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Our usual techniques for the identification of faults have left a gap in our understanding of the role that faults play in the subsurface. When dealing with reservoirs, especially matrix-producing reservoirs, we usually practice 'fault & fracture denial' and spend little time in mapping smaller-scale faults in the early exploration, appraisal and development phases.

We typically only focus on faults once drilling and production performance presents us with unexpected results, such as fluid losses and geomechanical problems during drilling, or reservoir compartmentalisation, water (or gas) channeling along fault planes or cross-flow between wells or zones.

This approach has resulted in problems in many reservoirs around the world, e.g. costly drilling issues, sub-optimal field developments, production deferrals, facility constraints, costly field re-developments incl. well work-overs and infill well drilling, and have even caused uneconomic fields.

Structural compartmentalisation has e.g. been found to be the number one risk to field developments in the North Sea.

The methods that we have employed in the past have led to a systematic under-sampling of smaller-scale fault populations in our fields, and through this to the systematic under-estimation of the effects and risks that faults can pose on the successful drilling, exploration and production of resources.

New seismic techniques in the identification of small-scale faults have shown in recent years that every well penetrates multiple small-scale faults in the subsurface, without these usually being identified through other methods. These intersections can result in many observations in wells – fluid losses during drilling, borehole stability issues, flow enhancement through natural fracture production (sweet spots), cross-flow between zones and wells, premature water production through fault channeling, and others.   Faults always affect and in fact channel fluid flow, either parallel to the fault plane when a fault is sealing (compartmentalisation), or directly along the fault plane when the fault is open.