Chevron (Australia)

Abstract Around the world many projects are being considered for the geological storage of CO2 in large saline aquifers. The aerial extent of pressure and saturation plume forecasts, known as Area of Review (AOR) in the United States, can have a significant impact on the monitoring costs and liabilities associated with existing legacy wells within the vicinity of the carbon storage projects. Appropriately modeling how aquifer systems react to large scale CO2 injection has relevance to potential geomechanical integrity, fault reactivation, seismicity, and impact on underground sources of drinking water (USDW). Static and dynamic models are generally built over a smaller portion of large saline aquifer system. This is typically tied to the balance between model size, fidelity, and computational expenses. Assigning the appropriate boundary conditions to replicate the true extent of the aquifer is investigated in this study. Scoping the aquifer's size, geology, and properties is an important step that allows for the quantification of the appropriate pore volume beyond the area of the numerical model. Results from our study indicate that using pore volume (PV) multipliers is a reasonable approach if accompanied by transmissibility reduction at the interface between the PV modifications and the reservoir model. A simple model was developed to create the true solution for comparison and verification purposes. Based on the results of this study, we find that using a combination of PV and transmissibility multipliers replicates the true solution more accurately. We demonstrate that large PV adjustments without transmissibility reductions overestimates the true aquifer strength, resulting in overall lower pressures due to large-scale CO2 injection. We demonstrate a systematic methodology for calculating the simultaneous PV increase and transmissibility reduction that scales easily for a wide range of scenarios. Further investigation shows that as the PV multiplier grows large, the approach of reducing the transmissibility with a single multiplier starts to choke off the large added pore volume. This study proposes an innovative approach which demonstrates that applying a gradually increasing PV multiplier combined with gradually reducing transmissibility is a more accurate representation of the true aquifer system when compared to a single large PV multiplier and a single transmissibility reduction. The proposed approach was applied to large 3-D models and significant impact was observed in pressure diffusion front shape and extent when compared to more simplified approaches. Assignment of boundary conditions for a variety of different scenarios were also investigated in this study. It was shown that this novel approach will be the most accurate method of applying appropriate boundary conditions in obtaining reliable AOR forecasts when modeling large aquifer systems for CO2 storage projects.

The Australian government has recently legislated a 43% emissions reduction target for 2030 to drive net zero ambitions for 2050. The government plans for carbon capture and storage (CCS) to play a significant role in achieving this through greenhouse gas storage licence rounds. Rapid screening of Australia’s carbon storage opportunities is necessary to position future acreage release and ultimately identify and mature carbon storage sites. An industry collaboration between Geoscience Australia and SLB has conducted a basin-scale carbon storage assessment project for the Barrow and Dampier sub-basins. The project has built and modernised a subsurface database fit for CCS screening. The dataset was used as the foundation to create a carbon storage opportunity portfolio and storage resource assessment for the area. The project has three major streams: (1) CCS-focussed reprocessing, depth imaging and merging of 29 legacy seismic surveys covering 26,150 km2 – focussed on detailed image resolution for containment analysis. (2) A basin-wide audit of 1620 wells and databasing of available log data, 129 wells were carried through for petrophysical and rock physics analysis relevant to CCS. (3) A portfolio of carbon storage opportunities and associated capacity assessment for the Barrow–Dampier including saline aquifers and depleted fields ranked on storage capacity, reservoir and seal properties and integrity. The results of this study will be released via the National Offshore Petroleum Information Management System as a public resource to expedite CCS implementation for the region.

The number of decommissioned oil and gas platforms will increase over the coming decades. In the tropics and sub-tropics, platforms may operate near biodiverse natural habitats, such as coral reefs. Abundant and diverse fish communities often aggregate around platforms, with different decommissioning options posing variable ecological effects on these assemblages. One decommissioning option is to repurpose platforms into artificial reefs, a process commonly termed “Rigs-To-Reefs” (RTRs). Many RTR programs attempt to retain or enhance habitat availability and associated fish assemblages. To help demonstrate the importance of RTR projects, the fish habitat value of RTRs can be estimated by comparing the fish communities of RTRs to those of adjacent natural habitats. Surveying fish habitats in turbid waters necessitates the use of methods that can quantify the abundance, biomass, and length of fishes irrespective of visibility. Using an imaging sonar (1.2. MHz) and implementing a novel, pixel-based approach analogous to echo-integration, this study estimated the relative biomass density and length distribution of fishes at seven toppled oil and gas platform jackets in a Reefed Jacket Zone (RJZ) in the nearshore western Gulf of Thailand in comparison with a nearby coral reef. Biomass density was comparable at each habitat, despite extreme variability across the RJZ, attributed to the spatiotemporal stochasticity of larger, schooling fishes. However, fishes were larger at the RJZ, a trend supported by simultaneous stereo-video footage. The relative benefits and drawbacks of imaging sonar encountered in this study are also described.

Abstract The Jansz-Io field is part of the ‘Greater Gorgon’ project, situated approximately 120km offshore the northwest coast in the Northern Carnarvon Basin offshore Western Australia. This study presents a two-part workflow for determining petrophysical and grain-size related properties of the late Jurassic Jansz Sandstone in the Jansz-Io Field. This field contains highly variable clays and cements distributed both vertically and spatially due to bioturbation and diagenetic processes. The relationship between saturation and pore structure, important for reservoir evaluation and modeling, is not well understood. The objective of the study is to use class-based machine learning (CbML) and nuclear magnetic resonance (NMR) pore-to-production workflows to improve the understanding of the reservoir properties. This will also reduce uncertainty in gas initially in place (GIIP) and estimated ultimate recovery (EUR) during static and dynamic modeling workflows. The first part of the workflow involves applying CbML to determine petrophysical properties. CbML was used to classify well logs into facies based on rock types. The resulting classification was used to determine core-calibrated continuous petrophysical properties in all wells. In the second part, novel NMR pore-to-production workflows were used to determine grainsize related properties. NMR data from 19 wells were normalized against different acquisition technologies, vendors, and conveyances using factor analysis and fluid substitution methods, to determine textural facies, effective porosity/water saturation, and grain-size distribution across the field. The workflow comprising CbML and NMR pore-to-production methodologies shows how AI/ML can assist alongside conventional workflows to maximize the return on investment of measurement acquisition. The results show that the fluidsubstituted NMR distribution and grain-size distribution by textural facies is integral to understanding the relationship between permeability, porosity, water saturation, and grain size. Insights from this study are being used to update the geological deposition model to reduce uncertainty in GIIP and EUR during static and dynamic modeling workflows. The integrated workflow enables the determination of continuous core-calibrated properties required for not only petrophysical evaluation but also for geological and reservoir modeling to optimize completions and production. The significance of the study lies in its ability to improve the understanding of reservoir properties and reduce uncertainty in GIIP and EUR, leading to more accurate reservoir modeling and optimized production. The novelty of the study lies in the combination of CbML and NMR pore-to-production methodologies to determine petrophysical and grain-size related properties of the Jansz-Io Field.

Presented on Wednesday 17 May: Session 13 The oil and gas industry will play a significant role as the world works to achieve its climate change goals. A lower carbon future will require partnership and collaboration across supply chains because no one company, industry, or nation – acting alone – can meet the world’s energy and climate goals. For 70 years, Chevron Australia has played an important role in delivering oil, natural gas, and other products to power human progress. As the world’s energy demand continues to grow, we aim to grow our traditional energy business, which will continue to be a significant source of greenhouse gas emissions. To help advance a lower carbon future, we are striving to reduce the carbon emissions intensity of our traditional operations and seeking to grow lower carbon businesses; while continuing to deliver the reliable, affordable energy the world needs. This paper will share the strategies and efforts underway to reduce the carbon intensity of Chevron Australia’s upstream assets by enabling the supply chains that support our business. To access the Oral Presentation click the link on the right. To read the full paper click here

Presented on Wednesday 17 May: Session 12 Engineering and Safety Culture are intrinsically linked. In the late-life asset world we are confronted with reduced resilience to MAEs, long history of changes to the assets, loss of corporate knowledge as our people turn over and life extension in line with ISO19900. Having a safety culture that acknowledges process safety in engineering is important and challenging. The continuous state of unease that process safety engenders in our people is often seen in higher-risk activities such as construction and drilling operations, and it is our experience that there are common leading indicators that late life operations and decommissioning teams share with projects and drilling and completions (D&C). This work examines the performance of leading indicators in safety culture during late-life asset operations and correlates them with both the development and discrete project life cycle. We also investigate some of the root causes behind the incidents and events that have emerged in late-life assets with often surprising results. Navigating the objectives-based regulatory framework within the Australian oil and gas industry requires a dynamic and collaborative approach, this paper provides a high-level outline of the decommissioning planning process in line with a standardised decommissioning management system. This paper also discusses the learnings from these operations on the effectiveness of the safety culture framework and the International Oil & Gas Producers (IOGP) lifesaving rules in the pre-decommissioning phase. To access the Oral Presentation click the link on the right. To read the full paper click here

The base case for decommissioning of oil and gas infrastructure under Australian laws and regulations is the full removal. However, alternative options may be considered, provided equal or better environmental, safety and well-integrity outcomes compared to complete removal can be demonstrated. In order to evaluate in-situ retention options, the composition of materials, including any contaminants, must be fully understood, along with degradation timeframes and exposure pathways to the marine environment. In this paper, we articulate measurable parameters for the evaluation of pipeline materials including their composition chemistry, material degradation products and their properties, environmental toxicity, and potential interaction of infrastructure components with seawater and ecological receptors. In the absence of measured data from the degradation of pipeline materials over time, theoretical modelling is an essential tool to evaluate the transportation, distribution, and fate of materials such as plastic particles from pipeline coatings. Most of the components present in oil and gas pipelines, when degraded, are either soluble in water or if insoluble, accumulate locally in the sediment. However, the accumulated components will be rapidly dissipated by the wave currents around the pipeline and physical movements within the sediments, which will prevent the chemicals from accumulating to concentrations that could cause toxicity.

Poster B4 Environmental genomics is a rapidly advancing field that promises to revolutionise the way in which industry conducts biodiversity monitoring. The International Association of Oil and Gas Producers Environmental Genomics Joint Industry Program (JIP) was formed in June 2019 with the aim of facilitating the development and uptake of environmental genomics within the oil and gas industry. Towards this goal, a white paper was produced that summarises the state‐of‐the‐art in environmental genomics research, and the opportunities and limitations of applying environmental genomics within industry. The white paper included a comprehensive literature review, and importantly, involved consultation with professionals from academic, regulatory and industry backgrounds from across the globe that had expertise in environmental genomics applications. While this consultation revealed a consensus that the application of environmental genomics has advanced greatly in a brief period, with demonstrable benefits, there was an acknowledgement that key aspects are still lacking that would allow confident application of genomics approaches within industry. Through the review and consultation process, a range of knowledge gaps and areas requiring further development were identified. To elucidate which of these areas were most critical to the successful application of environmental genomics within industry, the JIP is drafting guidance that describes sampling design considerations, minimum standards for laboratory analyses and approaches to genomics data interpretation. Through the drafting of guidance, the JIP hopes to determine which gaps are most critical, enabling these to be prioritised for targeted research. The guidance will then be updated regularly to capture the latest research outcomes. To access the poster click the link on the right. To read the full paper click here

Environmental genomics is a rapidly advancing field that promises to revolutionise the way in which industry conducts biodiversity monitoring. The International Association of Oil and Gas Producers Environmental Genomics Joint Industry Program (JIP) was formed in June 2019 with the aim of facilitating the development and uptake of environmental genomics within the oil and gas industry. Towards this goal, a white paper was produced that summarises the state-of-the-art in environmental genomics research, and the opportunities and limitations of applying environmental genomics within industry. The white paper included a comprehensive literature review, and importantly, involved consultation with professionals from academic, regulatory and industry backgrounds from across the globe that had expertise in environmental genomics applications. While this consultation revealed a consensus that the application of environmental genomics has advanced greatly in a brief period, with demonstrable benefits, there was an acknowledgement that key aspects are still lacking that would allow confident application of genomics approaches within industry. Through the review and consultation process, a range of knowledge gaps and areas requiring further development were identified. To elucidate which of these areas were most critical to the successful application of environmental genomics within industry, the JIP is drafting guidance that describes sampling design considerations, minimum standards for laboratory analyses and approaches to genomics data interpretation. Through the drafting of guidance, the JIP hopes to determine which gaps are most critical, enabling these to be prioritised for targeted research. The guidance will then be updated regularly to capture the latest research outcomes.