As oil and gas companies extend their presence to remote and ultra-deep waters, one of their main challenges is to maintain environmentally responsible operations while maximizing returns on investment. Attention is directed to the increasing power demand offshore which triggers a quest for alternative and cleaner power supplies. One proposed solution is presented through the conceptual study abbreviated OPera - the Offshore Power system for the new era. OPera consists of a highly efficient power hub and an electrical transmission system, supplying cleaner power to a network of offshore installations. To detail the OPera conceptual study, the Brazilian pre-salt area was selected as a case example. The power hub has a gas fired combined cycle power plant that increases power generation efficiency by more than 15 percent, compared with conventional gas turbines alone. The power generation arrangement reduces CO2 emissions with approximately 40 percent. By consolidating power generation, the power hub also allows equipment to run at more optimal load. This is a major benefit, as it further reduces fuel consumption and overall emissions. The power hub is fueled by associated gas or parts of the export gas produced. The OPera concept is highly flexible in size and configuration, making it relevant for different types of fields. The power plant consists of modular gas and steam units of 50 and 100 megawatt (MW) capacities, allowing the combined capacity to be tailored. Depending on water-depth, different platform and hull-designs can support the power plant. The power hub can connect with different numbers and types of installations, being located in different water depths.

Floating LNG production units are being proposed for a number of applications worldwide. The majority of those being proposed are based on use of a ship-shaped hull and intend to use some technology similar to that used in the LNG shipping industry. This paper will address how far the experience and technology used in shipping applications can be utilised directly in an offshore LNG project and how the gaps are being tackled today. DNV has been involved in many of the ongoing projects looking at technical feasibility and more detailed design of a number of FLNG concepts and has also carried out studies to address some of the key technological gaps identified between existing experience and proposed applications. These issues include limitations on use of traditional LNG containment systems, particularly of the membrane type, considerations of impact of FLNG operational modes on some design details traditional to the shipping industry, some consequences on layout and arrangement to take account of topside hazards, and some consequences of selection of the various liquefaction technologies available. This paper will address :Gas Ship versus FLNG applicationsCurrent thinking on Sloshing in membrane tanksDesign for continuous operation offshoreSome key issues and hazards influencing layout and arrangement Introduction The LNG chain requires at one end, facilities for liquefaction of the gas (an export terminal) and at the other end, facilities for regasifying it (a receiving terminal). Traditionally these terminals are located on land. The gas in the form of LNG is transported by ships designed specifically for that purpose (gas carriers). This in itself is well known technology, and a technology which has an extremely good safety record. However the current trend is to locate some of these terminals offshore, a trend which is driven, in some cases, by such factors as unavailability of suitable land sites, problems and delays in permitting, public opposition, and security considerations. In other cases the trend is driven by cost and schedule considerations. Solutions chosen for such offshore terminals may include concepts based on bottom-fixed structures or floating technology. Of the floating solutions the majority of those currently proposed are based on a ship-shaped hull (rather than a barge) and may involve either a purpose-built design or a conversion from an existing ship, typically a gas carrier. While each project would generally like to be considered as unique and adapted specifically to the specific application and location for which it is intended., it is not desirable to purpose-build any installation from first principles without taking account of technology used and experience gained in similar projects. For novel applications there may not be extensive equivalent experience on which to draw, however there will typically be elements of existing projects in related applications which may be utilized. This will be the case for Floating LNG units which will combine technology used in the land-based LNG industry (liquefaction and regasification plant), the offshore oil and gas industry (gas pre-treatment and FPSO design and mooring) and the LNG marine transport industry (ship design and LNG containment system design). A significant challenge for floating offshore LNG terminal design is to determine the relevance and applicability of experience and technology used in related industries. In some cases application of such experience may lead to solutions which are overly conservative, in other cases, to solutions which are not sufficiently conservative. In other cases again, it may be that there are issues which have not been addressed previously at all and which are unique to the offshore LNG application.

Liquefaction of natural gas is moving offshore as an economic means of developing natural gas fields. This trend is currently in the start phase with a number of projects at present under construction and many more at concept and engineering phases. These FLNG projects are being proposed for location in an increasingly larger number of geographical locations, coming under a number of different regulatory jurisdictions. There is currently little engineering experience associated with such FLNG applications and in addition standards and regulation specific to this new technology may lag behind industry developments. Different jurisdictions may also have varying approaches when it comes to means of ensuring safety on their own continental shelf. In addition there remain some technical challenges in applying some of the latest knowledge to ensure more optimal designs. This paper will address the approach adopted by DNV GL in specifying requirements for design and construction of offshore LNG production units and our view on how this approach relates to the bigger picture of regulatory compliance. In addition some key technological areas which DNV-GL see as a safety challenge with regard to such units will be discussed.It is intended to bring together experience gained from a number of projects and present some generic lessons related to the issues of safety and regulatory compliance which may be of use in future FLNG designs.

The International Maritime Organisation (IMO) is setting clear and ambitious goals for the decarbonisation of the shipping industry through the introduction of new regulations like the Energy Efficiency Design Index (EEDI), Energy Efficiency Existing Ship Index (EEXI) and Carbon Intensity Indicator (CII). However, these new regulations do not cover mobile offshore units like the Floating Production Storage and Offloading (FPSO) units that fall under the same maritime regime. To embrace sustainability in their corporate strategies and improve their public image, it is in the interest of existing oil and gas companies and operators to embark on a program of abating Greenhouse Gas (GHG) emissions through careful measurement and analysis. This paper is aimed at providing an overview of the typical FPSO’s GHG emissions that originates from sources such as power generation, flaring, leakages and tank venting. The paper goes in-depth concerning some potential abatement measures that can be taken to reduce such emissions. This is followed by a case study of an FPSO assessed for the voluntary DNV class notation, Abate, to discuss how a competent third-party like DNV can play a significant role in helping offshore oil and gas companies demonstrate and achieve abatement in GHG emissions from their assets.

A number of floating offshore gas terminals are currently in development, a number of FSRUs have been installed and it is expected that the first LNG FPSOs will be entering detailed design phase and construction in the near future. Based on our experience within the gas industry and various conceptual assessments, DNV has produced a Guidance on key issues to be addressed in such projects. The Guidance addresses design issues, including selection of containment system, structural analysis of Floating Offshore LNG Terminal hulls as well as construction and testing issues. The DNV Offshore Technical Guidance, OTG-02 " Floating Liquefied Gas Terminals??, an overview of which is presented in this paper, represents latest DNV and industry lessons on tackling design and construction issues for floating terminals. This paper will only address a selected number of topics from the DNV Offshore Technical Guidance, namely:Background for the GuidanceStructural designSide by Side AnalysisArrangement and LayoutRisk Assessment issuesIntegrated control systemsInspection of Containment SystemsValidity of Codes and Regulations The DNV Offshore Guidance itself additionally addresses issues such as :Conversion of gas shipsSloshing assessmentFatigue assessmentCorrosion issuesRegasification and liquefaction plantClassification and regulatory complianceAssessment of novel conceptsQualification of technology Introduction There are a number of options available for design of gas receiving and exporting terminals. Traditionally these have been built on land according to codes and standards, such as NFPA 59A, which have been specifically developed to address design and constructions issues of terminals to be built on relatively spacious sites but which may be in some proximity to the civil population on. These codes therefore include requirements and assumptions based on such arrangements. Building such installations offshore, or close to shore, poses different challenges, for which at present, there is little relevant experience.