--> Abstract: Determination of Fault Populations below the Limit of Seismic Resolution for Reservoir Models, by J. J. Walsh, J. Watterson, and G. Yielding; #91004 (1991)
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Determination of Previous HitFaultNext Hit Populations below the Limit of Seismic Resolution for Reservoir Models

WALSH, JOHN J., and JUAN WATTERSON, University of Liverpool, Liverpool, U.K., and GRAHAM YIELDING, Badley Ashton & Associates, Winceby, U.K.

Direct measurement of Previous HitfaultNext Hit displacement populations is possible only on the two disparate scales represented by seismic and by core data that are 2-3 orders of magnitude apart in terms of the Previous HitfaultNext Hit displacement values recorded.

Seismic data from several offshore oilfields have been analyzed to determine the observable Previous HitfaultNext Hit surface area per unit volume and its distribution with respect to Previous HitfaultNext Hit displacement values. On logarithmic plots of Previous HitfaultNext Hit displacement vs. cumulative frequency, the data

distributions have straight central segments with slopes of -0.5 to -1.0. Differences of slope represent real differences in the type of Previous HitfaultNext Hit population. Extrapolation of the straight segments beyond the limit of seismic resolution gives estimates of the Previous HitfaultNext Hit density at subseismic scales. Extrapolation has several justifications: (1) where available, measurements of Previous HitfaultNext Hit displacements in core conform with the predictions made by extrapolation of seismic data from the same field; (2) Previous HitfaultNext Hit data from coal mines and from outcrop show systematic distributions for displacements down to 1 cm; (3) numerical and analytical modeling of Previous HitfaultNext Hit displacement populations indicates a near-linear distribution down to the smallest displacements in a population. The rock volumes for which extrapolat ons are valid are determined by specific scaling laws.

Calculated Previous HitfaultNext Hit populations can be included in reservoir models either explicitly, as individual faults, or implicitly by adjustment of permeability values for defined scales of volume. In either case the effects of the specific sediment architecture and of the Previous HitfaultTop surface hydraulic properties must be taken into account.


AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)