Whispers from the Reservoir: Well Interference Testing Unlocks Insights for Optimal Well Spacing and Completions Design in a Delaware Basin Case Study

Abstract Optimizing well spacing in unconventional reservoirs employing multi-stage hydraulic fracturing remains a significant challenge. While overly close spacing incurs detrimental inter-well interference, excessive spacing leads to inefficient resource recovery. This study aims to present a workflow for pressure interference testing to optimize well spacing in unconventional reservoirs using early-time data. The proposed workflow integrates pressure interference testing with reservoir simulation and a real-world case study from the Delaware Basin, New Mexico. The case study focuses on three target reservoirs: Avalon, First Bone Spring Sand, and Second Bone Spring Limestone. To assess pressure communication and optimize well spacing, downhole pressure gauges were strategically deployed within each formation. This strategic placement enables the monitoring of pressure responses both during hydraulic fracturing and throughout production in each specific reservoir zone. Data analysis then evaluates the initial well spacing assumptions and identifies potential vertical and lateral communication between the zones. The Delaware Basin case study validates initial well spacing assumptions and provides early insights into reservoir connectivity. This information facilitates the optimization of completions design and well spacing. The study concludes that the pressure interference testing workflow offers a valuable tool for reservoir and completions engineers. Consequently, the workflow prevents loss of capital due to suboptimal design, ultimately leading to more efficient and cost-effective reservoir management. This paper presents a novel workflow that strengthens pressure interference testing by incorporating DQI (Devon Quantification of Interference) method. Additionally, this workflow transcends traditional pressure interference testing as it advocates for the integration of additional diagnostic techniques, such as fiber optics, offset pressure monitoring, and time-lapse geochemistry.