Strategies Study on Development Method of Ultradeep Fault-Controlled Fracture-Cave Condensate Gas Reservoirs in Shunbei Oilfield

There are great differences in geological conditions and reservoir characteristics between Shunbei ultradeep fault-controlled fracture-cave type condensate gas reservoir and other developed condensate gas reservoir, which make it difficult to exploit and lack of development countermeasures for reference. In order to explore the development method suitable for the characteristics of this new type of gas reservoir, based on the actual parameters of the gas reservoir, the quantitative modeling-simulation integration method is adopted to study the depleted development characteristics and pressure maintenance strategies of the fault-controlled fracture-cavity condensate gas reservoir. The results show that some development parameters such as stable production time, gas-oil ratio and connected reserves are deeply affected by retrograde condensate and stress sensitivity simultaneously, which makes the depletion development effect worse. For gas injection, methane injection has better miscibility and is easy to form gravity overburden gas cap flooding, which has the best oil increasement effect. For water injection, the development is greatly affected by relative permeability. The stronger water permeability in fracture is, the easier it is to cause fracture waterflooding in production, and the worse the development effect is. The premature injection timing will compress the production space of oil components in the depletion stage, and late injection timing will cause oil loss due to the retrograde condensation. So, there is an optimal injection timing above the dew point. The faster the injection-producing rate is, the worse the oil increasement is, however the impaction is limited. Meanwhile, the cumulative oil production value becomes bigger with the longer injection time, it’s worth mentioning that the growth rate becomes slower as injection time increase. Besides, for the well group that can form injection-production pattern, the scheme which adopt continuous injection and production mode first, and then switch to pulse injection and continuous production mode before gas channeling is the best strategy in a production full-cycle. For the isolated well, the gas huff-n-puff method can achieve a good effect of pressure supplement and oil increasement. Further, the optimal injection location is related to the factors such as reservoir distribution, reservoir connectivity, and location of produced well. It is necessary to ensure that there is sufficient distance between the injection and production wells, which can increase the swept volume and prevent gas channeling. Finally, the research results have provided effective support for the efficient development of fault-controlled fracture-cave condensate gas reservoirs in Shunbei No. 4 fault zone, and can also provide relevant reference for the development of the same type reservoirs.