Is Pumping Large Volume Sand Fracs Sustainable

Summary Mud rock “shales” by their very nature can be problematic to fracture stimulate given the wide variation in geology, rock properties and reservoir characteristics. Quite often, a positive production response from a well may be incorrectly credited to the completion and frac design when in reality the production was dominated by favorable reservoir characteristics. Conversely a poor production response from a well may be blamed on the completion and frac design when in fact poor reservoir quality is the controlling factor. The subject of this paper is a revisit of the physics behind production increases from hydraulic fracturing and results from detailed evaluations performed by experienced engineers with reservoir knowledge for the purpose of evaluating completion effectiveness and frac efficiency for shale and other low permeability formations. The findings presented show that in many cases pumping large volume sand frac designs result in an inefficient hydraulic fracture. This inefficiency is due to minimal production contribution from a relatively large portion of the hydraulically exposed fracture face and/or frac length. These findings are supported by current hydraulic fracturing theory and understanding. The evaluation methods utilized in these evaluations are not new, however they currently are underutilized by the industry for completion and frac analysis.