Flow and Transport Properties of Unconventional Reservoirs 2018
Harpreet Singh2019
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Abstract
Advances in Geo-Energy Research and serves as an Associate/Guest Editor for other international journals. Dr. Cai focuses on the petrophysical characterization and micro-transport phenomena in porous media, as well as fractal theory and its application. He has published more than 110 peer-refereed journal articles, three books, and numerous book chapters. Zhien Zhang is currently a postdoctoral researcher in the William G. Lowrie Department of Chemical and Biomolecular Engineering at Ohio State University. His research interests include advanced processes and materials (i.e., membranes) for CO2 capture, CCUS processes, gas separation, and gas hydrates. Dr. Zhang has published 80+ journal papers and 10+ editorials in high-impact journals, including Renewable and Sustainable Energy Reviews. He has written three Hot Papers (top 0.1%) and 10 Highly Cited Papers (top 1%). He also serves as an Editor or Guest Editor for several international journals, including Applied Energy, Fuel, and Journal of Natural Gas Science and Engineering. He currently works as a Visiting Professor at the University of Cincinnati. Qinjun Kang is a senior scientist at the Earth and Environmental Sciences (EES) Division of Los Alamos National Laboratory (LANL). His current research focuses on the modeling and simulation of transport and interfacial processes in porous media at the pore (nano/meso) scale, and on multiscale models bridging different scales. His work is applied to problems in a broad range of engineering and science disciplines, including the geologic storage of carbon dioxide and nuclear waste, conventional and unconventional hydrocarbon exploration and production, the fate and transport of underground contaminants, and the engineering of energy storage and conversion devices (e.g., fuel cells and batteries). Dr. Kang has coauthored more than 100 publications, which have been cited nearly 6000 times. He has been invited to give 20+ talks at various international and national conferences, universities, national laboratories, and industries, and has organized/chaired sessions at numerous conferences. He is currently a member of the Editorial Board or an Associate Editor for multiple journals, and has served as a reviewer for over 50 journals and numerous funding agencies, including DOE and NSF. Dr. Kang has been a top publisher in the EES Division at LANL since 2010.
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Society of Petroleum Engineers - International Petroleum Technology Conference 2014, IPTC 2014: Unlocking Energy Through Innovation, Technology and Capability
2014
We first present a new method to generate stochastic random networks representing the pore space of different rocks with given input pore and throat size distributions and connectivity-these distributions can be obtained from an analysis of pore-space images. The stochastic networks can be arbitrarily large and hence are not limited by the size of the original image. We then develop a rate-dependent network model that accounts for viscous forces by solving for the wetting and non-wetting phase pressure and which allows wetting layer swelling near an advancing flood front. We propose a new time-dependent algorithm by accounting for partial filling of elements. We use the model to study the effects of capillary number (N cap , the ratio of viscous forces to capillary forces), mobility ratio (M) and network size on imbibition displacement patterns and saturation profiles. By employing large networks we reproduce Buckley-Leverett profiles directly from pore-scale modelling thereby providing a bridge between pore-scale and macro-scale transport. We show how capillary and viscous forces act over different length scales and how this behaviour can be incorporated into averaged mathematical models of the flow.
Journal of Petroleum Science and Engineering
Dissolution of liquefied carbon dioxide in a turbulent tubing flow for geologic sequestration in aquifers is simulated. The problem is solved by a two-fluid approach in a three dimensional formulation. For accurate calculation of the droplet dissolution rate, an evolution of droplet size distribution along a tubing is modelled by the population balance equation accounting for droplet breakup, coalescence and interphase mass transfer. The dissolution rate in a horizontal tubing is rather slow due to gravity-induced droplet stratification. The dissolution process in a horizontal tubing is compared with that in a coiled tubing wound on a horizontal reel. In a coiled tubing flow, droplet stratification significantly decreases due to the gravity force causing periodical motion of droplets across the tubing. At relatively high flow velocities, CO2 droplets are well-dispersed even across a horizontal tubing. Droplet dissolution is rather fast in this case, and a notable difference in the dissolution rates in straight and coiled tubing is not observed. An effect of the flow rate on the dissolution process at different tubing diameters is illustrated. Thus, numerical studies show that a coiled tubing can be efficiently used for intensification of liquefied carbon dioxide dissolution for relatively low and moderate flow rates.
Assessment of Geochemical Limitations to Utilizing CO2 as a Cushion Gas in Compressed Energy Storage Systems
Environmental Engineering Science
Compressed energy storage (CES) of air, CO 2 , or H 2 in porous formations is a promising means of energy storage to abate the intermittency of renewable energy production. During operation, gas is injected during times of excess energy production and extracted during excess demands to drive turbines. Storage in saline aquifers using CO 2 as a cushion or working gas has numerous advantages over typical air storage in caverns. However, interactions between CO 2 and saline aquifers may result in potential operational limitations and have not been considered. This work utilizes reactive transport simulations to evaluate the geochemical reactions that occur during injection and extraction operational cycles for CES in a porous formation using CO 2 as a cushion gas. Simulation results are compared with similar simulations considering an injection-only flow regime of geologic CO 2 storage. Once injected, CO 2 creates conditions favorable for dissolution of carbonate and aluminosilicate minerals. However, the dissolution extent is limited in the cyclic flow regime where significantly smaller dissolution occurs after the first cycle such that CO 2 is a viable choice of cushion gas. In the injection-only flow regime, larger extents of dissolution occur as the fluid continues to be undersaturated with respect to formation minerals throughout the study period and porosity increased uniformly from 24.84% to 33.6% throughout the simulation domain. For the cyclic flow conditions, porosity increases nonuniformly to 31.1% and 25.8% closest and furthest from the injection well, respectively.
Journal of Natural Gas Science and Engineering
Coal fines production and structural collapse during waterflooding process was widely observed and reported in several coalbed methane (CBM) fields. Besides, fines migration also plays a major role in the destruction of coal cleats and consequently, declining the gas recovery. This paper presents the coal fines production in lignite core as a function of kaolinite. Actually, it is a clay fine particle that rests on coal surface under the dominances of the four forces, namely, lift, drag, gravity, and electrostatics. Under hydrodynamic and thermodynamic forces these fines detach from the rock surface and migrate in the porous interspace, and at a certain point it is captured, and thereby deteriorating the well productivity and structural collapse as well. Many researchers have investigated these fines migration mechanisms in anthracite and bituminous coals, but to best of our knowledge till date this research was not carried out in lignite coals. In order to successfully demonstrate this mechanism in lignite, three sets of coreflood experiments have been conducted under ambient conditions for analyzing the coal and kaolinite fines transport and their impact on gas recovery. Lignite samples are procured from Neyveli Mines at Cauvery Basin in Southern India and then the simulated version is used for the analysis. The coreflood results revealed that the gas recovery increases for increasing PVI and that there is an observation of pressure drop across the core for increasing PVI and this phenomenon is attributed to enhancing concentration of fines. Additionally, the water flow velocity elevates the velocity of coal fines and the microstructural analysis indicated the presence of kaolinite flakes among coal fines. The entire experimental model was tested against the statistical model in SPSS and showed good agreement. Overall, it is understood that even lignite reservoirs are prone to fines migration and permeability decline.
An integrated core-based analysis for the characterization of flow, transport and mineralogical parameters of the Heletz pilot CO 2 storage site reservoir
International Journal of Greenhouse Gas Control, 2016
Heletz, Israel is the location for an onshore deep saline CO 2 storage pilot site. The 'Heletz sandstone' is the building unit of the deep saline reservoir. Based on core samples of sandstone and caprock taken from the newly drilled injection (H18A) and monitoring wells (H18B), this article examines and reports the petrophysical properties of the Heletz Formation reservoir important for the short and long term trapping of CO 2. A suite of laboratory and pore-scale CT-based modeling techniques are employed to determine the flow and transport parameters used by the continuum-scale numerical simulators and the mineral composition necessary for the understanding of mineral trapping processes. The effect of diagenesis on the reservoir parameters was determined in the laboratory using sedimentological, petrological, and petrophysical analyses. Variations in 87 Sr/ 86 Sr isotope composition and fluid inclusion analysis bring additional information about the diagenetic development and define the status quo of fluid-mineral reactions before CO 2 injection. Cathodoluminescence microscopy and SEM/XRD revealed the amounts of minerals in the sandstone samples and caprock and explained the poor binding of the sandstone which may lead to mobilized material during injection. Digital image analysis on thin sections, cathodoluminescence, and SEM were integrated with attributes derived from mercury intrusion porosimetry, steady state gas permeametry or nuclear magnetic resonance to form an essential outline for the Heletz Formation reservoir. This relates storage space, injectivity and storage efficiency to features such as grain size, pore size distribution, effective porosity, intrinsic permeability, or tortuosity. Furthermore, the laboratory and numerical CT-based investigation techniques are compared and discussed. The benefit of combining experimental methods and numerical simulations on pore-scale models is the increase in confidence of the parameter accuracy, fundamental for the success of the planned activities at Heletz.
IOSR Journal of Engineering (IOSR-JEN) Volume 5 ~ Issue 4 ~ Version 2
The development of oil and gas exploration and petroleum geology in the global transfer from the micro pore throat in oil and gas traps, continuous oil and gas gradually to the nano pore aggregation tendency. A large number of research literature, starting from the connotation of coal bed methane CBM, discussed the geological conditions for reservoir forming, as well as the influence of coal bed methane reservoir geological factors.
Improving multi-phase flow modelling of CO<sub>2</sub>/brine/rock systems using van Genuchten's empirical model
2019
In recent years, assessing the safety and feasibility of long-term geological CO2 sequestration (GCS) usually relies on model-based forecasting of the sub-surface behaviour of CO2. In the application of two-phase flow in porous media, numerical simulations are usually implemented using empirical formulations by either Brooks-Corey (BC) or van Genuchten (vG) to describe the transport properties in a CO2/brine/rock system. The forward modelling of GCS is often prompted by uncertainties in fluid flow and transport processes, which are majorly governed by structural complexity resulting from the sedimentary properties of the porous media. Since flow characteristics can vary within the reservoir and sealing formation, this thesis investigates the consequences of sedimentary heterogeneities, such as gradation, cementation, interbedded argillaceous units, in the storage formation on the transport and flow processes of CO2/brine systems. The study focuses on CO2 storage in siliciclastic aquifers and examines the effects of the dynamic representation of grain-scale heterogeneities on multiphase fluid flow during geological CO2 storage. This was implemented by relating a number of sedimentary processes and structures in the reservoir and caprock formation to the constitutive functions of relative permeability and capillary pressure using the van Genutchten's empirical model. A set of continuum-scale numerical simulations was conducted to investigate the impact of variability in these constitutive functions using simulators that are based on Darcy-flow physics. Firstly, the pore geometry parameter, which is an empirical constant in both BC and vG model, was described for different clastic rocks using numerical validation of statistical data from soil physics. This enables the adaptability of the pore geometry parameter to the type of clastic rock, thus proposing a new methodology for the effective characterisation of the pore geometry parameter for different clastic rocks. The effect of key parameters in the vG empirical model, such as the pressure strength coefficient, the pore geometry parameter and the connate saturation (wetting and non-wetting), on GCS was also incorporated in the numerical investigations. Trapping mechanisms such as structural, residual and dissolution are assessed in this thesis using Bunter Sandstone Formation (Chapter 4), Mercia Mudstone Group (Chapter 5) and Utsira Sandstone Formation (Chapter 6) as case studies. Results showed that relative permeability assumptions have a significant impact on the afore listed trapping mechanisms as well as the pore pressure distribution within the reservoir and caprock formation. It argues for the adequate representation of small-scale heterogeneities in large-scale forward modelling of CO2 storage, especially when describing the capillary pressure and relative permeability functions. The characterisation of the pore gemetry parameter serves as a formative tool for describing capillary pressure and relative permeability heterogeneities that could arise from sedimentary structures in clastic reservoir formations and their subsequent impact on CO2/brine transport processes in a porous medium. ii Acknowledgement I would like to thank my supervisors Seyed Shariatipour, Adrian Wood and John Williams for all the guidance they have provided on this project. My gratitude goes to the British Geological Survey (Nottingham) for providing access to research facilities during a six-week visit and to all members of the CO2 Storage Team for technical discussions and providing useful recommendation during the numerical study that was conducted there. I would also like to thank the Faculty Research Centre for Fluid and Complex Systems as well as the Doctoral College for supporting my research mobility across the UK and several other European countries. The students and staff in Maudslay House with whom I have spent many days in the office and shared a cuppa are all thanked. Special thanks goes to my family, The Onojas, The Cireasas and The Azubuikes, for the encouragement through the years. This project is dedicated to my wife, Annamaria Onoja, with a heartfelt appreciation for her love and unwavering support during this experience. Multumesc Frumos Ufedo Mi.
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Clean Energy Systems in the Subsurface: Production, Storage and Conversion
Springer Series in Geomechanics and Geoengineering, 2013
Exploring CO2 geological storage mechanisms at the pore scale using microfluidics approaches
HAL (Le Centre pour la Communication Scientifique Directe), 2019
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Assessment of the CO2 sealing efficiency of pelitic rocksTwo-phase flow and diffusive transport
Greenhouse Gas Control Technologies 7, 2005
The capillary sealing efficiency of intermediate to low permeable rocks has been investigated by CO 2 , N 2 and CH 4 breakthrough experiments on initially fully water-saturated samples of different lithological compositions. Gas breakthrough experiments were performed by creating an instantaneous high pressure gradient up to 20 MPa across sample plugs of 1-2 cm length. Monitoring the resulting gas flux after breakthrough and the final pressure difference maintained across the sample at the end of the experiments reveals information on the effective permeability coefficients to the gas phase as a function of capillary pressure and the minimum capillary pressure (P d) for which the seal starts to leak. For the rock samples tested in this study the minimum capillary displacement pressures (P d) ranged from < 0.1 up to 6.7 MPa. The maximum effective permeability coefficients range from 10-23 to 10-18 m 2 for the N 2 and CH 4 experiments, and from 10-24 to 10-20 m 2 for the CO 2 experiments. Absolute (single phase) permeability coefficients (k abs), determined by steady state fluid flow tests prior to the gas breakthrough experiments, ranged between 10-15 and 10 22 m 2. For samples with nominal k eff(max)-values <10 24 m 2 gas transport was attributed to molecular diffusion. Using a newly developed experimental setup , molecular diffusion experiments with CO 2 were performed on water-saturated rock and coal samples from different locations. Experiments were conducted at subsurface pressure and temperature conditions (fluid pressures ~ 6 MPa; temperatures 45 & 50°C) and yielded effective diffusion coefficients between 1•10 9 and 3•10 11 m²/s.
Reactive Transport: Experiments and Pore-Network Modelling
Dissolution and deposition phenomena are key issues in the CO 2 geological storage. In the past few years, it has been proven that CO 2 injection can lead to important pore structure modifications which mainly depend on the thermodynamic conditions, the rock and fluid composition and the flow regime. Predicting these modifications and their impact on the reservoir permeability and porosity is crucial for the success of CO 2 sequestration projects. This paper presents an experimental and numerical study to evaluate in a comprehensive manner the impact of the deposition regimes on the relationships between permeability and porosity. Experiments have been performed in glass micromodels to visualize deposition mechanisms for different regimes. A reactive transport model using the pore-network approach has been developed to simulate the deposition phenomenon in the case of a single-phase flow. This numerical model is based on solving the macroscopic convection-diffusion equation. Its mac...
In-situ pore-scale imaging and image-based modelling of capillary trapping for geological storage of CO2
International Journal of Greenhouse Gas Control, 2019
We describe an imaging and pore-scale modelling study of capillary trapping in the Paaratte Sandstone formation in the Otway Basin, Australia. Three-dimensional X-ray computed tomography (micro-CT) was used to characterize the pore structure of the reservoir core. We obtain in-situ pore-scale images of the distribution of CO 2 :brine analogue fluid pairs (octane:brine) within reservoir samples during low capillary number drainage and imbibition flooding experiments. The images were recorded using time-lapse X-ray micro-tomography at elevated pressure. The observed two-phase fluid distributions are consistent with a water wet system. The micro-CT images are used directly as input to a geometrically accurate quasi-static pore-scale simulation model. The validity of the quasi-static assumption is investigated by comparing on a pore-by-pore basis the simulated and imaged fluid distributions. The pore filling states are in good agreement both for drainage and imbibition displacements and the computed capillary trapping curve agrees with experimental data. This indicate that quasistatic pore-scale physics can be used to obtain averaged or continuum flow properties for low capillary number displacements. We perform a sensitivity study of the impact of the advancing contact angle on capillary trapping. The magnitude of residual trapping increases with decreasing contact angle. Land's trapping coefficient increases with increasing contact angle. We compute capillary pressure and relative permeability scanning curves. Simulated relative permeability hysteresis is compared with that predicted by the industry-standard Carlson's and Killough's models. Killough's model reproduces the simulated data more accurately.
The special issue “Underground storage of CO2 and energy” in the framework of the 3rd Sino-German conference in May 2013
Acta Geotechnica, 2014
Greenhouse gas emissions, energy security and sustainability are three of the greatest contemporary global challenges to mankind today. The Sino-German Group of scientists have composed a special issue, which is a collection of diverse quality scientific works, that will try to elucidate the current developments in CO 2 geologic sequestration research to reduce greenhouse emission including measures to monitor surface leakage, groundwater quality and the integrity of caprock, while ensuring a sufficient supply of clean energy.
Pore-scale heterogeneity, energy dissipation and the transport properties of rocks
Geophysical Research Letters, 1995
The pore structure of rocks is highly complex, with wide variations in pore size and shape. In this work, pore-scale heterogeneity was simulated by distributing spheres, tubes and cracks with variable dimensions on a square lattice. The transport properties of 100 such network realizations, covering 11 orders of magnitude in permeability, were calculated. Seeking the appropriate averaging procedure to calculate the permeability and electrical conductivity from the local pore parameters, we computed the energy locally dissipated in each bond during fluid or electric flow and the energy globally dissipated in the whole network. By equating the latter to the sum of the former, we obtained averaging expressions exactly predicting the transport properties of the network realizations. Since these relations hold on a wide variety of heterogeneous networks covering a broad range of permeabilities and electrical conductivities, we propose that they should also be valid on rocks. We can thus gain insights into how pore-scale heterogeneity affects the transport properties of rocks.
Investigating underground CO2 storage in porous media using geological labs on chip
HAL (Le Centre pour la Communication Scientifique Directe), 2018
CO2 geological storage in deep saline aquifers represents a mediation solution for reducing the anthropogenic CO2 emissions. Consequently, this kind of storage requires adequate scientific knowledge and tools at the pore scale to evaluate injection scenarios or to estimate reservoir capacity. In this context, porous media designed inside high pressure / high temperature microfluidic reactors (micromodel or geological labs on chip-GLoCs) turn out to be excellent tools to complement the classical core-scale experimental approaches to investigate the different mechanisms associated with CO2 geological storage in deep saline aquifers). This paper will first highlight the latest results obtained at ICMCB concerning the application of the GLoCs to study the invasion processes of CO2 in water and brine saturated GLoCs. In particular, direct optical visualization and image treatments allow following the evolution of the CO2/brine phase distribution within the pores, including displacement mechanisms and pore saturation levels. Finally, we will present some ongoing work aiming at integrating in situ spectroscopy techniques in HP microreactors to get information about the dissolution and mineralization trapping. Beyond CO2 geological storage investigations, the GLoCs could also find wider applications in geological-related studies such as Enhanced Oil Recovery, shale gas recovery or geothermal energy.
Energy geotechnology: Implications of mixed fluid conditions
2010
Multi phase fluids are common in energy-related geotechnical problems, including gaswater, gas-oil, ice-water, hydrate-water, and oil-water fluid conditions. The generalization of classical unsaturated soil mechanics concepts to energy geotechnology requires physical understanding of surface tension, contact angle, capillary pressure, solubility and nucleation. Eventually, these pore-level processes affect the granular skeleton. Together, pore and particle-scale interactions upscale through the sediment structure to affect its macroscale response. Possible emergent phenomena include fluid percolation, residual saturation and recovery efficiency; fluid driven fractures, lenses, fingering and pipe formation; bubble migration and bottom blow up.
Geophysical assessments of renewable gas energy compressed in geologic pore storage reservoirs
SpringerPlus, 2014
Renewable energy resources can indisputably minimize the threat of global warming and climate change. However, they are intermittent and need buffer storage to bridge the time-gap between production (off peak) and demand peaks. Based on geologic and geochemical reasons, the North German Basin has a very large capacity for compressed air/gas energy storage CAES in porous saltwater aquifers and salt cavities. Replacing pore reservoir brine with CAES causes changes in physical properties (elastic moduli, density and electrical properties) and justify applications of integrative geophysical methods for monitoring this energy storage. Here we apply techniques of the elastic full waveform inversion FWI, electric resistivity tomography ERT and gravity to map and quantify a gradually saturated gas plume injected in a thin deep saline aquifer within the North German Basin. For this subsurface model scenario we generated different synthetic data sets without and with adding random noise in order to robust the applied techniques for the real field applications. Datasets are inverted by posing different constraints on the initial model. Results reveal principally the capability of the applied integrative geophysical approach to resolve the CAES targets (plume, host reservoir, and cap rock). Constrained inversion models of elastic FWI and ERT are even able to recover well the gradual gas desaturation with depth. The spatial parameters accurately recovered from each technique are applied in the adequate petrophysical equations to yield precise quantifications of gas saturations. Resulting models of gas saturations independently determined from elastic FWI and ERT techniques are in accordance with each other and with the input (true) saturation model. Moreover, the gravity technique show high sensitivity to the mass deficit resulting from the gas storage and can resolve saturations and temporal saturation changes down to ±3% after reducing any shallow fluctuation such as that of groundwater table.
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