Otway Basin technical reports

Technical Report 1 - New porosity and permeability measurements from legacy core

New porosity and permeability measurements have been acquired as part of the Victorian Gas Program (VGP) from selected legacy core samples from key reservoir units in the onshore Otway Basin

Technical Report 2 - New seal capacity measurements from legacy core and cuttings

New seal capacity measurements have been acquired as part of the Victorian Gas Program (VGP) from selected legacy core and cuttings samples taken from known and potential sealing units in the Victorian onshore Otway Basin.

Technical Report 3 - Mineralogical and textural characterisation of sedimentary rock samples

New mineral analysis has been undertaken as part of the Victorian Gas Program (VGP) from selected legacy core and cuttings samples and three surface samples taken from 21 sedimentary geological formations in the Victorian onshore Otway Basin.

Technical Report 4 - New source rock geochemistry from legacy core and cuttings

New organic geochemistry analyses have been undertaken as part of the Victorian Gas Program (VGP) from selected legacy core and cuttings samples taken from carbonaceous and coal-bearing geological units from Victoria's onshore Otway Basin.

Technical Report 5 - New vitrinite reflectance measurements from legacy core and cuttings

New vitrinite reflectance measurements have been acquired from selected legacy core and cuttings samples from proven and potential petroleum source rock formations in the Victorian onshore Otway Basin.

Technical report 6 - Full Spectrum FALCON® airborne gravity and aeromagnetic survey

An airborne gravity, gravity gradiometry and magnetic survey was undertaken as part of the Victorian Gas Program, using CGG's FALCON® airborne data acquisition system. The survey has resulted in the largest airborne gravity dataset ever collected in Victoria.

Technical Report 7 - New palynology results from legacy core and cuttings

A major review of the biostratigraphy (the study of fossils to date rock formations) of the onshore Otway Basin was undertaken as part of the Victorian Gas Program (VGP). The study was conducted in two parts: (1) a palynology study and (2) a study of micropalaeontology. This report details the findings of the palynology component of the study.

Technical Report 8 - New micropalaeontological results from legacy core

A major review of the biostratigraphy (the study of fossils to date rock formations) of the onshore Otway Basin was undertaken as part of the Victorian Gas Program (VGP). The study was conducted in two parts: (1) a palynology study and (2) a study of micropalaeontology. This report details the findings of the micropalaeontology component of the study.

Technical Report 10 - New kerogen kinetics data from legacy rock cuttings, Onshore Otway Basin, Victoria

New kerogen kinetics data have been acquired from selected legacy rock cuttings samples from proven and potential petroleum source rock formations in the Victorian onshore Otway Basin to complement sparse historical kinetic measurements held by the Geological Survey of Victoria.

Technical Report 12 - An elemental chemostratigraphic study, Onshore Otway Basin, Victoria

A major elemental chemostratigraphic study of Victoria's onshore Otway Basin was undertaken as part of the Victorian Gas Program. Elemental chemostratigraphy is the study of rock units whereby chemical compositions are used to distinguish between geological units and to correlate rock packages across geographic locations. This report details the findings of this new and comprehensive study resulting from the elemental analysis of 4319 legacy cuttings samples from 11 wells.

Technical Report 13 - Regional baseline stygofauna survey

A regional baseline stygofauna survey across the onshore Otway Basin was conducted as part of the Victorian Gas Program. The survey sampled 80 bores within the State Observation Bore Network, providing a baseline dataset to assist in identifying subsurface groundwater dependent ecosystems.

Technical Report 15 - Regional atmospheric baseline methane and carbon dioxide measurements

Two atmospheric surveys were conducted, covering 12,000 km of roads, to establish a regional baseline concentration for methane and carbon dioxide and identify primary sources of atmospheric methane in the onshore Otway Basin.

Technical Report 21 - A regional baseline of quality and hydrocarbon occurrence in groundwater Onshore Otway Basin, Victoria

A regional assessment of groundwater chemistry, environmental isotopes, dissolved methane, and hydrocarbon occurrence has been conducted across the Otway Basin as part of the Victorian Gas Program. This baseline study is the most complete deep groundwater chemistry dataset collected in the Otway Basin by the Victorian Government to date, building on existing data and providing a baseline measure of groundwater conditions.

Technical Report 23 - Groundwater sample collection and analytical methods for hydrochemical and dissolved gas analyses Onshore Otway Basin

A regional assessment of groundwater chemistry, environmental isotopes, dissolved methane (CH4), and hydrocarbon occurrence has been conducted across the Otway Basin as part of the Victorian Gas Program. This report presents detailed field sampling and laboratory analysis methods for all groundwater samples collected.

Technical Report 25 - Geochemical interpretations of groundwater processes and methane origin

A regional assessment of groundwater chemistry, environmental isotopes, dissolved methane (CH4), and hydrocarbon occurrence has been conducted across the onshore Otway Basin as part of the Victorian Gas Program. This report presents the chemical analysis of results and interpretations from groundwater samples collected. It is intended to supplement the Otway Basin regional baseline technical report and lend further context to results and interpretations presented within that overview report.

Technical Report 34 - Groundwater impact assessment - conceptual report

A regional groundwater model has been developed to quantify groundwater and surface water impacts in relation to possible onshore conventional gas developments in the Otway Basin.

Technical Report 35 - Regional 3D geological framework model

A new regional 3D geological framework for the onshore and offshore Otway Basin has been built using existing seismic and well data held by the Geological Survey of Victoria. This also included a more detailed 3D model of the Port Campbell Embayment and Shipwreck Trough. This study supersedes previous regional interpretations.

Technical Report 37 - Groundwater impact assessment - Numerical model development and calibration, Onshore Otway Basin, Victoria

As part of the Victorian Gas Program, a South-West Victorian regional groundwater model was developed to quantify groundwater and surface water impacts of potential onshore conventional gas developments. The model was developed in three stages: 1) construction of a conceptual groundwater model; 2) development and calibration of a numerical groundwater model, and 3) application of possible gas development scenarios and potential impacts to existing groundwater conditions. This report is focuses on the second stage.

Technical Report 38  - Groundwater impact assessment - Conventional gas development scenarios

The potential impacts of onshore conventional gas development on groundwater and surface water in the Victorian Otway Basin have been assessed as part of the Victorian Gas Program (VGP). A calibrated regional-scale groundwater model has considered combinations of future onshore conventional gas developments, to simulate the potential impacts that hypothetical development may have on groundwater in the Otway Basin.

Technical Report 39 - Regional velocity modelling and depth conversion

A velocity model was built to convert time surfaces to depth as part of the Otway Basin three-dimensional geological framework model’s development.  This new model will ensure that all available seismic interpretations are depth converted for use in petroleum systems modelling across the study area and over known hydrocarbon accumulations and associated source rocks onshore and offshore.

Technical Report 50 - Resource and land use planning model

A strategic land assessment of the Otway geological basin in the South-West region of Victoria has been undertaken as part of the Victorian Gas Program’s scientific research into the risks, benefits and impacts of onshore conventional gas. This assessment was undertaken to ensure that any potential future onshore conventional gas exploration and development can take the local context into account.

Technical Report 55 - The application of seismic inversion methods to geophysical prospecting in the Port Campbell Embayment Onshore

The Port Campbell Embayment is located in the eastern onshore Otway Basin and is host to gas discoveries in the Waarre Formation. This study uses the multi-fold seismic data from three 3D seismic surveys acquired of the area to first, refine the structural and stratigraphic interpretation across the area, and second, to apply two geophysical inversion methods to identify potential gas accumulations.

Technical Report 56 - Fault and top seal integrity across the Port Campbell Embayment

A study of petroleum systems components (reservoir, seal and source) was undertaken to assess the hydrocarbon prospectivity of the Victorian Otway Basin and to estimate the potential for further onshore and offshore discoveries within Victoria’s jurisdiction. This report investigates the impact of faults on hydrocarbon prospectivity in the Port Campbell Embayment in the onshore Otway Basin. The behaviour of faults over geological time influences the distribution of hydrocarbons in a petroleum system through migration, entrapment and leakage.

Technical Report 57 - Fault and top seal integrity in the Mussel Platform and the nearshore eastern Otway Basin

A study of petroleum systems components (reservoir, seal and source) was undertaken to assess the hydrocarbon prospectivity of the Victorian Otway Basin and to estimate the potential for further onshore and offshore discoveries within Victoria’s jurisdiction. This report investigates the impact of faults on hydrocarbon prospectivity on the Mussel Platform and in the nearshore eastern Otway Basin. The behaviour of faults over geological time influences the distribution of hydrocarbons in a petroleum system through migration, entrapment, and leakage.

Technical Report 58 - Environmental assessment of decommissioned petroleum wells using regional baseline data, Onshore Otway Basin, Victoria

As part of the Victorian Gas Program’s environmental studies. This report presents an assessment of the variation in environmental receptors proximal to decommissioned petroleum wells with the new regional-scale environmental baseline data collected as part of the VGP.

Technical Report 60 - Site scale groundwater impact assessment, Onshore Otway Basin

The potential for environmental impacts in the onshore Otway Basin was assessed at a site scale using groundwater impact modelling as part of the Victorian Gas Program’s environmental studies. Through the modelling, the potential for mixing between aquifers and reservoirs was assessed.