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The AAPG/Datapages Combined Publications Database

Houston Geological Society Bulletin


Houston Geological Society Bulletin, Volume 53, No. 03, November 15, 2010. Pages 25 and 27.

Abstract: The Structure, Content, and Growth of Previous HitFaultNext Hit Zones Within Sedimentary Sequences and Their Effects on Hydrocarbon Flow

John Walsh
Previous HitFaultNext Hit Analysis Group, School of Geological Sciences, University College Dublin, Ireland

Existing models for the growth of Previous HitfaultNext Hit zones associated with normal faulting of sedimentary sequences range from conceptual models for Previous HitfaultNext Hit zone architecture, incorporating components such as Previous HitfaultNext Hit core and damage zone, through to a variety of Previous HitfaultNext Hit wear models that attempt to explain established quantitative correlations between Previous HitfaultNext Hit displacement and Previous HitfaultNext Hit rock thickness. Despite the importance of normal faults in a variety of application areas, no unified model for Previous HitfaultNext Hit zone evolution has been developed which incorporates the broad range of Previous HitfaultNext Hit-related features and processes. Exploring links between the scaling of different Previous HitfaultNext Hit zone components and Previous HitfaultNext Hit displacement, this talk presents a quantitative model for Previous HitfaultNext Hit zone evolution which attempts to reconcile Previous HitfaultNext Hit zone structure with the repetitive operation of a small number of processes, including Previous HitfaultNext Hit segmentation and refraction, and asperity removal. This model helps to reconcile the main characteristics of Previous HitfaultNext Hit zones developed within a broad range of host rock sequences and at different deformation conditions, but still recognizes the inherent complexities of natural Previous HitfaultNext Hit zones.

This model for Previous HitfaultNext Hit zone structure is also consistent with recent studies of high-quality outcrops which illustrate how the combined effect of host-rock rheology and prevailing deformation processes is capable of generating the full range of Previous HitfaultNext Hit rock types, including those which have a major impact on hydrocarbon flow, such as shale/clay smears within poorly consolidated sediments through to shaley Previous HitfaultNext Hit gouges within lithified sediments. The incorporation of either shale smears or shaley gouge within Previous HitfaultNext Hit zones contained in siliciclastic sequences is now recognized as one of the principal means of forming some Previous HitfaultNext Hit-bounded traps and can have a major impact on intra-reservoir flow. Existing empirical constraints demonstrate that Previous HitfaultNext Hit rock permeabilities decrease with increasing clay fraction and provide a means of predicting Previous HitfaultNext Hit rock permeabilities in the subsurface. New approaches are briefly described which are capable of incorporating the flow effects of faults in both hydrocarbon exploration and production models. Recently published studies show that these methods provide an improved basis for modelling faults contained within reservoir production or hydrocarbon migration flow models of siliciclastic sequences, in which faults behave as barriers or baffles to flow.

Faults are represented as planes in conventional reservoir cellular models and yet they contain Previous HitfaultNext Hit rocks with permeabilities that differ from those of the host rock. From Manzocchi et al. (1999). Petroleum Geoscience, 5, 53-63.

Faults in a reservoir model in which across-Previous HitfaultNext Hit sequence juxtaposition is explicitly included in the model geometry, with Previous HitfaultNext Hit rock properties represented by cross-Previous HitfaultNext Hit transmissibility multipliers on the cell faces along the Previous HitfaultTop surface (using the method of Manzocchi et al. 1999).

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