MICROSCOPIC nanorobots may sound as futuristic as flying saucers and teleportation, but research already is under way at Saudi Aramco to put nanotechnology to work in oil reservoirs throughout the kingdom.

Many people think of the oil “reservoir” as a tank. But in the petroleum industry, the reservoir is solid rock, as solid as the wall in your office - or even more so. Oil is trapped in tiny pores within these rocks and travels between the pores through small passageways called “pore throats,” which are even smaller than the pores.
Saudi Aramco’s EXPEC ARC representatives at the February Applied Technology Workshop. From left are Hiba Dialdin; Dr Mazen Kanj, workshop chairman; Dr Muhammad Al-Saggaf; Rami Kamal, workshop committee member; and Modiu Sanni.
Reservoir rock holds oil in tiny pores connected by “pore throats,” outlined in red, which are even smaller than the pores. Nanorobots must be small enough to pass through the pore throats.
So anything that moves through the reservoir has to be smaller yet; it has to be at the nanoscale.
Last year, Saudi Aramco’s EXPEC Advanced Research Center (EXPEC ARC) introduced the concept of Resbots, or reservoir robots - tiny nanorobots less than 1/100th the width of a human hair - that could one day be deployed like an army in reservoirs through injected water. During their journey, they would analyse the reservoir pressure, temperature and fluid type, storing information in onboard memory. A number of them then would be retrieved from crude oil at the producing wells to download that information, thus effectively mapping the reservoir.
That form of reservoir mapping would be more effective than any existing method since it would attain direct contact with the reservoir. Eventually, real-time communication and powered mobility also would be added.
However, the long journey to using nanorobots starts with answering a very simple question: What is the largest size Resbot that can go through the reservoir and not get caught in the pore throats? After all, there is no sense in wasting time and money on nanorobots if microrobots can do the job (and those can be manufactured now). On the other hand, there is also no use in deploying those robots only to be caught in the pore throats around the wellbore, where they would be worse than no good, failing to gather information and damaging to the reservoir in the bargain.
To that end, EXPEC ARC has analysed 850 core plugs from the Arab-D reservoir in Ghawar and mapped the distribution of the pore throat sizes. From that analysis, one can draw the conclusion that most of the pore throats are larger than roughly 500 nanometers, which establishes a target for miniaturisation efforts.
To validate that result, an experiment is being performed in which nanoparticles (dumb Resbots) are being injected into representative Ghawar core plugs. The number of particles that manage to get through the plug are counted – such that the size question can be answered empirically.
Saudi Aramco is leading the way in nanotechnology. EXPEC ARC organised the industry’s first Society of Petroleum Engineers nanotechnology gathering. The Applied Technology Workshop (ATW) was held in February under the title: “Nanotechnology in Upstream E&P: Nanoscale Revolutions to Mega-scale Challenges?”
Nanorobots less than 1/100th the width of a human hair could one day be deployed like an army in reservoirs through injected water.
More than 90 scientists, researchers, analysts and engineers from 20 countries participated in the workshop, including major oil companies (Saudi Aramco, Chevron, BP, Shell, Total and others), major service companies, and well-known academic institutions (MIT, Rice, etc.). Also in attendance were nanotechnology companies completely outside the oil industry (3M, Lockheed Martin, etc.).