Reservoir Characteristics Of He-8 Pool In Sulige Gas Field And Studying On The Geologic Origin Of The Formation Water

Sulige Gas field in Ordos Basin is the main source of "Gas Transportation from Western to Eastern", Especially the He-8 gas pool has supplied 8606.68×10⁸m³ gas storability in all. But there are 26 wells begin to. yield water one after another, since the gas pool to be produced. So the purpose of this paper mainly aimed at the characteristics of sedimentary facies, distribution of sand body, compaction of reservoir, anisotropism, and explore the geological origin of He-8 formation water.He-8 lower 2 to He-8 upper 2 formation of Sulige Gas field mainly be characterized as anastomosed stream fluvial deposit phase, Shan 1 and He-8 upper 1 formation characterized as meandering river fluvial deposit phase. In the whole diagenetic process, there existed stronger activities of compaction and cementation, which leaded to the lower porosity with 6.90%,and the permeability with 0.2640×10^-3μm²,attributied to the compacted sand reservoir with Lower porosity &lower permeability. Because of the stronger bobbing of rivers, different parts of sand body presented unevenly, differ in thickness, wide distribution of interbeds, the high mean permeability contrast. Besides, the pore configurations have expressed stronger anisotropism inside the single sand body, and have tremendous differences on PC curves between every interval. As a result, He-8 Gas reservoirs have stronger anisotropism.By comparative analysis of formation water of He-8, the water mould of He-8 are mostly CaCl₂â…£and CaCl₂â…¤, which pertains to ancientry residuary water, named as "the compacted water" be released by compressing stress of formation. As the same time, by multidisciplinary analysis of structure of the region, reservoir characteristics, and origin of reservoir, the mainly geological contribution factors which leaded to the widely formation water distribution and water yielding of gas wells can be attributed to the layer inversion in the period of smoothly constitute and evolutionary process, dispersive and disconnected gas storage sandbodies caused by the bobbing of anastomosed stream bank, differences of gas &water displacement in the lower permeability sand bodies caused by the facets of compaction and anisotropism..