Abstract

An area in the Southern Perth Basin has been identified as a potentially suitable site for CO2injection, due to its proximity to major CO2emission sources and the presence of potentially suitable geology. The project for testing and proving up of the storage area is known as the South West Hub Project or SW Hub. Recently acquired 2D seismic and well data have allowed a detailed description of facies, measurement of rock properties and development of a 3D structural model for the area. This 3D model has been used as the basis for a preliminary fault seal analysis and also for the development of simplified geomechanical models for the SW Hub using FLAC3D. The geomechanical modelling used in situ stress (magnitude, orientation) and pore pressure conditions as a starting point and then simulated CO2injection from a single well at rates of 1 to 5 million tons per year for 20 years. No matter whether weak or strong faults were used, no faults were reactivated nor the top seal breached under any of the simulated injection rates. Average uplift in the weak fault scenario was modelled at between 0.4 and 1.8 cm for injection rates of 1 to 5 million tons per year. The strong fault model showed slightly smaller uplifts. The majority of uplift was noted in the first 5 years of injection and flattened off rapidly after this point in time. This is consistent with geomechanical models from other CO2storage sites and from actual field measurements.

1. INTRODUCTION

Suitable geology and proximity to large sources of carbon dioxide led to the Southern Perth Basin being investigated as a potential geological storage site [1]. The specific area selected is in the region of the Harvey- 1 well (Figure 1) around 150 km south of Perth in Western Australia. This has become known as the South West Hub project and this area is currently undergoing extensive site assessment in terms of reservoir quality, containment potential, structural geology, facies analysis, rock properties and the like.

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