Abstract
The complex nature of deep water sediments requires the use of a full field 3D static model to enable better understanding of the reservoir characteristics of the field. This study focuses on the 3D static modelling of the 458 reservoir in Botti field to facilitate field development.
The Botti field is a partially appraised field located about 20km offshore Nigeria. A total of four wells have been drilled in the field and only two wells encountered the target reservoir. The depositional environment is mainly deep water slope channel sands with some submarine fans.
The morphological uncertainties relating to the slope channel sands deposits, requires a detailed 3D static model which defines reservoir characteristics such as channel orientation, continuity and connectivity.
The reservoir evaluation involved the use of core-log integration to identify the facies in the reservoir, seismic interpretation as well as correlation using a sequence stratigraphic approach to understand the reservoir architecture and property distribution.
Using the information obtained from analysed data, an analogue field and literature review, a conceptual model was proposed for the reservoir which served as a precursor for a 3D static model.
To quantify the uncertainties associated with the In-place volume, a monte carlo simulation was done to obtain the P10, P50 & P90 STOIIP values.
Sensitivity analysis using a tornado chart to evaluate impact of STOIIP parameters on the hydrocarbon in-place volumes were done and it showed that N/G had the highest impact on the STOIIP.
The results of this study show that the 458 reservoir is a weakly confined channel complex system made up of the 458_1, 458_2 & 458_3 channel complexes.
A P50 STOIIP was estimated as 150MMstb. This is about 43% reduction in the initial volume calculated before the full field static model.
