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Brinkley, Kourtney (Devon Energy) | Ingle, Trevor (Devon Energy) | Haffener, Jackson (Devon Energy) | Chapman, Philip (Devon Energy) | Baker, Scott (Devon Energy) | Hart, Eric (Devon Energy) | Haustveit, Kyle (Devon Energy) | Roberts, Jon (Devon Energy)
Abstract This case study details the use of Sealed Wellbore Pressure Monitoring (SWPM) to improve the characterization of fracture geometry and propagation during stimulation of inter-connected stacked pay in the South Texas Eagle Ford Shale. The SWPM workflow utilizes surface pressure gauges to detect hydraulically induced fracture arrivals athorizontal monitor locations adjacent to the stimulated wellbore (Haustveit et al. 2020). A stacked and staggered development in Dewitt County provided the opportunity to jointly evaluateprimary completion and recompletion efforts spanning three reservoir target intervals. Fivemonitor wells at varying distances across the unit were employed for SWPM during the stimulation of four wells. An operational overview, analysis of techniques, correlation with seismic attributes, image log interpretations, and fracture model calibration are provided. Outputs from this workflow allow for a refined analysis ofthe overall completion strategy. The high-density, five well monitor array recorded a total of 160 fracture arrivals at varying vertical and lateral distances, with far-field fracture arrivalsprovidingsignificant insight into propagation rates and geometry. Apronounced trend occurred in both arrival frequency and volumes pumped as monitor locations increased in distance from the treatment well. Specific to target zone isolation, it was identified that traversing vertically in section through a high stress interval yielded a 30% reduction inarrival frequency. An indirect relationship between horizontal distance and arrival frequency was also observed when monitoring from the same interval. A decrease in fracture arrivals from 70% down to 8% was realized as offset distance increased from 120 to 1,700 ft. The results from this study have proven to be instrumental in guiding interdisciplinary discussion. Assessing fracture geometry and propagation during stimulation, particularly in the co-development of a stacked pay reservoir, is paramount to the determination of proper completion volume, perforation design, and well spacing. Leveraging the observations of SWPM ultimately provides greater confidence in field development strategy and economic optimization.
This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 199731, “Monitoring the Pulse of a Well Through Sealed Wellbore Pressure Monitoring: A Breakthrough Diagnostic With a Multibasin Case Study,” by Kyle Haustveit, SPE, Brendan Elliott, SPE, and Jackson Haffener, SPE, Devon Energy, et al., prepared for the 2020 SPE Hydraulic Fracturing Technology Conference and Exhibition, The Woodlands, Texas, 4-6 February. The paper has not been peer reviewed. A pressure-monitoring technique using an offset sealed wellbore as a monitoring source has led to advancements in quantifying cluster efficiencies of hydraulic stimulations in real time. Sealed wellbore pressure monitoring (SWPM) is a low-cost, nonintrusive method used to evaluate and quantify fracture-growth rates and fracture-driven interactions during a hydraulic stimulation. The measurements can be made with only a surface pressure gauge on a monitor well. To date, more than 1,500 stages have been monitored using the technique. The complete paper reviews multiple SWPM case studies, collected from projects in the Anadarko and Permian Delaware basins; this synopsis will concentrate on the concepts behind, and the validation of, the technique. Introduction SWPM is performed on a well that acts as a closed system. The well cannot be connected to a formation through perforations or other types of access points; the casing must be sealed. Uncompleted wells can be used if the shallowest perforations are isolated from the formation. In an existing producing well, a plug must be set above the shallowest perforations to create a closed system from the top of the plug to surface where the pressure measurement is recorded. The wellbore should be filled with low-compressibility fluid (e.g., completion brine) to amplify the pressure response created during monitoring. Fractures intersecting the sealed wellbore cause local deformation, which results in a small volume reduction in the closed system (system being the fluid volume inside of the casing) and generates a discernible and distinct pressure response. Pressure can be recorded either using a surface gauge or a downhole gauge. Multiple sealed wellbores can be used as monitor wells for a single treatment well, allowing for a more-detailed understanding of fracture growth rates during a stimulation. The field execution of SWPM is simple and does not require any tools to enter the wellbore. A surface gauge provides the necessary data needed to evaluate the fracture interactions with the monitor wellbore. There is no need to alter zipper operations if sealed wellbores are available. The main restriction SWPM introduces to operations is the necessity to leave new wellbores, designated as monitors, unprepped by not opening toe sleeves or shooting perforations for Stage 1 until monitoring of the offset treatment wells is complete. Because the pressure response in the monitor well is a result of a fracture intersection at the wellbore, the method reduces the uncertainty related to the location of the monitor point commonly associated with other offset pressure-monitoring techniques.