Name: microfluidic fabrication techniques for high-pressure testing of microscale supercritical co2 foam transport in fractured unconventional reservoirs
Uploaded: 2020-07-02T13:30:00
Description: Watch this Scientific Journal Video about Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs at JoVE.co

The authors from the University of Wyoming gratefully acknowledge support as part of the Center for Mechanistic Control of Water-Hydrocarbon-Rock Interactions in Unconventional and Tight Oil Formations (CMC-UF), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science under DOE (BES) Award DE-SC0019165. The authors from the University of Kansas would like to acknowledge the National Science Foundation EPSCoR Research Infrastructure Improvement Program: Track -2 Focused EPSCoR Collaboration award (OIA- 1632892) for funding of this project. Authors also extend their appreciation to Jindi Sun from the Chemical Engineering Department, University of Wyoming for her generous help in instrument training. SAA thanks Kyle Winkelman from the University of Wyoming for his help with constructing the imaging and UV stands. Last but not the least, the authors gratefully acknowledge John Wasserbauer from microGlass, LLC for useful discussions regarding the SLE technique.

CAUTION: This protocol involves handling a high-pressure setup, a high-temperature furnace, hazardous chemicals, and UV light. Please read all relevant material safety data sheets carefully and follow chemical safety guidelines. Review pressure testing (hydrostatic and pneumatic) safety guidelines including required training, safe operation of all equipment, associated hazards, emergency contacts, etc. before starting the injection process.
1. Design geometrical patterns
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	<li>Design a p...

<ol>
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S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shale+gas+and+non-aqueous+fracturing+fluids:+Opportunities+and+challenges+for+supercritical+CO2.">Shale gas and non-aqueous fracturing fluids: Opportunities and challenges for supercritical CO2.</a> Applied Energy. 147 (1), 500-509 (2015).</li><li>Hosseini, H., Tsau, J., Peltier, E., Barati, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lowering+Fresh+Water+Usage+in+Hydraulic+Fracturing+by+Stabilizing+scCO2+Foam+with+Polyelectrolyte+Complex+Nanoparticles+Prepared+in+High+Salinity+Produced+Water.">Lowering Fresh Water Usage in Hydraulic Fracturing by Stabilizing scCO2 Foam with Polyelectrolyte Complex Nanoparticles Prepared in High Salinity Produced Water.</a> SPE-189555-MS. , (2018).</li><li>Gregory, K. B., Vidic, R. D., Dzombak, D. 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B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+stable+scCO2-high+salinity+brine+interface+for+waterless+fracturing+using+polyelectrolyte+complex+nanoparticles.">Highly stable scCO2-high salinity brine interface for waterless fracturing using polyelectrolyte complex nanoparticles.</a> Abstract Paper of American Chemical Society. 256, (2018).</li><li>Al-Muntasheri, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+Review+of+Hydraulic-Fracturing+Fluids+for+Moderate-+to+Ultralow-+Permeability+Formations+Over+the+Last+Decade.">Critical Review of Hydraulic-Fracturing Fluids for Moderate- to Ultralow- Permeability Formations Over the Last Decade.</a> SPE Production &amp; Operations, SPE-169552. 29 (04), 243-260 (2014).</li><li>Tong, S., Singh, R., Mohanty, K. 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W., Christophersen, A., Skibenes, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mobility+control+during+CO2+EOR+in+fractured+carbonates+using+foam:+Laboratory+evaluation+and+numerical+simulations.">Mobility control during CO2 EOR in fractured carbonates using foam: Laboratory evaluation and numerical simulations.</a> Journal of Petroleum Science and Engineering. 135, 442-451 (2015).</li><li>Middleton, R., Viswanathan, H., Currier, R., Gupta, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CO2+as+a+fracturing+fluid:+Potential+for+commercial-scale+shale+gas+production+and+CO2+sequestration.">CO2 as a fracturing fluid: Potential for commercial-scale shale gas production and CO2 sequestration.</a> Energy Procedia. 63, 7780-7784 (2014).</li><li>Guo, F., Aryana, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+sweep+efficiency+due+to+foam+flooding+in+a+heterogeneous+microfluidic+device.">Improved sweep efficiency due to foam flooding in a heterogeneous microfluidic device.</a> Journal of Petroleum Science and Engineering. 164, 155-163 (2018).</li><li>Nazari, N., Hosseini, H., Jyun-Syung, T., Shafer-Peltier, K., Marshall, C., Ye, Q., Ghahfarokhi, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+Highly+Stable+Lamella+Using+Polyelectrolyte+Complex+Nanoparticles:+An+Environmentally+Friendly+scCO2+Foam+Injection+Method+for+CO2+Utilization+Using+EOR.">Development of Highly Stable Lamella Using Polyelectrolyte Complex Nanoparticles: An Environmentally Friendly scCO2 Foam Injection Method for CO2 Utilization Using EOR.</a> Fuel. 261, 11636 (2020).</li><li>Nguyen, V. H., Kang, C., Roh, C., Shim, J. 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F., Coddington, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancement+of+storage+capacity+of+CO2+in+megaporous+saline+aquifers+using+nanoparticle-stabilized+CO2+foam.">Enhancement of storage capacity of CO2 in megaporous saline aquifers using nanoparticle-stabilized CO2 foam.</a> International Journal of Greenhouse Gas Control. 87, 134-141 (2019).</li><li>Guo, F., Aryana, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+experimental+investigation+of+nanoparticle-stabilized+CO2+foam+used+in+enhanced+oil+recovery.">An experimental investigation of nanoparticle-stabilized CO2 foam used in enhanced oil recovery.</a> Fuel. 186, 430-442 (2016).</li><li>Guo, F., He, J., Johnson, A., Aryana, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stabilization+of+CO2+foam+using+by-product+fly+ash+and+recyclable+iron+oxide+nanoparticles+to+improve+carbon+utilization+in+EOR+processes.">Stabilization of CO2 foam using by-product fly ash and recyclable iron oxide nanoparticles to improve carbon utilization in EOR processes.</a> Sustainable Energy and Fuels. 1, 814-822 (2017).</li><li>Wang, Y., Shahvali, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Discrete+fracture+modeling+using+Centroidal+Voronoi+grid+for+simulation+of+shale+gas+plays+with+coupled+nonlinear+physics.">Discrete fracture modeling using Centroidal Voronoi grid for simulation of shale gas plays with coupled nonlinear physics.</a> Fuel. 163, 65-73 (2016).</li><li>Tiggelaar, R. M., Benito-Lopez, F., Hermes, D. C., Rathgen, H., Egberink, R. J. M., Mugele, F. G., Reinhoudt, N. D., van den Berg, A., Verboom, W., Gardeniers, H. J. G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication,+mechanical+testing+and+application+of+high-pressure+glass+microreactor+chips.">Fabrication, mechanical testing and application of high-pressure glass microreactor chips.</a> Chemical Engineering Journal. 131, 163-170 (2007).</li><li>Marre, S., Adamo, A., Basak, S., Aymonier, C., Jensen, K. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+and+Packaging+of+Microreactors+for+High+Pressure+and+High+Temperature+Applications.">Design and Packaging of Microreactors for High Pressure and High Temperature Applications.</a> Industrial and Engineering Chemistry Research. 49, 11310-11320 (2010).</li><li>Paydar, O. H., Paredes, C. N., Hwang, Y., Paz, J., Shah, N. B., Candler, R. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+3D-printed+microfluidic+chip+interconnects+with+integrated+O-rings.">Characterization of 3D-printed microfluidic chip interconnects with integrated O-rings.</a> Sensors Actuators A: Physical. 205, 199-203 (2014).</li><li>Jim&#233;nez-Mart&#237;nez, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pore-scale+mechanisms+for+the+enhancement+of+mixing+in+unsaturated+porous+media+and+implications+for+chemical+reactions.">Pore-scale mechanisms for the enhancement of mixing in unsaturated porous media and implications for chemical reactions.</a> Geophysical Research Letters. 42, 5316-5324 (2015).</li><li>Jim&#233;nez-mart&#237;nez, J., Porter, M. L., Hyman, J. D., Carey, J. W., Viswanathan, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mixing+in+a+three-phase+system:+Enhanced+production+of+oil-wet+reservoirs+by+CO2+injection.">Mixing in a three-phase system: Enhanced production of oil-wet reservoirs by CO2 injection.</a> Geophysical Research Letters. 43, 196-205 (2016).</li><li>Rognmo, A. U., Fredriksen, S. B., Alcorn, Z. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Experimental+Investigation+of+Flow+Regimes+in+Imbibition+and+Drainage+Using+a+Microfluidic+Platform.">An Experimental Investigation of Flow Regimes in Imbibition and Drainage Using a Microfluidic Platform.</a> Energies. 12 (7), 1-13 (2019).</li><li>Burshtein, N., Chan, S. T., Toda-peters, K., Shen, A. Q., Haward, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D-printed+glass+microfluidics+for+fluid+dynamics+and+rheology.">3D-printed glass microfluidics for fluid dynamics and rheology.</a> Current Opinion in Colloid &amp; Interface Science. 43, 1-14 (2019).</li><li>Wang, Y., Aryana, S. A., Banerjee, S., Barati, R., Patil, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Creation+of+Saturation+Maps+from+Two-Phase+Flow+Experiments+in+Microfluidic+Devices.">Creation of Saturation Maps from Two-Phase Flow Experiments in Microfluidic Devices.</a> Advances in Petroleum Engineering and Petroleum Geochemistry. Advances in Science, Technology &amp; Innovation. , 77-80 (2019).</li><li>Hermans, M., Gottmann, J., Riedel, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective,+Laser-Induced+Etching+of+Fused+Silica+at+High+Scan-Speeds+Using+KOH.">Selective, Laser-Induced Etching of Fused Silica at High Scan-Speeds Using KOH.</a> Journal of Laser Micro/Nanoengineering. 9, 126-131 (2014).</li><li>Iliescu, C., Jing, J., Tay, F. E. 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This work presents a protocol related to a fabrication platform to create robust, high-pressure glass microfluidic devices. The protocol presented in this work alleviates the need for a cleanroom by performing several of the final fabrication steps inside a glovebox. The use of a cleanroom, if available, is recommended to minimize the potential for contamination. Additionally, the choice of the etchant should be based on the desired surface roughness. The use of a mixture of HF and HCl as the etchant tends to reduce surf...

Hydraulic fracturing has been used for quite some time as a means to stimulate flow especially in tight formations1. Large amounts of water needed in hydraulic fracturing are compounded with environmental factors, water-availability issues2, formation damage3, cost4 and seismic effects5. As a result, interest in alternate fracturing methods such as waterless fracturing and the use of foams is on the rise. Alternative methods may provide important benefits such as reduction in water use6, compatibility with water sensitive formations7, minimal to no plugging of the formation8, high apparent viscosity of the fracturing fluids9, recyclability10, ease of clean-up and proppant carrying capability6. CO2 foam is a potential waterless fracturing fluid that contributes to more efficient production of petroleum fluids and improved CO2 storage capacities in the subsurface with a potentially smaller environmental footprint compared to conventional fracturing techniques6,7,11.
Under optimal conditions, supercritical CO2 foam (scCO2 foam) at pressures beyond the minimum miscibility pressure (MMP) of a given reservoir provides a multi-contact miscible system that is able to direct flow into less permeable parts of the formation, thereby improving sweep efficiency and recovery of the resources12,13. scCO2 delivers gas like diffusivity and liquid like density14 and is well suited for subsurface applications, such as oil recovery and carbon capture, utilization and storage (CCUS)13. The presence of the constituents of foam in the subsurface helps reduce the risk of leakage in long-term storage of CO215. Moreover, coupled-compressibility-thermal shock effects of scCO2 foam systems may serve as effective fracturing systems11. Properties of CO2 foam systems for subsurface applications have been studied extensively at various scales, such as characterization of its stability and viscosity in sand-pack systems and its effectiveness in displacement processes3,6,12,15,16,17. Fracture level foam dynamics and its interactions with porous media are less studied aspects that are directly relevant to the use of foam in tight and fractured formations.
Microfluidic platforms enable direct visualization and quantification of the relevant microscale processes. These platforms provide real-time control of the hydrodynamics and chemical reactions to study pore-scale phenomena alongside recovery considerations1. Foam generation, propagation, transport and dynamics may be visualized in microfluidic devices emulating fractured systems and fracture-microcrack-matrix conductive pathways relevant to oil recovery from tight formations. Fluid exchange between fracture and matrix is directly expressed in accordance with the geometry18, thereby highlighting the importance of simplistic and realistic representations. A number of relevant microfluidic platforms have been developed over the years to study various processes. For example, Tigglaar and coworkers discuss fabrication and high-pressure testing of glass microreactor devices through in-plane connection of fibers to test flow through glass capillaries connected to the microreactors19. They present their findings related to bond inspection, pressure tests and in-situ reaction monitoring by 1H NMR spectroscopy. As such, their platform may not be optimal for relatively large injection rates, pre-generation of multiphase fluid systems for in situ visualization of complex fluids in permeable media. Marre and coworkers discuss the use of a glass microreactor to investigate high-pressure chemistry and supercritical fluid processes20. They include results as a finite-element simulation of stress distribution to explore the mechanical behavior of modular devices under the load. They use nonpermanent modular connections for interchangeable microreactor fabrication, and the silicon/Pyrex microfluidic devices are not transparent; these devices are suited for kinematic study, synthesis and production in chemical reaction engineering where visualization is not a primary concern. The lack of transparency makes this platform unsuitable for direct, in situ visualization of complex fluids in surrogate media. Paydar and coworkers present a novel way to prototype modular microfluidics using 3D printing21. This approach does not seem well-suited for high-pressure applications since it uses a photocurable polymer and the devices are able to withstand only up to 0.4 MPa. Most microfluidic experimental studies related to transport in fractured systems reported in literature focus on ambient temperature and relatively low-pressure conditions1. There have been several studies with a focus on direct observation of microfluidic systems that mimic subsurface conditions. For example, Jimenez-Martinez and co-workers introduce two studies on critical pore-scale flow and transport mechanisms in a complex network of fractures and matrix22,23. The authors study three-phase systems using microfluidics under reservoir conditions (8.3 MPa and 45 &#176;C) for production efficiency; they assess scCO2 usage for re-stimulation where the leftover brine from a prior fracturing is immiscible with CO2 and the residual hydrocarbon23. Oil-wet silicon microfluidic devices have relevance to mixing of oil-brine-scCO2 in Enhanced Oil Recovery (EOR) applications; however, this work does not directly address pore-scale dynamics in fractures. Another example is work by Rognmo et al. who study an upscaling approach for high-pressure, in situ CO2 foam generation24. Most of the reports in literature that leverage microfabrication are concerned with CO2-EOR and they often do not include important fabrication details. To the best of the authors&#8217; knowledge, a systematic protocol for fabrication of high-pressure capable devices for fractured formations is currently missing from the literature.
This work presents a microfluidic platform that enables the study of scCO2 foam structures, bubble shapes, sizes and distribution, lamella stability in the presence of oil for EOR and hydraulic fracturing and aquifer remediation applications. The design and fabrication of microfluidic devices using optical lithography and Selective Laser-induced Etching29 (SLE) are discussed. Additionally, this work describes fracture patterns that are intended to simulate the transport of fluids in fractured tight formations. Simulated pathways may range from simplified patterns to complex microcracks based on tomography data or other methods that provide information regarding realistic fracture geometries. The protocol describes step-by-step fabrication instructions for glass microfluidic devices using photolithography, wet-etching and thermal bonding. An in-house developed collimated Ultra-Violet (UV) light source is used to transfer the desired geometric patterns onto a thin layer of photoresist, which is ultimately transferred to the glass substrate using a wet-etching process. As part of quality assurance, the etched patterns are characterized using confocal microscopy. As an alternative to photolithography/wet-etching, an SLE technique is employed to create a microfluidic device and a comparative analysis of the platforms is presented. The setup for flow experiments comprise gas cylinders and pumps, pressure controllers and transducers, fluid mixers and accumulators, microfluidic devices, high-pressure capable stainless-steel holders along with a high-resolution camera and an illumination system. Finally, representative samples of observations from flow experiments are presented.

<table>
	<tbody>
		<tr>
			<td>1/4&#8221; bolts and nuts</td>
			<td></td>
			<td></td>
			<td>For fabrication of the metallic plates to sandwich the glass chip between them for thermal bonding</td>
		</tr>
		<tr>
			<td>3.45 x 3.45 mm UV LED</td>
			<td>Kingbright</td>
			<td></td>
			<td>To emitt LED light</td>
		</tr>
		<tr>
			<td>3D measuring Laser microscope</td>
			<td>OLYMPUS</td>
			<td>LEXT OLS4000</td>
			<td>To measure channel depths</td>
		</tr>
		<tr>
			<td>40 mm x 40 mm x 10 mm 12V DC Cooling Fan</td>
			<td>Uxcell</td>
			<td></td>
			<td>To cool the UV LED lights</td>
		</tr>
		<tr>
			<td>120 mm x 38 mm 24V DC Cooling Fan</td>
			<td>Uxcell</td>
			<td></td>
			<td>To cool the UV LED lights</td>
		</tr>
		<tr>
			<td>5 ml (6 ml) NORM-JECT Syringe</td>
			<td>HENKE SASS WOLF</td>
			<td>Lot #16M14CB</td>
			<td>To rinse the chip before each experiment</td>
		</tr>
		<tr>
			<td>Acetone (Certified ACS)</td>
			<td>Fisher Chemical</td>
			<td>Lot #177121</td>
			<td>For cleaning</td>
		</tr>
		<tr>
			<td>Acid/ corossion resistive tweezer</td>
			<td>TED PELLA</td>
			<td></td>
			<td>To handle the glass piece in corosive solutions</td>
		</tr>
		<tr>
			<td>Acid/solvent resistance tweezers</td>
			<td>TED PELLA, INC</td>
			<td>#53009 and #53010</td>
			<td>To handle the glass in corrosive solutions</td>
		</tr>
		<tr>
			<td>Alloy X</td>
			<td>AMERICAN SPECIAL METALS</td>
			<td>Heat Number: ZZ7571XG11</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium hydroxide (ACS reagent)</td>
			<td>Sigma Aldrich</td>
			<td>Lot #SHBG9007V</td>
			<td>To clean the chip at the end of process</td>
		</tr>
		<tr>
			<td>AutoCAD</td>
			<td>Autodesk, San Rafael, CA</td>
			<td></td>
			<td>To design 2D patterns and 3D chips</td>
		</tr>
		<tr>
			<td>BD Etchant for PSG-SiO2 systems</td>
			<td>TRANSENE</td>
			<td>Lot #028934</td>
			<td>An improved buffered etch formulation for delineation of phosphosilica glass &#8211; SiO2 (PSG), and borosilica glass &#8211; SiO2 (BSG) systems</td>
		</tr>
		<tr>
			<td>Blank Borofloat substrate</td>
			<td>TELIC</td>
			<td>CG-HF</td>
			<td>Upper substrate for UV etching</td>
		</tr>
		<tr>
			<td>Borofloat substrate with metalizations</td>
			<td>TELIC</td>
			<td>PG-HF-LRC-Az1500</td>
			<td>Lower substrate for UV etching</td>
		</tr>
		<tr>
			<td>Capture One photo editing software</td>
			<td>Phase One</td>
			<td></td>
			<td>To Capture/Edit/Convert the pictures taken by Phase One Camera</td>
		</tr>
		<tr>
			<td>Capture station</td>
			<td>DT Scientific</td>
			<td>DT Versa</td>
			<td>To place of the chip in the field of view of the camera</td>
		</tr>
		<tr>
			<td>Carbon dioxide gas (Grade E)</td>
			<td>PRAXAIR</td>
			<td>UN 1013, CAS Number 124-38-9</td>
			<td>non-aqeous portion of foam</td>
		</tr>
		<tr>
			<td>Chromium etchant 1020</td>
			<td>TRANSENE</td>
			<td>Lot #025433</td>
			<td>High-purity ceric ammonium nitrate systems for precise, clean etching of chromium and chromium oxide films.</td>
		</tr>
		<tr>
			<td>Circulating baths with digital temperature controller</td>
			<td>PolyScience</td>
			<td></td>
			<td>To control the brine and CO2 temperatures</td>
		</tr>
		<tr>
			<td>CO2</td>
			<td>Airgas</td>
			<td>100% pure - 001013 - CAS: 124-38-9</td>
			<td>For CO2/scCO2 injection</td>
		</tr>
		<tr>
			<td>Computer</td>
			<td></td>
			<td>NVIDIA Tesla K20 Graphic Card - 706 MHz Core - 5 GB GDDR5 SDRAM - PCI Express 2.0 x16</td>
			<td>To process and visualize the images obtained via the Phase One camera</td>
		</tr>
		<tr>
			<td>Custom made high pressure glass chip holder</td>
			<td></td>
			<td></td>
			<td>To tightly hold the chip and its connections for high pressure testing</td>
		</tr>
		<tr>
			<td>Cutrain (Custom)</td>
			<td></td>
			<td></td>
			<td>To protect against UV/IR Radiations</td>
		</tr>
		<tr>
			<td>Deionized water (DI)</td>
			<td></td>
			<td></td>
			<td>For cleaning</td>
		</tr>
		<tr>
			<td>Digital camera with monochromatic 60 MP sensor</td>
			<td>Phase One</td>
			<td>IQ260</td>
			<td>Visualization system</td>
		</tr>
		<tr>
			<td>Ethanol, Anhydrous, USP Specs</td>
			<td>DECON LABORATORIES, INC.</td>
			<td>Lot #A12291505J, CAS# 64-17-5</td>
			<td>For cleaning</td>
		</tr>
		<tr>
			<td>Facepiece reusable respirator</td>
			<td>3M</td>
			<td>6502QL, Gases, Vapors, Dust, Medium</td>
			<td>To protect against volatile solution inhalation</td>
		</tr>
		<tr>
			<td>Fused Silica (UV Grade) wafer</td>
			<td>SIEGERT WAFER</td>
			<td>UV grade</td>
			<td>Glass precursor for SLE printing</td>
		</tr>
		<tr>
			<td>GIMP</td>
			<td>Open-source image processing software</td>
			<td></td>
			<td>To characterize image texture and properties</td>
		</tr>
		<tr>
			<td>Glovebox (vinyl anaerobic chamber)</td>
			<td>Coy</td>
			<td></td>
			<td>To provide a clean, dust-free environment</td>
		</tr>
		<tr>
			<td>Heated ultrasonic cleaning bath</td>
			<td>Fisher Scientific</td>
			<td></td>
			<td>To accelerate the etching process</td>
		</tr>
		<tr>
			<td>Hexamethyldisilazane (HMDS) Cleanroom&#174; MB</td>
			<td>KMG</td>
			<td>62115</td>
			<td>Primer for photoresist coating</td>
		</tr>
		<tr>
			<td>Hose (PEEK tubing)</td>
			<td>IDEX HEALTH &#38; SCIENCE</td>
			<td>Natural 1/16&#34; OD x .010&#34; ID x 5ft, Part # 1531</td>
			<td>Flow connections</td>
		</tr>
		<tr>
			<td>Hydrochloric acid, certified ACS plus</td>
			<td>Fisher Chemical</td>
			<td>Lot # 187244</td>
			<td>Solvent in RCA semiconductor cleaning protocol</td>
		</tr>
		<tr>
			<td>Hydrogen Peroxide</td>
			<td>Fisher Chemical</td>
			<td>H325-500</td>
			<td>Solvent in RCA semiconductor cleaning protocol</td>
		</tr>
		<tr>
			<td>ImageJ</td>
			<td>NIH</td>
			<td></td>
			<td>To characterize image texture and properties</td>
		</tr>
		<tr>
			<td>ISCO syringe pump</td>
			<td>TELEDYNE ISCO</td>
			<td>D-SERIES (100DM, 500D)</td>
			<td>To pump the fluids</td>
		</tr>
		<tr>
			<td>Kaiser LED light box</td>
			<td>Kaiser</td>
			<td></td>
			<td>To illuminate the chip</td>
		</tr>
		<tr>
			<td>Laser printing machine</td>
			<td>LightFab GmbH, Germany.</td>
			<td>FILL</td>
			<td>Glass-SLE chip fabrication</td>
		</tr>
		<tr>
			<td>Laser safety glasses</td>
			<td>FreeMascot</td>
			<td>B07PPZHNX4</td>
			<td>To protect against UV/IR Radiations</td>
		</tr>
		<tr>
			<td>LED Engin 5W UV Lens</td>
			<td>LEDiL</td>
			<td></td>
			<td>To emitt LED light</td>
		</tr>
		<tr>
			<td>Light Fab 3D Printer (femtosecond laser)</td>
			<td>Light Fab</td>
			<td></td>
			<td>To selectively laser Etch of fused silica</td>
		</tr>
		<tr>
			<td>LightFab 3D printer</td>
			<td>LightFab GmbH, Germany</td>
			<td></td>
			<td>To SLE print the fused silica chips</td>
		</tr>
		<tr>
			<td>MATLAB</td>
			<td>MathWorks, Inc., Natick, MA</td>
			<td></td>
			<td>To characterize image texture and properties</td>
		</tr>
		<tr>
			<td>Metallic plates</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Micro abrasive sand blasters (Problast 2)</td>
			<td>VANIMAN</td>
			<td>Problast 2 &#8211; 80007</td>
			<td>To craete holes in cover plates</td>
		</tr>
		<tr>
			<td>MICROPOSIT 351 developer</td>
			<td>Dow</td>
			<td>10016652</td>
			<td>Photoresist developer solution</td>
		</tr>
		<tr>
			<td>Muffle furnace</td>
			<td>Thermo Scientific</td>
			<td>Thermolyne Type 1500</td>
			<td>Thermal bonding</td>
		</tr>
		<tr>
			<td>N2 pure research grade</td>
			<td>Airgas</td>
			<td>Research Plus - NI RP300</td>
			<td>For drying the chips in each step</td>
		</tr>
		<tr>
			<td>NMP semiconductor grade - 0.1&#956;m Filtered</td>
			<td>Ultra Pure Solutions, Inc</td>
			<td>Lot #02191502T</td>
			<td>Organic solvent</td>
		</tr>
		<tr>
			<td>Oven</td>
			<td>Gravity Convection Oven</td>
			<td>18EG</td>
			<td></td>
		</tr>
		<tr>
			<td>Phase One IQ260 with an achromatic sensor</td>
			<td>Phase One</td>
			<td>IQ260</td>
			<td>To visulize transport in microfluidic devices using an ISO 200 setting and an aperture at f/8.</td>
		</tr>
		<tr>
			<td>Photomask</td>
			<td>Fine Line Imaging</td>
			<td>20,320 DPI FILM</td>
			<td>Pattern of channels</td>
		</tr>
		<tr>
			<td>Photoresist (SU-8)</td>
			<td>MICRO CHEM</td>
			<td>Product item: Y0201004000L1PE, Lot Number: 18110975</td>
			<td>Photoresist</td>
		</tr>
		<tr>
			<td>Polarized light microscope</td>
			<td>OLYMPUS</td>
			<td>BX51</td>
			<td>Visual examination of micro channels</td>
		</tr>
		<tr>
			<td>Ports (NanoPort Assembly)</td>
			<td>IDEX HEALTH &#38; SCIENCE</td>
			<td>NanoPort Assembly Headless, 10-32 Coned, for 1/16&#34; OD, Part # N-333</td>
			<td>Connections to the chip</td>
		</tr>
		<tr>
			<td>Python</td>
			<td>Python Software Foundation</td>
			<td></td>
			<td>To characterize image texture and properties</td>
		</tr>
		<tr>
			<td>Safety face shield</td>
			<td>Sellstrom</td>
			<td>S32251</td>
			<td>To protect against UV/IR Radiations</td>
		</tr>
		<tr>
			<td>Sealing film (Parafilm)</td>
			<td>Bemis Company, Inc</td>
			<td></td>
			<td>Isolation of containers</td>
		</tr>
		<tr>
			<td>Shutter Control Software</td>
			<td>Schneider-Kreuznach</td>
			<td></td>
			<td>To adjust shutter settings</td>
		</tr>
		<tr>
			<td>Smooth ceramic plates</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Stirring hot plate</td>
			<td>Corning&#174;</td>
			<td>PC-620D</td>
			<td>To heat the solutions</td>
		</tr>
		<tr>
			<td>Sulfuric acid, ACS reagent 95.0-98.0%</td>
			<td>Sigma Aldrich</td>
			<td>Lot # SHBK0108</td>
			<td>Solvent in RCA semiconductor cleaning protocol</td>
		</tr>
		<tr>
			<td>Syringe pump (Standard Infuse/Withdraw PHD ULTRA)</td>
			<td>Harvard Apparatus</td>
			<td>70-3006</td>
			<td>To saturate the chip before each experiment</td>
		</tr>
		<tr>
			<td>Torque wrench</td>
			<td>Snap-on</td>
			<td>TE25A-34190</td>
			<td>To tighten the screws</td>
		</tr>
		<tr>
			<td>UV power meter</td>
			<td>Optical Associates, Incorporated</td>
			<td>Model 308</td>
			<td>To measure the intesity of UV light</td>
		</tr>
		<tr>
			<td>UV power meter</td>
			<td>Optical Associates, Incorporated</td>
			<td>Model 308</td>
			<td>To quantify the strength of UV light</td>
		</tr>
		<tr>
			<td>UV radiation stand (LED lights)</td>
			<td></td>
			<td></td>
			<td>To transfer the pattern to glass (photoresist layer)</td>
		</tr>
		<tr>
			<td>Vaccum pump</td>
			<td>WELCH VACCUM TECHNOLOGY, INC</td>
			<td>1380</td>
			<td>To dry the chip</td>
		</tr>
		<tr>
			<td>Variable DC power supplies</td>
			<td>Eventek</td>
			<td>KPS305D</td>
			<td>To power the UV LED lights</td>
		</tr>
	</tbody>
</table>

microfluidic fabrication techniques for high-pressure testing of microscale supercritical co2 foam transport in fractured unconventional reservoirs

Pressure limitations of many microfluidic platforms have been a significant challenge in microfluidic experimental studies of fractured media. As a result, these platforms have not been fully exploited for direct observation of high-pressure transport in fractures. This work introduces microfluidic platforms that enable direct observation of multiphase flow in devices featuring surrogate permeable media and fractured systems. Such platforms provide a pathway to address important and timely questions such as those related to CO2 capture, utilization and storage. This work provides a detailed description of the fabrication techniques and an experimental setup that may serve to analyze the behavior of supercritical CO2 (scCO2) foam, its structure and stability. Such studies provide important insights regarding enhanced oil recovery processes and the role of hydraulic fractures in resource recovery from unconventional reservoirs. This work presents a comparative study of microfluidic devices developed using two different techniques: photolithography/wet-etching/thermal-bonding versus Selective Laser-induced Etching. Both techniques result in devices that are chemically and physically resistant and tolerant of high pressure and temperature conditions that correspond to subsurface systems of interest. Both techniques provide pathways to high-precision etched microchannels and capable lab-on-chip devices. Photolithography/wet-etching, however, enables fabrication of complex channel networks with complex geometries, which would be a challenging task for laser etching techniques. This work summarizes a step-by-step photolithography, wet-etching and glass thermal-bonding protocol and, presents representative observations of foam transport with relevance to oil recovery from unconventional tight and shale formations. Finally, this work describes the use of a high-resolution monochromatic sensor to observe scCO2 foam behavior where the entirety of the permeable medium is observed simultaneously while preserving the resolution needed to resolve features as small as 10 &#181;m.

This section presents examples of physical observations from scCO2 foam flow through a main fracture connected to array of micro-cracks. A glass microfluidic device made via photolithography or SLE is placed inside a holder and in the field of view of a camera featuring a 60 megapixel, monochromatic, full-frame sensor. Figure 11 illustrates the process of fabrication microfluidic devices and their placement in the experimental setup. Figure 12 is illu...

Watch this Scientific Journal Video about Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs at JoVE.co

Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs

This paper describes a protocol along with a comparative study of two microfluidic fabrication techniques, namely photolithography/wet-etching/thermal-bonding and Selective Laser-induced Etching (SLE), that are suitable for high-pressure conditions. These techniques constitute enabling platforms for direct observation of fluid flow in surrogate permeable media and fractured systems under reservoir conditions.

Microfluidic Fabrication Techniques for High-Pressure Testing of Microscale Supercritical CO2 Foam Transport in Fractured Unconventional Reservoirs

Pressure limitations of many microfluidic platforms have been a significant challenge in microfluidic experimental studies of fractured media. As a ...

This protocol is a multi-disciplinary collaborative effort between the University of Kansas and the University of Wyoming. We had a need for testing of our patented, polyelectrolyte complex nanoparticles using high pressure microfluidics. And it started a collaborative effort between our research group and Dr.Aryana's research group to take advantage of his state-of-the-art facilities.We would like to acknowledge NSF for funding part of this project, and thank the tertiary or recovery program for providing their facilities and support needed for this project. In addition, this work was in part supported by CMCUF and the Energy Frontier Research Center funded by the DOE. This protocol and its application to surrogate complex permeable media and their high pressure conditions, is the result of a collaboration between two research groups one from the University of Wyoming and the other from the University of Kansas.This protocol details, the fabrication procedure for a robust microfluidic platform in the absence of clean room facilities. This platform enables direct visualization of flow in complex geometries under high pressure conditions. The described technique can be used to age complex channel networks in glass substrates that mimic a structures from subsurface media and withstand high pressure conditions experienced during CO2 utilization and storage.This method may be used to provide insight into intersections and transport of complex fluids in impermeable media in the context of CCUS. When performing this protocol patients and extreme caution are required to minimize the risk of physical injury and failures in the fabrication process. Visual demonstration of this method enables effective communication of the steps that are critical in its successful execution.Begin by pouring an adequate amount of chrome etching solution into a beaker and heating it to approximately 40 degrees Celsius. Then place the mask directly on the side of the borosilicate substrate that is covered with chrome and photo resist. Transfer the geometrical pattern into the layer of photo resist by exposing the stack of the substrate and the mask to UV light.Remove the photo mask and substrate stack from the UV stage then remove the photo mask and submerge the substrate and the developer solution for approximately 40 seconds. Cascade rinse the substrate by flowing deionized water on top of the substrate and over all of its surfaces at least three times. After allowing the substrate to dry, submerge it in the preheated chrome etchant for approximately 40 seconds thereby transferring the pattern from the photo resist to the chrome layer.Remove the substrate from the solution, cascade rinse it with deionized water and allow it to dry. Using a brush, apply several layers of HMDS to the uncovered face of the substrate and allow it to dry. Apply one layer of photo resist on top of the primer, then place the substrate in an oven at 60 to 90 degrees Celsius for 30 to 40 minutes.Afterwards, leave the pattern substrate in the etchant solution for a predetermined amount of time, based on the desired channel depths. Remove the substrate from the etchant, using a solvent resistant pair of tweezers and cascade rinse it with deionized water. Expose the substrate to NMP solution preheated to 65 degrees Celsius for approximately 30 minutes to remove the photo resist.Cascade rinse it with acetone followed by ethanol and deionized water. Place the clean substrate in chrome etchant and heated to approximately 40 degrees Celsius for about one minute. Then characterize the channel depth using laser scanning, confocal microscopy.Mark the positions of the inlet and outlet holes on a blank borosilicate substrate by aligning the cover plate against the etched substrate. Use a micro abrasive sandblaster and 50 micro meter aluminum oxide micro sandblasting media to blast through holes in the marked locations. Cascade rinse both the etched substrate and the cover plate with deionized water.Then bring a one to four hydrogen peroxide sulfuric acid piranha solution to a boil and submerge the substrate and the cover plate in the solution for 10 minutes. After rinsing the substrate and cover plate, submerge them in the buffer etchant for 30 to 40 seconds and rinse them again. Next, submerge the substrate and cover plate for 10 minutes in a six to one to one water, hydrogen peroxide, hydrochloric acid solution that is heated to approximately 75 degrees Celsius.Press the substrate and cover plate tightly against each other while submerged then remove them from the solution, cascade rinse them and submerge them in deionized water. Make sure that the substrate and the cover plate are firmly attached to each other, press them against each other and carefully remove them from the water. Align the substrate and cover plate carefully while they are submerged in DI water and repeat the procedure until no air bubbles are observed between the two.Place the stack substrates between two smooth 1.5 two centimeter thick glass ceramic plates for bonding. Place the glass ceramic plates between two metallic plates made of alloy x. Making sure that the glass wafers and the ceramic metallic holder are centered.Hand tighten the nuts and place the holder in a vacuum chamber for 60 minutes at approximately 100 degrees Celsius. Then remove the holder from the chamber and carefully tighten the nuts. Place the holder inside a furnace and execute a heating program according to manuscript directions.Remove the thermally bonded microfluidic device from the furnace and rinse it with water. Then bath sonicate it in hydrochloric acid for one hour. Fill the tanks of the carbon dioxide and water pumps with enough fluids for the experiment and use a syringe to fill the brine accumulator and flow lines with the surfactant solution.Place the saturated microfluidic device in a pressure resistant holder and connect the inlet and outlet ports to the appropriate lines using 0.01 inch inner diameter tubing. Increase the temperature of the circulating bath, which controls the temperature of the brine and carbon dioxide lines to the desired temperature. Increase the back pressure and brine pump pressure simultaneously in gradual steps while maintaining continuous flow from the outlet of the back pressure regulator.Increase the pressure up to 7.38 mega pascal and stop the pumps. Increase the carbon dioxide line pressure to a pressure above 7.38 mega pascal then open the carbon dioxide valve and allow the super critical carbon dioxide mixed with the high pressure surfactant solution to flow through an inline mixer and generate foam. Wait until flow is fully developed inside the device and the channels are saturated, monitoring the outlet for the onset of foam generation.Turn on the camera to capture detailed images of flow inside the channels. Carbon dioxide foam transport and stability in the UV lithography microfluidic device, during the first 20 minutes of generation and isolation is shown here. The multi-phase moved across the micro cracks and foam was generated through the micro-fractures.The foam was generated in a selective laser induced etching microfluidic device, starting from ambient condition with no flow to fully developed, super critical carbon dioxide foam at high and low flow rates. Foam distribution and stability was imaged under reservoir conditions during the first 20 minutes of generation and isolation. The distribution of bubble diameters was determined using image J.Quantification of the foam microstructure was performed using raw images, post processed images and their binarised equivalents.When attempting this practical, it is important to carefully examine the pattern on the chrome layer under a yellow light to ensure the desired pattern is transferred correctly. Variations of these methods include high pressure injection of oil, polymer solutions and low salinity brines to develop an understanding of the physics of flow of complex fluids through direct visualization.

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