Webinar Continuous Stress Tensor Determination from Wireline Logs

Technical Presentation by Nick Harvey, Principal, Harvey Rock Physics presents a novel workflow for continuous determination of the in-situ stress tensor from wireline log data.

Building on the successful AusIMM Hunter Region Branch July Tech Talk, this session addresses a key limitation of conventional overcoring: discrete point measurements that often miss spatial variability in heterogeneous rock masses.

Time: 11:00am GST

Date: Tuesday, August 18, 2026

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Introduction

Accurate characterisation of the full stress tensor is fundamental to geomechanical design in mining, civil engineering and resource extraction. Conventional techniques such as overcoring deliver discrete point measurements that may not adequately capture spatial variability within heterogeneous rock masses. The workflow presented addresses this limitation by providing continuous, interval-by-interval estimates of stress orientation and magnitude.

Figure 1: Example of continuous principal stress determination from wireline logs (anonymised example)

Technical Approach

The method integrates three complementary wireline datasets:

• Acoustic borehole image analysis – Utilisation of borehole ovality and breakout features to constrain stress orientations.

• Full-wave sonic data – Provision of elastic moduli and anisotropy information for magnitude estimation.

• Density logging – Supply of overburden stress and lithological constraints.

A proprietary tensor optimisation procedure is then applied to compute the principal stresses (σ₁, σ₂, σ₃) on a continuous basis throughout the logged interval. This yields a high-resolution stress profile that reveals vertical and lateral variations often overlooked by traditional discrete measurement techniques.

Demonstrated Application

The workflow has been applied to three boreholes drilled through heterogeneous lithologies in contrasting geological settings. In each case, the continuous stress profiles obtained compared favourably with available overcoring measurements while providing complete interval coverage. The results demonstrate the method’s ability to identify critical stress variability that point-scale techniques may miss, with direct implications for mine design, ground control and geotechnical risk assessment.

Industry Relevance

This presentation is particularly relevant to professionals engaged in mine design, ground control, geotechnical engineering and risk management within the mining sector. The approach offers a practical means of obtaining high-resolution stress information from existing or planned wireline logging programmes, supporting more informed decision-making in excavation design and stability analysis.