Refining the Carbonate Paradigm for Revamping Mature Oil Fields: Integration of Regional-Scale and High-Resolution Stratigraphy in the Upper Cretaceous Natih Formation, Oman

Carine Grélaud¹*, Philippe Razin¹, Peter Homewood², Henk Droste³, Anne Schwab⁴, and Volker Vahrenkamp^5
1Bordeaux University, France
²Oman Geo-Consultants, France
³Shell, Oman
⁴Aberdeen University, UK
⁵PDO
*[email protected]

Seismic stratigraphy is commonly used by industry, at regional scales, to identify and define plays and targets. This study combines a high-resolution sequence stratigraphic study carried out by fieldwork on outcrop, together with seismic forward modelling of both regional scale features and discrete geobodies, and the iteration with high-resolution 3-D industry seismic covering areas adjacent to the outcrops. The resulting high-resolution seismic stratigraphic and sequence stratigraphic interpretations of a targeted field lying further away were significantly enhanced by the general regional model. Iteration between 3-D seismic, cored wells, outcrops and forward modelling has clarified the packaging of strata, or architectural elements, at different scales. Individual geobodies, at the scale of geomorphic units such as channels or carbonate shoals, may be resolved on attribute maps but are generally sub-seismic in scale. A larger-scale grouping of strata, architectural elements, here named “depositional assemblages”, is defined by both clinoform geometries and by seismic stratigraphic context. Facies associations of such units, identified from cored wells, proved to be significantly different, defining assemblage-specific depositional systems. The combination of high resolution sequence stratigraphy from outcrop studies, with the analysis of corresponding 3-D seismic and with forward seismic modelling provides a significantly more detailed geological model upon which to base the static reservoir models required to assess the re-engineering potential of a mature giant field.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain