A method for fine-scale vertical heterogeneity quantification from well data and its application to siliciclastic reservoirs of the UKCS

Abstract

The character of a geological reservoir is critical to the behaviour of fluids that are extracted from it or injected into it, and thus can determine the economic viability of a subsurface project. There are a range of variables of interest when characterising a reservoir. One of these is the degree of heterogeneity, a function of the variability of rock properties resulting from various depositional and post-depositional processes. Heterogeneous reservoirs typically pose more challenges than homogenous reservoirs. The quantification of heterogeneity is therefore of importance for hydrocarbon exploration and production and will become increasingly important for evaluating “advantaged” hydrocarbons and the suitability of sites for subsurface storage. Numerous approaches have been used to quantify geological heterogeneity, but each only provides an estimate of the true heterogeneity and lacks the ability to quantify fine-scale variability. Here we propose an approach that can quantify the fine-scale vertical heterogeneity from well logs and demonstrate our approach on siliciclastic reservoirs of the United Kingdom Continental Shelf (UKCS). We analyse the Leman Sandstone Formation, Bunter Sandstone Formation, Maureen Sandstone Member, Andrew Sandstone Member, Balmoral Sandstone Member, and Forties Sandstone Member, which are important from both petroleum and energy transition perspectives. Our approach can be used to provide new insights into the differences between units and the geospatial nature of heterogeneity within each unit. This can be used to support evaluation/screening activity and to identify suitable analogues from which geologically plausible 3D reservoir models can be generated in a data-driven manner.