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.

Online pipeline management systems provide real-time and look-ahead functionality for production networks. However, they are limited by a dearth of data to inform their predictions. This represents a barrier to a true, high-fidelity ‘digital twin’ where greater integration with new sensor technologies is needed to bound model predictions and improve their reliability. In this work, we present a novel MEG (Mono-ethylene glycol) sensing system from OneSubsea, the AquaWatcher v2.0, and validate it in our newly-constructed HyJump flowloop.

The HyJump flowloop has a unique subsea jumper-like geometry, with three low points and two high points and is equipped with a MEG sensor - mounted on the second low point. The sensor features an open-ended microwave frequency probe mounted flush to the pipe wall which measures the apparent permittivities of the liquid phases in the vicinity of the probe tip. It can determine the MEG concentration or water salinity by processing the measured permittivities, and has further shown that it may be able to detect hydrate deposition. Experimental work was performed to test the performance of this novel equipment while enabling a more accurate calculation of the overall mass balance in the flowloop.

An experimental campaign was conducted where, in each measurement, the jumper low points were loaded with aqueous solutions of MEG at mass fractions between 10 and 30 wt%. The entire loop was then pressurized with Perth city natural gas to 1200 psi. The pipe wall temperature was controlled with a cooling jacket in the range of 25.2 °F to 35.6 °F. These conditions simulate transient shut-down and restart operations with a high probability of hydrate formation. Results illustrate that the MEG content readings measured by the sensor were consistently accurate within a 5% relative deviation with respect to the nominal values. Further, flow restrictions due to hydrate deposition were assessed in their severity through differential pressure measurements, where it was observed that the measured MEG content oscillates significantly during hydrate sloughing-type events.

The HyJump flowloop facility offers a unique testbed for new subsea sensors, enabling performance evaluations with internal fluids at subsea conditions. The deployment of these novel sensors in the field will both improve the performance of integrated pipeline management solutions and assist operators in optimizing MEG injection dosages to enable higher fidelity hydrate management in subsea pipelines.

As the oil and gas industry moves towards deep waters in search of hydrocarbon, production risers are unequivocally affected by it. A key factor is a dynamic behavior as it may lead to increased loads on the platform (floater), especially under severe environmental conditions.

This paper serves to analyze and compare the dynamic behavior between different kinds of production risers (Steel Catenary Risers, Flexible Dynamic Risers, and Free Standing Hybrid Risers) and their impact on the floating production platform (floater) in an actual field environment. The basic cost comparison is carried out briefly to assess their suitability in deep waters.

The production risers are modeled on Spar floater subjected to environmental conditions in the Gulf of Mexico. Hydrodynamic data such as added mass and damping coefficients, forces and motion Response Amplitude Operators (RAOs) of the Spar are first obtained using the simulation software MOSES through uncoupled analysis. Subsequently, coupled dynamic analysis is performed for the production risers using the dynamic analysis software OrcaFlex.Results and discussion evaluate the impact of the dynamic behavior and stress of the production risers as well as the cost.

Subsea jumpers are tie-in systems with a characteristic M-shaped geometry, employed to connect subsea facilities such as wellhead trees to manifolds. During well restart after a prolonged shut-down, subsea jumpers are exposed to a significant driving force for hydrate formation. Employing the recently-constructed HyJump flowloop, designed to mimic subsea jumpers operating at hydrate forming conditions, an experimental campaign was conducted to assess the influence of pipeline temperature, gas flow rate, liquid inventory, and inhibitor content on hydrate deposition during simulated shut-down and restart operations. In this work, we acquired baseline data on the gas sweep efficiency in HyJump for a wide range of gas restart velocities to characterize hydrodynamic behaviour in the absence of hydrates. Preliminary experiments were also conducted to evaluate the jumper operability in hydrate forming conditions.

The HyJump flowloop consists of a test section connected to independent gas and liquid injection equipment at the inlet and gas separation facilities at the outlet which allows a continuous recirculation of gas and a once-through pass of the liquid. The test section has a complex geometry, with three identical low points and two high points with horizontal length of 12′ 10" and 7′ 7", respectively, and total height is 13′ 2". The test section is equipped with 12 pressure and temperature sensors regularly distributed, a MEG sensor in the second low point, a throttling valve downstream of the first high point to mimic the wellhead choke, and a viewing window at the outlet. In gas sweep experiments, each of the three low points was loaded with 1.6 gallons of water and natural gas at 1200 psi. During these tests, the pipeline temperature was maintained above 60 °F where hydrates are not expected to form. The system was maintained for six hours at a pipeline temperature of 41 °F (17 °F sub-cooling) for hydrate formation tests. Gas sweep velocities were varied in a range between 0.06 and 3 ft/s.

The results illustrate that a superficial gas velocity of 3 ft/s was required to fully remove liquids from the jumper. However, gas velocities below 0.16 ft/s did not result in any substantive changes to the liquid inventory. Thus, low flow restart conditions could offer a significant driving force for hydrate formation in the jumper at low temperature. The preliminary gas restart tests conducted in hydrate forming conditions provided clear evidence of hydrate deposition at gas velocities below 0.16 ft/s.

Hydrate formation in subsea jumper spools is poorly understood and a rare topic of discussion within scientific literature. This unique "HyJump" facility offers new insight to assist operators mitigate the risk of hydrate blockage by manipulating gas restart rates after well shut-down in the absence of (or with severely limited) chemical inhibition.

At deepwater sites, skirted mudmats with a sliding mechanism have been the preferred choice to support pipeline or flowline end terminations (PLET or FLET) on soft clay seafloor to accommodate line expansions and contractions that occur during shutdown and restart cycles. The sliding mechanisms can experience line expansions of up to 4 m, or if it were to lock-up, horizontal forces in excess of 2,000 kN. The design and fabrication of sliding mechanisms for such large movements can often become challenging and costly. As an alternative, the industry is now designing mudmats that do not utilize sliding mechanism but rather slide directly on the seafloor, if necessary. While it is an attractive alternative and is gaining popularity, all aspects of direct sliding mudmat design are not sufficiently understood because of the complexity that arises from the interactions among the various components, i.e., flowline/pipeline, mudmat, jumpers, and the supporting soft seafloor behaving as one system. The design must ensure that the mudmat will not unduly sink, rotate or dig into the seafloor in the course of the back and forth sliding caused by many shutdown and startup cycles during the field's operating life. Therefore, it is essential to sufficiently understand the characteristics of the sliding motions and estimate as accurately as possible the resulting interaction forces in the flowline-mudmat-jumper-seabed system. This will allow the designer to avoid the risk of any system instability from incoherent component motions, or potential overstressing of connections.

This paper investigates the direct sliding behavior of the mudmat motions using realistic simulations of the flowline-mudmat-jumper-seabed system. The simulations rely on coupled Eulerian (soft seabed) and Lagrangian (flowline, mudmat and jumpers) finite element analysis (FEA) method. The simulations yield insight into the complex mudmat sliding behavior interacting with the jumper, the hydrocarbon line and the supporting seafloor. The simulations show that merely modeling the mudmat alone fails to capture the actual behavior of a real-life PLET/FLET's back and forth cycling on the seafloor, because for example, the restraints (and attendant stresses) at the flowline and jumper connections are not accounted for, or that slanting the sides of the mudmat reduces its tendency to self-embed decreasing connection stresses. The paper demonstrates that realistic simulations allow important visualization of mudmat interactions with flowline, jumper, and the seabed during the shutdown-startup cycles, and provide accurate determination of the associated critical responses.

In subsea production operations, wellhead jumpers are one of the subsea facilities more liable to the formation of hydrate blockages during restart operations. To manage hydrate formation and optimize the amount of thermodynamic hydrate inhibitors (e.g. mono-ethylene glycol; MEG) injected, a newly-constructed jumper-like facility (the HyJump flowloop) has been developed in Perth, to simulate shut-down and restart operations over a range of superficial gas velocities.

The test section of the flowloop has a unique geometry to mimic subsea jumpers, with three low points and two high points standing 13′ 2″ tall. The test section is fitted with twelve pressure and temperature sensors spread regularly, a MEG sensor, a valve to simulate the wellhead choke, and a viewing window. In each test, the jumper low points were loaded with aqueous solutions of MEG (0 to 30 wt%) and pressurized with domestic Perth natural gas at a pressure of 1200 psig and pipeline temperature ranging from 41°F to 25.8°F (+5 to -4°C).

The extent of hydrate restrictions or blockages was evaluated through the dynamic pressure drop behavior observed throughout the flowloop. A closer assessment of the pressure drop trace during gas restart suggests that the severity of the hydrate restriction decreases as the MEG content is increased above 10 wt%. Further, our preliminary experimental results illustrate that severe hydrate deposition in the jumper could be completely avoided by injecting MEG at concentrations above 20 wt%. This corresponds to an approximately 50% reduction in MEG content, where ≈38 wt% MEG dosage was required for complete thermodynamic hydrate inhibition at the pressure and temperature conditions used in this trial.

Our unique flowloop facility offers new insight toward hydrate formation in complex subsea jumper-like geometries. Our findings may assist operators in controlling the extent of hydrate formation and deposition in jumper geometries, by optimizing the MEG injection and subsequently supporting lower-CAPEX tieback development concepts.

The BC10 block encompasses multiple deepwater fields offshore Brazil and is tied-back to the FPSO ´Espirito Santo´. Since achieving first oil in 2009, the production was expanded through the Phase 2 and Phase 3 subsea tie-backs, having by early 2019 a total of 29 wells connected to the system. BC10 is a joint venture among Shell (operator), ONGC and Qatar Petroleum.

As part of the strategy of "filling the hub", the development team matured infill well opportunities, which materialized in New Oil throughout 2019. The delivery of this additional production was enabled by the deployment of various new technologies, which supported the accelerated schedule and low-cost mindset of the project. Most notable is the deployment of the Compact Manifold and jumpers with flexible lines integrated to the horizontal connectors.

In parallel to new wells, the Subsea team worked on a system debottlenecking that enabled the production of additional 2,000 bpd by routing selected fields to dedicated subsea pumps, instead of commingling low- and high-pressure systems into same inlet pressure pumps. This was enabled by installation of an electrical actuator that automated control of a formally manual valve at low CAPEX.

Looking forward, the BC10 Infills Project team is planning for Q1 2020 the installation of the next-generation of Xmas Trees. This Xmas Tree is significantly lighter and cheaper than the previous company standards Enhanced Vertical Deepwater Tree(EVDT). It required significant qualification effort from R&D to ensure all new components delivered as part of this new generation of XT are reliable and satisfy the systems functional requirements. The qualification is completed, it has been confirmed that the well OS2 will carry the first new technology Xmas Tree in 2020.

Summary Gas-hydrate plugging poses an operational challenge to offshore petroleum production and transportation. In this study, a computational-fluid-dynamics (CFD) model that uses ANSYS Fluent (ANSYS 2019) multiphase-flow-modeling techniques to simulate and analyze the effect of gas-hydrate flow in pipelines is proposed. For this purpose, the study attempted to integrate the ANSYS Fluent model with an existing commercial subsea-pipeline-visualization tool. To validate the simulation results, two case studies were conducted. The first study was about a pipeline whose dimensions are based on the specifications in existing literature (Balakin et al. 2010a). The second study was about a pipeline with more-complex geometry (M-shaped jumper with six elbows). The Eulerian/ Eulerian method was used to model the multiphase hydrate flow. The population-balance method (PBM) was then used to model hydrate agglomeration and its breakup mechanism in the flow. A parametric study of the stresses in the pipelines resulting from flowinduced vibration (FIV) was conducted to identify the regions that underwent the maximum stresses and deformations under various flow conditions. The tool can be used in the petroleum industry to identify the operational hazards in offshore structures and to take necessary safety measures to avoid any potential catastrophic events. Introduction Vibration induced on the walls of a subsea pipeline by a hydrate-slurry flow is one of the major factors contributing to the failure of the pipeline's components. In this study, a methodology to analyze the structural response of an M-shaped jumper to the mechanical vibrations caused by an unsteady hydrate flow in an offshore pipeline has been described. Initially, a CFD model of a hydrate flow inside a pipeline was developed.

Summary Gas-hydrate plugging poses an operational challenge to offshore petroleum production and transportation. In this study, a computational-fluid-dynamics (CFD) model that uses ANSYS Fluent (ANSYS 2019) multiphase-flow-modeling techniques to simulate and analyze the effect of gas-hydrate flow in pipelines is proposed. For this purpose, the study attempted to integrate the ANSYS Fluent model with an existing commercial subsea-pipeline-visualization tool. To validate the simulation results, two case studies were conducted. The first study was about a pipeline whose dimensions are based on the specifications in existing literature (Balakin et al. 2010a). The second study was about a pipeline with more-complex geometry (M-shaped jumper with six elbows). The Eulerian/ Eulerian method was used to model the multiphase hydrate flow. The population-balance method (PBM) was then used to model hydrate agglomeration and its breakup mechanism in the flow. A parametric study of the stresses in the pipelines resulting from flowinduced vibration (FIV) was conducted to identify the regions that underwent the maximum stresses and deformations under various flow conditions. The tool can be used in the petroleum industry to identify the operational hazards in offshore structures and to take necessary safety measures to avoid any potential catastrophic events. Introduction Vibration induced on the walls of a subsea pipeline by a hydrate-slurry flow is one of the major factors contributing to the failure of the pipeline's components. Initially, a CFD model of a hydrate flow inside a pipeline was developed.

This paper introduces new classes of hang-offs for Steel Catenary Risers (SCRs) and Steel Lazy Wave Risers (SLWRs). Bending and tension loads are totally decoupled in the riser hang-offs presented. The new hang-offs can be designed for any temperature or pressure that can be supported by SCRs or SLWRs. The novel devices have rotational stiffnesses considerably lower than are those of Flexible Joints or Titanium Stress Joints (TSJs). This results in fatigue life improvements in the upper regions of risers and in supporting vessel structure. The new hang-offs can be easily designed for greater riser deflections than are those feasible with traditional hang-offs. Methodology used in preliminary design is outlined. Simplified preliminary calculations are included and results of non-linear (large deflection) Finite Elements Analyses (FEAs) are provided. This work highlights possible practical implications of the new designs for the envelopes of the use of SCRs and SLWRs.