Evaluation For The Caprock Integrity Of The CO₂ Sequestration In Depleted Oil And Gas Reservoirs

Greenhouse effect continued increasing and deteriorating of the global climate,carbon dioxide reduetion has drawn international attention and become a common topic.CO2 capture and geologic sequestration is one of the most promising options for reducing atmospheric emissions of CO2.Its viability and long-term safety is crucial for implementing CO2 geologic storage.CO2 sequestration in depleted oil and gas reservoirs has low costs,short test term and lots of technological easy, Valued by Intergovernmental.and research institution.Today, some enhanced oil recovery projects has started the site test in our country.and the result of abandonment oil production rate was well.Putaohua reservoir in daqing changyuan of songliao basin as an example, with rock mechanics characteristics, physical property test as the means, the application of hydraulic fracture and fault stability quantitative evaluation technology, delve into carbon dioxide injection reservoir effect on the integrity of the cover. First, starting from the capillary sealing mechanism, considering the interface tension and wettability of capillary sealing ability, the influence of daqing changyuan tectonic putaohua reservoir caprock displacement pressure is 3.708 MPa. Second, discusses the dry and wet reaction of carbon dioxide-water-rock impact on the integrity of the cover, the results showed that after thousands of years, generally change cover lower part mineral rock and pore structure, but did not destroy the integrity of the cover of a complete set of; Finally, the application of cap rock of hydraulic fracture and fault stability quantitative evaluation method, think of daqing changyuan putaohua reservoir critical pressure of the hydraulic fracture structure, sliding and stability critical pressure were 13.94, 13.6 MPa and 14.4 MPa.On the basis of caprock development characteristics, cap rock and fault sealing capacity change stability evaluation results, combined with daqing changyuan area distribution and quantitative evaluation of putaohua reservoir in daqing changyuan of songliao basin sequestering carbon capacity of 1.41*109 m3.