Thierry Rives¹, Antonio Benedicto¹
(1) Elf Exploration Production, Pau, France

Abstract: 3D Fault segmentation: Implications for entrapment and compartmentalisation

In petroleum industry faults are key structures as they often border prospects and create reservoir compartments. They are usually considered as single more or less planar and continuous slip surfaces on seismic cross-sections or isobath maps. In the last few years, increasing 3D seismic quality and workstation performances, have allow improvement of 3D fault detailed architecture. On accurate seismic attribute maps faults often appear as discontinuous surfaces with relay zones. On very high quality seismic this “ segmentation ” is also visible on cross-sections. Outcrop observations and mechanical understanding of shale smear development confirm this architectural complexity of normal faults. Segmentation is directly related to ductile-brittle bedrock contrast in sedimentary series. Ductile beds are continuous between two fault segments while brittle beds are broken down by the fault segments. Nevertheless, horizontally, brittle beds may also be continuous within the relay ramp between two segments. Fault architecture can be defined as segmented when faults are formed by several sub-parallel surfaces with horizontal and vertical relay zones. As results, this non-continuity of faults (horizontal and vertical segmentation) becomes of major importance to understand fluid flow along or across faults. Segments and relays control 3D migration pathways and connections between reservoirs. Accurate 3D architecture of faults then appears crucial when evaluating fault entrapment prospects and for production strategies of compartmentalised reservoirs.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana