uu.seUppsala University Publications
Change search
Link to record
Permanent link

Direct link
BETA
Place, Joachim
Publications (6 of 6) Show all publications
Place, J., Ghafar, A. N., Malehmir, A., Draganovic, A. & Larsson, S. (2016). On using the thin fluid-layer approach at ultrasonic frequencies for characterising grout propagation in an artificial fracture. International Journal of Rock Mechanics And Mining Sciences, 89, 68-74
Open this publication in new window or tab >>On using the thin fluid-layer approach at ultrasonic frequencies for characterising grout propagation in an artificial fracture
Show others...
2016 (English)In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 89, p. 68-74Article in journal (Refereed) Published
Abstract [en]

Grouting the fractures encountered when constructing underground facilities is of primary importance for environmental, safety and economic reasons. The success of grouting operation, however, depends upon several parameters governing the grout propagation. Experimental benches replicating fractures have therefore been designed to study processes related to grout propagation. In this paper, we investigate the ultrasonic transport properties of such an idealized fracture whose 100 mu m aperture is about 0.02 the wavelength, and filled with various fluids flowing under external forcing. As the artificial fracture is made of two solid and parallel walls separated by a thin fluid layer, we use the thin fluid layer concept to study the compressional (P-) wavefield transmitted across and reflected off the fracture, with no mode-conversion considered. We demonstrate that air and various fluids (water, grouts of varied w/c - water to cement ratio) can be distinguished when injected into the fracture, both at atmospheric pressure or under over-pressure as done in real grouting cases in the field. Then, using an analytical solution, we verify our experimental data and predict the results that can be obtained with a different fracture aperture. Our results illustrate that replicating such ultrasonic measurements both in space and time would allow to monitor successfully the grout propagation within an artificial fracture. The detection of the filtration of the suspended cement particles of the grout, the formation and erosion of filter-cakes, are also in the scope of the method.

Keywords
Ultrasonic, Reflection, Grout, w/c ratio, Thin fluid layer, Monitoring, Fracture
National Category
Geophysics
Identifiers
urn:nbn:se:uu:diva-310767 (URN)10.1016/j.ijrmms.2016.07.010 (DOI)000387519300007 ()
Funder
Swedish Research Council Formas, 252-2012-1907Rock Engineering Research Foundation (BeFo)Swedish Transport Administration
Available from: 2016-12-19 Created: 2016-12-19 Last updated: 2017-11-29Bibliographically approved
Place, J., Géraud, Y., Diraison, M., Herquel, G., Édel, J.-B., Bano, M., . . . Walter, B. (2016). Structural control of weathering processes within exhumed granitoids: compartmentalisation of geophysical properties by faults and fractures. Journal of Structural Geology, 84, 102-119
Open this publication in new window or tab >>Structural control of weathering processes within exhumed granitoids: compartmentalisation of geophysical properties by faults and fractures
Show others...
2016 (English)In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 84, p. 102-119Article in journal (Refereed) Published
Abstract [en]

In the latter stages of exhumation processes, rocks undergo weathering. Weathering halos have been described in the vicinity of structures such as faults, veins or dykes, with a lateral size gradually narrowing with depth, symmetrically around the structures. In this paper, we describe the geophysical characterisation of such alteration patterns on two granitoid outcrops of the Catalan Coastal Ranges (Spain), each of which is affected by one major fault, as well as minor faults and fractures. Seismic, electric and ground penetrating radar surveys were carried out to map the spatial distribution of P-wave velocity, electrical resistivity and to identify reflectors of electromagnetic waves. The analysis of this multi-method and complementary dataset revealed that, at shallow depth, geophysical properties of the materials are compartmentalised and asymmetric with respect to major and subsidiary faults affecting the rock mass. This compartmentalisation and asymmetry both tend to attenuate with depth, whereas the effect of weathering is more symmetric with respect to the major structure of the outcrops. We interpret such compartmentalisation as resulting from the role of hydraulic and mechanical boundaries played by subsidiary faults, which tend to govern both the chemical and physical alterations involved in weathering. Thus, the smoothly narrowing halo model is not always accurate, as weathering halos can be strongly asymmetrical and present highly irregular contours delimiting sharp contrasts of geophysical properties. These results should be considered when investigating and modelling fluid storage and transfer in top crystalline rock settings for groundwater applications, hydrocarbon or geothermal reservoirs, as well as mineral deposits.

Keywords
Granitoid, Weathering, Fault, Damage zone, Alteration halo, Behind-the-cliff geophysics
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-313158 (URN)10.1016/j.jsg.2015.11.011 (DOI)000372763200007 ()
Available from: 2017-01-17 Created: 2017-01-17 Last updated: 2017-11-29Bibliographically approved
Bertrand, L., Geraud, Y., Le Garzic, E., Place, J., Diraison, M., Walter, B. & Haffen, S. (2015). A multiscale analysis of a fracture pattern in granite: A case study of the Tamariu granite, Catalunya, Spain. Journal of Structural Geology, 78, 52-66
Open this publication in new window or tab >>A multiscale analysis of a fracture pattern in granite: A case study of the Tamariu granite, Catalunya, Spain
Show others...
2015 (English)In: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201, Vol. 78, p. 52-66Article in journal (Refereed) Published
Abstract [en]

The in-depth investigation of fractured reservoirs is mainly limited to geophysical data that is in 3D and mostly on the scale of hundred meters to several kilometers or boreholes data that is in 1D and at meter to lower scale. The study of outcropping analogues of buried reservoirs is therefore a key tool for the characterization of the fault and fracture network at the reservoir scale. Tamariu granite has been the subject of this study with the aim to analyse faults and fractures from seismic to borehole scale. With the combination of satellite picture at different resolution and field study, we perform a statistical analysis focused of the length and orientation from infra centimeter crack to hundred kilometer length fault. On the whole range of scale studied, i.e. on 7 orders of magnitude, we have defined a length distribution following a power-law with an exponent a = -2. On the contrary to the length that can be modelled with a unique law, the orientation data shows a variation depending on the scale of observation: as the fault and fracture sets are suitable from the regional faults to the centimeter crack, the proportion of the sets varies at each scale of observation.

Keywords
Fracture network in granite, Reservoir analogue, Multiscale analysis, Length distribution, Relation between 1D and 2D sampling method
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-263446 (URN)10.1016/j.jsg.2015.05.013 (DOI)000360866400003 ()
Available from: 2015-10-06 Created: 2015-09-30 Last updated: 2017-12-01Bibliographically approved
Malehmir, A., Wang, S., Lamminen, J., Brodic, B., Bastani, M., Vaittinen, K., . . . Place, J. (2015). Delineating structures controlling sandstone-hosted base-metal deposits using high-resolution multicomponent seismic and radio-magnetotelluric methods: a case study from Northern Sweden. Geophysical Prospecting, 63(4), 774-797
Open this publication in new window or tab >>Delineating structures controlling sandstone-hosted base-metal deposits using high-resolution multicomponent seismic and radio-magnetotelluric methods: a case study from Northern Sweden
Show others...
2015 (English)In: Geophysical Prospecting, ISSN 0016-8025, E-ISSN 1365-2478, Vol. 63, no 4, p. 774-797Article in journal (Refereed) Published
Abstract [en]

Over the past few decades seismic methods have increasingly been used for the exploration of mineral, geothermal, and groundwater resources. Nevertheless, there have only been a few cases demonstrating the advantages of multicomponent seismic data for these purposes. To illustrate some of the benefits of three-component data, a test seismic survey, using 60 digital three-component sensors spaced between 2 m and 4 m and assembled in a 160 m-long prototype landstreamer, was carried out over shallow basement structures underlying mineralized horizons and over a magnetic lineament of unknown origin. Two different types of seismic sources, i.e., explosives and a sledgehammer, were used to survey an approximately 4 km-long seismic profile. Radio-magnetotelluric measurements were also carried out to provide constraints on the interpretation of the seismic data over a portion of the profile where explosive sources were used. Good quality seismic data were recorded on all three components, particularly when explosives were used as the seismic source. The vertical component data from the explosive sources image the top of the crystalline basement and its undulated/faulted surface at a depth of about 50 m-60 m. Supported by the radio-magnetotelluric results, however, shallower reflections are observed in the horizontal component data, one of them steeply dipping and associated with the magnetic lineament. The vertical component sledgehammer data also clearly image the crystalline basement and its undulations, but significant shear-wave signals are not present on the horizontal components. This study demonstrates that multicomponent seismic data can particularly be useful for providing information on shallow structures and in aiding mineral exploration where structural control on the mineralization is expected.

Keywords
Hard rock environment, Multicomponent, Landstreamer, Radio-magnetotelluric, Mineral exploration, Fault, Basement
National Category
Geophysics
Identifiers
urn:nbn:se:uu:diva-262442 (URN)10.1111/1365-2478.12238 (DOI)000360073400003 ()
Funder
Swedish Research Council Formas
Available from: 2015-09-16 Created: 2015-09-15 Last updated: 2017-12-04Bibliographically approved
Place, J., Malehmir, A., Högdahl, K., Juhlin, C. & Nilsson, K. P. (2015). Seismic characterization of the Grangesberg iron deposit and its mining-induced structures, central Sweden. Interpretation, 3(3), SY41-SY56
Open this publication in new window or tab >>Seismic characterization of the Grangesberg iron deposit and its mining-induced structures, central Sweden
Show others...
2015 (English)In: Interpretation, ISSN 2324-8858, E-ISSN 2324-8866, Vol. 3, no 3, p. SY41-SY56Article in journal (Refereed) Published
Abstract [en]

We have conducted a reflection seismic investigation over the apatite-iron deposit at Grangesberg in central Sweden. At the time of closure in 1989, the mine was operated using the sublevel caving method down to approximately a 650-m depth. This mining technique caused subsidence and generated a network of faults that propagated from excavated zones at depth up to the surface. The Grangesberg deposit is the largest iron oxide mineralization in central Sweden and is planned to be mined again in the coming years. It is therefore imperative to have a better understanding of the ore geometry and the fault network. A reconnaissance survey consisting of two seismic lines with a total length of 3.5 km was carried out to address these issues. The profiles intersect the Grangesberg deposit and open pit, as well as the major mining-induced fracture zone present in this area. A drop-hammer source mounted on a hydraulic truck was used to generate seismic signals; cabled and wireless receivers were used for the data recording. Preprocessing of the data first required the cable-and wirelessrecorded data sets to be merged before stacking all data available at each shot point. Source gathers exhibit reflections from the near surface, probably generated at lithological boundaries hosting the iron mineralization and other geologic structures. Deeper reflections were also observed. The metavolcanic assemblage hosting the mineralization and the anthropogenic fault network were depicted in the stacked sections, bringing in new elements to refine the geologic model of the area. This study also illustrated the ability of reflection seismic methods to delineate mining-induced structures in hard-rock environments. Low-velocity anomalies from the open pit and adjacent structures were depicted in tomographic sections along the two lines, which showed good agreement with known geologic features and the reflection seismic results.

National Category
Geophysics Geochemistry
Research subject
Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
Identifiers
urn:nbn:se:uu:diva-269284 (URN)10.1190/INT-2014-0212.1 (DOI)000364362900051 ()
Funder
Sida - Swedish International Development Cooperation AgencySida - Swedish International Development Cooperation Agency
Available from: 2015-12-15 Created: 2015-12-15 Last updated: 2017-12-01Bibliographically approved
Place, J., Blake, O., Faulkner, D. & Rietbrock, A. (2014). Wet Fault or Dry Fault? A Laboratory Approach to Remotely Monitor the Hydro-Mechanical State of a Discontinuity Using Controlled-Source Seismics. Pure and Applied Geophysics, 171(11), 2887-2897
Open this publication in new window or tab >>Wet Fault or Dry Fault? A Laboratory Approach to Remotely Monitor the Hydro-Mechanical State of a Discontinuity Using Controlled-Source Seismics
2014 (English)In: Pure and Applied Geophysics, ISSN 0033-4553, E-ISSN 1420-9136, Vol. 171, no 11, p. 2887-2897Article in journal (Refereed) Published
Abstract [en]

Stress variation and fluid migration occur in deformation zones, which are expected to affect seismic waves reflected off or propagating across such structures. We developed a basic experimental approach to monitor the mechanical coupling with respect to seismic coupling across a single discontinuity between a granite sample in contact with a steel platen. Piezoceramics located on the platen were used to both generate and record the P and S wave fields reflected off the discontinuity at normal incidence. This way, normal (B (n) ) and tangential (B (t) ) compliances were calculated using Schoenberg's linear slip theory (Schoenberg, J Acoust Soc Am 68:1516-1521, 1980) when the roughness, the effective pressure (P (eff), up to 200 MPa), and the nature of the filling (gas or water) vary. We observe that increasing the effective pressure decreases B (n) and B (t) , which is interpreted as the effect of the closure of the voids at the interface, permitting more seismic energy to be transmitted across the interface. Values of B (n) are significantly higher than those of B (t) at low P (eff) (< 60-80 MPa) in dry conditions, and significantly drop under water-saturated conditions. The water filling the voids therefore helps to transmit the seismic energy of compressional waves across the interface. These results show that the assumption B (n) a parts per thousand B (t) commonly found in some theoretical approaches does not always stand. The ratio B (n) /B (t) actually reflects the type of saturating fluids and the effective pressure, in agreement with other experimental studies. However, we illustrate that only the relative variations of this ratio seem to be relevant, not its absolute value as suggested in previous studies. Consequently, the use of B (n) against B (t) plots may allow effective pressure variation and the nature of the pore fluid to be inferred. In this respect, this experimental approach at sample scale helps to pave the way for remotely monitoring in the field the hydro-mechanical state of deformation zones, such as seismogenic faults, fractured reservoirs, or lava conduits.

National Category
Geophysics
Research subject
Geophysics with specialization in Solid Earth Physics
Identifiers
urn:nbn:se:uu:diva-239974 (URN)10.1007/s00024-014-0805-z (DOI)000345144300003 ()
Available from: 2015-01-05 Created: 2015-01-05 Last updated: 2017-12-05Bibliographically approved
Organisations

Search in DiVA

Show all publications