A practical approach for applying Bayesian logic to determine the probabilities of subsurface scenarios: Example from an offshore oilfield

Abstract

During appraisal of an undeveloped segment of a producing offshore oilfield, three well penetrations revealed unexpected complexity and compartmentalization. Business decisions on whether and how to develop this segment depended on understanding the possible interpretations of the subsurface. This was achieved using the following steps that incorporated a novel practical application of Bayesian logic:allowed an assessment of the usefulness of individual pieces of evidence, which could be used to guide value-of-information assessments for subsequent data acquisition. Finally, the process enabled rigorous Bayesian revision methods to be applied in a simple practical way that engaged the subsurface team without exposing them to the underlying mathematics. During field appraisal and development, when the subsurface is revealed gradually as more data are acquired and studied, the process outlined here provides a practical way of generating and modifying belief in a range of subsurface scenarios while minimizing exposure to potential biases and logical fallacies that could affect subsequent decision quality. It also helps to decide which scenarios are sufficiently probable that they need to be represented by detailed reservoir models.

An integrated procedure for reservoir connectivity study between neighboring fields

“…Moreover, the interpretation of seismic data carries non-uniqueness (Yin et al 2016). Therefore, the best method to cover these weaknesses is the reconciliation of different dataset to create diverse models and modifying or dropping some models after acquisition of new data (Smalley et al 2018;Walker and Evenick 2019).…”