Unconventional Proppant Combined With Channel Fracturing Increases Effectiveness

Abstract

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper IPTC 17409, “Channel Fracturing Enhanced by Unconventional Proppant Increases Effectiveness of Hydraulic Fracturing in Devonian Formations of Russia’s Oil Fields,” by Rifat Kayumov, SPE, Artem Klyubin, Andrey Konchenko, SPE, and Alexey Yudin, Schlumberger; and Alexander Khalzov, Vladislav Firsov, Evgeniy Nikulshin, Zdenko Kaluder, and Suleyman Sitdikov, SPE, Rosneft, prepared for the 2014 International Petroleum Technology Conference, Doha, Qatar, 20–22 January. The paper has not been peer reviewed. Implementation of channel fracturing enhanced by rod-shaped proppant brings substantial value for depleted Devonian formations in the Orenburg region of Russia. Highly conductive channels inside the proppant pack significantly minimize the influence of multiphase and non-Darcy flow on overall production. The use of rod-shaped proppant in the final stage provides the highest possible conductivity in the critical near-wellbore region and eliminates the potential problem of proppant flowback. Introduction Fracturing is a standard completion method for all wells producing from Devonian formations in the Orenburg region of Russia’s Volga-Urals basin. Experience has shown that these fracturing treatments usually have some specific differences from fracturing in other parts of Russia. Low fracturing-fluid efficiency forces the use of large pad volumes and special fluid-loss additives. These actions decrease the risk of premature screenout but lead to significant reduction of fracture conductivity and effective fracture half-length, and, subsequently, result in a decrease in post-fracturing production. Even with large pad fluid volumes, almost all fracturing treatments in Devonian sandstone formations were finished in a tip-screenout regime when proppant starts to pack in the fracture during the treatment. Just 5 years ago, proppant flowback was not observed frequently in Devonian formations. But, recently, the operating company noticed proppant- flowback problems becoming increasingly pronounced. The reason is reservoir- pressure depletion and severely increased multiphase flow inside the fractures. To overcome the increasing negative effects of multiphase and non-Darcy flow on fracture conductivity, channel-fracturing technology was used. Although channel fracturing has already resulted in outstanding performance elsewhere, the technology was still new for conditions in the Volga-Urals Devonian formations (i.e., significant proppant packing is not typical for channel fracturing). Therefore, it was important to evaluate productivity through pilot wells stimulated with the new technique. For many treatments in the fracturing campaign described here, channel fracturing was enhanced by rod-shaped proppant to eliminate potential proppant-flowback problems and maximize conductivity of the near-wellbore region.