Patent Application
20230330658
Microfluidic systems, also referred to as “lab-on-a-chip” devices, can be used to mimic reservoir environments for fundamental enhanced oil recovery studies. Using microfluidic systems can provide a mode of directly testing wettability alteration using different fluids for enhanced oil recovery, for example. Many conventional materials used for microfluidic devices, such as silicon, are not suitable for studying carbonate reservoir systems. Calcite microfluidics can be used to study reservoir properties; however, calcite microfluidics are uncommon and techniques for their fabrication are under development.
Few methods exist for fabricating calcite microfluidics and such methods tend to be complex and time consuming to execute. Accordingly, there exists a need for facile methods for fabricating calcite microfluidic devices.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In one aspect, embodiments disclosed herein relate to a method that includes 3d printing a polymer substrate comprising microfluidic channels and depositing calcite onto the polymer substrate then using atomic layer deposition to form a calcite microfluidic device.
In another aspect, embodiments disclosed herein relate to a 3d printed polymer substrate including microfluidic channels. The 3d printed polymer substrate has a calcite coating.
Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims.
In one aspect, embodiments disclosed herein relate to a method of making a calcite (CaCO3) microfluidic device. A schematic of a method 100 in accordance with one or more embodiments, as depicted in
As noted above, methods described herein include 3d printing a polymer substrate that includes microfluidic channels. As used herein, “3d printing” (also referred to as additive manufacturing) refers to a process that builds a three-dimensional (3d) object from a 3d model data, such as from a computer-aided design (CAD) model. 3d printing is generally a layer-by-layer process in which a 3d object is built one layer at a time, and each successive layer is added to the previously constructed layer(s). The 3d printing may be conducted using any suitable method, and in one or more particular embodiments, a fused filament fabrication (FFF) method may be used.
A schematic depiction of an FFF 3d printing apparatus 200 is shown in
To 3d print an object using the FFF apparatus 200, a first layer of a polymer material (in the form of the filament 206) is printed directly onto the substrate 202. It is printed by extrusion through the nozzle 210, which is configured to heat the filament for printing. As the filament 206 is extruded through the heated nozzle, a continuous bead (also referred to as a “road”) of the polymer is deposited onto the substrate 202. The nozzle 210 is moved over the substrate in a predetermined geometry to form a first layer of the object 204. Once the first layer is completed, the substrate 202 is lowered away from the nozzle 210 and a second layer of the polymer is deposited onto the first layer. This process is repeated to build an object layer-by-layer until the object 204 is completed.
As understood by a person of skill in the art, a CAD model of an object to be printed with suitable dimensions may be generated prior to 3d printing the substrate. The CAD model may be designed using commercially available software, such as software provided with a commercially available 3d printer. Other readily available software such as AutoCAD, Fusion 360 or TinkerCAD may be used.
The 3d printer used to print devices in accordance with the present disclosure is not particularly limited, and may be any of a wide variety of commercially available 3d printers known by those skilled in the art. In one or more particular embodiments, Utilimaker 3d printers available from Dynamism (Chicago, IL, USA) may be used. In order to print the devices disclosed herein, the printer may have a resolution of up to about 20 microns.
Any polymer suitable for use in FFF printing may be used to print the devices disclosed herein. For example, the polymer filament may be selected from the group consisting of polylactic acid, acrylonitrile butadiene styrene, polyethylene terephthalate glycol, polyethylene terephtathalate, high-impact polystyrene, thermoplastic polyurethane, aliphatic polyamides, and combinations thereof. In particular embodiments, the polymer filament may be polylactic acid.
The 3d printed substrate may have a suitable structure with microscale dimensions for creating a calcite microfluidic device. A top-down view of such a substrate 300 is shown in
The dimensions of the channels of the polymer substrate may be selected to mimic pores in a carbonate reservoir. For example, in one or more embodiments, the channels of the polymer substrate may have a width ranging from 10 to 500 microns. The width of the channels may have a lower limit of one of 10, 15, 20, 30, 50, 75, 100, 125, 150, 200 and 250 microns, and an upper limit of one of 100, 125, 150, 175, 200, 250, 300, 350, 400, 450 and 500 microns, where any lower limit may be paired with any mathematically compatible upper limit. The height of the channels may be from about 75 to 250 microns. For example, the height of the channels may have a lower limit of any of one 75, 80, 90, 100, 110, 125, 150, and 175 microns and an upper limit of any one of 125, 150, 175, 200, 225, and 250, where any lower limit may be paired with any mathematically compatible upper limit. The length of the channels may be selected based on the desired overall size of the microfluidic device. The channels of one or more embodiments may have a length ranging from 2.0 mm (millimeters) to 5.0 mm. The length of the channels may have a lower limit of one of 2.0, 2.25, 2.5, 2.75, 3.0, 3.25, and 3.5 mm and an upper limit of one of 3.75, 4.0, 4.25, 4.5, 4.75, and 5.0, where any lower limit may be paired with any mathematically compatible upper limit. As noted above, the sizes of the channels may be varied within the microfluidic device.
After 3d printing a polymer substrate, a calcite layer may be deposited on the polymer substrate using an atomic layer deposition (ALD) process. Atomic layer deposition is a thin film deposition technique in which a sequential gas-phase deposition processes is used to deposit layers of certain materials to build a thin film. ALD is a self-limiting process in which a gas is introduced into a deposition chamber, and a single atomic layer of the gaseous material deposits on a surface to form a single atomic layer. Once the single layer is formed, the gas is cleared from the deposition chamber and then another gas is introduced to form another layer on top of the previous layer. This process is repeated until the final material is formed.
In accordance with one or more embodiments, a calcite layer having a thickness of 50 to 150 nm (nanometers) may be formed using the following parameters. The temperature during the deposition may be between 250 and 325° C., and in particular embodiments, may be around 300° C. The gaseous precursors may be calcium 2,2,6,6-tetramethylheptan-3,5-dione (Ca(thd)2), carbon dioxide (CO2), and ozone (O3). The calcite coating may be made, for example, by flowing a Ca(thd)2 precursor over the polymer substrate to form a calcium layer, purging with nitrogen gas, flowing a O3 precursor over the polymer substrate to form an oxygen layer, purging with nitrogen gas, flowing a CO2 precursor over the polymer substrate to form an oxygen layer, purging with nitrogen gas, and repeating the previously recited steps until the calcite layer is formed. A non-limiting example of a single deposition cycle to form calcium carbonate may include a 3 second pulse of Ca(thd)2 followed by a 2 second nitrogen purge, a 3 second O3 pulse followed by a 2 second nitrogen purge, and a 3 second CO2 pulse followed by a 2 second nitrogen purge. The deposition cycle may be repeated a sufficient number of times to achieve a thickness of 50 to 150 nm. Specifically, the process may include from about 1,000 to about 3,000 cycles.
Once a suitable calcite coating has been formed, the uniformity of the calcite layer may be confirmed using scanning electron microscopy, and in some instances, focused ion beam scanning electron microscopy.
The 3d printed channels with a calcite coating may be packaged into a casing for final use as a microfluidic device. A cross sectional view of a final microfluidic device 400 in accordance with one or more embodiments is shown in
The device disclosed herein may be used to study fluid dynamics in calcite microchannels, which are configured to mimic pores in carbonate reservoirs. Carbonate reservoirs are routinely treated with acids to increase pore connectivity and ultimately enhance oil recovery in the reservoir. Acid achieves this effect by dissolving the carbonate rock. The devices disclosed herein may be used to visually observe the dissolution dynamics of various acid treatment mixtures on the deposited calcite, and thereby provide information about fluid flow dynamics. These observations can be used to quantify acid dissolution of the carbonate rock and to predict migration of brine through aquifers, such as calcite formations. Such observations may be made according to any technique known in the art. In particular, dissolution dynamics may be observed using an optical microscope equipped with a CCD camera.
Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. § 112(f) for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.
