Gas Hydrates and Flow Assurance
Combining the laboratory facilities of the Centre for Gas Hydrate Research (CGHR) and Centre for Flow Assurance Research (C-FAR) with our own, at Hydrafact we have access to some of the most advanced laboratory equipment for hydrate and flow assurance studies in Europe, if not Worldwide. The majority of our set-ups were custom built in-house based on designs developed through many years R&D experience in the petroleum industry.
High pressure set-ups for flow assurance studies include:
QCM (Quartz Crystal Microbalance) cells
Resistivity/conductivity and ultrasonic cells
Advanced cells for simulating flow through chokes and Joule-Thomson effect
Advanced cells for simulating hydrate formation/removal in well-tubing and/or annulus
For phase compositional analysis:
Combined gas chromatography / mass spectrometry (GC/MS)
Environmental Scanning Electron Microscope (ESEM)
For studies of sediment-hosted gas hydrates
Micromodels
Autoclave Cells
Autoclave cells are particularly suited to the assessment of LDHI performance (KHIs and AAs), and can be used to simulate various operating scenarios (e.g. flowing, shut-in/start-up). We have a large number of high-pressure autoclave cells of varying design available for flow assurance studies. Volumes range from 200 ml to 2 litres, with operating pressures up to 690 bar (10,000 psia). Parameters recorded include pressure, temperature and mixer rpm/power/voltage, which can be used to determine LDHI induction times and fluid (e.g. hydrate/water/oil slurry) viscosity.
Titanium Autoclave Rig
Rocking Cells
High pressure rocking cells are ideal for hydrate phase equilibrium measurements. At Hydrafact we have a variety of different rocking cells, these varying in volume from 200 to 600 ml, with operating pressures up to 2,000 bar (30,000 psia). A number of our rocking cells are of variable volume moving piston design; these are particularly useful in equilibrium studies as system pressure can be varied while composition is kept constant.
Ultra-High Pressure Rocking Rig
Windowed/Visual Cells
A number of our high-pressure autoclave and rocking cells are of windowed design, allowing visual studies of phase behaviour during experiments. Visual cells are equipped with magnifying digital cameras which can be used for still image and time-lapse/real time video capture to PCs.
Visual Rocking Rig
Capillary Sampling Device
Driven by an automated compressed air system, the capillary sampling device collects samples of the liquid and/or vapour phases in equilibrium which are transported via heated line directly to the GC for compositional analysis. As each sample is only a few microlitres in volume, many can be collected with a negligible change in bulk composition. This set-up is designed specifically for advanced compositional studies, such as inhibitor (methanol, ethanol) loss to the vapour phase and water content of natural gases.
QCM (Quartz Crystal Microbalance) cells
At Hydrafact, we have developed a number of novel QCM techniques for measurements of hydrate and wax phase equilibria. For wax measurements, QCM methods have proven considerably more reliable and versatile than existing techniques (e.g. ASTM standard cloud point determination). A number of our high-pressure cells can be equipped with QCMs for wax studies at pipeline conditions, yielding data for appearance/disappearance temperatures (WAT/WDT), build-up rates and inhibitor performance.
Quartz Crystal Microbalance (QCM)
Resistivity/Conductivity and Ultrasonic Cells
Measurement of fluid electrical properties can provide a means to determine changes in composition and/or the appearance/disappearance of new phases, including gas hydrates and ice. Likewise, ultrasonic properties can also provide information on phase transitions and nucleation phenomenon. At Hydrafact, we have a number of high-pressure cells equipped with conductivity and ultrasonic for hydrate and flow assurance studies.
Gas Water Content Cell
A new addition to our laboratory, based on infrared spectrometry, this set-up us capable of measuring the water content of natural gases at high pressures to ppm levels. It is ideally suited for studies of low water content natural gases where current data are limited and/or unreliable. A further advantage of the system is it can analyse water content in the presence of volatile organic inhibitors such as methanol and ethanol, where other systems fail.
Low Water Content Gas Rig
Advanced Cells: Choke Simulation and Cold Flow
At Hydrafact, we are always working on the development of novel experimental equipment to recreate as closely as possible real industrial processes. A new set-up has been constructed which can be used to simulate choke (Joule-Thomson cooling effect) conditions, and evaluate the performance of KHI and/or AAs for such scenarios.
As part of development of our patented cold flow technology - Hydraflow - a new large volume, high pressure (410 bar / 6,000 psia) set-up has been commissioned for simulation of multi-well oil/water/gas input into a pipeline. This cell is a large autoclave with the benefit of variable volume (piston control), allowing fluids to be continuously added/mixed and hydrate formation to occur without a change in system pressure.
C-FAR Flow Loop
Through its collaboration with the Centre for Flow Assurance Research (C-FAR) at Heriot-Watt University, Hydrafact will be offering flow loop studies starting in the summer of 2008. One of the few commercial flow loops available in Europe, the set-up comprises of a 1" (2.5 cm) diameter, 40 m length loop driven by a Moineau pump system. Housed in an environmental chamber, the loop can operate up to pressures of 200 bar (2,900 psia) from -15 to +20 °C. The loop will provide the upscaling link between laboratory studies and field implementation, being ideally suited for:
- LDHI evaluation - KHI assessment
- AA performance and hydrate/water/oil slurry transportability
- Hydraflow cold flow development
- Evaluating hydrate monitoring and early warning devices
Commissioning of the C-FAR flow loop cold room
Micromodels
Operating at pressures up to 41 bar (6,000 psia) from -20 °C to +80 °C, the heart of the micromodel is an etched glass pore model consisting either of specifically designed geometrical networks or reproductions of actual thin sections of real sediments. The model has an inlet and outlet which allows fluids to be pumped through the enclosed pore network. Pressure is monitored and controlled on both the inlet and outlet lines, allowing fluid flow to be closely controlled. A digital magnifying camera is used to capture video footage and still images of phase behaviour, which are stored by a PC.
Applications include:
- Visual studies of gas hydrate formation and dissociation in various fluid systems at the crystal scale (pores are around 40 micrometers in width)
- Assessing the effect of various chemicals (including salts, organic inhibitors and LDHIs) on hydrate crystal growth and morphology
- Visual observation of gas hydrate growth/dissociation patterns and distribution in sediment pores
- Simulating various gas production scenarios from sediment hosted gas hydrates
- Visual studies of wax and asphaltene deposition and the effects of inhibitors
Micromodel images of gas hydrates
Sediment Ultrasonic Cells
The Centre for Gas Hydrate Research is involved in a number of ongoing R&D projects looking at naturally occurring oceanic and permafrost gas hydrates. Topics covered include geophysical identification/quantification of deposits, potential for methane production from hydrates, the role of gas hydrates in subsurface CO2 storage/disposal, and wellbore stability in hydrate bearing sediments. As part of this research, a number of ultrasonic core holding cells have been developed. These can be utilised in geophysical and geomechanical studies of sediments hosting gas hydrates, yielding data on sonic velocities (P- and S-wave), sediment physical (e.g. porosity, permeability) and mechanical properties (e.g. shear strength, stress versus strain relationships).
Porous Media Cells
Designed by the Centre for Gas Hydrate Research as part of its research into hydrates in sediments, operating from -80 to +75 °C up to 410 bar (6,000 psia), these cells can be used to study hydrate phase behaviour in synthetic and natural porous media, including the effect of pore size/structure, phase saturation and wettability.
