Refining the Concepts of Connectivity and Continuity in Deepwater Environments

Hovadik, Joseph M.¹, David K. Larue² (1) Chevron, San Ramon, CA (2) Chevron, Bakersfield, CA

Business decisions in sparse well deepwater environments are constrained by the high cost of drilling. Therefore it is important to understand reservoir compartmentalization and stratigraphic connectivity for reservoir architectures that can range from relatively simple sheet-like deposits to more complex channel deposits. Static descriptive measures can be used to quantify characteristics of reservoir in deepwater systems. These static measures may have implications for interpretation or prediction of dynamic performance, and can draw attention to geological uncertainties that may impact flow behaviors. This presentation reviews, modifies and introduces techniques to characterize the spatial distribution of permeability in reservoir models, with emphasis placed on connectivity analysis. Topics include the relationship between connectivity and percolation theory, definition of types of reservoir connectivity, methods of measuring connectivity, connectivity as a function of distance, connectivity maps, categorical classifications of connectivity, types of reservoir path lengths and continuity lines. Static measures of reservoir connectivity are not input parameters to reservoir modeling (such as variogram range, channel width or sinuosity); they are not used to build the reservoir model but are only definable after the reservoir characterization has been constructed. Therefore understanding the impact on connectivity of variables commonly used in geostatistical modeling is important. The effects on connectivity of input modeling variables such as volume support, the variogram range, and geobody size are considered in this presentation. The third part of this presentation examines to what extend static measures are useful to explain and predict aspects of flow behavior. Examples of deepwater stratigraphic architecture will be shown with implications for connectivity and continuity.