Identification of fault and top seal effectiveness through an integration of hydrodynamic and capillary analysis techniques

Fault and top seal effectiveness has proved to be a significant risk in exploration success, and creates a large uncertainty in predicting reservoir performance. This is particularly true in the Australian context, but equally applies to exploration provinces worldwide. Seals can be broadly classified into fault, intraformational, and top seal. For geological time-scale processes, intraformational and top seals are typically characterised by their membrane seal capacity and fracture threshold pressure. Fault seals are typically characterised by fault geometry, juxtaposition, membrane seal capacity, and reactivation potential. At the production time scale, subtle variations in the permeability distribution within a reservoir can lead to compartmentalization. These are typically characterised by dynamic reservoir models which assume hydrostatic conditions prior to commencement of production. There are few references in the seals literature concerning the integration of hydrodynamic techniques with the various aspects of seal evaluation. The research for this PhD thesis by published papers includes: Methodology for characterising formation water flow systems in faulted strata at exploration and production time scales; a new theory of hydrodynamics and membrane (capillary) seal capacity; and case study evaluations demonstrating integrated multidisciplinary techniques for the evaluation of seal capacity (fault, intraformational and top seal) that demonstrate the new theory in practice. By incorporating hydrodynamic processes in the evaluation of total seal capacity, the evidence shows that existing shale gouge ratio – across fault pressure difference (SGR-AFPD) calibration plots need adjustment resulting in the calibration envelopes shifting to the centre of the plot.This adjustment sharpens the predictive capacity for membrane seal analysis in the pre-drill scenario. This PhD thesis presents the background and rationale for the thesis topic, presents each published paper to be included as part of the thesis and its contribution to the body of work addressing the thesis topic, and presents related published papers that are not included in the thesis but which support the body of published work on the thesis topic. The result of the thesis is a new theory and approach to characterising membrane seal capacity for the total seal thickness, and has implications for an adjusted SGR-AFPD calibration to be applied in pre-drill evaluations of seal capacity. A large portion of the resources and data required to conduct the research were made available by CSIRO and its associated project sponsors including the CO2CRC

Economic Synergies from Tighter Agri-Business and Coal Seam Gas Integration

In addition to government royalties, Australia’s coal seam gas (CSG) development has been beneficial in terms of facilitating regional economic development and growth, expansion of remote populations and facilities, increased employment opportunities and improved regional infrastructure, mainly in regional Queensland. There is substantial revenue potential for the Australian economy from the export of the resource to international energy markets. Many current CSG operations in Australia are located in prime agricultural-cattle grazing regions. Failure to identify potential coexistence opportunities between agribusiness promoting industries (API’s) and the CSG industry could limit the agriculture value chain and consequently restrict Australia’s food security and agricultural export potential. The economic benefits of the CSG industry combined with the importance of a sustained agricultural industry lay the foundation for investigating coexistence opportunities between these industries. Emphasis has been placed on potential synergies exhibited by the CSG industry (namely from CSG by-products) and the local agricultural industry which is typically dominated by API’s

A live test of automated facies prediction at wells for CO(2) storage projects

At least 900 m of image log data have been interpreted in detail through the Late Cretaceous and Cenozoic succession intersected at two purpose-drilled injection wells of the CO2CRC Otway Project. Interpretations have been calibrated against core observations where possible. Natural clusters for the combined signature of a common suite of coincident well log data were determined using an unsupervised Naive Bayesian classification algorithm called Autoclass. A deterministic relationship between these modelled clusters and interpreted image log facies provides a two-step facies prediction algorithm that can be applied using well log data acquired at other wells intersecting sedimentary successions prospective for CO2 storage. Earlier this year the Division of Resources & Energy, Department of Trade & Investment, of the Australian state of New South Wales drilled a new stratigraphic test well within the Pondie Range Trough of the Darling Basin. The new well, Mena Murtee-1, was drilled close to a 2D seismic tie line linking the Pondie Range Trough depocenter with an old petroleum exploration well, Pondie Range-1, that is sited on a flanking high. Analyses and interpretation of data acquired at Mena Murtee-1 is the latest step in reducing the uncertainty surrounding CO2 storage potential within the Darling Basin. Interpretation of core and image log data acquired at the new well has provided a means by which to test facies predictions made on the basis of the models developed within the Otway Basin.Mark Bunc

Fractionation processes of δ13C in a soil-shallow groundwater system of a potential CO2 sequestration site: Wandoan, QLD, Australia

Near-surface leakage detection is often a crucial part of verifying the success of CO sequestration projects, and it cannot be achieved without a detailed description of the natural state of an operational site prior to injection. Without baseline studies, it is difficult to define CO anomalies outside natural variation in the subsurface that may be related to leakage. CO concentrations and δC-CO values (of DIC, dissolved gas, and soil gas) were investigated to establish a baseline modelling of natural chemical processes leading to CO occurrence and δC-CO fractionation in the soil-groundwater interface on an example at the Glenhaven site in Queensland, Australia. This was analysed within the context of the hydrogeology and hydrogeochemistry of a shallow aquifer system

Coexistence Opportunities for Coal Seam Gas and Agribusiness

Australia's prospects to become a key energy exporter in the Asia-Pacific region has driven rapid development and expansion of its coal seam gas (CSG) industry, particularly in regional Queensland, Australia. The vast majority of Australia's current CSG developments and reserves are situated in agriculture-rich, cattle-grazing regions; therefore, it is critical to identify symbiotic relationships between agri-based industries and the CSG industry to achieve beneficial coexistence. The CSG industry has generated infrastructure such as gas and water pipelines, water storage and treatment facilities, transportation and electricity networks, and other CSG-associated services (e.g., accommodation, education, and medical facilities), which have the potential to improve regional communities and facilitate economic growth. This article aims to investigate these coexistence opportunities, including the use of by-products (mainly water produced during CSG extraction), infrastructure, and services generated from the CSG industry, which can provide value to the local industries. Focusing on the cattle value chain, the authors suggest an agri-based industrial coexistence model that indicates material-water flows and optimized utilization of infrastructure that not only promote coexistence between the agribusiness and CSG industries, but expand the cattle value-chain productivity in rural Queensland. A water balance has been conducted around the suggested coexistence model with the aim of quantifying water flows, to indicate the supply versus demand scenario associated with CSG-sourced water production. The results of the water balance indicate that CSG water supply has the potential to meet the requirements of agribusiness promoting industries