Hierarchical Characterization and Modelling of Deep-Water Slope Channel Reservoirs.



Soni K.1,2 Manzocchi, T.1,3, Haughton, P.W.D. 1,4, & Carneiro, M.1
1 - Irish Centre for Research in Applied Geosciences (iCRAG), University College Dublin, Belfield, Dublin 4, Ireland
2 - Present Address: Petroleum Affairs Division, Department of Communications, Climate Action and Environment, Ireland
3 - Fault Analysis Group, School of Earth Sciences, University College Dublin, Dublin, Ireland.
4 - Marine and Petroleum Geology Group, UCD School of Earth Sciences, University College Dublin

Abstract - Oil reservoirs hosted in deep-water slope channel deposits are a challenge to manage and model. A six-level hierarchical arrangement of depositional elements within slope channel deposits has been widelyrecognized, and dimensional (width and thickness) and stacking (amalgamation ratio and volume fraction)data have been acquired from published studies to establish parameters for a representative slope channelsystem. A new static modelling workflow has been developed for building models of channel complexesbased on a simplified hierarchical scheme using industry-standard object-based modelling methods and anew plugin applying the compression algorithm. Object-based modelling using the compression algorithmallows for independent input of volume fractions and amalgamation ratios for channel and sheet objectswithin a hierarchical modelling workflow. A base-case channel complex model is built at the resolutionof individual sandstone beds, conditioned to representative dimensional and stacking characteristics ofnatural systems. Inclusion of explicit channel axis and margin regions within the channels governs bedplacement and controls inter-channel connectivity where channels are amalgamated. The distribution ofporosity and permeability within these beds mimics grain-size trends of fining in the vertical and lateraldirections. The influence of various geological parameters and modelling choices on reservoir performancehave been assessed through water-flood flow simulation modelling. Omission of the compression methodin the modelling workflow results in a three-fold increase in oil recovery at water-breakthrough, becausethe resultant unnaturally high amalgamation ratios result in overly-connected flow units at all hierarchicallevels. Omission in the modelling of either the bed-scale hierarchical level, or of the axial and marginalconstraints on the bed placement in models that do include this level, results in a two-fold increase inoil recovery at water-breakthrough relative to the base-case, because in these cases the channel-channelconnections are too permissive.

SPE Norway Subsurface Conference, SPE-200763-MS, doi: https://doi.org/10.2118/200763-MS