Rationale and Aims: Carbon capture and storage (CCS) is one of the mitigation strategies with the greatest potential to reduce global CO2 emissions this century. The UK is well placed to implement this technology because of its existing oil and gas infrastructure, and its wealth of geologically suitable storage sites. A draft EU directive on CCS sets out strict conditions for potential storage sites regarding environmental impact assessment and monitoring requirements. However, at present, there is no internationally agreed protocol to quantify the risk that once emplaced, the CO2 will leak back to the surface or pollute groundwater resources. One major obstacle to such a protocol being agreed is the limited understanding of leakage mechanisms that might occur within the sealing sequences located above the storage reservoir. By analogy, similar mechanisms that are classically invoked for leakage from oil and gas accumulations might also be expected to apply to CO2 leakage. These comprise two end members: membrane or capillary leakage and hydraulic leakage. In addition, it has recently been recognised that the sealing sequences above a reservoir might be compromised by seal bypass systems that allow large fluid fluxes to bypass the pore or fracture networks. Identification of such bypass systems is thus a key requirement for any seal risking protocol, along with physical property characterisation of the sealing lithologies themselves. Bypass systems can be identified above any potential storage sites using 3D seismic data, but are limited by the spatial resolution of the seismic method. One possible novel approach to the identification of seal bypass, is by identification of seismic amplitude anomalies that can be shown to be associated with methane in the pore space of layers within the sealing sequence. By defining the spatial distribution of these methane anomalies, it would be possible to model the likeliest flow routes taking the methane through the seal, and hence define the leakage pathways for the vertically migrating methane. In this way, the spatial analysis of methane anomalies could act as a tracer for potential CO2 leakage, and so help define the risk of leakage. The aims of this PhD research are to develop workflows and methodologies of using 3D seismic data to track potential leakage routes of CO2 through likely sealing lithologies. The main thrust of this research will be to quantify the leakage flux of methane via contrasting leakage routes to yield a relative risk-based ranking of bypass systems and other leakage mechanisms for a range of potential storage sites. The hypothesis to be tested is that seal bypass systems can be uniquely identified by their impact on methane leakage. By placing this geospatial analysis of the leakage pathways in a context of the geological history, standard risk analysis techniques used by the petroleum industry can then be applied to risk of seal failure and leakage for CO2. The development of a workflow for evidence-based risk analysis of seal failure will be generic, and should ultimately be applied more widely to the global problem of assessing the viability of CO2 storage sites. The primary method will be 3D seismic interpretation and geospatial analysis of seal bypass systems and methane-related seismic anomalies above potential CO2 storage sites. Workstation interpretation and visualisation facilities in the Royal Society/Wolfson Laboratory for CCS in Cardiff and in Statoil's CCS Research Laboratory in Trondheim will be available. Methane-related seismic anomalies will be identified through rock physics modelling (Hampson-Russell) and wireline log calibration in petroleum boreholes using standard petrophysical interpretation software in Trondheim (TerraLog). The project will mainly exploit Statoil's comprehensive seismic/well database in the North Sea, one of the primary targets for shallow CCS in Europe, and where Statoil has pioneered CCS in the Sleipner Project.

The proposed research concerns the description of extreme free-surface flows with applications in both deep water offshore and the shallow water coastal locations. The work will involve the development of a new numerical model appropriate to the description of large surface water waves and their interaction with both fixed structures and floating vessels. The key feature linking these flows will be the occurrence of wave breaking; involving the break-up of the water surface, the entrainment of air and the rapid development of areas of highly turbulent flow. From a practical perspective such flows are extremely important because they are associated with the highest (limiting) water surface elevations, the largest water particle velocities and the maximum applied fluid loads. As a result, they are directly relevant to the design of all manner of marine structures and vessels.In order to simulate such flows, and in so doing provide improved physical understanding, the new numerical model will combine the advantages of two very different modelling procedures: a Boundary Element Method applied before the onset of wave breaking and Smooth Particle Hydrodynamics applied to the breaking and post-breaking fluid flow. By combining these procedures the proposed method will seek to create a robust and accurate model capable of describing a wide range of free-surface flows; particular attention being paid to those aspects of wave-structure and wave-vessel interactions that are critical for design and cannot be described by existing solution procedures.The model predictions will be validated against new laboratory observations. This will involve the use of scaled physical model tests and will consider a wide range of practically important fluid flows including:(i) Breaking waves, including both large-scale over-turning and spilling waves;(ii) Highly nonlinear effects in wave-structure interaction, including high-frequency wave scattering, vertical jetting where fluid is projected upwards to very high elevations creating wave-in-deck loads, and wave slamming on both vertical columns and the deck structure;(iii) Wave-vessel interactions, particularly the occurrence of green water inundation and large impact forces.In tackling these problems, the combined experimental and numerical studies will seek to provide new physical understanding of when and why these events occur, to assess their practical implications and to identify how they can best be modelled in engineering practice.The proposed work is relevant to a wide range of problems in fluid mechanics, with particular application to the effective design and safe operation of marine structures. Direct support from three key industrial practitioners is incorporated within the proposal. The project will also be relevant to the renewable energy industry. With interest in locating offshore wind farms in areas of high wind and therefore large wave activity, such structures are very susceptible to large-scale wave breaking and the associated impact forces. The shipping industry will also benefit from this project: the new model providing information to improve the design and/or safe operation of vessels to both increase survivability and, in the case of oil tankers, limit the potential for large-scale environmental impact and damage. Finally, the work also has a truly multi-disciplinary contribution, beyond the coastal/offshore/navel architecture boundaries, in the sense that the break-up of the water surface (specifically the entrainment of air) has implications for air-sea interactions in general, and mass exchange (CO2 absorption) in particular. Such issues are of fundamental importance to oceanographers studying the transfer processes at the ocean surface and contribute a key element to climate change modelling.

Climate change is a global challenge imposed by excessive emission of anthropogenic greenhouse gases to the atmosphere. It is estimated that CO2 is responsible for two-thirds of global challenge. To decelerate this global challenge, several inter-governmental agreements and legislation have been established to reduce the atmospheric CO2 effects (e.g. 2015 Paris agreement, 2019 UK NetZero) through a combination of various technological, societal and industrial actions. One of the key pathways to reduce CO2 atmospheric emission is carbon capture and storage (CCS). In CCS, CO2 is captured from anthropogenic sources and is injected into deep saline aquifers, depleted oil and gas reservoirs or other geological traps. Deep saline aquifers play an important role as their capacity for safe storage of CO2 is two orders of magnitude greater than depleted oil and gas reservoirs. Maintaining injection of CO2 into subsurface is a critical part determining the success of any CCS project, however, this is not always straightforward. Former studies show that with injection of dry super-critical CO2 in saline and hypersaline aquifers, salt forms in porous space and permeability decreases, leading to injectivity loss. Given this challenge it is essential to develop fundamental knowledge and a predictive model to establish know-how of injectivity loss under different thermodynamic conditions (pressure and temperature), hydrodynamic conditions (injection rate), and rock heterogeneity conditions, referred to as THR hereafter. The PINCH project aims to establish fundamental science to develop a novel predictive model and apply it to real field data supported by industries. PINCH brings together scientists from University of Manchester, Durham University, Princeton University, BP, Equinor, Shell to deliver project aims in five work packages (WP). WP1 addresses fundamental questions at pore scale to delineate impacts of THR conditions on salt formation and its aggregation regime under high-pressure high-temperature (HPHT) conditions. HPHT optical visualisation of micromodels and HPHT synchrotron-based X-ray imaging of micro-core flooding will be used to visualise the real-time change of pore morphology under different conditions. WP1 will deliver unique and valuable four-dimensional data sets to establish fundamental knowledge and to support WP3 data requirements. WP2 addresses similar research questions as WP1 in real rock materials at a larger physical scale (core). BGS will facilitate access to the rock materials required. Additionally, pressure injectivity and rock mechanical properties will be measured under different THR conditions. We will address the knowledge gaps in the role of these factors on the injectivity loss. This will assist development of predictive modelling as envisaged in WP3. WP3 is the core of PINCH project as a novel multiscale modelling approach is proposed. Pore-scale modelling will be developed to capture multiphase flow, phase change, salt formation. The model will be validated against the observations in WP1. Also a continuum-scale model will be developed which will incorporate the pore-scale modelling for parameterisation. The model will be validated against the experiments in WP2. WP4 will deliver a high-impact research all fundamental science established in WP1 and WP2 and the engineering tools developed in WP3 will be employed to address real-life laboratorial and field-scale challenge related to the injection of supercritical CO2 in hypersaline aquifers and subsequent injectivity loss. Three candidate CCS fields are Endurance, Quest and Snohvit. BP, Equinor, Shell will provide very strong in-kind contribution to PINCH by providing required data from the aforementioned fields and technical advise. To guarantee the impact of PINCH project, WP5 has been envisaged which covers impact generation, knowledge exchange between academia and industry, and training of junior staff.

The year 2011 recorded the highest ever global consumption of energy, estimated at more than 12 billion tonnes of oil equivalent. Because of this, and despite increasingly widespread deployment of renewable energy generation, annual global emissions of greenhouse gases are continuing to rise, underpinned by increasing consumption of fossil fuels. Carbon capture and storage (CCS) is currently the only available technology that can significantly reduce CO2 emissions to the atmosphere from fossil fuel power stations and other industrial facilities such as oil refineries, steel works, cement factories and chemical plants. However, achieving meaningful emissions reduction requires wide deployment of large scale CCS and will involve long term storage of very large volumes of CO2 in the subsurface. Ultimately, if CCS were to be rolled out globally, volumes of injected carbon dioxide could become comparable, on an annual basis, to world hydrocarbon production. The most likely sites for CO2 storage are depleted oil and gas fields or saline aquifers. Understanding and monitoring geomechanical processes within different types of storage site is crucial for site selection, for achieving long term security of storage and for instilling wider confidence in the safety and effectiveness of CCS. In many cases depleted hydrocarbon fields have experienced strong pressure decrease during production which may have affected the integrity of the caprock seal; furthermore, CO2 injection into saline aquifers will displace large volumes of groundwater (brine). In all cases, as injection proceeds and reservoir pressures increase, maintaining the geomechanical stability of the storage reservoir will be of great importance. Understanding and managing these subsurface processes is key to minimising any risk that CO2 storage could result in unexpected effects such as induced earthquakes or damage to caprock seal integrity. Experience from existing large-scale CO2 injection sites shows that monitoring tools such as time-lapse 3D seismic, micro-seismic monitoring and satellite interferometry have the potential to make a significant contribution to our understanding of reservoir processes, including fine-scale flow of CO2, fluid pressure changes, induced seismic activity and ground displacements. The DiSECCS project will bring together monitoring datasets from the world's three industrial scale CO2 storage sites at Sleipner (offshore Norway), Snohvit (offshore Norway) and In Salah (Algeria) to develop and test advanced and innovative monitoring tools and methods for the measurement and characterisation of pressure increase, CO2 migration and fluid saturation changes and geomechanical response. A key element of the research will be to identify those storage reservoir types that will be suitable for large-scale CO2 storage without unwanted geomechanical effects, and to develop monitoring tools and strategies to ensure safe and effective storage site performance. In addition, our research will explore public attitudes to CO2 storage. We will consider what insights may be drawn from previous proposed CCS schemes involving onshore storage and other activities that have aroused similar concerns (such as earthquakes associated with shale gas fracking near to Blackpool) and how this experience can inform proposed large-scale offshore storage operations in the future. In the past, public opposition to some onshore storage proposals has led to project delays and cancellation, for example, in the Netherlands, Denmark and Germany, and research has identified storage as the stage in the CCS chain that has most potential for concern to members of the lay public. Developing an improved understanding of potential societal responses to CO2 storage and monitoring is crucial for establishing a sustainable and successful CCS strategy; this research will contribute to this through a combination of case study analysis and participatory research with lay citizens.

Hydrocarbons and their derivative products are central to today's society. We know that the source of hydrocarbons are products of buried ancient plants and animals. Less clear, and question that petroleum geoscientists both academic and industrial are challenged with, is establishing the time that hydrocarbons, such as oil, form and how they are trapped in petroleum systems large enough to be exploited. To address this question of the origin and time of formation of hydrocarbons, the naturally occurring isotopic clock of 187Rhenium-187Osmium present in oil is utilized. This ability to directly date oil and not rely on multi-component models are important because petroleum explorers, need to know the origin of hydrocarbons in a sedimentary basin to constrain where they might be able to accumulate, or whether they are able to accumulate at all. With oil exploration drillholes costing multiple millions of dollars, every piece of data informing site location is of immense worth. Whilst the potential utility of the Rhenium-Osmium system to petroleum systems is now proven, its wide scale application and routine development by industry during exploration is still very much in its infancy. Thus, engagement with industry is needed to develop a portfolio of asset-based case studies needed to improve the understanding of Rhenium-Osmium systematics and assess the general applicability of the method to hydrocarbon-bearing basins worldwide. Work related to Objective (a) (see Objectives section above) will be to create a multi-company (BP, Total, Statoil, ConocoPhillips, Chevron, Shell, Chemostrat) Re-Os Advisory Board (ROAB) with two main purposes (as noted above). Work related to Objective (b) will involve ROAB members to become a strategic partner based on established relationships with companies already engaging in the use of Re-Os; and companies with shared interest in the application of Re-Os system above and beyond its current use. All of the founding ROAB members have global expertise in petroleum exploration and thus compliment, support and develop the PI and Co-I research capabilities establishing a strong-integrated research team, e.g., traditional industrial applied techniques (basin modeling, organic geochemistry) with novel Re-Os geochemistry and fracture network models. Work related to objective (c) includes a 2 workshop hosted by the PIs at Durham which will include a summary of the current knowledge base and will be followed by a think tank session on how the Rhenium-Osmium system can be better understood and developed for the end-user. An Impact Case Study will be developed with the help of a science writer in the Durham University Media Office.