Comparing Microfluidic Testing to Coreflooding and Beaker-Scale Testing.
Thomas de Haas
Microfluidics, by definition, is the science and technology of analyzing or processing fluids in channels from 1 to 1000 microns in diameter. The use of microfluidics in the oil and gas industry has a complex history that brings together aspects of molecular analysis, biodefence, molecular biology, microelectronics, and reservoir engineering.
Oil and gas microfluidic testing falls into two broad categories. Flow through porous media which is creating a physical analogue of the rock and observing fluid interactions at the pore-scale, and reservoir fluid analysis which is determining thermodynamic or chemical properties of reservoir fluids in a microscale-laboratory.
Example of a reservoir analogue (microfluidic porous media model) [top] and a fluid analysis microfluidic device [bottom] fabricated by Interface Fluidics.
Microfluidic technology has many advantages over traditional beaker-scale chemical analysis or large-scale coreflood or sand-pack flood testing. These advantages include:
Small sample size on the order of milliliters needed for a set of tests. This is important for downhole samples that are expensive to retrieve or for a prototype chemistry that has not been synthesized yet in large quantities.
High-resolution and high-sensitivity measurements due to the micro-scale imaging and precise control of fluid interactions.
Rapid results as fluid interactions can be observed over hours instead of days
Safe testing because the contained energy is tiny within the testing devices. Only nanoliters of fluid are at high-temperature and high-pressure in the microfluidic device.
Microfluidic technology is a tool that is used heavily in the biotech sector for diagnosing disease, synthesizing drugs, and analyzing DNA; however, microfluidics has not seen as much adoption in the oil and gas sector. This low adoption rate is likely due to the historically high cost of fabricating solvent-resistant, and pressure-tolerant, glass or silicon devices. Further, there have been slow turnaround times of commercial microfluidic device fabricators that limit design iteration.
Example of microfluidic device for biology made from a soft polymer (PDMS). Note that the fluid inlets and outlets are simply friction-fit needles. This system is designed for very low pressures. Image from NIST.
Prior to the 1990’s reservoir micromodels were developed by researchers around the world. These micromodels were usually made from glass and were etched using a pattern that was manually scribed onto a layer of wax and the glass was etched with hydrofluoric acid. In the 1990’s a revolution took place as microelectronic fabrication techniques were adopted by biologists (largely driven by military projects to detect bio-weapons). These techniques allowed for extremely accurate patterns to be transferred onto glass, silicon, or newly-developed soft polymers. Scientists used this technique to create miniature gas chromatographs, detect disease in body fluids, analyze cells, and even create organ-on-a-chip systems.
Early micromodel study by Mattax and Kyte. This study used a glass micromodel etched using a manually scribed wax coating. Many of the types of analysis that are performed now can trace their roots to these early works. Reproduced with permission. The Oil and Gas Journal, October 16, 1961. Pp 115-128.
Microfluidic technology is being adopted by oil and gas laboratories around the world as a rapid method for testing oil and gas fluid properties and quantifying how fluids interact in rock. It is a challenge to operate these tests reliably at high-temperature and high-pressure relevant to hydrocarbon reservoir conditions. Interface has solved this problem and is excited to work with you to solve your reservoir fluids challenges.
The best advantages that Interface brings to the world of microfluidics are quick test turnaround, custom reservoir analogue fabrication with features as shallow as 50 nanometers, high operating pressure/temperature, and deep knowledge of reservoir engineering in shale, offshore, conventional, and oilsands reservoirs.