PETROMAKS-Maksimal utnyttelse av petroleumsreserver

Over 60% of global hydrocarbon reserves lie in carbonate systems, a significant percentage of which contain paleokarst features. Paleokarst carbonate reservoirs have heterogeneous porosity and permeability, complicating efficient hydrocarbon (and groundwa ter) extraction. Paleokarst features range from metre-thick zones of porosity-permeability heterogeneity underlying unconformities (common), to collapsed cave systems (less common). We will create and test 3D paleokarst reservoir-analogue models made fr om superbly-exposed karsted carbonate reservoir analogues. The models are created by combining modern high-resolution digital outcrop mapping with high-resolution geophysical characterization of the subsurface. The dimensions required to capture a represe ntative architectural element on the reservoir- and seismic scale varies from less than a hundred metres for some unconformity-related paleokarst to over a kilometre for stratiform breccias and collapse pipes. Quantitative fluid-flow and seismic-response modelling using the petrophysical model are important goals. The present lack of analogue field-sized data sets hinders the accurate modelling of both small- and large-scale paleokarst carbonate reservoir features. 3D geological-petrophysical models have the ability to produce more realistic flow models. Another benefit is that they provide a means to evaluate and improve the modelling state-of-the-art. The data gathered in this proposed project will take full advantage of existing methods and provide a platform, if required, to improve these methods. Another focus is the seismic response of the reservoir analogue. Without realistic 3D architectural models, exploration seismic data are difficult to process and interpret correctly. We will also work to determine the links between karst architecture and basin evolution, relating the paleokarst to the groundwater flow in the basin. This is karst process research in pursuit of a predictive E&P tool.