China’s deep carbonate fracture-cavity oil and gas resources are abundant, and the cumulative proven oil in place is 40.66 × 108 tons; exploring these resources has become an important area for oil and gas exploration and development in China, as well as increasing reserves and production. Owing to the low description accuracy, diverse flow patterns, and difficulty in simulating and predicting carbonate fracture-cave bodies that are buried at depths of 6500–8000 m, water and gas injection channelling is likely to cause low oil displacement efficiency. Efficient development of such reservoirs is a worldwide problem. After the continuous and efficient development of theoretical and technological research and innovation, a detailed description and geological modelling technology for deep fracture-cavity reservoirs was developed, and on the basis of physical experiments and theoretical derivation, the stress-sensitive properties of rock permeability during the production process were determined, and the fluid flow law of multiscale composite media was established. On the basis of multiphase fluid dynamics, rock solid mechanics and thermodynamics, a fluid–solid–thermal joint mathematical model of composite media was established, and a numerical simulation solution and parallel computing software for the joint consideration of cavity, fracture, and hole weight changes were developed, which improved reservoir simulation accuracy and speed. Through research on an efficient development mechanism for numerical simulation, efficient water injection technology that is based on the fracture-cave structure and nitrogen injection-induced cave top flooding-enhanced oil recovery technology was developed. Since the popularization and initial application of the technology, it has supported the large-scale development and sustained high and stable production of the Tahe oilfield, which is the world's first deep superlarge fracture-cavity reservoir. Moreover, it has supported the major discovery and large-scale production of the Shunbei oilfield (also known as the “Shendi No. 1” oilfield), which is the world's deepest (8000 m) large-scale fault-controlled fractured-cavity oil and gas reservoir, and has achieved a significant transition from continental to marine facies in China's oilfield development. This study provides a technical reference and demonstrations for the development of deep and ultradeep carbonate reservoirs.