GRAVILOG: An update on the development and use of Borehole Gravity for Mining Exploration

Nind, Chris; MacQueen, Jeffrey D.; Wasylechko, Roman; Chemam, Madjid; Nackers, C.

doi:10.1071/aseg2013ab048

Cited by 6 publications

(7 citation statements)

References 5 publications

(5 reference statements)

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“…Typically, borehole gravity measurements are collected at discrete intervals by stopping a deployed gravity sensor at predetermined observation depths and performing a stationary measurement [ 41 ], before moving to the next observation depth, as illustrated in Fig 1 . From these measurements, the vertical gradient of gravity, Δ g /Δ z , is determined for the interval of interest by measuring the gravity difference, Δ g , and the vertical distance between two consecutive stations, Δ z .…”

Section: Borehole Gravity Surveysmentioning

confidence: 99%

“…Existing borehole gravity sensors used to perform such measurements typically rely on spring-based technology similar to that used in surface-based gravimeters [ 41 ]. To allow for operation down boreholes the technology used in surface-based sensors has been miniaturized, equipped with self-leveling capabilities and packaged to fit in narrow diameter borehole tools.…”

Section: Borehole Gravity Surveysmentioning

confidence: 99%

“…To allow for operation down boreholes the technology used in surface-based sensors has been miniaturized, equipped with self-leveling capabilities and packaged to fit in narrow diameter borehole tools. For example, the sensor discussed in reference [ 41 ] has a radial diameter of 57 mm, can be used to depths of 2,500 m and its self leveling capabilities allow it to be deployed in boreholes inclined up to 30° from vertical. It is typically deployed by conducting wireline cable [ 41 ].…”

Section: Borehole Gravity Surveysmentioning

confidence: 99%

“…For example, the sensor discussed in reference [ 41 ] has a radial diameter of 57 mm, can be used to depths of 2,500 m and its self leveling capabilities allow it to be deployed in boreholes inclined up to 30° from vertical. It is typically deployed by conducting wireline cable [ 41 ]. Atom interferometry based sensors will need to reach a similar or greater level of deployability to be a competitive tool across all of the applications in which gravity sensing is currently used.…”

Section: Borehole Gravity Surveysmentioning

confidence: 99%

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Magneto-optical trapping in a near-suface borehole

et al. 2023

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Borehole gravity sensing can be used in a number of applications to measure features around a well, including rock-type change mapping and determination of reservoir porosity. Quantum technology gravity sensors, based on atom interferometry, have the ability to offer increased survey speeds and reduced need for calibration. While surface sensors have been demonstrated in real world environments, significant improvements in robustness and reductions to radial size, weight, and power consumption are required for such devices to be deployed in boreholes. To realise the first step towards the deployment of cold atom-based sensors down boreholes, we demonstrate a borehole-deployable magneto-optical trap, the core package of many cold atom-based systems. The enclosure containing the magneto-optical trap itself had an outer radius of (60 ± 0.1) mm at its widest point and a length of (890 ± 5) mm. This system was used to generate atom clouds at 1 m intervals in a 14 cm wide, 50 m deep borehole, to simulate how in-borehole gravity surveys are performed. During the survey, the system generated, on average, clouds of (3.0 ± 0.1) × 105 87Rb atoms with the standard deviation in atom number across the survey observed to be as low as 8.9 × 104.

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Section: Borehole Gravity Surveysmentioning

confidence: 99%

Section: Borehole Gravity Surveysmentioning

confidence: 99%

Section: Borehole Gravity Surveysmentioning

confidence: 99%

Section: Borehole Gravity Surveysmentioning

confidence: 99%

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Magneto-optical trapping in a near-suface borehole

et al. 2023

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“…Land-based gravity surveys can commonly achieve micro-Gal (μGal) accuracy with measurements repeatability as low as 3 μGal (Krahenbuhl et al, 2011;Van Camp et al, 2017). Borehole gravimeters like Gravilog TM (Nind et al, 2013) can operate in small diameter boreholes that deviate from vertical by up to ~60°. Emerging three-axis microgravity technology microelectromechanical system (MEMS) gravimeter and subsequent modeling studies indicate that valuable direction/azimuthal information could also be recovered for reservoir surveillance although no actual field experiment has been implemented (Lofts et al, 2019).…”

Section: Monitoring Of Ccs Site With Time-lapse Gravity Surveysmentioning

confidence: 99%

Time-lapse gravity monitoring of CO2 migration based on numerical modeling of a faulted storage complex

Appriou

Bonneville

Zhou

et al. 2020

International Journal of Greenhouse Gas Control

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In this study, the performance of both surface and borehole time-lapse gravity monitoring to detect CO2 leakage from a carbon storage site is evaluated. Several hypothetical scenarios of CO2 migration in a leaky fault, and thief zones at different depths at the Kimberlina site (California, USA) constitute the basis of the approach. The CO2 displacement is simulated using the TOUGH2 simulator applied to a detailed geological model of the site. The gravity responses to these CO2 plumes are simulated using forward modeling with sensors at ground surface and in vertical boreholes. Results of inversion on one scenario are also presented. The surface-based gravity responses obtained for the different leakage scenarios demonstrate that leakage can be detected at the surface in all the scenarios but the time to detection is highly variable (10 to 40 years) and dependent on the detection threshold considered. Borehole measurements of the vertical component of gravity provide excellent constraints in depth when they are located in proximity of the density anomaly associated with the presence of CO2, thus discriminating multiple leaks in different thief zones. Joint inversion of surface and borehole data can bring valuable information of the occurrence of leakages and their importance by providing a reasonable estimate of mass of displaced fluids. This study demonstrates the importance of combining multiphase flow simulations with gravity modeling in order to define if and when gravity monitoring would be applicable at a given storage site.

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Monitoring Carbon Storage Sites With Time‐Lapse Gravity Surveys

Appriou

Bonneville

2022

Geophysical Monitoring for Geologic Carbon Storage

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GRAVILOG: An update on the development and use of Borehole Gravity for Mining Exploration

Cited by 6 publications

References 5 publications

Magneto-optical trapping in a near-suface borehole

Magneto-optical trapping in a near-suface borehole

Time-lapse gravity monitoring of CO2 migration based on numerical modeling of a faulted storage complex

Monitoring Carbon Storage Sites With Time‐Lapse Gravity Surveys

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