Wells in the Eagle Ford shale are primarily completed with plug-and-perf fracturing treatments, where perforation clusters are spaced tightly together to create a high density of fractures along the wellbore. A challenge associated with this method that has become apparent through production logging and recent fiber optic studies is that not all perforation clusters are effectively stimulated and therefore do not contribute to production (Holley and Kalia 2015; Denney 2012). One method to increase the number of stimulated perforation clusters is to incorporate a biodegradable particulate diverting agent into the fracture treatment to divert fluid during the injection. Production comparisons and real-time fiber-optics analysis are methods to evaluate the ability of this diverting agent to increase the number of propped fractures per stage and allow for increased stimulated area along the wellbore.
In the Eagle Ford shale, a 61-well study across five areas was conducted in La Salle and McMullen Counties to gain an understanding of how the diverter can impact stimulation cluster efficiency and production performance. Of the 61 wells, 13 were selected to incorporate the diverting agent into the fracturing treatment, and 48 were used as control wells.
One of the 13 wells incorporated fiber-optic technology to provide an extensive diagnostic and reservoir characterization tool to gain subsurface understanding of the diverting agent effectiveness. In this diagnostic well, fiber-optic cable was permanently installed with distributed acoustic sensing (DAS) and distributed temperature sensing (DTS) to monitor the hydraulic fracture stimulation and the downhole production profile for the life of the well. Real-time DAS and DTS monitoring were used during the stimulation treatment to monitor the distribution of fracturing fluid for each stage. This allowed for real-time operational improvements to the diverter deployment to help achieve more efficient fluid distribution. Additionally, a cased-hole pulsed-neutron log (PNL) was deployed in the lateral section of this diagnostic well. The data from this log were interpreted to characterize variations in reservoir properties along the lateral and validated the geosteering placement of the horizontal wellbore.
The 61-well study assessed the industry challenges associated with cluster efficiency in horizontal plug-and-perf treatments as well as the application and methodology of using a diverter. The production of these wells was analyzed to validate the diverter's performance, and the fiber-optic data provided subsurface insight to validate the effectiveness of the diversion through examination of the real-time DAS data.