Abstract

Subsurface structural and stratigraphic analysis is used primarily to reconstruct buried environments and to analyze post depositional changes to the rocks. The objective is to understand how these various aspects of the geology impact on the ultimate economic recovery of hydrocarbons. In situ analysis of electrical images of the borehole wall after calibration to a known lithological source, such as cores and logs, represents a new approach to the study of subsurface geology.

A large number of key formation characteristics can be derived from the visual analysis of a calibrated image. For example, direct structural analysis, including analysis of the in-situ stress regime is possible through borehole breakout analysis. Fracture and fault identification and orientation, as well as depositional environment and sequence analysis plus the distribution and nature of diagenesis can be derived. Palaeocurrents, sediment maturity, sorting and texture, together with reservoir (sand body) orientation and quality can all be measured and inferred.

With the advent and integration of these new techniques, it is hoped that more prospects and reservoirs will be thoroughly investigated.