The role and value of ‘high-impact biostratigraphy’ in reservoir appraisal and development

Abstract

Abstract:Over recent years changes in the application of biostratigraphy in the reservoir appraisal and development arena have greatly increased the impact and value of the discipline, giving it a central role in integrated reservoir description. These changes include placing emphasis on local field-scale bioevents to erect a reservoir framework of time slices through which reservoir heterogeneity can be modelled and the application of biosteering to maximize reservoir penetration. In addition, palaeoenvironmentally diagnostic benthonic microfacies are used to model the lateral continuity of intra-reservoir mudstones in an attempt to understand their potential as baffles/barriers to fluid flow. The evolution of this cost-effective methodology is discussed by reference to three Palaeocene turbidite reservoirs from the North Sea UK continental shelf (UKCS); the Donan, Forties and Andrew fields.

Geologic Time and Stratigraphy

“…High-resolution or "high-impact" biostratigraphy generally is used at the exploration scale, but it also can be used to correlate stratigraphic intervals in reservoirs, if a good biostratigraphic zonation has been established for the particular strata (Payne et al, 1999). In the North Sea, for example, detailed biozonation of Tertiary strata has been identified and has led to more refined correlations among wells within reservoirs.…”

“…On the right are shown the two wells, but with a more refined and accurate biozonation based upon micropaleontological analysis. From Payne et al (1999). Reprinted with permission from Geological Society of London.…”

An old field in a new landscape: the renaissance of Donan

“…4). At this time, no field-specific biostratigraphy had been attempted to constrain any of the correlations and the existing biostratigraphic control was of too low resolution to be used in a meaningful way (Payne et al 1999). The low net to gross reservoir sands were interpreted by BP as having been deposited during gradual and regional scale east-to-west retreat of the Andrew Fan.…”

“…In order to improve the understanding of the reservoir architecture during these first years of production, a high-resolution dinocyst-based biostratigraphy study was initiated using core data (Payne et al 1999). This led to a revision of the geological model from a simple layer-cake model with an upper sand deposited contemporaneously across the whole field, to a more heterogeneous system with sand bodies pinching out over relatively short distances (Fig.…”

“…Revised Donan model adapted fromPayne et al (1999) based on high-resolution biostratigraphy indicating a more heterogeneous system than previously modelled.…”