ORCID Profile
0000-0002-7066-8124
Current Organisations
Curtin University
,
CSIRO
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Publisher: American Chemical Society (ACS)
Date: 02-05-2014
DOI: 10.1021/EF500361R
Publisher: Elsevier BV
Date: 03-2023
Publisher: American Chemical Society (ACS)
Date: 18-01-2018
Publisher: American Chemical Society (ACS)
Date: 31-05-2012
DOI: 10.1021/JP3021613
Abstract: In this work, the effect of the surface energy between the hydrate clusters and the aqueous phase on the hydrate formation of carbon dioxide was thoroughly investigated. Our results show that the threshold pressure for hydrate formation is less sensitive to the temperatures if the surface energy is not larger than 7 mJ/m(2). However, the threshold pressure is very sensitive to the temperatures and increases significantly with the surface energy if it is over 7, 9, and 10 mJ/m(2) for the temperatures of 279, 277.45, and 276 K, respectively. The value of the surface energy for the CO(2) hydrate/water system was determined as 9.3 mJ/m(2) by comparing our results with the experimental data for stable CO(2) hydrate formation at the temperature range of 277.45-278.85 K and at pressures of 55-165 bar. This value is very close to the recently reported value of 7.5 ± 1.4 mJ/m(2) from molecular simulation. A theoretical method was proposed for computing the induction time of hydrate formation adopting a composite of the time required for critical nuclei formation and their growth to a detectable size. By using this method, the surface energy was avoided in the induction time calculation and an average crystallite volume of 0.238 mm(3) at the induction time was derived based on the experimental data. It provides an approach for predicting the induction time for gas hydrate formation.
Publisher: American Chemical Society (ACS)
Date: 14-10-2014
DOI: 10.1021/EF501609M
Publisher: OTC
Date: 30-04-2018
DOI: 10.4043/28777-MS
Abstract: Over the past decade, the paradigm of gas hydrate research has transitioned from avoidance via thermodynamic inhibition toward management, where a limited amount of hydrate may be allowed to form in the flowline. This new paradigm enables new field development concepts, including longer-distance subsea tie-backs and limited chemical inhibition. This presentation reviews research datasets from flowloops on hydrate deposition phenomena and includes an initial analysis on the impact of shear stresses on hydrate deposits. This study integrates experimental data from unique high-pressure laboratory flowloops, including single-pass, gas-dominant and recirculating, liquid-phase flowloops. The flowloops have visual observation ports that allow video imaging to be performed throughout the high pressure tests. These apparatuses together are estimated to provide coverage over 1-200 Pa of flowing shear stress at the wall, over a range of total liquid inventories and water holdup. For this work, conceptual diagrams of deposition in oil, water, and gas-dominant systems are presented. Film growth rates are derived at the Colorado School of Mines (CSM) from visual observation in a deposition loop. Hydrate particle deposition rates are determined from a gas-dominant flowloop in Western Australia by fitting experimental data obtained from gas-dominant systems. The results demonstrate that the absolute shear stress required to prevent hydrate particles from depositing at the wall, or to remove/slough deposited hydrate from the wall, can vary with the primary fluid phase. Initial shear stress calculations from a specific test estimate that less than 5 Pa can be required to remove/slough hydrates from the wall in the aqueous phase, while more than 100 Pa may be required in a gas-continuous pipeline. This review suggests that deposition and flowing shear stress may be critical considerations in the design and operation of hydrocarbon systems, to help prevent hydrate blockage in industrial operations.
Publisher: CSIRO
Date: 2015
Publisher: OTC
Date: 27-10-2020
DOI: 10.4043/30186-MS
Abstract: 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 c aign 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.
Publisher: SPE
Date: 18-10-2010
DOI: 10.2118/132968-MS
Abstract: Hydrate management during transient operation of subsea flow lines has been identified as one of the greatest challenges for deep water O& G production. Experiments using natural gas and de-ionized water were conducted in a laboratory flow loop (1" diameter and 40 m length) to investigate the dynamics of hydrate formation during simulated shut-in and restart conditions. Variables studied include different operational pressures and sub-coolings. This work will provide valuable information for the establishment of cost-effective strategies to guarantee the continuous flow of fluids in subsea production systems, particularly during transient operations such as scheduled maintenance or unplanned shut-downs. During the shut-in period hydrate appears to nucleate along the gas-water interface and grow as a film that spreads across the entire interface. At a pressure of 1,500 psi and sub-cooling of 15°C, dendrite crystals start to appear at the film and grow into the water phase until a thickness is reached where further grow stops. It is noted that, although hydrate is observed as a thin film during the shut-in period, most of the water is converted to hydrate upon restart. At every pressure condition evaluated in this study, slurry like hydrate flow has been observed upon restart, being flushed along the pipe-line by the gas flow. Transient operations of subsea flow lines require strict adherence to operational procedures which include depressurization and flushing of the lines with thermodynamic hydrate inhibitors. The results of our work suggest that the blockage is more likely to occur during restart so operating procedures must be designed to minimize the risk of hydrate blockage based on specific factors such as driving force, water content, and gas flow rate. It is considered that the flow loop experiments could provide valuable insight into the dynamics of hydrate blockages formed under flow conditions in gas dominant flows.
Publisher: CSIRO
Date: 2012
Publisher: SPE
Date: 12-11-2020
DOI: 10.2118/202375-MS
Abstract: 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 c aign 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.
Publisher: Elsevier BV
Date: 02-2018
Location: Venezuela (Bolivarian Republic of)
Location: Venezuela (Bolivarian Republic of)
Location: Venezuela (Bolivarian Republic of)
No related grants have been discovered for Mauricio Di Lorenzo.