3-D Characterisation of CO2 Containment in the South West Hub, Perth Basin

Abstract

The South West Hub Carbon Capture and Storage project is located in the southern part of the onshore Perth Basin. The storage complex reservoir, primary and secondary seals are represented by the Triassic lower Lesueur Sandstone (Wonnerup Member), the Upper Lesueur Sandstone (Yalgorup Member) and the Early Jurassic basal Eneabba Formation, respectively. The South West Hub is well into the pre-competitive data acquisition feasibility phase. Following the collection of 2D seismic and the drilling of the Harvey-1 stratigraphic well, the Preparation Phase (2011–2013) included initial geological modelling and a first-order assessment of fault properties. The integration of this work with advanced geophysical data and rock properties analysis highlighted that fault systems are likely to intersect the target CO₂ storage complex reservoir and the potential top seals; however the likelihood of migration of CO₂ across and up faults would be generally low due to the geometry of faults and the modelled in situ stress field. In 2014, 3D prestack time and prestack depth migration algorithms coupled with velocity analysis and poststack attribute analysis were used on a 150km² 3D seismic survey to improve the seismic imaging of the reservoir, seals and overburden in the South West Hub. A constrained 3D geomodel that captures the structural and stratigraphic architecture was populated with depositional facies derived from 3D forward stratigraphic modelling. The geomodel included more than 60 fault planes and clearly identified the key reservoir and seal compartments which was critical for the placement of wells for the 2014–2015 Well Drilling Program and for developing monitoring strategies. The geomodel was used to assess CO₂ containment potential. The impact on fault reactivation of the stress and pore pressure variations due to injection scenarios were calibrated and maximum CO₂ column heights supported by faults were locally defined. The fault membrane seal capacity was predicted from the facies model and the fault properties; it allowed the evaluation of CO₂ migration scenarios between reservoir compartments, from reservoir to thief zone in the seal or to the overburden.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015