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SPE-173333

Refracturing on Horizontal Wells in the Eagle Ford Shale in South Texas - One Operator’s Perspective


Diakhate, Mamadou, Pioneer Natural Resources, Gazawi, Ayman, Pioneer Natural Resources, Barree, Robert David, Barree & Associates, Cossio, Manuel, Pioneer Natural Resources, Tinnin, Beau, Pioneer Natural Resources, McDonald, Beth, Pioneer Natural Resources, Barzola, Gervasio, Pioneer Natural Resources


Abstract

This paper outlines a REFRAC pilot testing program conducted in the Eagle Ford shale. As wells in the Eagle Ford accumulate production over time and the pressure around the horizontal wellbore declines, it is important to protect the wells and associated reserves from any offset fracture stimulation and communication that could potentially cause damage. Re-fracturing trials in older fields such as the Barnett have yielded a positive enhancement of the well performance. This paper gives an evaluation in the eagle ford of the effectiveness of the refrac on protection of the older wells.

Actual re-fracturing pumping data from this field is used to demonstrate the type and mechanism of fracture reorientation.

Re-fracturing an old horizontal well with 5000 ft. lateral length and more than 800 existing perforation holes in the casing is very challenging and does require a careful integration of reservoir knowledge, completions skills and experience. The technical team of Pioneer Natural Resources has developed an integrated workflow to design and execute a re-fracturing job for an Eagle Ford well. The work flow include: 1) Reservoir study to identify the lower pressure areas along the lateral. This is done by integrating all the surveillance data from the well such as micro-seismic, tracer logs, production data. 2) Identify wells within the drilling schedule that are offsetting older unit primary wells with high cumulative production. 3) Design of a single fracturing job with several sub-stages separated by diverting agents. Volumes and pump schedules will be specific for each candidate based on proximity to offset well, lateral length, and existence of geological structures. The candidate wells in the pilot program will be re-fractured and the re-fracturing field execution procedure will be adjusted based on lessons learned from this pilot experimentation. The results from these pilot wells when looking at the fracture gradient changes before and after refrac, the radio-active tracers and well performance will be evaluated following field execution.