Enhancing Fracture Network Complexity Using Carbonated Slickwater Fracturing

Abstract Fracturing with slickwater has been widely adopted over the past couple of decades in the development of shale and tight formations. This paper proposes the use of CO2-foamed slickwater, termed carbonated slickwater, as a potential fracturing fluid that maintains suitable proppant carrying capacity while achieving less freshwater consumption, faster and efficient flowback recovery, improved hydrocarbon recovery due to CO2 miscibility with reservoir fluids, deeper CO2 penetration, and potentially higher fracture network complexity and more extensive stimulated reservoir volume. A circulating-loop foam rheometer was utilized in this study to compare the rheological behavior of slickwater and CO2-foamed slickwater at 50% foam quality. The slickwater, with and without foaming, was tested under a wide range of conditions, including under pressures up to 2500 psi, temperatures up to 300°F, and shear rates up to 1500 1/s. The stability of CO2 foamed slickwater was tested for 30 min at 250°F, 275°F, and 300°F. The viscosity increased to 6.3 cp from 2.7 cp after 50% foaming with CO2 measured at a constant shear rate of 1000 1/s and 300°F. The foaming characteristic can be measured on site using a simple blender test described in this paper. Static foam stability describes the change in foam height or liquid drainage with time known as foam half-life also measured at atmospheric conditions. Using the blender test, around 70% foam quality was achieved, which gave more than a one-hour foam half-life under atmospheric and static conditions. In this paper, we have explored foamed slickwater as a potential alternative fluid to slickwater for fracturing unconventional formations. We theorize that because of the similar viscosity, carbonated slickwater would have similar fracture propagation/complexity and proppant-carrying capability. During shut-in after fracturing, the CO2 could stimulate additional smaller fractures, ultimately leading to more fracture complexity. Additionally, during flowback, CO2 can maximize flowback recovery pumped slickwater.