Abstract

Spatial continuity and linkage of faults may substantially affect fluid flow either by compartmentalizing the reservoir or by increasing the tortuosity of flow pathways, whether the faults act as seals or conduits; therefore, understanding fault linkage geometry should improve reservoir flow simulation models and, in turn, significantly reduce the number of wells required to drain reserves.

A method has been developed to infer, in three dimensions, the fault tip-line geometry below the seismic resolution, as well as potential fault linkage using 3-D (three-dimensional) seismic data and geomechanical models based on elastic dislocation. A 3-D numerical model of the faulted reservoir and its surroundings is constructed using seismic interpretation. Such a model, combined with an appropriate set of boundary conditions, is used to compute the fault slip distribution, as well as vertical displacement field. By comparing the interpreted fault slip distribution to the computed slip distribution adjacent to potential intersection lines, the geomechanical models can constrain the geometry of the faults and the location of the intersection line between faults. The interpreted structure contour map and theoretical displacement field also are compared to constrain the fault geometry.

Two subsurface examples from the Oseberg Syd oil field, northern North Sea, illustrate how such geomechanical analyses can increase confidence in seismic interpretation to refine fault connectivity and reservoir compartmentalization.

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