CO2 emulsion/foam is a promising method for controlling the mobility and improving the volumetric sweep efficiency in CO2 enhanced oil recovery (CO2-EOR) process. Recently, amine surfactants attract the attention of the researchers as CO2 emulsifiers/foamers, because of their switchable property: the surfactants are nonionic and CO2 soluble at high pH, and are cationic and water soluble at low pH. However, the efficiency of the commercial switchable amine surfactants is usually suppressed at high salinity (> 200 g/L TDS) and temperature (> 100 °C). Thus, novel switchable alkyl-amine surfactants are designed in house based on the hydrophilic and CO2-philic balance for rapidly generating strong and stable CO2 emulsions at high salinity and high temperature. These novel surfactants are evaluated and compared to a commercial one with respect to the solubility in brine and CO2, and emulsifying ability in bulk and in porous media at high temperature, high pressure and high salinity.
The novel surfactants show outstanding performance: soluble in 220 g/L NaCl brine at pH≤8 from room temperature to 120 °C, soluble in CO2 at relatively low pressure (91 bar) and high temperature (110 °C). The surfactants are thermally stable at 110 °C and pH=4 in the absence of O2. Strong CO2 emulsion/foam is observed in both bulk test and in silica sandpack with 0.2 (wt)% of the surfactant in brine. Additionally, the apparent viscosity of the CO2 emulsion/foam at 110 °C is significantly higher than that at lower temperatures. Comparing to the commercial surfactants, the CO2 emulsion/foam is stronger and generated faster by the novel surfactants. These novel surfactants can be synthesized using commercially available feeds and simple industrial processes. Thus, the novel surfactants are promising for generating the CO2 emulsion/foam, especially in the hot and salty carbonate reservoirs.
Navigation in ice poses a number of hazards, which may have significant consequences if not addressed. Significant efforts are frequently made to ensure the ship is designed and constructed for the anticipated ice conditions, however, operational aspects play a crucial role in mitigating risks and avoiding hazards in ice transits. This paper outlines some of the operational situations that may occur during ice navigation and illustrates the potential risks, and explores some of the elements for the risk management necessary for safe navigation in ice. Further, the paper discusses the influence of the operations with a particular emphasis on how these can be applied to ice transit simulations, with an application case study used as an illustrative example to highlight these elements.
ABSTRACT:The addition of a small amount of flexible organic polymers in a turbulent flow can strongly decrease friction pressure drop, allowing thereby substantial increase in crude export pipeline capacity. This effect, known as "Drag Reduction", is widely implemented on various industrial sectors: petroleum, medicine, hydrodynamics, etc. Only a few tens of parts per million by weight of Drag Reducing Agents (DRA) are required, making these additives economically attractive. These long-chain polymers are known to be very sensitive to high shear and are for example completely destroyed through boosting pressure pumps in place throughout long export crude pipelines (> 300 km), requiring the installation of new DRA injection skids at the downstream of each pump station. However these long-chain polymers have been shown to be sensitive to mechanical degradation occurring during the transport within the pipeline, phenomenon which progressively reduces the overall DRA efficiency. An original experimental study, combining two experimental apparatus, a classical rheometer and a specially designed laboratory turbulent flow loop, was carried out to monitor such degradation phenomenon. Different commercial oil soluble DRAs have been tested on various fluids including crude oil and model kerosene, under a large range of experimental conditions in terms of geometrical configuration, temperature and flow rates. The experimental results highlight a clear link between degradation kinetics and flow dissipated energy and led to a patented law allowing the evaluation of DRA efficiency as a function of the dissipated energy, which is directly correlated to pipeline length. This new law is aimed at optimising polymer initial concentrations in order to achieve the desired DRA efficiency by covering the degradation which will occur during transport. Such model will allow better implementation of DRA usage in crude export pipes at the design development stage and not just using them for flow de-bottlenecking cases.
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