Using Quantitative Fault Seal Analysis to Reduce Risk in Assessing Prospect Fill Scenarios: A Case Study From the Sole Pit Basin (Southern North Sea)

Abstract

The purpose of appraisal is to establish the full extent of the potential hydrocarbon accumulation. This is typically achieved using prospect fill scenarios. A simple, quick approach in deriving these studies is to assume faults to be either sealing or leaking. However, this does not capture the inherent complexity of fault-seal behaviour. Assigning faults inappropriate sealing potential can result in, among other negative outcomes, underestimated prospect evaluation and missed pay. We present a case study from one such area of complex structure located in the Sole Pit Basin (Southern North Sea). The study area is characterised by NW/SE trending faults formed during Mid-Late Jurassic extension that are crossed by NNE trending faults and lineaments. We use published methods to convert fault rock properties at reservoir-reservoir juxtapositions to threshold pressures and use these to predict trappable column heights. By assessing fault behaviour in relation to known structural spill points we can better critically assess trap fill and potential leak points outside of the discovery, improving the appraisal process. This case study illustrates the significantly improved prospect understanding resulting from a quantitative fault seal analysis. The ability to demonstrate an accurate predictive model helps reduce risk and serves as an important input to volumetric calculations. This enables a more targeted appraisal programme, with associated risk, cost and time reductions.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017