No oil left behind?

Nanotech Research Making Strides

Sean Murphy
Sean Murphy

The three-year-old Advanced Energy Consortium (AEC) has a lofty goal to locate and extract the billions of barrels of potentially available petroleum supply remaining in place following conventional recovery.

To get from here to there the organization – managed by the Bureau of Economic Geology, University of Texas – is funding scientific research in the infinitesimally small and unexplored nanorealm.

“The AEC is focused specifically on application of nano-scale technologies to the exploration and improved recovery of oil and gas,” said Sean Murphy, AEC program manager. “The goal is to develop subsurface micro- and nano-sensors that can be injected in oil and gas wellbores.

“These incredibly small sensors can migrate out of the wellbores and into and through pores of the surrounding geological structure to collect data about the physical and chemical characteristics of hydrocarbon reservoirs,” he noted.

Interest in AEC research has spread beyond the oil and gas companies.

These transmission electron microscope (TEM) micrographs illustrate the Colvin (Rice University) Group’s ability to synthesize magnetite (Fe3O4), controlling nanocrystal grain sizes and size distributions (histograms).
These transmission electron microscope (TEM) micrographs illustrate the Colvin (Rice University) Group’s ability to synthesize magnetite (Fe3O4), controlling nanocrystal grain sizes and size distributions (histograms).

A recent national meeting of the American Chemical Society included a special session on nano-technology for the oil and gas industry. Twenty-three papers were presented, with 90 percent of them authored by researchers funded by the AEC.

The organization is focused on three specific areas, which Murphy summarized:

♦ Contrast agents.

Molecules or nanoparticles having augmented electromagnetic, acoustic or other properties that can be dispersed in fracturing or injection fluids in order to increase the ability to sense the spatial extent of those fluids by using available borehole, surface and borehole-surface-imaging techniques.

♦ Nanomaterial sensors.

Molecular and material-based sensors, predominantly fabricated using bottom-up techniques (chemical synthesis and/or self assemblage, most of which require retrieval and interrogation). They show an irreversible and detectable state change upon exposure to discrete or threshold-level variations in physical or chemical conditions in the reservoir.

♦ Microfabricated sensors.

Sensors (predominantly) fabricated using top-down techniques that can continuously measure physical or chemical reservoir properties. They are able to store or transfer data back to the wellbore, and have a demonstrable path toward further miniaturization. These include micro- and nanoelectronics, microelectro-mechanical systems (MEMS) and nanoelectro mechanical systems (NEMS) devices and their supporting subsystems.

Focusing on the Next Step

The AEC is in the process of transitioning from a scientific-dominated startup phase to a more focused research and development phase, according to David Chapman, AEC project manager.

A common metric to gauge the maturity of technology was developed by NASA. Dubbed Technical Readiness Levels (TRL), developing research is measured on a scale of 1-10.

“Most of the work we’re doing now is in the two to five range,” Chapman said. “We decided that as a group, we’ll take our work to the TRL six and seven, which entails a technology demonstration.

“In the case of oil and gas, that would be a demo in a field environment,” he noted. “We want to take things as far as a demo and then likely pass it to industry.”

Contrast agents are the first they will demonstrate in the field, with magnetic contrast agents being the most near term.

“Contrast agents are of particular interest to our members because of the potential to enable higher resolution, real-time imaging to delineate the location and path of fluids injected into the reservoir,” Murphy emphasized.

“With contrast agents, we’re using the properties of nano material without having to do a lot to them,” he said. “In the case of magnetic nano-particles, the particles themselves have a magnetic permeability, or susceptibility that’s an inherent property of that nano-particle.

“The magnetic strength is enhanced because of the size of the particles, to the point it gives us the capability to do things we can’t do with bulk materials,” Murphy noted. “We coat the particles so they have long-term stability in the reservoir, and they can move through the reservoir or fracture.

“It’s their inherent properties we’re leveraging, so that’s what makes them our near-term project,” he continued. “Nano-materials and micro sensors will take a lot more integration, so they will be longer term projects for us.”

Existing geophysical tools can be used to develop images using these magnetic nano-scale, material contrast agents.

Regarding contrast agents, Chapman said they will require hundreds of kilograms of the material – more than typically manufactured by most chemical plants.

The extent and efficiency of waterfloods are currently getting the once-over by the researchers.

“If we can image where the flood goes by adding magnetic contrast agents to it, that would give the ability to see where the fluids are moving,” Murphy said. “We’re challenging ourselves to do a magnetic waterflood demo in the next couple of years.”

Impact on Fracturing

The AEC already is reporting nano-tech success stories, one of which focuses on hydraulic fracturing.

In this case, nano-proppants have been developed via a program initially funded by the AEC at Rice University’s Smalley Institute for Nanoscale Science and Technology, which is a technical partner. These stable, uniform-size proppants have considerable potential to enhance hydraulic fracturing applications.

They already are being used commercially.

In addition to these advanced proppants to help keep the fluid injection-created fractures open, the possibility exists that benign nano particles can be added to the hydro-fracking toolkit to detect the extent and intensity of the fracking process.

The particles must be custom-designed so they will be both stable and mobile within the fluids.

Nano particles can be made up of any kind of material. In fact, any chemistry can be scaled down to nano-scale size particles, and the researchers are investigating a wide range of chemistries. Materials used must be stable and able to survive in the harsh reservoir environment, which can be thousands of feet underground.

In addition to the array of ongoing research by U.S. universities, companies and other AEC participants, the group is planning to expand its scope geographically.

“We’re looking to initiate some new projects,” Murphy said, “which will probably be international in scope, funding the best research universities in the world for some of that research.”

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Emphasis: Downhole Geology