4-D Sequential Restoration and Its Applications

Restoration is defined as the operation that moves presently deformed rock units to their pre deformation position. 2D restoration of cross sections is common practice since many years. 3D restoration on volumes becomes now available, as 3D modelling capabilities of modern software increase (Dulac et al., 2011). 4D restoration aims at creating the full suite of restored 3D volumes of rock describing the evolution through geological times of a 3D faulted and folded structure, typically at basin or prospect scale.

The paper will start describing how 4D restoration is performed. 4D restoration extends the well known backstripping method (Sclater & Christie, 1980) and is a sequence of 3D restoration steps. In backstripping, the only vertical movements are allowed. In 4D restoration, lateral movement in any direction are possible, because faults are taken into account. Layers move along faults through time, as fault throws are cancelled. The orientation of lateral movement might change through time, because of the structural complexity of fault patterns. As in backstripping, 4D restoration successively removes each stratigraphic unit in reverse order.

The possible applications of 4D restoration will then be described.

1. To quality control the present day interpretation of seismic picks (eg. a normal fault at present day should not be transformed into a reverse fault in the past in a pure extensional regime).

2. To provide inputs to petroleum system modelling, including maturity, pressure or migration modeling.

3. To provide inputs to sedimentary depositional modeling.

4. To compute the evolution of fault throw and fault related property through time.

5. To derive the strain evolution through time.

The strain changes are stepwise computed and may be related to reservoir fracturing at prospect or reservoir scale. At basin scale, the dilatancy might be used to select optimal fractured areas in tight reservoir rocks, or to avoid those areas when seal breaching is a risk.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California