while using SRV dimensions obtained from analytical models in making well spacing decisions. The reason for that is the assumption of rectangular shape for SRV representation, which is not a realistic case. Upon drilling several pressure monitoring wells in the Permian Basin and comparing them with multiple diagnostic tools, we found that the actual SRV vertical drainage is not uniform. Inaccurate characterizations of fracture height and half lengths would result in either overcapitalizing the project or not draining the reservoir efficiently. The objective of this study is to provide guidance for improving stacked development in the Permian Basin with the understanding of depletion patterns around individual wells both vertically and laterally. Pressure depletion profiles from several vertical monitoring wells in the Permian Basin are used to define the depletion patterns. Downhole microseismic data are also utilized to bridge any gaps. Several fully developed sections are used as case studies to validate the frac geometries and assumptions. The learnings from this study will be tremendously useful in applying RTA to optimize vertical and lateral spacing of unconventional wells across the Permian Basin.