The early shale gas mining in North America mainly used linear adhesive fracturing fluid, and later, with the deepening of the research and the requirements of component control, the slippery water fracturing fluid system was gradually used. Because of its low viscosity, slippery water can easily communicate micro-cracks and layered seams at different scales, forming a complex volume of network cracks.
Hydraulic fracturing technology has been widely used in oil and gas industry to increase production since 1947. Linear and crosslinked guars are the most commonly used fracturing fluid system. Concerns over damage to conductivity caused by viscous fluids in unconventional reservoirs, the industry has developed an alternative fracturing fluid called slickwater, which consists mainly of water and the low concentration of linear polymer. Slickwater has the characteristic of poor sand carrying capacity, and it is necessary to develop a smart slickwater to improve sand carrying capacity.
The paper introduces a new smart slickwater with high proppant- carrying capability for shale reservoirs. The fluid system consists of linear self-assembled agent, which can improve the viscosity of slickwater at low concentration and maintain a high drag reduction rate. The advantage of the smart slickwater is that only one chemical additive is used, and when the concentration is 0.05%, the drag reduction rate can reach more than 75%, and when the concentration is 0.2%, the proppant ratio can reach 30%, replacing the linear and crosslinked guars.
Laboratory experiments were conducted using the smart slickwater to display excellent static and dynamic sand carrying capacity. The smart slickwater is used in Changqing Oilfield(China), compared with the traditional slickwater, the product is less expensive to use, less water for fracturing, less types and dosage of chemicals required, less equipment needed.
The new smart slickwater with high proppant- carrying capability can change the existing structure of fracturing fluid system.