Experimental study of electrical heating to enhance oil production from oil-wet carbonate reservoirs

New approaches for enhanced oil recovery (EOR) with a reduced environmental footprint are required to improve recovery from mature oil fields, and when combined with carbon capture and storage (CCS) can provide useful options for resource maximisation during the net zero transition. Electrical heating is investigated as a potential EOR method in carbonate reservoirs. Samples were placed in an apparatus surrounded by a wire coil across which different DC (direct current) voltages were applied. Monitoring the imbibition of both deionized water (DW) and seawater (SW) into initially oil-wet Austin chalk showed that water imbibed into the rock faster when heated in the presence of a magnetic field. This was associated with a reduction in the water–air contact angle over time measured on the external surface of the sample. Without heating, the contact angle reduced from 127° approaching water-wet conditions, 90°, in 52 min, while in the presence of heating with 3 V, 6 V, and 9 V applied across a sample 17 mm in length, the time required to reach the same contact angle was only 47, 38 and 26 min, respectively, while a further reduction in contact angle was witnessed with SW. The ultimate recovery factor (RF) for an initially oil-wet sample imbibed by DW was 13% while by seawater (SW) the recorded RF was 26% in the presence of an electrical heating compared with 2.8% for DW and 11% for SW without heating. We propose heating as an effective way to improve oil recovery, enhancing capillary-driven natural water influx, and observe that renewable-powered heating for EOR with CCS may be one option to improve recovery from mature oil fields with low environmental footprint

Comparison of CO2 trapping in highly heterogeneous reservoirs with Brooks-Corey and van Genuchten type capillary pressure curves

Geological heterogeneities essentially affect the dynamics of a CO2 plume in subsurface environments. Previously we showed how the dynamics of a CO2 plume is influenced by the multi-scale stratal architecture in deep saline reservoirs. The results strongly suggest that representing small-scale features is critical to understanding capillary trapping processes. Here we present the result of simulation of CO2 trapping using two different conventional approaches, i.e. Brooks-Corey and van Genuchten, for the capillary pressure curves. We showed that capillary trapping and dissolution rates are very different for the Brooks-Corey and van Genuchten approaches when heterogeneity and hysteresis are both represented.Comment: 10 pages 6 figure

Protein–like fully reversible tetramerisation and super-association of an aminocellulose

Unusual protein-like, partially reversible associative behaviour has recently been observed in solutions of the water soluble carbohydrates known as 6-deoxy-6-(v-aminoalkyl)aminocelluloses, which produce controllable self-assembling films for enzyme immobilisation and other biotechnological applications. Now, for the first time, we have found a fully reversible self-association (tetramerisation) within this family of polysaccharides. Remarkably these carbohydrate tetramers are then seen to associate further in a regular way into supra-molecular complexes. Fully reversible oligomerisation has been hitherto completely unknown for carbohydrates and instead resembles in some respects the assembly of polypeptides and proteins like haemoglobin and its sickle cell mutation. Our traditional perceptions as to what might be considered ‘‘protein-like’’ and what might be considered as ‘‘carbohydrate-like’’ behaviour may need to be rendered more flexible, at least as far as interaction phenomena are concerned

Numerical modeling for the prediction of residual CO<inf>2</inf>trapping in water-wet geological porous media

© 2016 Society of Petroleum Engineers. All rights reserved. Residual trapping of CO2has been identified as a reliable and rapid way to dispose large CO2quantities. Several experimental investigations have been completed where residual trapping in sandstone was measured; these programmes identified that initial CO2saturation and rock porosity are significant parameters which influence the residual saturation and thereby residual trapping capacity and effectiveness. In order to further improve fundamental understanding a computational tool need to be developed with which residual CO2saturations can be predicted. Pore-scale two-phase fluid flow simulation is performed based on the integration of x-ray micro-tomography images (which provide a detailed description of the rock's pore space) and Navier-Stokes equations. X-ray micro-tomography (approximately (6µm)3voxel size) images of F42 sand pack were used. The extracted pore morphology of each medium was obtained by segmenting the images based on their greyscale contrast using image processing software AVIZO Fire. These binary images were converted initially into surface and volume meshes which were then fed into a commercially available computational fluid dynamics code (ANSYS-CFX). Three dimensional transient, laminar flow fields were obtained by solving the continuity and Navier-Stokes equations using an Eulerian-Eulerian multi-phase flow approach. To incorporate the effect of capillary forces, free surface model was used which solved the pressure gradient at the interface correctly. The model assumes isothermal condition with no mass transfer between the brine and CO2. The inlet and outlet boundary conditions include CO2flow rate and the pressure respectively. We simulated the drainage condition in this paper. Approximately 1.5 million tetrahedral elements were used to generate volume mesh, and the convergence criterion for all variables was set to 10-3. Initially all pore space was filled with brine, and then CO2was injected from one inlet side at constant flow rate, obtained from the experiments. When the system was at connate water saturation, we stopped our simulation. The residual saturation depends on the flow rate of super critical CO2. The computations described here are a rapid, cost-effective and can reveal vital information for the planning of carbon geo-sequestration projects and associated risk and capacity assessments

Investigating impact of various properties on relative permeability and non-wetting phase fractional flow in brine/oil system in water-wet reservoir rock by numerical simulation

© 2017, Society of Petroleum Engineers. In this paper, pore-scale numerical modelling predictions are performed to investigate variations in relative permeability behaviour and oil fractional flow under a range of different parameters (contact angle, capillary number and flow direction) through Brine/Oil system in Ottowa F42 Sand Pack. AVIZO (high-performance 3D image processing software) is used to separate the Micro-computed tomography (micro-CT) images of the pore spaces of rocks from grains of Ottowa F42 Sand Pack. ANSYS-CFX (high- performance CFD based simulator) is used to generate volume mesh and carry-out numerical simulation. The simulation results were analysed and compared with other experimental and numerical works. At low capillary number, the relative permeability curves were not smooth. Almost similar trends for relative permeability were observed for the imbibition process by alternate injection of oil and brine. Increase in contact angle showed less effect on fluid relative permeability and oil fractional flow. Also, alternate injection of fluids in imbibition showed a little response on fluid relative permeability and oil fractional flow. The outcomes of this investigation will be extended to intermediate-wet and oil-wet media and also for carbonate formations

Genome sequence of Galleria mellonella (greater wax moth)

10.1128/genomeA.01220-17Genome Announcements62e01220-1