SPECIAL NOTE: THE CORRECT DATE FOR THIS EVENT IS DEC. 16. The incorrect date was printed in the December 2015 GCS Connect newsletter. We apologize for this error.
There is little doubt that the success and reliability of frac-pack completions in the Gulf of Mexico (GoM) have become the yardstick by which GoM sand control completions are measured. Simultaneously, stress-caging has become standard practice as a method to overcome the challenges associated with drilling through depleted zones in order to cope with complex mud-window constraints for new developments and infill wells.
While these two techniques, in isolation, represent uniquely optimal solutions to their individual challenges, there is growing evidence that their application within the same wellbore has the potential to create a major issue. The stress-cage application is ostensibly based on the premise of creating an increased hoop stress around the wellbore (that may include small, plugged fractures) and thereby an increased fracture gradient, which allows for drilling through substantial depletion. However, the presence of a range of widely distributed particle sizes in the mud system, as well as increased general solids loading, can result in deep and invasive plugging of the permeable formations and any smaller fractures within the same open-hole sections. When these plugged formations then become the target for subsequent fracturing operations, there is a significant potential to create near-wellbore issues that complicate or bring into question the ability to install a frac-pack completion.
This presentation will discuss a number of examples of the application of stress-cage, in which resulting fracturing operations appear to have been hampered or complicated by the drilling of the section with stress-cage material and/or the associated mud conditions. These examples will provide evidence of such interactions, but just as importantly, demonstrate the potential contradiction that these two techniques represent. All of this poses the fundamental question of whether we are creating the unfraccable by drilling the undrillable.