Growing interest in the commercialization of stranded offshore gas fields coupled with industry forecasts indicating that worldwide demand for natural gas will increase is leading to significant interest in the development of offshore liquefied natural gas (LNG) production plants or floating LNG (FLNG). Offshore LNG production is an emerging technology; therefore, there is a lack of in-service experience and a need for a sound regulatory framework for safety requirements. This paper will explain the approach that ABS has taken in establishing classification rules for FLNG that are contained in two (2) new ABS Guides for FLNG concepts. As an emerging technology, there is an increased need to develop safety regulations to allow investors, regulators and the public to gain confidence in this emerging field. From a classification society perspective, ABS has developed Rules and standards for the design, construction and operational maintenance of gas carriers and the new emerging floating gas transportation concepts such as FLNG, including transfer and storage based on our working experience with various FLNG projects. This paper also identifies tools and software developed by ABS to address novel features and their application to FLNG structures that are significantly larger in size than conventional carriers and have cargo tanks in a two-row configuration that can be extremely difficult to analyze. ABS has provided Approval in Principle (AiP) and Front-End Engineering Design (FEED) approval to designers for various FLNG concepts. Based on experience gained from these projects, ABS has developed safety requirements to class FLNG structures, process and related safety systems that will enhance the overall safety aspect of this novel concept. These safety requirements provided the foundation for two (2) new ABS Guides. This paper identifies the principal safety considerations and hazards that must be assessed and mitigated when developing FLNG concepts. Safety requirements for the hull, cargo storage, transfer, process facility, mooring system and various safety systems will also be discussed. Guidance from ABS was developed with cooperation from the industry and through experience gained by working on various LNG and offshore floating production projects. Introduction With the growing focus on environmental issues and society and government pressure to reduce ‘green house’ gases, there has been increasing focus on natural gas as a cleaner energy source. Over the last ten years ABS has seen increasing focus on natural gas and LNG production by oil and gas producers. Most of this LNG is supplied to the consumers by converting the gas to LNG, transporting it by ship, regasifying the LNG at a terminal and then distributing it to the consumer through a pipeline networks. However, a considerable portion of the world's natural gas reserves fall into the category termed ‘offshore stranded’, where the conventional means of production and transportation is not practical or economical to produce these reserves. As demand for cleaner energy increases, these offshore stranded gas fields look more attractive to energy companies and they have been actively looking for new technologies to provide solutions to commercialize these ‘offshore stranded’ gas fields. This has led to the development of Floating Liquefied Natural Gas (FLNG) plants for the production, storage and transfer of LNG to vessels. At present, FLNG appears to offer the best alternative for the development of stranded gas assets.
In the ongoing process of the offshore industry to improve safety aspects of drilling operations, ABS continues to provide support by developing enhanced safety requirements. This paper addresses the latest research that ABS performed to enhance its understanding of critical safety aspects in drilling operations and subsequent utilization of the results in updating the ABS Guide for the Classification of Drilling Systems (ABS CDS Guide).Several U.S. government regulatory initiatives have been implemented relative to offshore drilling operational safety. Other governmental regulators have also taken a similar approach in assessing their existing regulations with the focus on safety improvements. In parallel, the revised ABS CDS Guide provides updated safety requirements to assist industry to (1) improve overall safety in drilling operations and (2) meet regulatory compliance for the drilling systems.ABS commenced the criteria revision process with a gap-analysis between the existing offshore drilling practices and technology (including deepwater), applicable U.S. and worldwide regulations, recognized industry codes and standards, etc. Additionally, a survey was conducted with manufacturers, operators, and drilling contractors to identify main areas where the safety aspect of drilling operation could be improved. Based on the research and survey, industry's participation was a critical element in the rule making process -it provided insight into various safety issues, concerns in drilling operations and improved understanding between the industry and the regulators or Class society. From this process, ABS was able to develop additional measures to enhance existing criteria for drilling operations, while adopting a holistic approach to the classification process of drilling systems and equipment with consideration to the applicable regulatory initiatives. This paper outlines the currently developing regulatory changes to the U.S. drilling industry that may potentially impact worldwide drilling activities. This paper highlights the new safety requirements from our research and from the U.S. regulatory perspective, including: BOP recertification, maintenance, and testing, API RP 53 rewrite to API Spec 53 for adoption into the U.S. CFR, management of safety and environmental systems of API RP 75, safety case initiatives and the role of third-party certification. This paper discusses the adoption of a performance-based standard for offshore drilling operations in conjunction with the current prescriptive regulatory regime. OTC 22758Through a re-examination of current technology and experience, ABS has updated the ABS MODU Rules and the ABS CDS Guide. This paper focuses on the update of the ABS CDS Guide as is specific to drilling operations. This paper discusses the background of regulatory requirements along with initiatives by ABS, U.S. regulatory bodies and industry code and standards committees to assist the offshore industry in achieving safety enhancements in offshore drilling operations through the updating of ru...
This paper presents an overview of API 17 Technical Report TR12: Consideration of External Pressure in the Design and Pressure Rating of Subsea Equipment, a technical report prepared by a work group under the auspices of the API Subcommittee 17 (API SC17). This subject is of significant interest for current deepwater subsea projects where well shut-in pressures may only be slightly higher than 15K API Rated Working Pressure (RWP), and progressing to 20K API RWP equipment results in significant cost increases and/or delivery delays. At first glance, it seems logical that the high external seawater pressure in deep water (3000 -4500 psi) could offset a significant portion of the internal pressure, keeping the differential pressure acting on the equipment to 15K equivalent, or less. This would allow for a higher well shut-in pressure than the equipment API RWP with consideration to the external hydrostatic pressure. This approach has been taken with 10K equipment on several medium water depth projects in the past (with special qualification testing). However, recent regulatory rulings and technical studies have called this practice into question. There are several technical issues discussed in this paper, some subtle, that must be evaluated and resolved before attempting to use equipment above its API RWP based on the presence of external hydrostatic pressure (from ambient seawater pressure or from the fluid column in risers or flowlines). API 17TR12 contains detailed guidelines on these issues, and proposes methods for evaluation and qualification that should be used when considering the effects of hydrostatic external pressure on API RWP. Early Background InformationAPI Specification 6A -Specification for Wellhead and Christmas Tree Equipment -was initially developed for land wells and offshore platform wells (shallow water), prior to the advent of subsea drilling and production operations in deep water locations, and did not address the special design considerations related to ambient pressure effects present in deep water application. For API 6A equipment, the design basis did not include analysis of external pressure effects from ambient seawater, and specifically excluded fatigue analysis and localized bearing stress evaluation.Additionally, the term "Rated Working Pressure"was defined as the "maximum internal pressure that the equipment is designed to contain and/or control", and consequently, RWP was interpreted to mean the "absolute internal pressure". For surface applications, where external pressure acting on surface equipment is only 14.7 psi, the differential pressure (for design calculations) is essentially equal to internal pressure.
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