Study On Geological Characteristics Of Fine-grained Reservoir And The Gas-water Distribution In Sebei Gas Field

The formation of Sebei gas field was deposited during Quaternary time. Moreinvestigation need to be conducted on problems that are leaking of water and sand,and the complexity of water-gas distribution caused by shallow burial, low degree ofdiagenesis, and loose but mud-sand interbedded structure. Fundamental studiesincluding core descriptions, running samples through analysis, and distinguishing andcomparing different sand layers, will help better understand the geologicalcharacteristics of Sebei reservoir and the gas-water distribution in further study.In order to describe the geological characteristics of the reservoir, such aspetrographic characteristics of reservoir rock, type of reservoir space, and type ofpore structures, observations of cores and thin sections, X-diffraction and scanningelectron microscopic analysis, and capillary injection test are needed to be conducted;carried out single sand body of the gas and water distribution on the basis of thereservoir geological characteristics, there are three types of formation water in Sebeifield: boundary water, interlayer water (single water layer, residuary water, boundwater), intra-layer water(restraining barrier water), four original gas-waterdistribution modes: structurally controlled edge water surrounding mode, the highparts of the micro-control of local water-rich low mode, shale the packer gas waterinterbedded mode, high porosity and mudstone compartment control of water pattern.Based on the results of all the analyses, standards of the timing of water breakingthrough for each divided sand body will be established. A map of water-gasdistribution, and research plan on water-gas distribution in Sebei will be made basedon the locations, flowing directions, and expected volume of the breaking throughwater, which can be calculated according to the established standard. It is also shown from the result that water-gas distribution is mainly affected by the parameters oflogging, producing rate of gas and its producing technic, microstructures of reservoir,and the high permeable layers.