Local-Sand-Enabled Channel Fracturing. Case Study from Jurassic Formations in Uvat Region

Abstract

Western Siberia has a long and successful history of channel hydraulic fracturing technology implementation. However, there is an urgent need to further reduce the cost of hydraulic fracturing. As a solution, it was proposed to use local suppliers of quartz sand to replace a substantial proportion of the more expensive ceramic proppant. Based on the principles of the classical channel fracturing, fracture permeability is provided by creating open channels in the intervals between proppant clusters. Open channels are created by feeding proppant in pulses simultaneously with a continuous supply of fiber, which subsequently dissolves under the action of reservoir temperature. The use of quartz sand during hydraulic fracturing in reservoirs with high stresses is thus possible only with the channel fracture method of proppant placement and is justified by the fact that the fracture conductivity in this case does not depend on the permeability of the proppant itself. Open channels play a key role. Thus, the need to reduce the cost of service is justified not only economically, but also technologically. The first step in the implementation of the technology was the successful application of traditional channel fracturing using ceramic and resin-coated proppant at the fields in the Uvat region, more than 60 operations in total. The best results on productivity were obtained in multi-stage hydraulic fracturing operations in horizontal wells, where additional effects of up to 20% relative to the standard method were obtained. Advantages in the form of accelerated operations (up to 15%) were also confirmed by reducing the duration of the preparatory work; minimize workover cleanouts after premature screen-out due to minimized risks since fibers and pulses of pure liquid ensure better proppant admittance. Significantly reduced costs for logistics and storage of proppaant, which is most relevant in the conditions of autonomous fields. As a result of a successful pilot campaign, it was decided to test injection of quartz sand during channel fracturing operations. Laboratory tests have been carried out and a risk analysis has been formalized, which described in detail in following sections. The first candidates during the pilot campaign were injection wells followed by a testing plan at a producing well stock. The experience of using quartz sand during hydraulic fracturing is innovative for sandstones after numerous attempts at the hydraulic fracturing dawn decades ago that revealed insufficient sand conductivity and required a switch to expensive ceramic proppant. The reincarnation of the perspectives of quartz sand in medium permeability reservoirs was provided by the channel fracturing method, which removes the connection between proppant permeability and fracture conductivity due to the presence of open channels. The experience in the Uvat region will be the first published in Russia and will allow further developments in this direction.