CFD-DEM simulation of proppant transport by supercritical CO2 in a vertical planar fracture

Full-Sample X-ray Microcomputed Tomography Analysis of Supercritical CO2 Fracturing in Tight Sandstone: Effect of Stress on Fracture Dynamics

“…Although fractures are relatively narrow in aperture, the presence of several fracture branches tends to facilitate the development of conductive fracture networks. In field applications, proppants are pumped to keep the fractures open and further enhance oil and gas production. , …”

“…The significant decline in the production of conventional oil and gas reservoirs around the world has led to the commercial development of unconventional resources, such as tight sands. However, the efficient development of these resources still faces numerous challenges. − As of this writing, the commercial development of unconventional oil and gas reservoirs typically involves the multistage hydraulic fracturing of horizontal wells by injecting a mixture of water and chemical additives (known as slickwater) at high pressures . This inevitably leads to problems such as clay swelling (in formations with clay minerals), environmental contamination, and formation damage, among others. − Therefore, various researchers have considered the use of other fracturing fluids that minimize formation damage and are more environmentally friendly.…”

Numerical Study on Proppant Transport in Supercritical Carbon Dioxide under Different Fracture Shapes: Flat, Wedge-Shaped, and Bifurcated

“…At present, most proppant migration studies set the length of the cuboid to 0.3–2 m. ,, Under this size, the reliability of the research results can be ensured and the unnecessary waste of computing resources can be avoided. The fracture width obtained by hydraulic fracturing is 1–5 mm, while the fracture obtained by supercritical carbon dioxide fracturing is smaller because of its low viscosity . So, we set the fracture to 0.6 × 0.15 × 0.002 m. We used a structured grid for division and set the grid cell to 0.001 m, as shown in Figure .…”

“…However, supercritical carbon dioxide proppant transport experiments rarely do, though Sun et al conducted a preliminary test, but it cannot be applied to this verification. Song et al verified by analyzing the reasonableness of each aspect of the accumulation stage model, and Zheng compared with existing slickwater proppant migration experiments by replacing supercritical carbon dioxide with slickwater. To ensure an accurate and reasonable model, this paper forms the two aspects to be verified.…”

“…At this time, the density of carbon dioxide is similar to that of slickwater, but the viscosity of carbon dioxide is similar to that of conventional gas, and it also has higher diffusivity. Supercritical carbon dioxide with lower viscosity and high diffusion properties can enter smaller pores and connect the pores more easily. , The research of Wang et al and Bennour et al showed that supercritical carbon dioxide fracturing has a smaller initiation pressure and a more complex fracture network than water-based and oil-based fracturing, which will be more conducive to shale gas production. In addition, compared with other working fluids, carbon dioxide also has strong adsorption.…”