A Feasibility Study for Steel Catenary Risers Connected to a Spread-Moored FPU Monohull in a Field Offshore Brazil

Author(s):  
Jack Pollack ◽  
Kent B. Davies ◽  
David C. Riggs

Until recently, the feasibility of connecting Steel Catenary Risers (SCRs) to monohull FPU / FPSOs (Floating Production Units / Floating Production Storage Offloading) had not been proven for deepwaters offshore Brazil. Extreme deepwater applications have required the use of steel risers to avoid hydrostatic collapse. Since SCRs are usually limited by fatigue, due to seabed interaction in the Touch Down Zone (TDZ), the effect of monohull vessel motions on SCR fatigue life had been an issue to be resolved. In the past, only semi-submersibles had been considered for these Brazil applications. Today it can be shown that spread-moored ship-shapes are sufficiently stable for the connection of several large diameter SCRs.

2021 ◽  
Author(s):  
Cynthia F. Corbett ◽  
Elizabeth M. Combs ◽  
Peyton S. Chandarana ◽  
Isabel Stringfellow ◽  
Karen Worthy ◽  
...  

BACKGROUND Medication non-adherence is a global public health challenge that results in sub-optimal health outcomes and increases healthcare costs. Forgetting to take medicines is one of the most common reasons for unintentional non-adherence. Research findings indicate that voice-activated virtual home assistants (VHAs), such as Amazon Echo and Google Home devices, may be useful in promoting medication adherence. OBJECTIVE Create a medication adherence app (skill) for Amazon Echo devices and measure the use, usability, and usefulness of that skill. METHODS A single-group mixed methods cohort feasibility study was conducted with females who took oral contraceptives (n=25). Participants were undergraduate students (mean age = 21.8, SD 6.2) at an urban university in the Southeast United States. Participants were given an Amazon Echo Dot with MedBuddy, a new medication reminder skill for Echo devices created by our team, attached to their study account, which they used for 60 days. Participants self-reported baseline and post-study medication adherence. MedBuddy use was objectively evaluated by tracking the participants’ interaction with MedBuddy through Amazon Alexa. The usability and usefulness of MedBuddy were evaluated through a post-study interview with participants responding to both quantitative and qualitative questions. RESULTS Participants’ interactions with MedBuddy, as tracked through Amazon Alexa, only occurred on half of the study days (mean of 50.97, SD 29.5). Compared to baseline, at study end participants reported missing their medication less in the past one and six months (χ 2 = .884 and .420 respectively, McNemar’s test p < .001 for both). However, there was no significant difference in participants’ reported adherence to consistently taking medication within the same two-hour time frame each day the past one or six months at the end of the study compared to baseline (χ 2 = 3.544 and 5.526 respectively, McNemar’s test p = .63 and p = .13 respectively). Overall feedback about usability was positive, and participants provided constructive feedback about features of the skill that could be improved. Participants’ evaluation of the usefulness of Medbuddy was overwhelmingly positive. Most participants (65.2%, n=15) said they would continue to use MedBuddy as a medication reminder in the future if provided the opportunity and the majority (91.3%, n=21) said they would recommend it to others. MedBuddy features that participants enjoyed were an external prompt separate from their phone, being able to hear the reminder prompt from a separate room, multiple reminders, and verbal responses as prompts. CONCLUSIONS The results of this feasibility study indicate the MedBuddy medication reminder skill may be useful in promoting medication adherence, but the skill could benefit from further usability enhancements.


Author(s):  
Shinobu Kaneda ◽  
Hirokazu Tsuji

In the past study the plastic region tightening has been applied to the bolted flange joint with smaller nominal diameter and its advantages have been demonstrated, however, behavior of the bolted flange joint with larger diameter is not investigated. Flange rotation of the bolted flange joint with large diameter increases when the internal pressure is applied. Gasket stress is not uniform and it may cause leak accident. So, it is necessary to investigate the behavior of the larger diameter flange. The present paper describes the behavior of bolted flange joint with large diameter under plastic region tightening. Firstly, API 20-inch flange joint tightened to the plastic region by bolt with a smaller diameter and superiority in the uniformity of the axial bolt force is demonstrated. And then the internal pressure is applied to the bolted flange joint and the behavior of the additional axial bolt force is demonstrated. The axial bolt force decreases with increasing the internal pressure, and the load factor is negative due to increasing of the flange rotation. However, the load factor of the bolted flange joint tightened to the plastic region by using the bolt with the smaller diameter approached zero. Using the bolts with smaller diameter is advantageous to the flange joint with the larger diamter, whose load factor is negative, to prevent the leakage. Additionally, the leak rate from the bolted flange joint is measured and the sufficient sealing performance is obtained.


2021 ◽  
Vol 73 (06) ◽  
pp. 41-41
Author(s):  
Alex Crabtree

Last year, this feature opened, almost inevitably, with comments on the effects the COVID-19 pandemic might have on our industry. Unfortunately, a year later, we probably have all experienced the effects, both personal and work-related. One of these effects is that there has been re-evaluation of what’s important. To understand what is important takes some reflection and evaluation of the past. In previous features, the focus has been on what is new or reimagined. Therefore, I thought that, in selecting papers for this year’s feature, it would be useful to select ones that look at coiled tubing operations performed and that have been evaluated in one way or another. From Bolivia comes a paper that reviews some 25 well interventions performed. Most of these operations are of a type that will be familiar to the reader. Also, some of the challenges that were faced in performing these coiled tubing operations will be familiar. These operations used a range of established types of coiled tubing operations and blended the techniques to meet particular operating conditions, especially location and logistics challenges. All conclusions and best practices that resulted, however, may not be familiar to all readers. During the past few years, many coiled tubing papers have focused on the use of coiled tubing in multizone fracturing operations, especially plug milling. An area of coiled tubing use in fracturing operations that has had less of an audience recently has been the use of coiled tubing in annular fracturing operations. This activity is still routinely being performed, particularly in Canada. The question has long existed about how the pipe is being eroded. In the related paper in this feature, the authors explain how they have tried to answer that question and have shared some of their review insights. In the past decade, coiled tubing size, weight, and grade all have continued to increase. Looking back at this trend and thinking about its effect on pressure control equipment led the developers in the third of this year’s papers to work on solutions for shear rams. This is particularly relevant after having just passed the 11th anniversary of the tragic Macondo disaster. Again, this year, I ask everyone to stay well. Recommended additional reading at OnePetro: www.onepetro.org. OTC 30408 Design and Safety Considerations To Perform Coiled Tubing Operations in Large-Diameter, High-Temperature Geothermal Wells by Ishaan Singh, Schlumberger, et al. SPE 204446 Implementing Business Analytics Software To Optimize Coiled Tubing Operations: A Digital Approach to Operations Efficiency by Xaymaca Bautista Alarcon, Royal Oaks Energy Services, et al. SPE 203272 The Reinvention of a Well-Established Coiled Tubing Intervention Work Flow Creates New Perspectives for Acidizing Openhole Horizontal Tight Carbonate Water Injectors by Sameer Punnapala, ADNOC, et al.


2021 ◽  
Author(s):  
Ghiath Guy Mansour

Abstract Fatigue is a primary challenge in the design of steel catenary risers (SCRs) and different measures and methods are utilized to mitigate it. Traditional upset ends and steel lazy wave risers (SLWRs) are such methods to mitigate fatigue. SLWRs were first used in 2009 on the Espirito Santo floating, production, storage, and offloading (FPSO) vessel of Shell Company's Parque das Conchas (BC-10) project offshore Brazil. SLWRs have been used increasingly since then and gained popularity especially in recent years. A novel patented tubular connection assembly referred to as Flared Thickened Ends (FTEs) improves the fatigue life of SCRs and welded connections in general. This novel assembly has many advantages. It overcomes the thickness limitation of welding traditional upset ends and reduces offshore welding time, cost, and risk. When FTEs are used in simple SCRs, they render simple SCRs a robustly viable alternative at significantly lower cost, shorter schedule, and with many additional advantages as compared to SLWRs. Of the many advantages, simple SCRs are more straightforward to configure, analyze, design, and install using varied installation methods and vessels. Simple SCRs use less materials and offer better long-term integrity, especially for insulated SCRs. In addition, they have a smaller footprint and are less prone to clashing than SLWRs.


Author(s):  
U. O. Akpan ◽  
T. S. Koko ◽  
P. A. Rushton ◽  
A. Tavassoli ◽  
M. Else

For deepwater development in the Gulf of Mexico, steel catenary risers (SCRs) supported from both SPAR and semi-submersible platforms have proven to be successful solutions for in-field flowlines, tie-backs, and export systems. It is envisaged that this will continue to be a promising solution in ultra deep-water applications, up to and beyond 10,000 ft. The study, commissioned by the Mineral Management Service (MMS), investigated the reliability of large-diameter SCRs in ultra-deepwater operations. The primary damage mode considered is fatigue failure. A probabilistic methodology for fatigue reliability is developed, which utilizes deterministic cumulative fatigue damage indicators, namely the stress levels and cycles associated with the various sea states and the fatigue strength of the members. Uncertainties in structural load and material properties are accounted for by assigning probability distributions and standard deviations to the deterministic stress levels. Furthermore, fatigue strength parameters, Miner’s indices, and capacities are modeled as random variables. First order reliability method (FORM) is employed for estimating fatigue reliability. The methodology is applied to three deterministic case studies presented by Intec Engineering (2006a, 2006b). The case studies involved either a SPAR or a semi-submersible platform. For the sake of brevity, a case study involving only a SPAR platform is presented in this paper. The effect of uncertainties in parameters on fatigue reliabilities is investigated. It is observed that the fatigue reliability estimates followed similar trends as the deterministic cumulative damage results, and hence can be used to complement deterministic estimates. Additional benefit and insight gained from the probabilistic study, which can be used for design decisions, include information regarding probabilistic importance and probabilistic sensitivity analysis. For case study presented here, it is seen that in general, uncertainty in the fatigue strength exponent (m) has the highest impact on fatigue reliability of SCRs. The second most important random variable is the stress range (S), which captures uncertainties in parameters such as loads and material properties. Parametric sensitivity studies on the fatigue strength parameters indicate that SCR reliability is sensitive to both the standard deviation and probability distribution of the parameters, thus highlighting the need for accurate probabilistic calibration of the random variables.


Author(s):  
Wenwei Zhang ◽  
Zhenyong Zhang ◽  
Jinyuan Zhang ◽  
Peng Yang

China National Petroleum Corporation (CNPC) has constructed large-diameter high-strength pipelines (X70 and X80) in the past decades in areas of seismic activities, mine subsidence, and slope movement using strain-based design (SBD) technology. More pipelines being constructed now traverse regions of active seismic activities, mine subsidence, slope movement, and discontinuous permafrost. CNPC is also interested in moving to linepipe grades higher than X80. In view of the recent development of various tensile strain models, work was undertaken to evaluate those models and determine the most appropriate models for current and future applications. In this paper, selected tensile strain models are reviewed and evaluated against an experimental database. The database of 80 tests from public-domain publications contains both full-scale pipe tests and curved wide plate tests with 46 tests from high strength pipes (X80 and above). The calculated tensile strain capacity from the selected models was compared with the test data. The models were evaluated and the applicability of the models to the linepipes of different strength levels was discussed.


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