Study on the controlling factors of reservoir development and gas/water distribution pattern of complex gas reservoir with bottom water: A case study in Longgang reef flat carbonate gas field, Sichuan Basin

Controlled by the deposition and diagenesis, the reservoir heterogeneity of carbonate gas reservoir is serious and the gas water distribution is also complex. This field shows scattered bottom water characteristics. The paper takes the Longgang gas reservoir as an example to analyses the controlling factors of reservoir development, gas water distribution and gas well development characteristics. Results showed the field of Longgang is controlled by sedimentary facies, dolomitization, dissolution and fracture. The favorable sedimentary facies is the material basis in the development of reservoir. The dolomitization is a plus factor. The dissolution is a key factor and the fracture is an effective way to increase permeability. Gas water analysis indicated Longgang gas reservoir had four gas water distribution patterns which included thin formation edge water, thick massive bottom water and layered gas reservoir. Gas water distribution and enrichment regulation were controlled by structure, reservoir permeability body morphology, physical properties, fracture, the tight layer updip direction of reservoir permeability body, and the degree of gas supply in the process of gas accumulation. The wells which have different gas water distribution pattern have different development characteristics. According to these characteristics, we can make the development strategies so as to improve the effect of gas reservoir development.