What's new in production

In this industry, as elsewhere in work and life, “intelligent” and “smart” modify a proliferating number of gadgets. Even so, it seems surprising (and counterintuitive) that proppants are being imbued with that quality.

That’s the intention, at least. As recently reported in KU Today, University of Kansas researchers have earned a $3.5-million grant from the Department of Energy’s Office of Fossil Energy, in partnership with Houston-based E&P company EOG Resources and in collaboration with the University of California-Los Angeles. These entities will develop a new Smart MicroChip Proppants technology that could make unconventional reservoir development by hydraulic fracturing more efficient for energy producers.

Smart microchip proppants. Masoud Kalantari, KU assistant professor of chemical and petroleum engineering and director of the Computational Earth Science and Smart Analytics Lab, aims to develop “smart microchip proppants,” or sand-grain-sized microchips to be injected into unconventional reservoirs with traditional proppants. This will give well operators unprecedented precision in visualizing fracture networks in real time.

“The impact would be transformational,” Kalantari said. “During the past 10 years or so, since the shale boom started in the United States, companies have drilled thousands of unconventional horizontal wells in unconventional reservoirs. Technically, when we frac, we’re pumping water mixed with sand called ‘proppants’ to keep those fractures open, but we don’t know exactly the geometry and extent of those fractures. This project offers an innovative and breakthrough technology for improved subsurface fracture characterization, visualization and diagnostics of unconventional reservoirs.”

According to the university’s online news source, Kalantari said he envisioned a “closed-loop fracture diagnostic and modeling architecture for enhancing fracture design and optimizing well spacing. “The innovative element of this battery-less sensor technology includes real-time, cost-efficient, high-resolution and “direct” fracture mapping, with varying microchip sizes that match different proppants sizes—as small as 100-mesh size.

“The smart microchip proppants, once injected in the formation, generate real-time data to better evaluate the dynamics of the reservoir, proppants distribution, embedment and the conductive fracture geometry,” Kalantari said. “Due to the complexity of hydraulic fracturing, coming up with the right spacing between the wells makes the optimum development of unconventional reservoirs challenging. This technology will support the U.S. operators to maximize the efficacy of recovery from unconventional resources while minimizing the environmental footprint, by optimizing the well spacing and improving completion design.”

Electromagnetic energy will power smart microchips. “There’s no battery small enough, so we’ll develop a tool to put in the wellbore and then send electromagnetic energy that will power these smart microchips,” Kalantari said. “When they’re remotely powered, they provide their location signal back to the wellbore. Each one of them will provide a signal to the location of those microchips. Based on that, you can generate a detailed visualization of how proppants have propagated.”

In case all this doesn’t disabuse you of the idea that proppants are commodity materials, other ongoing developments might. Take “Swellable Proppants for In-Situ Well Stimulation,” as a current National Energy Technology Laboratory (NETL) project is titled.

The goal is to develop an “engineered ice” or “rusting rebar” proppant that can deliver large localized forces to fracture rock under high constraining forces, similar to how water freezing or rebar rusting causes fractures in rock and concrete structures. The overall objective … is to develop a new class of structural expandable proppant particles that can deliver a pumpable formulation capable of exerting considerable force to open and extend fracture networks.

Promising potential impact. The capability to have a pumpable material that can be triggered to provide the controlled application of high forces while remaining highly permeable is a potentially enabling fracture technology for resource extraction. When applied to oil and gas stimulation operations, the ability to expand existing fracture networks without the use of large volumes of water or other fluids can greatly reduce costs and environmental impacts. The proposed controlled application of force through in-situ reaction with formation fluids after placement will provide a new tool for reservoir engineers to utilize in enhancing the economics of extracting natural resources.

In-situ proppant formation. Chang et. al. (2015) have proposed a way to form proppants downhole and within the fracture after the fracturing has been completed. The fracturing fluid, itself, forms the proppant and, therefore, little or no material is carried back to be treated or disposed of. The size of the proppant can be varied from less than 1 mm to more than 20 mm in diameter, within a very narrow distribution of the size desired by modifying the composition of the injection fluid. No polymer is required to suspend the proppant, hence no breakers are required. The in-situ formed proppants are perfectly spherical particles, with hardness equal or exceeding conventional proppants. Highly permeable solid masses can also be formed within the fracture, using hydraulic fluids containing no solids. Hydraulic fluids can be formulated to form proppants and highly permeable blocks at various temperatures, and at various pre-determined times after initial fracturing, to accommodate shallow and deep fractures.