The Study On The Sequence, The Sedimentary Facies And The Characteristic Of The Dolomite Reservoir Of Cambrian In The North Of The Tarim Basin

In this paper, the research object is the Cambrian carbonate rocks in North Tarim area, using the carbonate sequence stratigraphy, seismic stratigraphy, sedimentology and reservoir sedimentology theory, the field outcrop and thin section, seismic and well logging curve combination, to carry out research on the Cambrian sequence, sedimentary facies and reservoir. Through reservoir development and distribution, as well as the sequence and sedimentary facies, combined with reservoir development controlling factors, Research dolomite reservoir in the study area development and distribution.Combined with seismic, the three-order sequence framework of the Cambrian drilling and seismic profiles is established. This study suggests that the Cambrian in north Tarim is divided into ten three-order sequences, Among the-m, the Yuertusi formation was appropriately divided into two three-order seque-nces; The Xiaoerblak formation is appropriately divided into two three-order s-equences; The Wusonggel formation and the Shayilike formation is appropriate-ly divided into a three-order sequence; The Awatage formation and Xiaqiulitage formation is appropriately divided into four level-three sequence. Three-order sequences can achieve the contrast in the whole area combined with seismic sequence analysis, to establish the three-order sequences correlation framework of Cambrian in the study area.Through the thin section observation of rocks, according to the difference of dolomite structure, structure, color, composition, combined with the lithofacies paleogeography, sedimentary structure in the study area, analysis of the lower Cambrian Yuertusi formation sedimentary facies can be divided into the shelf and the basin facies; The Xiaoerbulake formation of the lower Cambrianis is mild slope basin facies, and slope facies can be further divided into internal ramp, middle ramp, outer ramp; From Wusonggeer formation of the lower Cambrian to the Xiaqiulitage formation of the upper Cambrian, The Cambrian carbonate model has been developed in the study area, Studying on the drilling section, the sedimentary is divided into basin, platform margin, restricted platform facies,and the platform margin can be further divided into tidal flat lagoon facies, microfacies, intraplatform microfacies.Divided seismic sedimentary facies boundary, combining with construction diagram and sedimentary facies of drilling well, the sedimentary facies of Yuertusi formation is basin facies; The sedimentary facies of Xiaoerbulake formation is slope and basin facies; The sedimentary facies of Wusonggeer formation is restricted platform, ramp and basin facies; The sedimentary facies of Shayilike formation is restricted platform, open platform, platform margin, slope and basin facies; The sedimentary facies of Awatage formation is evaporation platform, restricted platform, open platform, platform margin, slope and basin facies; The sedimentary facies of Xiaqiulitage formation is restricted platform, open platform, platform margin, slope and basin facies.Through the analysis of core, thin section observation and the order degree of dolomite, the dolomitization of Cambrian in the study area is mainly evaporation pump dolomitization mechanism, seepage reflux dolomitization mechanism, shallow burial dolomitization mechanism, hydrothermal dolomitization mechanism. Combined with logging, logging analysis, dolomite reservoir in the study area is mainly fractured reservoir and solution pore type reservoir. Most of the primary porosity has been exhausted. Thermal dissolution, weathering dissolution is the main mechanism of solution pore type reservoir.The dolomite reservoir development zones are mainly in the South of Tianshan area and reservoir development area related to karstification, hydrothermal dolomite reservoirs development area controlled by tectonic fracture,Cambrian platform margin area.