Characterization of a complex near-surface structure using well logging and passive seismic measurements

Abstract

Abstract. We combine geophysical well logging and passive seismic measurements to characterize the near-surface geology of an area located in Hontomin, Burgos (Spain). This area has some near-surface challenges for a geophysical study. The irregular topography is characterized by limestone outcrops and unconsolidated sediments areas. Additionally, the near-surface geology includes an upper layer of pure limestones overlying marly limestones and marls (Upper Cretaceous). These materials lie on top of Low Cretaceous siliciclastic sediments (sandstones, clays, gravels). In any case, a layer with reduced velocity is expected. The geophysical data sets used in this study include sonic and gamma-ray logs at two boreholes and passive seismic measurements: three arrays and 224 seismic stations for applying the horizontal-to-vertical amplitude spectra ratio method (H/V). Well-logging data define two significant changes in the P -wave-velocity log within the Upper Cretaceous layer and one more at the Upper to Lower Cretaceous contact. This technique has also been used for refining the geological interpretation. The passive seismic measurements provide a map of sediment thickness with a maximum of around 40 m and shear-wave velocity profiles from the array technique. A comparison between seismic velocity coming from well logging and array measurements defines the resolution limits of the passive seismic techniques and helps it to be interpreted. This study shows how these low-cost techniques can provide useful information about near-surface complexity that could be used for designing a geophysical field survey or for seismic processing steps such as statics or imaging.

Underground Water-Level Monitoring by Integrated Study of Geoelectric, Logging, Cutting and Pumping Data in Industrial Area of Candi Sub-District, Sidoarjo

“…This is also consistent with previous studies that the resistivity of the subsurface layer corresponds to geological parameters such as fluid, porosity, and rock minerals (Jufriadi & Ayu, 2014), and the distribution of resistivity in each layer to a depth of several meters below the surface (Pranata, Jufriadi, Ayu, & Wahyuningsih, 2016). Resistivity geo-electric data needs to be integrated with logging data to provide accurate information about subsurface conditions (Benjumea, Macau, Gabàs, & Figueras, 2016), although the use of logging data is not effective especially if it is used in investigations in large area scales because drilling is needed. The logging data provides information on geophysical parameters, including self potential, resistivity, and temperature (Hodlur, Dhakate, & Andrade, 2006).…”

Joint interpretation of magnetotelluric, seismic, and well-log data in Hontomín (Spain)

“…An interesting task to face in the future would be to merge these results with other geophysical (e.g. Benjumea et al, 2016) and geochemical (Elio et al, 2013;Nisi et al, 2013) studies carried out in the area, to better constrain the location and geometry of the karst, and clay and water content variations.…”

“…The selection of Hontomín as a pilot CO 2 storage site motivated a multidisciplinary characterization of the area, aimed to unravel the main characteristics of the subsurface structures. This includes geochemical Nisi et al, 2013;Permanyer et al, 2013), geophysical (Rubio et al, 2011;Alcalde et al, 2013aAlcalde et al, , b, 2014Ogaya et al, 2013Ogaya et al, , 2014Ugalde et al, 2013;Vilamajó et al, 2013Vilamajó et al, , 2015Benjumea et al, 2016) and hydro/geomechanical (Canal et al, 2013;Martínez-Landa et al, 2013) studies. Amongst them, this work aims to integrate the seismic (Alcalde et al, 2013a, b; and MT (Ogaya et al, 2013(Ogaya et al, , 2014 characterization results, together with the available log data, to expand our knowledge of the subsurface of Hontomín.…”

Validation of a fast semi-analytic method for surface-wave propagation in layered media

“…5(a) does not have strong discontinuities. However, in certain basins, the velocity profile can be more discontinuous because of the presence of other shallow low-velocity sedimentary layers (Benjumea et al 2016) or, and (c), vertical velocity perturbations against time, for the Los Angeles Basin model, at various distances from the source, respectively, from top to bottom, r = 18.1, 26, 34 km. Panels (d), (e) and (f), corresponding energy spectral density against frequency for the same simulation parameters computed from the numerical simulation (the blue line) and the analytic model with the fundamental-mode and first overtone Rayleigh wave (the dashed red line).…”