Study On Relatively Prolific Reservoir Distribution Of Sulige Gasfield

The Sulige gas field is a strong heterogeneity gas pool with huge area, low pressure, low permeability and low reserve abundance. The effective reservoirs are those relative high permeable units distributed among the low permeability background. Because of their deep burial depth, small size and thin thickness, the enrichment distribution proves an important task for gas field development. This dissertation studied the genesis, control factors and distribution of effective reservoir, basically demonstrated the relatively prolific reservoir distribution of Sulige Gasfield.The Shihezi and Shanxi formation are braided channel filling with a long distance source on swamp background in Sulige Gas Field. The braided channels can be divided into two types by the hydrodynamic strength, high energy channel and low energy channel, totally 8 types of microfacies. The high energy channel controls the distribution of the coarse grained sandstones, which control the distribution of effective reservoir. Only the coarse grained and conglomeratic sandstones in the braided channel sandy sediments can be effective sandstones, while the medium and fine grained sands would be invalid. The coarse grained sands are mostly distributed in the channel bars and the bottom of some channel filling sediments. The medium and fine grained sands are mostly distributed in the channel filling sediments. Two kinds of channels-high energy channel and low energy channel-were identified in the braided multi-channel system in the He8 intervals. The high energy channels control the distribution of main channel bars.The main pore types of effective reservoir are secondary origin, and there is a close connection among sandstone grain size, sandstone ingredients and their petrophysics. The coarse sandstones have a relative high reservoir quality with high content of hard quartzite and quartz grains, which favors the preservation of primary pores, and it leads to the flowing of pore flows and occurrence of secondary pores more easily. The medium and fine grained sandstones are inclined to be bad or invalid reservoir quality, with high content of soft lithic fragments, which leads to tight compaction, poor preservation of primary pores and poor development of secondary pores. Totally, the depositional hydro-dynamics controls the sandstone structure and component, and then controls the diagenesis and pore evolution. Based on the relationship of sedimentary microfacies, lithofacies, diagenetic facies and petrophysics, the genetic and distributed models of the four kinds of sandstones were built up.The sandstones in Sulige gas field are wide spreaded, while the effective sandbodies are dispersively distributed with small size and poor continuousness and connectivity. The width of a single effective sandbody is almost less than 800 meter. The effective sandbodies are distributed in the tight sandstones and mudstones in shapes of isolated points or narrow strips.