Abstract:
Geological evaluation of source-reservoir coupling relationship has made significant progress in lacustrine shales. However, most evaluation focuses on macroscopic description and qualitative analysis. Lacking of a quantitative parameter system still restricts the application of geological evaluation in effectively guiding exploration and development. In this paper, we take the Shahejie Shale Formation in the Dongpu Sag as the target. Analysis of the hydrocarbon-source and reservoir characteristics indicates that the oil and gas accumulation in the Shahejie Formation belongs to a typical source-reservoir coexistence pattern. Therefore, porosity and TOC are both significant. The source-reservoir coupling coefficient (SRCC) is proposed to be one of the key parameters in geological "sweet spot" prediction. To achieve the quantitative SRCC evaluation, an exponential model based on vertical P-wave velocity is established with the rock physics experimental data. Based on the cumulative frequency distribution characteristics of SRCC, three Classes (Class I, Class II, and Class III) are set with SRCC of 2.1 and 0.7 as thresholds. Single-well evaluation suggests that Class I and Class II source-reservoir configurations are dominant in Shahejie Shale Formation. Layers with Class I has both high hydrocarbon generation potential and excellent reservoir performance. Layers with Class I are almost corresponding to two dominant lithofacies: laminated argillaceous mixed shales and laminated calcareous mixed shales. The findings provide a foundation for optimization of “sweet spot” section, design of horizontal well target windows in Qianliyuan Depression.