The current status and development prospects of CCUS-EOR technology development are sorted out from the perspective of ecological development. A good foundation is laid to promote the world low-carbon development pattern and the development of CCUS-EOR technology in oil-rich, low-permeability reservoirs. By analyzing the differences between China and the United States regarding the technology level, application scale, and production effect, the development gaps between different countries in terms of CO₂ burial for enhanced oil and gas recovery are derived. In response to these gaps, recommendations for responsive technology research and supporting infrastructure construction are proposed, which are of reference significance for advancing the development of large-scale CCUS technology for all of humanity.

The sealing integrity of cement sheath in offshore wells is seriously threatened under high-temperature conditions, resulting in gas channeling and other problems. Given the lack of experimental results, in this study relevant samples of a cement slurry sealing section of a typical offshore high-temperature well have been prepared and analyzed. In particular, the mechanical properties have been assessed with a triaxial pressure servo instrument and a high-temperature curing kettle. The density and the Poisson’s ratio of the samples have also been tested. The stress-strain curve has been drawn to obtain the elastic modulus and the compressive strength. The rock brittleness index has been calculated according to the measured elastic modulus and the Poisson’s ratio, together with the brittleness and the compressibility of the cement samples. The test results show that the mechanical properties and bonding strength of the cement samples are optimal at 130°C, medium at 150°C, and poor at 180°C.

Low-carbon oil exploitation: Carbon dioxide flooding technology

Status and Prospects of Dual-Gradient Drilling Technologies in Deep-Water Wells

One of the main obstacles hindering the exploitation of high-temperature and high-pressure oil and gas is the sealing integrity of the cement sheath. Analyzing the microstructure of the cement sheath is therefore an important task. In this study, the microstructure of the cement sheath is determined using a CT scanner under different temperature and pressure conditions. The results suggest that the major cause of micro-cracks in the cement is the increase in the casing pressure. When the micro-cracks accumulate to a certain extent, the overall structure of the cement sheath is weakened, resulting in gas channeling, which poses a direct threat to the safe production of oil and gas. A change in the casing temperature has a limited effect on the microstructure of the cement sheath.