Production from organic-rich shale petroleum systems is extremely challenging due to the complex rock and flow characteristics. An accurate characterization of shale reservoir rock properties would positively impact hydrocarbon exploration and production planning. We integrate large-scale geologic components with small-scale petrophysical rock properties to categorize distinct rock types in low porosity and low permeability shales. We then use this workflow to distinguish three rock types in the reservoir interval of the Niobrara shale in the Denver Basin of the United States: The Upper Chalks (A, B, and C Chalk), the Marls (A, B, and C Marl), and the Lower Chalks (D Chalk and Fort Hays Limestone). In our study area, we find that the Upper Chalk has better reservoir-rock quality, moderate source-rock potential, stiffer rocks, and a higher fraction of compliant micro- and nanopores. On the other hand, the Marls have moderate reservoir-rock quality, and a higher source rock potential. Both the Upper Chalks and the Marls should have major economic potentials. The Lower Chalk has higher porosity and a higher fraction of micro-and nanopores; however, it exhibits poor source rock potential. The measured core data indicates large mineralogy, organic-richness, and porosity heterogeneities throughout the Niobrara interval at all scale.
Unconventional petroleum systems are highly complex hydrocarbon resource plays both at the reservoir scale and at the pore scale (Aplin and Macquaker, 2011; Loucks et al., 2012; Hart et al., 2013; Hackley and Cardott, 2016). These organic-rich sedimentary plays, generally described as shale reservoirs, are composed of very fine silt-and clay-sized particles with grain sizes < 62.5 μm (Loucks et al., 2009; Nichols, 2009; Passey et al., 2010; Kuila et al., 2014; Saidian et al., 2014). They undergo extensive post-depositional diagenesis that transforms rock composition and texture, hydrocarbon storage and productivity, and reservoir flow features (Rushing et al., 2008; McCarthy et al., 2011; Jarvie, 2012; Milliken et al., 2012). Although some shale rock facies can retain depositional attributes during diagenesis, many critical reservoir properties, such as, mineralogy, pore structure, organic richness and present-day organic potential, etc., are significantly perturbed (Hackley and Cardott, 2016).
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.
Sprunt, Eve (author of A Guide for Dual Career Couples) | Ali, Hendratta (Fort Hays State University) | Capello, Maria Angela (Kuwait Oil Company) | Whitesell, Laurie (Oklahoma State University) | Prasad, Manika (Colorado School of Mines)
Two surveys were distributed to faculty and student members of the Society of Exploration Geophysicists in 2016 by the SEG Women’s Network Committee (WNC). The surveys focused on assessing issues that women have raised about the academic environment. Student responses reveal that Geosciences department leadership (head/chairs) are critical to recruitment and retention of female and possibly other underrepresented groups. Despite positive actions including anti-harassment and parental-leave policies, the faculty responses indicate that gender-bias gaps still exist. One critical gap is that young female faculty are more likely than their male colleagues to be in non-tenuretrack roles. Also, female academics are more likely to report age discrimination and uncomfortable social interactions with peers of the opposite sex.
Presentation Date: Tuesday, October 16, 2018
Start Time: 1:50:00 PM
Location: 204C (Anaheim Convention Center)
Presentation Type: Oral
The effective stress coefficient determines the influence of confining and pore pressures on rock properties. We measured the permeability of the Lockatong mudstone sample as a function of pore and confining pressures. Using our established laboratory protocol for such measurements, we estimate the effective stress coefficient for permeability. We use an initial stress cycle to remove the effects of inelastic deformation and microfractures due to core damage. The permeability values lie between 1.8 μD (in the first stress cycle) and 100 nD. The effective stress coefficient for permeability is found to be greater than one (nk = 1.28) at the lowest differential stress. We observe a strong dependence of effective stress coefficient with differential pressure – effective stress coefficient decreased from 1.28 at 2.5 MPa to 0.65 at 60 MPa. The measured permeabilities obey a simple power law dependence on the calculated effective stress.
Presentation Date: Tuesday, October 16, 2018
Start Time: 8:30:00 AM
Location: 202A (Anaheim Convention Center)
Presentation Type: Oral
Summary Understanding of the pore structure of rocks and its pressure dependency has been a longstanding area of interest. More recently, pore structures and pore sizes have been mapped using induced polarization measurements (Revil et al. 2014, Niu et al., 2016). However, studies on the pressure dependency of Complex Resistivity (CR), also known as Induced Polarization (IP), and how they relate to pore deformation are almost nonexistent. In this study, we performed IP measurement on three sandstone samples with little to no clay content and observed the changes in real and quadrature conductivity with increasing confining pressure, while pore pressure was kept constant. The results from the IP measurements show that the real and quadrature conductivities both decrease with increasing pressure.
Robinson, Judy (Rutgers University Newark) | Slater, Lee (Rutgers University Newark) | Keating, Kristina (Rutgers University Newark) | Robinson, Tonian (Rutgers University Newark) | Parker, Beth (University of Guelph) | Rose, Carla (University of Guelph) | Prasad, Manika (Colorado School of Mines)
Summary Geophysical length scales derived from complex resistivity (CR) and nuclear magnetic resonance (NMR) measurements offer promise for the noninvasive estimation of permeability. Petrophysical relationships linking NMR length-scales to permeability have been used in both sandstone and mudstone formations. In contrast, petrophysical relations linking CR length-scales to permeability have been limited to sandstones and unconsolidated sediments. The purpose of our study was to evaluate the predictive capability of CRbased permeability relations when applied to mudstones and to compare the predictions against those determined from NMR models. Introduction The robust estimation of permeability from geophysical measurements remains one of the grand challenges in hydrogeophysics.
High resolution elastic imaging of laboratory rock/core samples can provide valuable information about the quantitative small-scale physio-chemical changes including stress changes and fluid flow. We present the application of 3D Full Waveform Inversion (a high resolution imaging technique) to a laboratory acoustic data that we acquired with high spatial ultrasound source-receiver distribution.
SUMMARY Compressional deformation in fluids and rocks is influenced by similar viscoelastic effects, as in shear case. In this paper we introduce the importance of bulk viscosity and modulus in frequency-dependent response of elastic velocities. We conducted experiments to measure bulk modulus and attenuation of two heavy-oil saturated rock samples by confining pressure cycling method under varying oscillation frequencies (within teleseismic frequency band 0.001 - 1 Hz), and compared these measurements to a more conventional axial stress-strain technique. We plan to extend the frequency range of the pressure cycling apparatus as well as to modify the setup in order to measure frequency-dependent bulk viscosities of viscoelastic fluids. INTRODUCTION The bulk modulus of any pore fluid must be used to interpret the seismic response and perform a fluid substitution for Direct Hydrocarbon Indicator analysis.
The mechanisms of ultrasonic attenuation in reservoir rock are known to be sensitive to multiple rock physical properties; this study focuses on ultrasonic experiments that measure the anisotropic attenuation in shales as function of hydrostatic confining pressure; four Eagleford and Bakken samples were measured using new experimental setup that allows measuring anisotropic acoustic properties of sample simultaneously with only one core plug. Our tests show that P-wave attenuation is sensitive to confining pressure, and attenuation anisotropy is stronger than velocity anisotropy, especially for more isotropic samples; the highly active change of attenuation with pressure supports the opinion that attenuation is a highly sensitive parameter to rock intrinsic properties. Moreover, attenuation as a function of pressure clearly suggests a two-phase attenuation mechanism exists in shale: high aspect ratio pores/microcracks closure and the related scattering attenuation on crack surfaces dominate attenuation behavior under low pressure, while at high pressure the main mechanism shifts to intrinsic attenuation caused by grain/crack friction and anelasiticity. The measured anisotropy data could be used for understanding the loss mechanisms responsible for seismic attenuation, and would benefit the development of theoretical attenuation rock physics models, as well as the interpretation of well logging and seismic surveys in shale reservoirs.
Presentation Date: Wednesday, October 19, 2016
Start Time: 10:20:00 AM
Presentation Type: ORAL
The dielectric property is a useful parameter that can be used to infer other properties of porous media such as water saturation, permeability, etc. The dielectric properties (mHz to MHz) of isotropic porous media have been extensively studied. However, related studies are very rare for anisotropic porous media. In this study, we have measured the directional dielectric spectra of two sedimentary rocks (one Bakken shale sample and one Lyons sandstone sample) using the combination of 2- and 4- electrode methods in the frequency range between 10-3 and 107 Hz. It is shown that the dielectric constant of these two samples generally increases as the frequency decreases. This is because, as the frequency decreases, more polarization mechanisms start to contribute to the measured dielectric constant. It is also shown that the dielectric anisotropy in these samples decreases as the frequency increases, indicating that different polarization mechanisms induce different degrees of dielectric anisotropy.
Presentation Date: Monday, October 17, 2016
Start Time: 1:25:00 PM
Presentation Type: ORAL