Investigation of the Hydrate Plugging and Non-Plugging Properties of Oils

Sjöblom, Johan; Øvrevoll, Bodhild; Jentoft, GunnHeidi; Lesaint, Caterina; Palermo, Thierry; Sinquin, Anne; Gateau, P.; Barré, Loı̈c; Subramanian, Siva; Boxall, J.; Davies, Simon; Dieker, Laura E.; Greaves, David; Lachance, Jason W.; Rensing, Patrick J.; Miller, Kelly T.; Sloan, E. Dendy; Koh, Carolyn A.

doi:10.1080/01932690903224698

Cited by 93 publications

(73 citation statements)

References 11 publications

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“…According to the procedures developed by Pradilla et al [29], the concentration was detected to be 0.31 wt% in this crude oil. To generate the emulsions, water was added drop-wise to the oil phase under continuous homogenization at 17,500 RPM, according to the procedure described by Sjöblom et al [30]; the emulsions were all sheared for 300 seconds to ensure the total kinetic energy input to the system was constant. Emulsion samples were left to ripen for two hours prior to use in the rheometer.…”

Section: Emulsion Preparation and Characterizationmentioning

confidence: 99%

High pressure rheological measurements of gas hydrate-in-oil slurries

Qin

Aman

Pickering

et al. 2017

Journal of Non-Newtonian Fluid Mechanics

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Gas hydrates are ice-like solids that may form in crude oil flowlines under high pressure and at low temperature, resulting in the formation of viscous hydrate-laden oil slurries. The magnitude of the slurry viscosity has been suggested as a primary means of determining the risk and severity of flow blockage, but there is a dearth of data available to calibrate predictive models of hydrate-in-oil slurry viscosity. This work deploys a controlled-stress, high-pressure rheometer to characterize the rheological properties of methane hydrate-incrude oil slurries, which were generated in situ from water-in-oil emulsions. A vane blade rotor was found to maintain sufficient methane saturation in the oil phase during the hydrate growth period to allow near full conversion of the water. Dynamic measurements with the rheometer were able to separate the contributions to the viscosity change as the emulsion converted to a hydrate slurry due to (i) formation of the solid particles and (ii) reduction of the methane content in the oil continuous phase. For 5-30 vol% watercut systems, the slurry viscosity increased between 20 and 60 times during hydrate growth, whereas, under equivalent conditions for a 20% watercut emulsion, the viscosity increase due to the desaturation of methane from the oil phase was less than a factor of two. The steady-state hydrate-in-oil slurry demonstrated shear thinning behavior at both 1 and 5 °C. The measured slurry relative viscosity deviated between 12 and 212% from the current industry-standard hydrate-in-oil slurry viscosity model, indicating the need for model improvement. After an eight-hour annealing period to simulate subsea shut-in, the yield stress of the hydrate-in-oil slurries varied between 3 and 25 Pa over 5 to 25 vol% hydrate.

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Section: Emulsion Preparation and Characterizationmentioning

confidence: 99%

High pressure rheological measurements of gas hydrate-in-oil slurries

Qin

Aman

Pickering

et al. 2017

Journal of Non-Newtonian Fluid Mechanics

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“…Once cooled, the sample was stirred at 8000 rpm using a high-speed homogenizer (Virtis Sentry Cyclone IQ2 Homogenizer), while water was added slowly using a syringe. (9). The total stirring time depends on water cut of the emulsion.…”

Section: Emulsion Preparationmentioning

confidence: 99%

Measurement of the water droplet size in water-in-oil emulsions using low field nuclear magnetic resonance for gas hydrate slurry applications

et al. 2015

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Turbulent flow in oil and gas pipelines often results in the formation of a water-in-oil (W/O) emulsion. Small water droplets in the pipeline provide a large total surface area for hydrate formation at the water/gas saturated oil interface, which can lead to full conversion of water to gas hydrate. As a result, this may prevent the formation of large hydrate aggregates that can cause hydrate particle settling and eventually plugging. It is thus of particular interest to determine the water droplet size of an emulsion. Since water droplet size of the emulsion provides information about the hydrate particle size in the slurry, it is crucial to determine the water droplet size in a W/O emulsion. In this work, the water droplet size of model W/O emulsion systems was measured using two techniques, diffusion-transverse relaxation (T2) experiments using low-field nuclear magnetic resonance (NMR) and optical microscopy image analysis techniques. The T2 distribution of the emulsion was also measured. The water volume fraction was varied from 10–70 vol%. The NMR and microscopy image analysis results show the droplet size ranging from 3.5 to 4.5 μm and 2 to 3 μm, respectively. Both techniques show a minimum size of 2 and 4 μm at 50 vol% water cut. There are two main reasons for the small difference in droplet size distribution (DSD) measured using these techniques: NMR provides DSD of the entire emulsion sample as opposed to the optical microscopy technique that only captures a small sample of the emulsion. In addition, since the NMR method does not require sample preparation, the characteristics and properties of the emulsion are maintained. Using microscopy images, the sample is compressed between two glass slides. This will disturb the properties of the emulsion. By combining the diffusion-T2 and T2 distributions, the surface relaxivity was determined to be 0.801 μm/s for the W/O emulsion. The DSD obtained from the NMR method in this work was compared with microscopy analysis, and results show there is reasonable agreement between the two methods. This paper provides a comparison of the two methods that can be used to determine the water droplet size of W/O emulsions. This study indicates that a relatively simple quantitative NMR method can be utilized to determine the water droplet size of W/O emulsions before gas hydrate formation and hence can be used to assess the gas hydrate slurry properties and plugging risk of W/O systems.

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“…2 shows the geometry in terms of horizontal length and depth from sea level, which consists of a slanted well with a diameter of 5 in., a departure of 2000 m, and a depth of 1800 m. The well is connected to a straight flowline with a slight uphill slope, a diameter of 0.1524 m, and a horizontal length of approximately 13 km, followed by the bend into the riser that leads up to the platform or FPSO. Table 1 presents a summary of the Caratinga crudeoil properties and composition measured by Sjöblom et al (2010).…”

Section: Offshore-well Hydrate Risk Assessmentmentioning

confidence: 99%

Hydrate Risk Assessment and Restart-Procedure Optimization of an Offshore Well Using a Transient Hydrate Prediction Model

Zerpa

Sloan

Koh

et al. 2012

Oil and Gas Facilities

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A produced-hydrocarbon stream from a wellhead encounters formation of solid gas-hydrate deposits, which plug flowlines and which are one of the most challenging problems in deep subsea facilities. This paper describes a gas-hydrate model for oil-dominated systems, which can be used for the design and optimization of facilities focusing on the prevention, management, and remediation of hydrates in flowlines. Using a typical geometry and fluid properties of an offshore well from the Caratinga field located in the Campos basin in Brazil, the gas-hydrate model is applied to study the hydrate-plugging risk at three different periods of the well life. Additionally, the gas-hydrate model is applied to study the performance of the injection of ethanol as a thermodynamic hydrate inhibitor in steady-state flow and transient shut-in/restart operations. The application of the transient gas-hydrate model proved to be useful in determining the optimal ethanol concentration that minimized the hydrate-plugging risk.

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Investigation of the Hydrate Plugging and Non-Plugging Properties of Oils

Cited by 93 publications

References 11 publications

High pressure rheological measurements of gas hydrate-in-oil slurries

High pressure rheological measurements of gas hydrate-in-oil slurries

Measurement of the water droplet size in water-in-oil emulsions using low field nuclear magnetic resonance for gas hydrate slurry applications

Hydrate Risk Assessment and Restart-Procedure Optimization of an Offshore Well Using a Transient Hydrate Prediction Model

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