LIVE WEBINAR – Validation and Analysis Procedures for Juxtaposition and Membrane Fault Seals in Oil and Gas Exploration

Kindly supported by Rock Flow dynamics

This live webinar will take place at:

11am         – Perth
12.30pm  – Adelaide and Darwin
1pm          – Brisbane, Canberra, Hobart, Melbourne, Sydney

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Tickets are free for members (please log in to see this) and $10 for non members.

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Abstract

Recent structural geology research on geological faults and fault zones coupled with analysis of known hydrocarbon accumulations has shed new light on the problem of fault seal in oil and gas exploration. Faults are best thought of as paper thin zones, with a patchwork of behaviour governed by both areas where significant fault gouge or fine grained material is present, and where it is absent.

The authors propose and validate methods for analysis of fault-bounded traps in oil and gas exploration. Analysis generally considers lateral seals due to 1) juxtaposition of the top seal against the reservoir across the fault, and 2) juxtaposition combined with impermeable/high capillary entry pressure fault rocks such as clay gouge or other fault related materials (membrane seal). Neglecting 3D effects for illustration purposes, the cross section below shows two inferred hydrocarbon fill levels. Level A is the result if juxtaposition seal is the only effective barrier to cross fault flow, and Level B is the result if membrane seal were also effective.

The authors argue that fault seal analysis procedures should consider multiple instances of 3D Allan maps (normal to fault plane views – see Figure below) which consider both geometrical and stratigraphic uncertainty. To validate the proposed methods, multiple case studies of successful discoveries have been back analyzed – for these case studies the model predictions were compared with the independently observed hydrocarbon water contact (IHWC) obtained from drilling.

Stochastic juxtaposition analysis with no contribution from fault rock membrane seal or SGR was found to give the smallest error in estimation of the observed IHWC. The inclusion of any fault rock seal mechanisms in the analyses matches or increases predicted hydrocarbon column heights compared to juxtaposition analysis alone. Based on over 40 case studies, the authors conclude there is no reason to include fault rock membrane seals in exploration prospect risking.

A recent publication in the Journal of the Geological Society of London is freely available from Research Gate:

https://www.researchgate.net/publication/335040180 Validation and Analysis Procedures for Juxtaposition and Membrane Fault Seals in Oil and Gas Exploration