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TCP is a strong, noncorrosive, spoolable, lightweight technology which is delivered in long lengths, resulting in a reduction of transportation and installation costs. TCP is installed using small vessels or subsea pallets, significantly reducing CO2 emissions. It is also 100% recyclable. Strohm secured a contract with Total and ExxonMobil for a qualification-testing program for a high-pressure, high-temperature (HP/HT) thermoplastic composite pipe (TCP). The qualification project will create a foundation for further development of this TCP technology for riser applications.
Bring your experience to influence the industry and help shape its future by submitting a paper proposal for consideration. Call for Papers is now closed. Authors will be notified of the status of their abstract submission by week commencing 18 November 2019. Abstracts should be between 225-350 words outlining your presentation. It should clearly state what topic it is relevant to within the event programme and what the outcomes of the presentation will be.
Ghorbel, Fathi H. (Department of Mechanical Engineering, Rice University, Houston, TX, USA) | Kapusta, Sergio (Energy and Environment Initiative, Rice University, Houston, TX, USA) | Allen, John (Society for Underwater Technology, and Subsea Systems Institute, Houston, TX, USA)
The Subsea Oil and Gas industry is quickly moving toward deeper waters, complex, challenging, and dynamic working environments, while requiring the highest level of safety. Tasks that have been historically undertaken by workers in shallow waters are now performed by Remotely Operated underwater Vehicles (ROV) at water depths that humans cannot survive. ROV's are being used for intervention (Work-class ROV's, WROV) and for surveillance on drilling and production systems and pipeline. ROVs inherently have several limitations including requirement of a large operating crew, a need of a dynamically positioned surface vessel, tether management, and high cost mobilization and demobilization. Autonomous Underwater Vehicles (AUV) are now emerging with new capabilities and technologies that could make them more efficient and more cost effective than ROVs. New paradigms in shape, autonomy, sensing and communication and physical capabilities are needed to make AUVs the tool of choice for deepwater industry. An ideation and roadmapping workshop on the Development of AUVs for Subsea Applications was held at Rice Uni-versity that (i) generated a consensus from Oil & Gas operators, service providers, technology developers and providers, academics and policy makers of the anticipated needs and wishes for AUV technology in10 years, (ii) identified gaps between current status and future needs, and (iii) developed a roadmap of specific technical needs, gaps and solutions, and identified how and when those gaps might be closed.
Copper alloys are used in many seawater applications due to their environmentally assisted cracking resistance, general corrosion, pitting and crevice corrosion resistance as well as their anti-fouling properties. Age hardenable copper alloys such as copper-beryllium (Cu-Be), are used in subsea applications for split-lock rings and trunnions due to excellent galling resistance as it provides low coefficient of friction.
Due to criticality of subsea designs and significant consequence of offshore failures, advanced design assessment and verification analysis is required. One of the material properties used for design verification analysis is Fracture Toughness (FT); in some applications, it is required that the service environment degradation effect be considered in obtaining material properties.
In this work, FT of a specifically prepared Cu-Be alloy was measured in air and in seawater with cathodic protection condition. The effect of loading rate on the cracking resistance of the material was determined initially and then three FT tests at the proper loading rate were performed using compact tension test specimens. It was found that loading rate does not play a significant role in FT values, and the average environmental FT is consistently comparable to its in-air values indicating the alloy’s resistance to hydrogen embrittlement. Scanning electron microscopy studies revealed ductile features with facets of transgranular cracking on the fracture surface.
Copper alloys are being used in seawater applications for decades due to their resistance to seawater corrosion and biofouling as well as their fabricability. Formation of an adherent, thin and protective film on the surface upon exposure to seawater is attributed to the corrosion resistance of copper alloys. The film formation and its maturity depend on the temperature and its composition and color depend on the alloying elements. Copper alloys are not susceptible to cracking in chloride and sulfide containing environments and are not susceptible to hydrogen embrittlement. However, the presence of ammonia may increase corrosion rate of the alloys.1,2
High pressure high temperature (HPHT) technology and field development have received much attention in recent years. Materials for HPHT environments, including ultra-high strength alloys and soft polymer compounds will in some cases be close to their capability limits. Materials testing and qualification have therefore been challenging for HPHT equipment design and project execution. At the same time, lower oil prices have put cost pressures on project developments. To overcome both technical and financial challenges while ensuring satisfactory project safety and performance, holistic and systematic solutions promoting materials standardization and innovation are necessary. In this paper, case studies and lessons learned from several recent and widely recognized Joint Industry Projects on subsea materials are presented. The philosophy of materials standardization and innovation behind these efforts will be discussed and their positive impacts on HPHT materials qualification and testing will be summarized.
Environmentally assisted cracking of high strength nickel based alloys under was investigated in 3.5wt% NaCI under cathodic polarization. Rising displacement tests were performed on C22HS and MP98T were performed at a slow K-rate of 0.005Nmm−3/2/s. The results suggest that there is no significant environmental effect for MP98T, however C22HS exhibited a decrease in the initiation toughness. Tests performed under K control under a range of conditions on 718 and K-500. In general, the crack growth rate (CGR) measured under constant K were lower than those obtained under rising displacement tests under similar conditions. The CGR in both 718 decreased with decreasing potential. The CGR was also observed to depend strongly on the loading mode. There was a strong effect of increasing K, with increasing K tests resulting in substantially higher CGR’s than at constant under similar conditions. The above results suggest that the rate limiting step for crack propagation may be the generation of hydrogen at the crack tip. A crack tip strain rate based model was applied to rationalize the data though more work is needed to establish the various parameters associated with the model.
High strength nickel based alloys like Monel K-500, Inconel 718, Inconel 625+/725 have been known to be susceptible to hydrogen embrittlement/1-3/. Slow strain rate tests revealed susceptibility to intergranular cracking in K-500 in seawater over a range of applied cathodic potentials from -850mV to - 1000mV SCE/4/. Field failures of K-500 were attributed to hydrogen embrittlement in seawater under cathodic charging/5/. It was suggested that in these cases that high hardness associated with cold work from rolling threads on fasteners may have been the primary cause of enhanced susceptibility to hydrogen embrittlement/5/. The presence of carbon films along the grain boundaries was also attributed to increased susceptibility, though the exact mechanism that is operative was not clear/6/.
Constant load and double-cantilever-beam (DCB) testing performed on UNS N07718 and UNS N07725 demonstrated that under cathodic polarization of -1 V to -1.1 V SCE (in synthetic seawater) these materials are resistant to hydrogen embrittlement/3/. However, the observation of failures in the field suggest that there may be other factors responsible for cracking which were not simulated in the published work. It is possible that in constant load tests the absence of a pre-crack coupled with dynamic straining may be a reason for not observing cracking.
Slow rising displacement tests (K-rates of ~0.3 to 0.5MPa√m/h) have been employed recently to evaluate susceptibility of nickel based alloys to hydrogen embrittlement in seawater under cathodic polarization/711/. The results indicate that materials such as K-500, and Inconel 718 exhibit susceptibility under these conditions, with Kth values significantly lower than measured in dead loaded/rising step loaded tests/7,9/. The slow rising displacement tests have been valuable in trying to discern susceptibility as measured via Kth. However, it is interesting to note that in a number of systems evaluated using the slow rising displacement method/7-12/, the measured steady plateau CGR even at low K-rates is on the order of 10” 6 to 10−4mm/s/8-12/. More recent work that has demonstrated that the CGR’s of Inconel 718 are sensitive to K-rates/7/ and when measurements were performed at K-rates significantly lower than 0.5MPaVm/6/. Similar data has been observed for K-500 when comparing the CGR data under rising displacement versus constant load conditions/7/. In this context, it is important to note the measured CGR’s at K-rates of 0.5MPaVm/h may not be meaningful for developing damage tolerant designs (CGR of 10−6mm/s would result in a crack extension of ~1inch/year). Under these conditions it is clear that hydrogen embrittlement is present, it is important to note that any predictive model needs to address the observed sensitivity to K-rate. Recent efforts to model the measured CGR have essentially focused on the relating the measured CGR to the effective diffusivity of H, and the concentration of hydrogen, without accounting for the observed strain rate dependencies in any manner/10-12/.
Subsea separation and produced water re-injection (PWRI) or discharge has long been considered as an enabling technology for developing deepwater / ultra deepwater and marginal fields. It is an integral part of the subsea processing strategy which brings many economical, operational and environmental benefits for the offshore Oil & Gas industry. However, one of the key technology gaps remaining is in relation to water quality measurement for subsea separated produced water. This review is based on JIPs that NEL has conducted and its recent involvement in a RPSEA project. The review also includes progress made by operators and vendors.
Existing practice for subsea water quality measurement involves in sending an ROV (Remotely Operated Vehicle) to take a produced water sample and then bring it to surface for analysis. This practice is extremely expensive, time consuming and not good for operations. The technology gap has in many ways prevented the widespread of using subsea separation and produced water re-injection systems.
Good progress has been made in developing a subsea water quality measurement device in recent years. This has been achieved through a combination of efforts by operators, government bodies, vendors and independent organizations. Technologies that have the best potential for subsea applications include: Light scattering; Microscopy imaging; Laser Induced Fluorescence; Ultrasonic acoustic.
Laser Induced Fluorescence;
Most of the above-mentioned technologies are currently surface proven. They are of Technology Readiness Level (TRL) of 3 in relation to subsea applications, which means that they are prototype developed, function and performance assessed. Some of the key progresses to date are resulted from the use of LED as a light source, better fouling mitigation approaches, purposefully conducted lab and surface field trials. Further progresses are anticipated in which some of the mentioned technologies will be developed to TRL 4 (environmental tested) and TRL 5 (system integrated).
There are currently very few references in the literature on the subject. This paper will add valuable information to the public domain regarding the status of the development of subsea produced water quality measurement sensors.
An electric choke can be an essential component of a subsea system and could represent the next major leap in subsea innovation. This paper presents the added functionality that an electric choke can bring to a subsea system during production startups and shutdowns as well as how it can improve condition monitoring and downhole instrumentation protection.
The electric choke can be easily integrated to a hydraulic or electric control system. It is driven by a motor and does not require stepping, therefore enabling greater control and precision. A comparison is presented between typical operations of a field using a traditional hydraulic choke versus an electric choke. We will also look at some of the additional benefits an infinite number of positions can bring to the system for production and injection field operations.
Electrically actuated chokes provide several advantages during production startup and shutdown. An unlimited number of precise positionings means that wells can be brought onstream and shut down gradually to prevent formation damage.
For monitoring purposes, there is an improved response time in diagnostics and interpretation of measurements coming from the downhole valves, sensors, wellhead, and subsea instrumentation. This improved response and additional information, including actuator motor power consumption, actuator motor speed, and valve and choke position, enable better condition monitoring, and through predictive analytics, uptime can be optimized and interventions can be reduced.
In long-offset fields, electrically actuated chokes provide protection of downhole equipment, such as surface-controlled subsea safety valves (SCSSVs) and downhole screens. Electric subsea production control systems have been around since the late 1990s. Because of the recent economic climate, the industry is now looking for more effective ways to produce hydrocarbons, and removing hydraulics from the system seems to be a cost-effective and technically feasible solution. Electrically actuating chokes provides great benefits and opens the door for fully electric systems in the future.
Silva, R. C. (Dorf Ketal) | Pazinatto, M. (Dorf Ketal) | Marcorighi, J. B. (Dorf Ketal) | Dias, P. (Petrobras) | Sampaio, T. P. (Petrobras) | Bitencourt, J. (Dorf Ketal) | Hanna, A. W. (Dorf Ketal) | Paprocki, J. (Dorf Ketal) | Gomes, M. T. (Dorf Ketal) | Rocha, R. B. (Dorf Ketal)
This study presents the development of an innovative product which provides the combined functions of H2S sequestration and flow improvement in subsea applications. The product was applied and validated in an offshore field of Campos Basin for use via umbilicals in production wells.
The methodology is based on stabilization of the non-nitrogenated scavenger in the presence of solvents consisting of compounds with different ionicities. The efficiency of the combined product was demonstrated in relation to H2S abatement in the organic phase, as well as to flow improvement. Evaluations of elastomer compatibility, solvent loss, heat and cold stress testing, particle size and corrosivity of metallic materials qualified the product for umbilical injection. Field validation was performed in a production well that presented flow instability, high viscosity and high levels of produced H2S.
The combined product had a strong influence on water separation, promoted a good O/W interface formation, and showed high quality separated water, capacity to sequester H2S and reduce oil viscosity. In the approval phase for subsea application via umbilicals, the product achieved satisfactory results in all tests, satisfying internal specifications, and was considered suitable for this type of application. In the third and final stage, the product was tested in the field. The product application reduced the H2S level of the gas stream by approximately 90% and arrival pressure by over 20%, while well productivity increased by approximately 9%.
The results obtained at the laboratory scale for product development match its performance in the field. Accordingly, the laboratory techniques used were shown to reliably reproduce production conditions, which is extremely important in the development of more effective products.
Subsea gas compression and pumping technologies have been identified as a solution for accessing gas reservoirs that may be otherwise either inaccessible or economically unfeasible to drill. Subsea stations offer a fast-track development solution with flexible, multiphase deployment, and other inherent advantages whilst filling this application. Pumping stations require a significant amount of process equipment improvements and integration solutions; however, we will focus here on the rotating machinery, process pumps in specific. In the present research, all available operator or manufacturer's reports and published papers are reviewed and a criterion is developed for subsea pump selection base on: