Carbon capture and storage (CCS) is a key technology to mitigate the environmental impact of carbon dioxide (CO2) emissions. An understanding of the potential trapping and storage mechanisms is required to provide confidence in safe and secure CO2 geological sequestration1,2. Depleted hydrocarbon reservoirs have substantial CO2 storage potential1,3, and numerous hydrocarbon reservoirs have undergone CO2 injection as a means of enhanced oil recovery (CO2-EOR), providing an opportunity to evaluate the (bio)geochemical behaviour of injected carbon. Here we present noble gas, stable isotope, clumped isotope and gene-sequencing analyses from a CO2-EOR project in the Olla Field (Louisiana, USA). We show that microbial methanogenesis converted as much as 13–19% of the injected CO2 to methane (CH4) and up to an additional 74% of CO2 was dissolved in the groundwater. We calculate an in situ microbial methanogenesis rate from within a natural system of 73–109 millimoles of CH4 per cubic metre (standard temperature and pressure) per year for the Olla Field. Similar geochemical trends in both injected and natural CO2 fields suggest that microbial methanogenesis may be an important subsurface sink of CO2 globally. For CO2 sequestration sites within the environmental window for microbial methanogenesis, conversion to CH4 should be considered in site selection.

Prison populations have been identified as having elevated levels of problem gambling prevalence, and screening for problem gambling may provide an opportunity to identify and address a behaviour that may otherwise lead to re-offending. A problem gambling screen for this purpose would need to be brief, simple to score, and be able to be administered, with limited training, by prison assessors. The Eight Screen was developed as a brief tool for Family Doctors to use in a patient population, but has also been used effectively in more generalised populations. In this study 100 inmates received into a medium security prison were screened using the Eight screen and the South Oaks Gambling Screen (SOGS), with those scoring three or more on either screen then being assessed by a specialist clinician using DSM-IV Pathological Gambling Disorder criteria. Twenty-nine inmates were screen positives who also correlated highly with assessed gambling pathology.The Eight Screen appears to be a suitable gambling screen for prison use and has since been adopted as an assessment instrument by the New Zealand Department of Corrections.

The original Gannet Project comprising five hydrocarbon accumulations in the Central area of the North Sea was under development at the time of the 1986 oil price collapse, at which point it was cancelled. Following redesign and stringent cost reduction, based on a simplified facilities concept, Kittiwake, the most productive and least complex of the five fields, was reinstated as a stand-alone development and is now operational. Adopting similar design strategies three of the remaining four original Gannet fields together with a further discovery made in 1987 are now being developed, central on Gannet A platform in a water depth of 95 metres with subsea satellites at Gannet B, Gannet C and Gannet D. The development of these four fields is for recoverable reserves of 170MM bbl of oil and condensate and substantial gas reserves of 704 BCF. First hydrocarbon deliveries are scheduled for October 1992. In addition to the extensive use of subsea development, other strategies were adopted to minimise capital expenditure and operating costs. These included:-(available in full paper) By end 1991 the Gannet A jacket and 330km ofsubsea pipelines were installed, and development drilling had commenced. Construction activities for the integrated deck are on schedule for installation in second quarter 1992. The cluster approach and stringent cost control has facilitated the economic development of the field under the UK tax regime at oil price scenarios at the lower end of expectations. BACKGROUND The original Gannet Project comprising five hydrocarbon accumulations in the Central Area of the North Sea (CNS) was under development at thetime of the 1986 oil price collapse, at which point the project was cancelled. A North Sea situation Map of the UK is provided in Fig. 1 and a more detailed Field Location Map of the CNS in Fig.2. At this time the Gannet development consisted of 5 fields -3 Gannet fields, Kittiwake and Guillemot. The plans were based on cluster development with standalone, modular installations provided with steel jackets and self-sufficient drilling modules, but including one subsea gas development with 4 wells. After the 1986 oil price collapse the introduction of new concepts was critical for economic viability. Kittiwake, the most productive and least complex ofthe five fields and the furthest away from the other fields was developed separately as a stand alone project utilising the concepts of an integrated deck and single lift installations of the jacket and topsides. For the development of the remaining fields to be commercially viable it was essential to find more cost effective engineering solutions for the extraction, processing, and evacuation of the reserves. It was also necessary to avoid reservoirs with too diverse recovery mechanisms and to ensure that each reservoir was justified on an incremental basis. Extensive reviews led to the decision not to include accumulations at Guillemot, the only reservoir needing water-injection. This led to thepreparation of development plans for Gannet A, B, C and a new discovery made in 1987, Gannet D.