Understanding Re-Fracturing Options

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Refracturing refers to the process of applying a second hydraulic fracturing stimulation after an initial period of production. The objective of refracturing is to create more reservoir contact in the un-depleted regions of the reservoir and to protect the refractured well from infill well fractures by re-pressurizing/re-stressing the depleted zones. Bullheading refracturing has been the primary method performed to refracture a horizontal well. During the treatment, no mechanical isolation is installed along the lateral, and all fractures are stimulated simultaneously. Bio-degradable diverting agent particulates are injected to temporarily plug the dominant fractures and divert treatment to the understimulated clusters along the wellbore. Although bullheading refracturing is cost effective, some wells may require mechanical isolation due to concerns of wellbore integrity. In the past couple years, several operators found it beneficial to run cemented liners. However, the cost of re-lining and re-complete the well is generally higher than bullheading refracturing. And it's very dependent on having the right wellbore construction for it.

When bullheading a refracturing treatment it is important to know which fractures are effectively stimulated during the treatment and which fractures are not. Many diagnostic methods have been applied to evaluate the treatment distribution, such as microseismic mapping, proppant tracer, and production logging. The diagnostics indicate that the treatment distribution in refracs is usually heel-dominated. In other words, most of the fluid and sand pumped during a refracturing ends up in the heel section of the wellbore while the toe side of the wellbore receives very little treatment.

SPE Paper No. SPE-194341-MS