A case study on statistical wireline log parameters in identifying shallow-water delta microfacies of Late Dongying Formation, northern Liaozhong Depression, Bohai Bay Basin

Abstract

The shallow-water deltaic deposits turn out to be one of the most potential reservoirs in Late Dongying Formation of northern Liaozhong Depression. Previous studies prove it difficult to identify the microfacies of shallow-water delta with conventional methods. In this paper, a new statistical method of wireline logs verified with cores is proposed to solve microfacies identification issue. It aims to combine wireline measurements with a lithofacies to produce an automatic lithologic description of the microfacies of shallow-deltaic deposits. In the meanwhile, the characteristics of microfacies can be shown by box map, standard QQ chart, anti-trend QQ chart, and crossplot resulted from statistical wireline parameters. Based on the charts mentioned above, statistical wireline characteristics can be summarized for the microfacies of shallow-water delta deposits and verified with core photos. Finally, the statistical wireline parameters are proved to be capable of identifying microfacies in the study area. In addition to the significance for academia, this new method and its application are of great importance for discovering potential reservoirs. Because shallow-water channel-fill sandstones and conglomerates frequently host important hydrocarbon reserves. Consequently, investigating shallow-water delta deposits microfacies is significant economically as well.