Partitioning of non-ionic surfactants between CO2 and brine

The partitioning of non-ionic surfactants in a CO2/synthetic brine system was studied for a selection of surfactants at reservoir conditions for CO2 enhanced oil recovery and aquifer storage. Alkyl and alkylphenol ethoxylates with different degrees of branching in their hydrophobic moiety were chosen. Generally, higher temperature and pressure promoted increased solubility in CO2. Branching of the hydrophobic moiety tends to favour CO2 solubility (higher partition coefficient). Highly branched moieties were found to hinder solubility probably due to a decrease of their conformational entropy. The addition of an aromatic ring connecting the ethoxylate moiety and the hydrophobic moiety seemed to have an adverse effect at lower temperatures. For two surfactants, the effect of concentration on partitioning was also studied. The partition coefficient decreased for increasing concentrations until a plateau was reached above the corresponding surfactant critical micelle concentration (CMC). This may indicate micelle formation both in the CO2 and in the aqueous phase.acceptedVersio

Pressure Dependency of the Membrane Structure Parameter and Implications in Pressure Retarded Osmosis (PRO)

Pressure retarded osmosis (PRO) can be used to exploit the mixing energy e.g. between river water and sea water. A PRO membrane must be highly permeable for water, whereas salt ions should be retained. Furthermore, the structure parameter of the membrane support and backing structure must be low. This paper summarises an assessment of the pressure dependency of the structure parameter for flat sheet membranes, and a transport model for PRO and procedures for determination of the pressure dependency of the structure parameter are presented. The results from laboratory experiments show that that the structure parameter increases significantly with increasing trans-membrane pressure. The increase in the structure parameter was observed to depend on both characteristics of the membrane and the fresh water spacer. Using a finely textured tricot spacer reduced the pressure dependency on the structure parameter, compared to a coarser spacer. Applying a non-woven backing material between the membrane and the fresh water spacer also reduced the impact of pressure. The results show that membranes suitable for river water/sea water PRO must have a sufficiently low structure parameter and additionally resist severe deformation at relevant operating pressures

First Approach to Measure Interfacial Rheology at High-Pressure Conditions by the Oscillating Drop Technique

An oscillating drop rheometer capable of operating under conditions of high pressure and high temperature has been built. The oscillating drop mechanism was able to support pressures as high as 1300 bar and successfully performed oscillations at constant pressure. Apparent elastic and viscous complex moduli were measured for a system of CO2 and synthetic seawater containing 100 ppm of a linear alkyl ethoxylate surfactant for different pressures and temperatures. The moduli had strong dependencies on both pressure and temperature. At temperatures of 40 and 80 °C, the apparent elastic modulus passed through a maximum for pressures between 100 and 300 bar. The harmonic distortion of the oscillations was calculated for all measurements, and it was found that drop oscillations below ca. 2.6 µL caused distortions above 10% due to a mechanical backlash of the motor.publishedVersio

Patenting the HIF Power System Using the SPRFD

This paper discusses the rationale for patenting inventions that enable the HIF power plant and the status of the prosecution of these patents. Our rationale for starting a business to pursue HIF power was its “suspended animation” despite being held since its 1976 debut to face “no showstoppers” and considered to be “the conservative approach to power production.” In turn, the rationale for patenting the unique features in our HIF approach is that intellectual property (IP) is essential to attract investors to a business endeavor that could readily be taken over by large competitors..

Concentration and Temperature Effects on Water and Salt Permeabilities in Osmosis and Implications in Pressure-Retarded Osmosis

Osmotic power extracted from the mixing of freshwater with seawater is a renewable energy resource that has gained increasing attention during recent years. The estimated energy can significantly contribute to the production of power worldwide. However, this power production will be subject to variation due to both local conditions and seasonal variation. The present paper explores the effect of concentration and temperature on water and salt fluxes in osmosis at zero transmembrane pressure for five different membranes. Further, the measured fluxes have been utilized to model water and salt permeabilities (A and B), and the structure parameter (S). The observed flux variations at different combinations of concentration and temperature have been ascribed to skin properties, i.e., changes in A and B of each membrane, whereas S was assumed constant within the range of concentrations and temperatures that were tested. Simplified equations for the variation in A and B with temperature and concentration have been developed, which enable A and B to be calculated at any concentration and temperature based on permeabilities determined from osmotic experiments at standard test conditions. The equations can be used to predict fluxes and specific power production with respect to geographical and seasonal variations in concentration and temperature for river water/seawater pressure-retarded osmosis. The obtained results are also useful for forward osmosis processes using seawater as draw solutionpublishedVersio

VERTEKS Kontinentalsokkelen – verdiskaper i verdensklasse?

En utredning om hvordan Norge kan motvirke den antatte nedgangen i petroleumssektorens verdiskaping gjennom økt vekt på FoU. Utredningen bygger på internasjonale og nasjonale forskningsbidrag, anvender anerkjente metoder for beskrivelse og rangering av nye teknologier, vurderer disse teknologienes potensiale i verdiskapingen og gir anbefalinger om hvilke områder FoU innsatsen bør rettes inn mot. Utredningen er gjennomført som et fellesprosjekt mellom RF-Rogalandsforskning, Sintef Petroleumsforskning og konsulentselskapet Berrefjord og Thomassen AS

An Evaluation of Graphene Oxides as Possible Foam Stabilizing Agents for CO2 Based Enhanced Oil Recovery

Graphene oxide, nanographene oxide and partially reduced graphene oxide have been studied as possible foam stabilizing agents for CO2 based enhanced oil recovery. Graphene oxide was able to stabilize CO2/synthetic sea water foams, while nanographene oxide and partially reduced graphene oxide were not able to stabilize foams. The inability of nanographene oxide for stabilizing foams was explained by the increase of hydrophilicity due to size decrease, while for partially reduced graphene oxide, the high degree of reduction of the material was considered to be the reason. Graphene oxide brine dispersions showed immediate gel formation, which improved foam stability. Particle growth due to layer stacking was also observed. This mechanism was detrimental for foam stabilization. Gel formation and particle growth caused these particles to block pores and not being filterable. The work indicates that the particles studied are not suitable for CO2 enhanced oil recovery purposes

VERTEKS Kontinentalsokkelen – verdiskaper i verdensklasse?

En utredning om hvordan Norge kan motvirke den antatte nedgangen i petroleumssektorens verdiskaping gjennom økt vekt på FoU. Utredningen bygger på internasjonale og nasjonale forskningsbidrag, anvender anerkjente metoder for beskrivelse og rangering av nye teknologier, vurderer disse teknologienes potensiale i verdiskapingen og gir anbefalinger om hvilke områder FoU innsatsen bør rettes inn mot. Utredningen er gjennomført som et fellesprosjekt mellom RF-Rogalandsforskning, Sintef Petroleumsforskning og konsulentselskapet Berrefjord og Thomassen AS.Norges forskningsråd- Industri og Energ

Increased CO2 storage capacity using CO2 -foam

Reduction of the CO2 mobility is beneficial during subsurface sequestration of anthropogenic CO2 in saline aquifers and hydrocarbon reservoirs by mitigating flow instabilities leading to early gas breakthrough and poor sweep efficiency. Injection of CO2 foam is a field-proven technology for gas mobility control. Foam generation and coalescence are compared between six commercially available surfactants with a range in CO2 solubility, during unsteady state injection of dense CO2-foam in a long sandstone outcrop core (1.15 m). Foam generation categories and foam decay were defined based on the observed changes in foam apparent viscosity during generation and coalescence. The degree of CO2 solubility influenced apparent viscosity development and peak foam strength for the tested surfactants. Variations in foam peak strength resulted in a range of water saturations at CO2 breakthrough (up to 24 percentage points difference observed experimentally), with implications for the CO2 storage capacity.publishedVersio

An Evaluation of Graphene Oxides as Possible Foam Stabilizing Agents for CO2 Based Enhanced Oil Recovery

Graphene oxide, nanographene oxide and partially reduced graphene oxide have been studied as possible foam stabilizing agents for CO2 based enhanced oil recovery. Graphene oxide was able to stabilize CO2/synthetic sea water foams, while nanographene oxide and partially reduced graphene oxide were not able to stabilize foams. The inability of nanographene oxide for stabilizing foams was explained by the increase of hydrophilicity due to size decrease, while for partially reduced graphene oxide, the high degree of reduction of the material was considered to be the reason. Graphene oxide brine dispersions showed immediate gel formation, which improved foam stability. Particle growth due to layer stacking was also observed. This mechanism was detrimental for foam stabilization. Gel formation and particle growth caused these particles to block pores and not being filterable. The work indicates that the particles studied are not suitable for CO2 enhanced oil recovery purposes