Application Prospects of Supercritical Carbon Dioxide in Unconventional Oil and Gas Reservoirs

Abstract

The technical problems during the development of unconventional oil and gas reservoirs are becoming more and more difficult to handle with conventional drilling and production methods. Supercritical carbon dioxide has so many good properties such as high rock-breaking drilling efficiency, strong dissolved displacement performance and unharmful effect on the reservoir that it can be used as a drilling, completion and production medium to effectively exploit the unconventional oil and gas reservoirs. The global distribution of unconventional oil and gas resources is introduced, application status of carbon dioxide in oil and gas development is discussed, and development prospects of supercritical carbon dioxide in the unconventional oil and gas reservoirs are systematically analyzed. Using supercritical carbon dioxide as a medium in the whole development process is an important trend of unconventional oil and gas development technologies.

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

“…The fracture is digitized by several voxels of size r, which means that the fracture is represented by small cubic boxes. So, the aperture of fracture can be calculated by = × t r n (10) where r is the resolution of the setup (which is 53 μm in this work), while n refers to the number of voxels in the direction of the normal to a fracture surface (making up the fracture aperture). As shown in Figure 9, the aperture map calculated from a commercial software package depicts the fracture thickness at different locations on the fracture surface.…”

“…One of such potential fracturing fluids is supercritical CO 2 (SC-CO 2 ), which is an anhydrous CO 2 that is obtained when the temperature and pressure exceed 31.1 °C and 7.38 MPa, respectively. Due to its special physical and chemical properties, SC-CO 2 has been considered as an alternative working fluid for the hydraulic fracturing of unconventional resources. − It is also well-known that SC-CO 2 fracturing can help to avoid clay swelling in the high-clay reservoirs and minimizes the contamination of the surface environment and subsurface aquifers. , It is also applicable in arid regions where the supply of water is limited. − Consequently, the development of unconventional resources using SC-CO 2 is regarded as promising technology recently. − …”