461 results found
Amaechi B, Iglauer S, Pentland CH, et al., 2014, An Experimental Study of Three-Phase Trapping in Sand Packs, TRANSPORT IN POROUS MEDIA, Vol: 103, Pages: 421-436, ISSN: 0169-3913
Andrew M, Bijeljic B, Blunt MJ, 2014, Pore-scale contact angle measurements at reservoir conditions using X-ray microtomography, ADVANCES IN WATER RESOURCES, Vol: 68, Pages: 24-31, ISSN: 0309-1708
Leal AMM, Blunt MJ, LaForce TC, 2014, Efficient chemical equilibrium calculations for geochemical speciation and reactive transport modelling, GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 131, Pages: 301-322, ISSN: 0016-7037
Andrew M, Bijeljic B, Blunt MJ, 2014, Pore-scale imaging of trapped supercritical carbon dioxide in sandstones and carbonates, INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 22, Pages: 1-14, ISSN: 1750-5836
Amin SM, Weiss DJ, Blunt MJ, 2014, Reactive transport modelling of geologic CO2 sequestration in saline aquifers: The influence of pure CO2 and of mixtures of CO2 with CH4 on the sealing capacity of cap rock at 37 degrees C and 100 bar, CHEMICAL GEOLOGY, Vol: 367, Pages: 39-50, ISSN: 0009-2541
Guadagnini A, Blunt MJ, Riva M, et al., 2014, Statistical Scaling of Geometric Characteristics in Millimeter Scale Natural Porous Media, TRANSPORT IN POROUS MEDIA, Vol: 101, Pages: 465-475, ISSN: 0169-3913
Dambani SL, Blunt MJ, Tendo F, et al., 2014, Analysis of injectivity decline in some offshore water injectors, Pages: 1417-1437
The challenges and risks relating to injectivity decline due to injection of particulate-laden water are well documented in the petroleum industry and elsewhere. Although different theories have been advanced to rationalize this problem, the modeling aspects remain largely unresolved, putting huge investments at risk. By combining the fractional-flow and deep-bed filtration (DBF) theories, this work formulates a new model for describing reservoir impairments due to suspension transport by injection water. The critical settling velocity of the suspended particulates is determined from fractional-flow theory and used to create a condition at which particle settling will occur, dependent on its size. The particle settling velocity as obtained from Stokes law for laminar flow (NRE <<1) is compared to the critical settling velocity, which is a function of the residence time of the particles, to obtain the optimum transported particle size profile in the formation. Furthermore, the average size of transportable particulates and their total volumes are then obtained and used to determine the volume of deposits which is in turn used to develop a new injectivity decline model for predicting permeability impairment due to the deposition of suspended particles in the porous media. The resulting models are validated by analyzing reported dataset from two water injectors offshore Niger Delta. Overall, the results are reasonable as the impairment model rationalized available field dataset satisfactorily. The developed models should find relevance in the following field applications: (1) quantifying formation damage; (2) optimising water treatment facilities design; (3) implementing an effective and safe backflow operation. Copyright 2014, Society of Petroleum Engineers.
Menke H, Bijeljic B, Andrew M, et al., 2014, Dynamic pore-scale imaging of reactive transport in heterogeneous carbonates at reservoir conditions, 12th International Conference on Greenhouse Gas Control Technologies (GHGT), Publisher: ELSEVIER SCIENCE BV, Pages: 5503-5511, ISSN: 1876-6102
Andrew M, Bijeljic B, Blunt M, 2014, Reservoir Condition Pore Scale Imaging of the Capillary Trapping of CO2, 12th International Conference on Greenhouse Gas Control Technologies (GHGT), Publisher: ELSEVIER SCIENCE BV, Pages: 5427-5434, ISSN: 1876-6102
Reynolds C, Blunt M, Krevor S, 2014, Impact of reservoir conditions on CO2-brine relative permeability in sandstones, 12th International Conference on Greenhouse Gas Control Technologies (GHGT), Publisher: ELSEVIER SCIENCE BV, Pages: 5577-5585, ISSN: 1876-6102
Nunes JPP, Raeini AQ, Bijeljic B, et al., 2014, Simulation of carbonate dissolution at the porescale using a streamline method, Pages: 2549-2553
Carbon dioxide is currently being injected into saline aquifers and depleted oil and gas reservoirs with both enhanced oil recovery (EOR) and carbon capture and storage (CCS) purposes. The injected CO2 in contact with the reservoir fluids creates an acidic mixture that can potentially react with the host rock causing changes in the petrophysical properties of the reservoir. From the experimental point of view much work has been recently published in the scientific literature about the impact of acidic brine in carbonate reservoirs. These laboratory results indicate that strong rock-fluid interactions may occur, however, pore-scale models capable of predicting how the petrophysical changes associated with these reactions can be related to transport properties are yet to be developed. The recent increase in computational power and tomographic capability made possible the acquisition of high resolution images of heterogeneous carbonates that are very suitable to study in detail the flow and transport properties of such rocks. In this paper we demonstrate how micro-CT images of carbonate rocks can be used to model reactive transport at the pore scale. We apply a particle tracking algorithm based on a pore-scale streamline tracing method to simulate carbonate dissolution.
Andrew MG, Bijeljic B, Blunt MJ, 2014, Reservoir-condition pore-scale imaging -contact angle, wettability, dynamics and trapping, Pages: 2804-2808
Firstly capillary trapping is examined in a range of five different rock types, including both carbonates and sandstones. Rocks are imaged both after drainage and imbibition, and in all cases between 65-70% of the CO2 in place after drainage was trapped. Trapped cluster size distributions are compared to rock connectivity as determined using pore network modelling. Better connected pore-spaces tend to have more large clusters relative to small clusters, and visa-versa. This is important as small clusters are more difficult to remobilise by viscous and gravitational forces. They also present a relatively larger surface area for reaction and mineralization. Secondarily wettability is analysed by measuring contact angle manually. In order to do this the contact line was found in 3D and the data set resampled onto planes perpendicular to the contact line at a particular point. Contact angles ranging from 35-55o were found, indicating that the super-critical CO2-brine-carbonate system is weakly water wet. The range in contact angles is interpreted as the result of contact angle hysteresis associated with surface heterogeneity. Finally the first images of CO2 drainage at reservoir conditions are also presented, imaged at Diamond Light Source, represented an unprecented depth of information about pore-scale flow processes.
Menke HP, Bijeljic B, Andrew MG, et al., 2014, Dynamic pore-scale imaging of reactive transport in heterogeneous carbonates at reservior conditions, Pages: 2554-2558
Four carbonate rock types were studied, two relatively homogeneous carbonates, Ketton and Mt. Gambier, and two very heterogeneous carbonates, Estalliades and Portland Basebed. Each rock type was imaged using dynamic x-ray microtomography under the same reservoir and flow conditions to gain insight into the impact of heterogeneity. A 4-mm carbonate core was injected with CO2-saturated brine at 10 MPa and 50oC for 2 hours. Depending on sample heterogeneity and X-ray source, tomographic images were taken at between 30-second and 20-minute time-resolutions and a 4-micron spatial resolution during injection. Changes in porosity, permeability, and structure were obtained and a pore-throat network was extracted. Furthermore, pore-scale flow modelling was performed directly on the binarized image and used to track velocity distributions as the pore network evolved.
Petvipusit R, El Sheikh AM, King PR, et al., 2014, Robust optimisation using spectral high dimensional model representation - An application to CO2 sequestration strategy
Successful CO2 sequestration relies on operation strategies that maximise performance criteria in the presence of uncertainties. Designing optimal injection strategies under geological uncertainty requires multiple simulation runs at different geological models, rendering it computationally expensive. A surrogate model has been successfully used in several studies to reduce the computational burden by approximating the input-output relationships of the simulator with a limited number of simulation runs. However, building the surrogate is a challenging problem since the cost of building the surrogate increases exponentially with dimension. In the current work, we propose the use of Adaptive Sparse Grid Interpolation coupled with High Dimensional Model Representation (ASGI-HDMR) to build a surrogate of high-dimensional problems. This surrogate is then used to assist with finding robust CO2 injection strategies. High Dimensional Model Representation (HDMR) is an ANOVA like technique, which is based on the fact that high-order interactions amongst the input variables may not necessarily have an impact on the output variable; the combination of low-order correlations of the input variables can represent the model in high-dimensional problem. Adaptive Sparse Grid Interpolation (ASGI) is a novel surrogate technique that allows automatic refinement in the dimension where added resolution is needed (dimensional adaptivity). The proposed technique is evaluated on several benchmark functions and on the PUNQ-S3 reservoir model that is based on a real field. For the PUNQ-S3 model, robust CO2 injection strategies were estimated efficiently using the combined ASGI-HDMR technique. Based on our numerical results, ASGIHDMR is a promising approach since it requires significantly fewer forward runs in building an accurate surrogate model for high-dimensional problems in comparison to ASGI without coupling with HDMR. Hence, the ASGI-HDMR enables efficient construction of the surrogates
Abushaikha AS, Blunt MJ, Gosselin OR, 2014, Interface Control Volume Finite Element method for modelling fluid flow in heterogeneous porous media
Modelling fluid flow in highly heterogeneous and fractured reservoirs is a challenging task. These reservoirs typically have a complex structure with large and sharp variations in their material properties. Node Control Volume Finite Element (NCVFE) has been used to model those types of reservoirs at the fracture scale for the last decade. However, since the control volumes are constructed around the nodes and the material properties are assigned on elements, there is a loss of accuracy and associated fluid smearing when modelling multi-phase flows. We present a new numerical method to improve the modelling of multi-phase fluid flow in these reservoirs, called Interface Control Volume Finite Element (ICVFE). The method drastically decreases the smearing effects observed with other CVFE methods, such as NCVFE, while being mass conservative and numerically consistent. The pressure is computed at the interfaces of elements, and the control volumes are constructed around them, instead of at the element nodes. This assures that a control volume straddles, at most, two elements, which decreases the fluid smearing between neighbouring elements when large variations in their material properties are present. Lowest order Raviart-Thomas vectorial basis functions are used for the pressure calculation, and Lagrange basis functions are used to compute fluxes. The method is a combination of Mixed Hybrid Finite Element (MHFE) and FE methods. Its accuracy and convergence are tested using three dimensional tetrahedral elements to represent heterogeneous and fractured reservoirs. Our new approach is shown to be more accurate than current methods in the literature. Significance • The ICVFE produces less unphysical flows than NCVFE while honouring the material properties of the domain. • It also models more accurate fluid saturation profiles than NCVFE. • The ICVFE method defines the primary variables (pressure and saturation) on the interfaces of elements. Therefore, it
Raeini AQ, Bijeljic B, Blunt MJ, 2014, Numerical Modelling of Sub-pore Scale Events in Two-Phase Flow Through Porous Media, TRANSPORT IN POROUS MEDIA, Vol: 101, Pages: 191-213, ISSN: 0169-3913
Gharbi O, Bijelic B, Boek ES, et al., 2013, Changes in Pore Structure and Connectivity Induced by CO2 Injection in Carbonates: A Combined Pore-Scale Approach, International Conference on Greenhouse Gas Technologies (GHGT) 11, Energy Procedia, Publisher: Elsevier, Pages: 5367-5378
We investigate at the pore scale fluid-rock interactions that occur in the context of carbon dioxide (CO2) storage in saline carbonate aquifers. Brine saturated with super critical CO2 is injected into two carbonate samples (Estaillades limestone and an aquifer sample) at typical storage conditions (9 MPa and 50oC). Dry high resolution micro-computed tomography scans are obtained prior to and after the experiments and the pore structure, connectivity and computed flow fields are compared using image analysis and pore-scale modeling techniques. We perform direct simulations of transport properties and velocity fields on the 3D scans and we extract representative pore-throat networks to compute average coordination number and assess changes in pore and throat size distributions. In this study, we experimentally mimic near wellbore region conditions by injecting fluids at relatively high flow rates. For high Péclet and Damköhler numbers, experimental observations confirm the formation of highly conductive channels i.e wormholes. A significant increase in porosity and permeability is found with fewer pore and throats after dissolution while the average coordination number does not change significantly. Flow becomes concentrated in the wormhole regions after reactions although a very wide range of velocities is still observed.
Petvipusit R, Elsheikh AH, Laforce T, et al., 2013, A robust multi-criterion optimization of CO2 sequestration under model uncertainty, Sustainable Earth Sciences, SES 2013: Technologies for Sustainable Use of the Deep Sub-Surface
Successful CO2 storage in deep saline aquifers relies on economic efficiency, sufficient capacity and longterm security of the storage formation. Unfortunately, these three criteria of CO2 storage are generally in conflict, and often difficult to guarantee when there is a lack of geological characteristics of the storage site. We overcome these challenges by developing: 1) multiwell CO2 injection strategies using a multi-criterion optimization to handle conflicting objectives; 2) CO2 injection management that is robust against model uncertainty. PUNQ-S3 model was modified as a leaky storage to study injection strategies associated with the risks of CO2 leakage under geological uncertainty. Based on our numerical results, the NSGA-II with the ASGI technique can effectively obtain a set of efficient-frontier injection strategies. For the uncertainty assessment, the impact of the model uncertainty to the outcomes is significant. Therefore, our findings suggest using the mixture distribution of the objective-function values, as opposed to the traditional Gaussian distribution to cover model uncertainty.
Leal AMM, Blunt MJ, LaForce TC, 2013, A robust and efficient numerical method for multiphase equilibrium calculations: Application to CO2-brine-rock systems at high temperatures, pressures and salinities, ADVANCES IN WATER RESOURCES, Vol: 62, Pages: 409-430, ISSN: 0309-1708
AlSofi AM, Blunt MJ, 2013, Control of Numerical Dispersion in Streamline-Based Simulations of Augmented Waterflooding, SPE JOURNAL, Vol: 18, Pages: 1102-1111, ISSN: 1086-055X
Al-Ansi N, Gharbi O, Raeini AQ, et al., 2013, Influence of micro-computed tomography image resolution on the predictions of petrophysical properties, Pages: 1291-1298
Micro-CT scanning is a non-destructive technique that can provide three-dimensional images of rock pore space at a resolution of a few microns. . However, these greyscale images cannot be directly input into simulators to predict flow properties; they require image processing to segment the solid and void space in the rock. Dynamic and static single phase properties can then be computed using the images directly or on extracted equivalent network models. In this paper, we study the effect of imaging resolution (five different voxel sizes ranging from 6-20 μm) of Clashach and Doddington sandstone on predicted single phase properties (porosity and absolute permeability) and network properties. Experimental data is used to validate the predictions. The results suggest that the computed porosity was largely independent of resolution and in good agreement with the measured value, while image resolutions of a few microns are sufficient to determine the permeability of a high-permeability rock such as Doddington but may not be sufficient for lower permeability samples. The topologically representative networks are sensitive to resolution, adding additional smaller pores and throats as the resolution is increased. This latter reason was confirmed by a network extraction analysis that indicated the average throat radius was 6 nm, similar to the highest resolution used and insufficient to image all important features of the pore space properly. Copyright © 2013 International Petroleum Technology Conference.
Goater AL, Bijeljic B, Blunt MJ, 2013, Dipping open aquifers-The effect of top-surface topography and heterogeneity on CO2 storage efficiency, INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 17, Pages: 318-331, ISSN: 1750-5836
Andrew M, Bijeljic B, Blunt MJ, 2013, Pore-scale imaging of geological carbon dioxide storage under in situ conditions, GEOPHYSICAL RESEARCH LETTERS, Vol: 40, Pages: 3915-3918, ISSN: 0094-8276
Tanino Y, Blunt MJ, 2013, Laboratory investigation of capillary trapping under mixed-wet conditions, WATER RESOURCES RESEARCH, Vol: 49, Pages: 4311-4319, ISSN: 0043-1397
Bijeljic B, Mostaghimi P, Blunt MJ, 2013, Insights into non-Fickian solute transport in carbonates, Water Resources Research, Vol: 49, Pages: 2714-2728, ISSN: 0043-1397
 We study and explain the origin of early breakthrough and long tailing plume behavior by simulating solute transport through 3‐D X‐ray images of six different carbonate rock samples, representing geological media with a high degree of pore‐scale complexity. A Stokes solver is employed to compute the flow field, and the particles are then transported along streamlines to represent advection, while the random walk method is used to model diffusion. We compute the propagators (concentration versus displacement) for a range of Peclet numbers (Pe ) and relate it to the velocity distribution obtained directly on the images. There is a very wide distribution of velocity that quantifies the impact of pore structure on transport. In samples with a relatively narrow spread of velocities, transport is characterized by a small immobile concentration peak, representing essentially stagnant portions of the pore space, and a dominant secondary peak of mobile solute moving at approximately the average flow speed. On the other hand, in carbonates with a wider velocity distribution, there is a significant immobile peak concentration and an elongated tail of moving fluid. An increase in Pe , decreasing the relative impact of diffusion, leads to the faster formation of secondary mobile peak(s). This behavior indicates highly anomalous transport. The implications for modeling field‐scale transport are discussed.
Rhodes M E, Bijeljic B and Blunt M J, 2009, A Rigorous Pore-to-Field-Scale Methodology for Single-Phase Flow Based on Continuous Time Random Walks
Pentland CH, Al-Mansoori S, Iglauer S, et al., 2010, Measurement of non-wetting phase trapping in sand packs, SPE 115697
Pentland CH, Tanino Y, Iglauer S, et al., 2010, Capillary Trapping in Water-Wet Sandstones: Coreflooding Experiments and Pore-Network Modeling, SPE Annual Technical Conference and Exhibition
Bijeljic B, Blunt M J, 2006, A Physically-based Description of Dispersion in Porous Media, Annual Technical Conference of the Society of Petroleum Engineers
Sobers LE, Blunt MJ, LaForce TC, 2013, Design of Simultaneous Enhanced Oil Recovery and Carbon Dioxide Storage With Potential Application to Offshore Trinidad, SPE JOURNAL, Vol: 18, Pages: 345-354, ISSN: 1086-055X
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