The Analysis Of Formation Sensitivity Of Middle And Down Permian Series, Zizhou-Qingjian Area, Ordos Basin

This thesis takes the sedimentary rocks and the formation geology theories as the foundation, keeps the formation protection technique principles as leading, makes the most advanced analytical test technique, studies the layer characteristics and potential damage factors in details , with a great deal of indoor sensitivity evaluation experiments and related experiments and data, points out the layer damage mechanism, and in the end puts forward the protected measures and suggestions of the formation.The eastern of the Upper Permian Series gas reservoir of the ORDOS BASIN is low porosity and low permeability tight sandstone ,with complicated composition, the porosity structure is bad and diagnoses strength, the clay-mineral type and produce variety greatly, the fracture growth. The layer rock is mainly lithic sandstone, the lithic quartz sandstone and quartz sandstones. The average permeability is 0. 84-10^-3μm² , the average porosity is 6.10%, the maximal radiuses of pore throats ranges from 0. 404 μ m to 6. 14 μ m, average 1.67 μm, the average throat radiuses is 0. 267 μm. In sum, the reservoir is low permeability and low porosity and especially the low porosity and low permeability.With the geologic data and indoor evaluation experiment, the paper points out that the area have serious stress sensibility and water phase trapping damage , because of the thin throat, micro-fractures and sheet or curl throat; the acid sensibility is serious for more ironed mineral; while the velocity sensitivity, water sensitivity, salinity sensitivity, and alkali sensitivity are weak in average. The degree of these sensitivities are related to the types of clays. The sensitivity of the samples with high chlorite or illite are much serious than those with high kaolinite.The protection of the fractured tight sandstones should abide with the principles of first fracture, second rock . The exploration and development of tight gas should employ both damage control and stimulation .The protection from water lock should avoid using water-based fluid as can as and the fluid would reverse in time to reduce the invalidation of the water-based fluid ;the protection from press sensitivity should design the reasonable pressure in production and test process and the restrained mud should be used in drilling .