Burial Dissolution And Its Reform Of Cambrian And Ordovician Reservoir In Bamai-Katake Area,Tarim Basin

The study strata of this thesis is the carbonate formation in Cambrian-Ordovician of midwest and southwest inTarim basin which include three tectonoic units named Bachu uplift,Katake uplift and Maigaiti slope.The early study in this area is mainly focus on the superficial karst weathering and accumulated a wealth of experience and academic achiecements.However,the deeper part of these strata is lack of research.This thesis combine geology with geochemistry and through lots of core and thin section observation built the lithology identification mark for burial dissolution.Moreover,the kinds of the burial dissolution,their dissolution fluid charecteristics and their effects on the reservoir was study based on the geochemistry burial dissolution related mineral.The dissolution symbol,precipitated symbol and associate mineral characteristic of the dissolution with magnesium-rich dissolution fluid was conclude through lithology study.Geochemistry studies show that there are two kinds of dolomitic fluid.The one from the deep fault show a character of high in ⁸⁷Sr/⁸⁶Sr and low in?¹⁸O with the high temperature and salinity.The dissolution associated with this fluid could form lots of effective pore with saddlelike dolomite.Another associate with formation hydrothermal fluid shows a geochemistry character similar to the matrix dolomite but higher in homogenization temperature.The dissolution with this fluid can hardly form the effective pore in the strata.The intrusion of diabase is a common phenomenon in study area.The surrounding carbonate is easily to marbleization due to the high temperature.Usually,during the matbleization the petrophysics of the surrounding carbonate is stable due to the lack of dissolution fluid.However,the surrounding carbonate could form effective reservoir during magmanisim which is unsaturation on carbonate rocks.This kind of dissolution often accompany with the precipitation of fluorite,sphalerite,galena and anhydrite.The geochemical character of this kind of dissolution is fluorite with high⁸⁷Sr/⁸⁶Sr and homogenization temperature and sulfide with low?³⁴S.According to the study of different kinds dissolution of Cambrian-Ordovician in Bamai area.The porosity evolution is divided to dolomite and limestone.And the model of the dissolution in this area is build reference to the fault distribution.