The move of offshore oil and gas development into deepwater has required that the mooring systems for floating drilling and production platforms/vessels shift from catenary mooring systems to taut-leg mooring systems, requiring the need for a low cost deepwater anchor that can withstand major uplift mooring forces and be designed and easily installed to the design penetration with a high degree of reliability.Many deepwater anchor concepts have been proposed to meet the above requirements in recent years. The four most widely known concepts are discussed in this paper to represent the entire range of concepts in terms of operating principles. The selected anchor concepts discussed herein include two relatively proven anchor concepts, the suction caisson and the vertical loaded (drag embedment plate) anchor (VLA), and two developmental anchor concepts, the SEPLA (Suction Embedded Plate Anchor) and the Torpedo/Deep Penetrating Anchor (DPA).Each anchor type considered in this paper has a different level of technology maturity. The suction caisson is presently the preferred anchor for taut-leg mooring systems for permanent facilities and is probably the most mature in terms of installation experience and prediction of holding capacity, but there are economic issues associated with the fabrication and installation of suction caisson anchors due to their large size. The VLA is probably second in the overall level of maturity from the standpoint of prediction of holding capacity and installation confidence, but there are installation issues and limitations associated with the size, number, and hence cost of marine vessels required to drag the anchors to design penetration, to key the anchors, and to proof load the anchors. The SEPLA and Torpedo/DPA anchors trail in level of maturity and require the most technological development to attain a mature state of practice in the future. This paper will review these four anchors that show the greatest opportunity to serve the needs for deepwater mooring and describe the state of practice in terms of design and installation reliability. The objective of this paper is to discuss the uncertainties (areas requiring further development) of each anchor, the advantages and disadvantages, and to offer the authors' opinions of future technology development direction and focus.The general conclusions regarding future development of the practice of deepwater anchors are as follows:• Torpedo/DPA anchors appear to be the most promising option for improvement in cost reduction and simplifying installation • Future research activities are recommended for Torpedo/DPA anchors in the following order of priority: 1. analytical penetration studies, 2. analytical studies to determine the optimum number, size, and configuration of fins, 3. small and full scale field testing to measure penetration and holding capacity in various soil profiles and optimize installation procedures, and 4. design method verification and documentation.

The Riser and Flowline Monitoring (RFM) project deployed one of the most comprehensive subsea structural monitoring systems to date on a Tahiti infield (production) Steel Catenary Riser (SCR) and associated flowline. State-of-the-art motion and strain measurement devices are optimally placed along the SCR to continuously measure and store real-time full scale riser response. In addition, RFM project is the first to implement monitoring devices on a flowline to measure the flowline buckling, a phenomenon that is predicted during repeated start up/shut down. The project goals are two-fold:1. Understand fundamental hydrodynamic behavior of SCRs and flowlines, specifically, floater motion induced response of catenary risers, Vortex Induced Vibration of catenary risers, riser behavior at the pull tube exit region, riser-soil interaction at the touchdown region, flowline buckling, flowline axial walking, and flow assurance characteristics of infield flowlines. The information generated will be used in future riser designs.2. The information will be used to validate Tahiti riser and flowline system robustness and conduct "health checks" on the fatigue critical risers and flowlines, particularly after significant environmental or operational events. This paper describes the monitoring system configuration, the technology deployed, and the installation methods.

Design of deepwater risers involves the use of multiple conservative design parameters to account for the uncertainty in the understanding of the behavior of complex structures. As the oil industry moves into deeper and harsher waters, the design tolerances are getting stretched. Chevron has been monitoring the structural response of a deepwater Gulf of Mexico steel catenary riser (SCR) to improve the understanding of riser behavior and to evaluate the existing analysis and design methodologies against actual field measurements. The following paper presents a selected set of results from benchmark of SCR response in storm conditions against analytical predictions, based on industry standard methodologies. The predictions are based on a finite element analysis (FEA) modeling of the riser structure with empirically formulated models for hydrodynamics and soil-structure interaction. Predicted riser response in terms of accelerations and stresses along the length are compared against field measurements showing good overall agreement.

Over the past several years, the focus of the oil industry has shifted towards Integrity Management (IM) of offshore platforms. A typical IM program of an offshore platform covers subsea equipment, riser/flowline, processing facilities and topsides. However, the integrity of the riser system is especially critical due to its complex dynamic response and as failures have potential to cause significant impact on life and environment. As part of Chevron's IM efforts on their deepwater floating systems, Chevron has instrumented one of its deepwater GoM platform SCRs with motion and strain monitoring devices. A key objective of the SCR monitoring program is to ensure that the response of the production riser is within safe operating conditions and pre-emptively identify any potential threats to riser integrity. To maximize the benefits of the SCR IM program, riser monitoring data is processed in conjunction with prevalent environmental, vessel and riser operating conditions. Typically a riser design process contains a standard set of requirements, based on environmental and vessel conditions, that need to be satisfied before the riser is deemed suitable for use. As part of the SCR IM program, additional factors unaccounted during riser design have been identified that have an impact on riser response. Hence the value of a riser monitoring program to account for the limitations of the riser design process and to confirm the overall integrity of the riser system is established. This paper discusses the methodology used and provides a summary of key findings from the processing of field measurements. The importance of monitoring will be highlighted and recommendations to operators for future integrity management programs will be provided.

The Riser and Flowline Monitoring (RFM) project deployed one of the most comprehensive subsea structural monitoring systems to date on a Tahiti infield (production) Steel Catenary Riser (SCR) and associated flowline. State-of-the-art motion and strain measurement devices are optimally placed along the SCR to continuously measure and store real-time full scale riser response. In addition, RFM project is the first to implement monitoring devices on a flowline to measure the flowline buckling, a phenomenon that is predicted during repeated start up/shut down. The project goals are two-fold:1. Understand fundamental hydrodynamic behavior of SCRs and flowlines, specifically, floater motion induced response of catenary risers, Vortex Induced Vibration of catenary risers, riser behavior at the pull tube exit region, riser-soil interaction at the touchdown region, flowline buckling, flowline axial walking, and flow assurance characteristics of infield flowlines. The information generated will be used in future riser designs.2. The information will be used to validate Tahiti riser and flowline system robustness and conduct "health checks" on the fatigue critical risers and flowlines, particularly after significant environmental or operational events. This paper describes the monitoring system configuration, the technology deployed, and the installation methods.