Gas and Water Distribution Patterns and Development Suggestions for Low Permeability and Thick Bottom Water Gas Reservoirs with Low Amplitude Structures

Focusing on Dengying Formation gas reservoir in the north of Sichuan Basin, it is a key field for domestic Carbonate rock gas reservoirs to increase reserves and production in recent years. Drilling revealed that there are water free, limited water bodies, and edge and bottom water gas areas. Complex gas water relations restrict the large-scale development of gas reservoirs. Therefore, taking Dengying Formation gas reservoir in north central Sichuan Basin as the research object, taking a new perspective of combining natural gas source, migration channel, filling degree and drilling gas and water distribution, the gas and water distribution model of large, low gentle structure, low permeability and thick gas reservoir is established, revealing the gas and water distribution law of this type of gas reservoir, and the following understandings are obtained from the research: Dengying Formation in central Sichuan is a gas reservoir with side generation and side reservoir, The main transmission conductors of natural gas are the deep and large faults that connect the source reservoir and the unconformity surface related to the Dengying Formation, creating a regional and cluster structure where natural gas reservoirs are mainly distributed along the unconformity surface today; Controlled by the influence of multiple factors such as current structure, paleostructure, lithofacies and unconformity surface, as well as the constraints of its own huge thick reservoir, the gas filling degree is generally low, resulting in the existence of water free, limited water, edge and bottom water and other forms of gas water relations; Adopting a centralized scale production and development approach for large-scale natural gas enriched gas reservoirs; For discontinuous gas reservoir groups, a rolling evaluation and deployment approach is adopted to improve the success rate of development and reduce development risks.