Refracturing: Technology and Reservoir Understanding are Giving New Life to Depleted Unconventional Assets

Fig. 1—Refracturing stages and composite pills are pumped in sequence to promote diversion of fluid and proppant to rock bearing higher pressures and production potential. Increasing treating pressure and other measurements are combined to confirm occurrence of diversion.

The unconventional boom that has swept across North America over the past decade is a testament to how game-changing technology combined with expanded knowledge and understanding has transformed the paradigm of hydrocarbon production. Ongoing development of horizontal drilling and completion technologies and sophisticated downhole logging tools have been instrumental in increasing efficiency to make oil and gas shale plays economically viable. Today, more than 70,000 horizontal wells are producing from unconventional resource plays with massive, multistage fracturing campaigns.

Over the years, however, operators have learned that reservoir heterogeneity and low-permeability rock present challenges that can limit the potential of unconventional development. Despite the fast pace of technological advances, production log analyses reveal that conventional completion designs, including the practice of placing perforation clusters evenly along the lateral, may not be the best approach to production in these plays. Production logs show that on average, 40% of the perforation clusters in a given lateral are not contributing to production.

Unconventional wells also exhibit rapid declines from initial production (IP) rates, sometimes by as much as 60% to 80% during the first year of operation. If early IP rates are not managed, or choked, properly, subsequent steep declines can cause long-term damage to the fracture conductivity.

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Refracturing: Technology and Reservoir Understanding are Giving New Life to Depleted Unconventional Assets

Sherif Foda, Production Group President, Schlumberger

01 July 2015

Volume: 67 | Issue: 7

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