Summary
The goal of this research was to develop methods for acquiring reservoir
pressure and temperature data near the wellbore and farther out into the
formation and to correlate such information to fracture connectivity and
geometry. Existing reservoir-characterization tools allow pressure and
temperature to be measured only at the wellbore. The development of
temperature- and pressure-sensitive nanosensors will enable in-situ
measurements within the reservoir. This paper provides the details of the
experimental work performed in the process of developing temperature
nanosensors. The study investigated the parameters involved in the mobility of
nanoparticles through porous and fractured media. These parameters include
particle size or size distribution, shape, and surface charge or affinity to
rock materials.
The principal findings of this study were that spherically shaped
nanoparticles of a certain size and surface charge compatible with that
expected in formation rock are most likely to be transported successfully,
without being trapped because of physical straining, chemical, or electrostatic
effects. We found that tin-bismuth (Sn-Bi) nanoparticles of 200 nm and smaller
were transported through Berea sandstone. Larger particles were trapped at the
inlet of the core, indicating that there was an optimum particle size range. We
also found that the entrapment of silver (Ag) nanowires was primarily because
of their shape. This conclusion was supported by the recovery of the spherical
Ag nanoparticles with the same surface characteristics through the same porous
media used during the Ag nanowires injection. The entrapment of hematite
nanorice was attributed to its affinity to the porous matrix caused by surface
charge. The hematite coated with surfactant (which modified its surface charge
to one compatible with flow media) flowed through the glass beads, emphasizing
the importance of particle surface charge.
Preliminary investigation of the flow mechanism of nanoparticles through a
naturally fractured greywacke core was conducted by injecting fluorescent
silica microspheres. We found that silica microspheres of different sizes
(smaller than the fracture opening) could be transported through the fracture.
We demonstrated the possibility of using microspheres to estimate fracture
aperture by injecting a polydisperse microsphere sample. It was observed that
only spheres of 20 μm and smaller were transported. This result agreed
reasonably well with the measurement of hydraulic fracture aperture (27 μm), as
determined by the cubic law.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
8 July 2011
- Meeting paper published:
30 October 2011
- Revised manuscript received:
11 June 2012
- Manuscript approved:
17 June 2012
- Published online:
28 November 2012
- Version of record:
6 December 2012
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