Geophysical Monitoring with Seismic Metamaterial Contrast Agents

Miller, Quin R. S. (Pacific Northwest National Laboratory) | Schaef, H. Todd (Pacific Northwest National Laboratory) | Nune, Satish K. (Pacific Northwest National Laboratory) | Jung, Ki Won (Pacific Northwest National Laboratory) | Burghardt, Jeffrey A. (Pacific Northwest National Laboratory) | Martin, Paul F. (Pacific Northwest National Laboratory) | Prowant, Matthew S. (Pacific Northwest National Laboratory) | Denslow, Kayte M. (Pacific Northwest National Laboratory) | Strickland, Chris E. (Pacific Northwest National Laboratory) | Prasad, Manika (Colorado School of Mines) | Pohl, Mathias (Colorado School of Mines) | Jaysaval, Piyoosh (Pacific Northwest National Laboratory) | McGrail, B. Peter (Pacific Northwest National Laboratory)



Acoustic impedance tube and forced-oscillation seismic core test measurements were conducted to examine the low-frequency properties of acoustic metamaterial contrast agents. Water-stable suspensions of metal-organic framework (MOF) nanoparticles increased sound transmission loss (100-1250 Hz) and seismic attenuation (10-70 Hz), and reduced Young's modulus of nanofluid-saturated Berea Sandstone cores. Preliminary measurements were used to parameterize a seismic wave velocity model. These results indicate that injectable MOF nanofluid contrast agents have potential to enhance seismic delineation of subsurface fluids and structures.


Subsurface monitoring of injected fluids and fracture networks is a critical component of geologic carbon storage and enhanced hydrocarbon recovery operations. Detection sensitivity, volumetric distribution, and migration paths of injectates are commonly difficult to obtain with geophysical techniques, especially in reservoirs containing complex secondary fracture networks (Figure 1) and/or extensive layering. Our goal is to develop a new class of seismic contrast agents to enable monitoring of injected fluids and gas-brine-hydrocarbon interfaces via conventional seismic imaging methods. We recently demonstrated that microporous metal-organic frameworks (MOF) are low-frequency (100-1250 Hz) absorptive acoustic metamaterials, exhibiting anomalous sound transmission loss and tunable resonance (Miller et al., 2018). Herein, we describe a novel class of injectable MOF nanofluid seismic contrast agents for enhanced mapping and monitoring of subsurface fluids and structures. We report increased low-frequency sound transmission loss due to water-stable MIL-101(Cr) (MIL: Materials Institute Lavoisier) nanoparticle suspensions and demonstrate that MIL-100(Fe) nanofluids influence the 10-70 Hz anelastic and elastic properties of saturated Berea Sandstone cores. These MOF nanofluid-based injectable contrast agents have the potential to comprise a disruptive high-performance geophysical technology for monitoring geologic CO2 storage, oil and gas extraction, enhanced geothermal systems, and hydraulic fracturing.

Materials and Methods

Two MOF-based nanofluids were evaluated in this study. The two types of MOFs used in this study were chosen due to their similarity with previously-studied MOFs (Miller et al., 2018; Schaef et al., 2017) that exhibited notable low-frequency acoustic properties. The ~0.5 wt% nanofluids used in this study were prepared by synthesizing MIL-101(Cr) (Férey et al., 2005) nanoparticles [nanoMIL-101(Cr)] following previously-reported procedures (Schaef et al., 2017). NanoMIL-101(Cr) was selected for its very high specific surface area (SSA) of 2917 m2/g and its potential to form water-stable nanofluids (Nandasiri et al., 2016). MIL-100(Fe) (Horcajada et al., 2007) nanoparticles [nanoMIL-100(Fe)] were also synthesized for low-frequency property testing. MIL-100(Fe) nanoparticles were prepared using a similar method to that used for nanoMIL-101(Cr). Iron nitrate nonahydrate (0.5g, 1.23 mmol), 1,3,5-benzene tricarboxylic acid (0.174g, 0.83 mmol), and modulator 4-methoxy benzoic acid (9.4 mg, 0.62 mmol) were added to 40 mL of water. The heterogeneous suspension was mixed thoroughly followed by sonication for five minutes at room temperature. The mixture was then heated to 160 °C for 12 hours in a Teflon-lined autoclave. The reaction mixture was cooled to room temperature, isolated via centrifugation, and washed with deionized water and ethanol twice to produce a ~0.5 wt% nanofluid.