Carbonate Lithology and Microfacies Logging Identification in the Gucheng Area

Due to limited availability of rock samples, it was difficult to conduct systematic characterization and other relevant studies on carbonate sedimentary facies. In order to take advantage of high-resolution logging tool which yields a curve rich with information, petrophysicists implemented a new method to identify carbonate lithology and microfacies. To accomplish their goal, they utilized well log data and resulting curves in the Gucheng Area. After the logging curve was calibrated with of the types of microfacies derived from the rock samples, and correlated with the relationships of response between conventional logging parameters and carbonate lithology and microfacies. Then,optimal sensitive logging curves such as DEN, DT, PE, U, Th and K were selected, and a new parameter combination was proposed. The next step involved preparing two charts for identifying carbonate lithology and sedimentary microfacies, and they had a coincidence rate of 85.4% and 81.4%, respectively. Moreover, the function relationship was defined to quantitatively classify the sedimentary microfacies types according to energy within the depositional environment, and the energy parameter curves for microfacies were provided. Microfacies identified with this technique and their energy parameter curves were applied in the space division and correlation of facies belts and sedimentary cycles. Results showed that the microfacies identified and sedimentary energy distribution characteristics were consistent with that of sedimentary facies belts that had been determined previously by identifying patterns in of slices of core. Because of the positive results from the application of the technique, the results suggest that thethe technique can be used as an essential complement of fine-grained sedimentary facies study.