Stacked-Pay Development Insights from Routine Sealed Wellbore Pressure Monitoring (SWPM)

Abstract Over the past 5 years, cross-well strain measurements during hydraulic fracturing such as Sealed Wellbore Pressure Monitoring (SWPM) and fiber optics, have enabled direct measurements of fracture growth. Routine collection of SWPM data by Devon Energy has resulted in a substantial cross-well dataset that provides unique insight into fracture growth across multiple North American basins. Through these datasets, the length, height, shape, and spatiotemporal evolutions of a given formation's hydraulic fracture is seen to vary dramatically. For this analysis, the authors selected good quality SWPM datasets from stacked-bench horizontal developments across multiple basins. The data was analyzed to understand fracture length and height growth, leveraging simple concepts and analytical models to calibrate fracture growth in vertically offset monitoring benches. Insights into the geometry was farther compared to stress logs and fracture models to build a robust explanation of the observed geometry. This analysis shows there is no standard fracture geometry seen across formations, quantified by a simple ratio of fracture length to height of the dominant fracture measured through SWPM and other strain-based diagnostics. Certain formations exhibit strong vertical containment resulting in vertically short fractures, with wells exceeding a fracture length/height ratio of 20, (e.g. 4000-foot length and 200-foot height). Other formations are higher stress than overlaying/underlying rock, resulting in an hourglass geometry of uncontained growth with length/height ratios around 2.5 (e.g. 3000-foot length and 1200-foot height). Often these geometries were unexpected and contradicted uncalibrated fracture models, showing the importance of calibration in modeling. This paper demonstrates the value of extensive cross-well strain datasets such as SWPM for a formation for informed development decisions. Furthermore, the work shows large variation in fracture geometry that is more strongly tied to the inherent permeability and stress state of the rock than any control from completion design.