255 / 2019-06-30 20:21:01

Logging evaluation for sedimentary microfacies and reservoir validity of the Cambrian dolomite in the Tazhong area

Sedimentary Microfacies; Deep Buried Dolomite; Effective Reservoir; Logging Identification; Cambrian in Tazhong Uplift

The exploration potential of the Cambrian in the Tazhong uplift of the Tarim Basin is relatively large, but types and classification systems of the sedimentary microfacies need to be clarified. The development law of effective reservoirs under the control of sedimentary microfacies is not clear, and the logging identification method of sedimentary microfacies is lacking. In this paper, the petrological characteristics and the types of sedimentary facies of the Cambrian dolomite reservoirs in the Tazhong uplift are studied by using the basic geological data including cores and thin sections. The results show that the Xiaoerbulake Formation (Є1x) is mainly gentle slope platform deposition, the Wusonggeer Formation (Є1w) is evaporate platform deposition, the Shayilike Formation (Є2s) is the open platform deposition, and the Awatag Formation (Є2a) is the evaporate platform deposition, and the Lower Qiulitage group (Є3xq) is the limited platform deposition; the identification plates for petrological characteristics and logging response of residual grain dolomite, microbial dolomite, fine crystal dolomite and gypsum are established. The sedimentary microfacies of different formations of the Cambrian reservoirs in the study area were completed by combining the petrological features and the typical face markers. Through the confirm of core and logging data, various logging identification plates for sedimentary microfacies based on core sheets and well logging were established. The identification plate was used as a reference to complete the identification of sedimentary microfacies in typical wells. Through the study of the development characteristics of reservoirs in different sedimentary microfacies, the relationship between sedimentary microfacies and reservoir validity and hydrocarbon-bearing relationship is discussed. For typical sedimentary microfacies such as shoal in the Xiaoerbulake and Lower Qiulitage Formations and the gypsodolomite flat in the Wusonggeer and Awatage Formations are favorable microfacies for the development of effective reservoirs, and the prediction of the development of dominant reservoirs based on logging data is realized. The results can provide reference for the study of logging and sedimentology in deep buried dolomite reservoirs in Tazhong area.