Energy of acoustic signals in a borehole

Markova, I.; Jarillo, G. Ronquillo; Markov, M.

doi:10.1111/1365-2478.12750

Cited by 3 publications

(2 citation statements)

References 14 publications

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“…A very strong attenuation is measured in the 50-54 m depth interval, as attenuation measured in the two deepest levels (85-90 and 110-120 m) is weaker. The energies of the different wave packets depend on the permeability of the different ways, with the sensitivity to permeability changes partly evidenced by a loss in the total energy of the acoustic signal (P-waves, pseudo-Rayleigh waves, Stoneley waves) but mainly marked by the loss of energy of the pseudo-Rayleigh waves [17].…”

Section: Full Wave Acoustic Logging and Vertical Seismic Profile Withmentioning

confidence: 99%

Contribution of Full Wave Acoustic Logging to the Detection and Prediction of Karstic Bodies

Mari

Porel

Delay

2020

Water

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A 3D seismic survey was done on a near surface karstic reservoir located at the hydrogeological experimental site (HES) of the University of Poitiers (France). The processing of the 3D data led to obtaining a 3D velocity block in depth. The velocity block was converted in pseudo porosity. The resulting 3D seismic pseudo-porosity block reveals three high-porosity, presumably-water-productive layers, at depths of 30–40, 85–87 and 110–115 m. This paper shows how full wave acoustic logging (FWAL) can be used to validate the results obtained from the 3D seismic survey if the karstic body has a lateral extension over several seismic. If karstic bodies have a small extension, FWAL in open hole can be fruitfully used to: detect highly permeable bodies, thanks to measurements of acoustic energy and attenuation; detect the presence of karstic bodies characterized by a very strong attenuation of the different wave trains and a loss of continuity of acoustic sections; confirm the results obtained by vertical seismic profile (VSP) data. The field example also shows that acoustic attenuation of the total wavefield as well as conversion of downward-going P-wave in Stoneley waves observed on VSP data are strongly correlated with the presence of flow.

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Section: Full Wave Acoustic Logging and Vertical Seismic Profile Withmentioning

confidence: 99%

Contribution of Full Wave Acoustic Logging to the Detection and Prediction of Karstic Bodies

Mari

Porel

Delay

2020

Water

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“…15c) has a low vertical resolution, the sampling interval over depth being 2.5 m. Figure 15c (left part) shows a comparison between PLT and VSP flow logs. Despite the difference in vertical resolutions between PLT and VSP flow logs (1 cm for the PLT, 2.5 m for the VSP), both profiles are in good agreement and confirm that there exists an active flowing karstic body at 52 m depth as detected by the total acoustic signal attenuation log [27].…”

Section: Example Of a Near Surface Karstic Reservoirmentioning

confidence: 66%

Characterizing flow in the first hundred-meter depth of a fractured aquifer using hybrid seismic methods, acoustic logging, and flow-log measurements

Mari

Delay

Porel

et al. 2021

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Understanding subsurface flow, especially in fractured rocks only housing water through a few preferential pathways, is still challenging. The point is mainly associated with the poor accessibility of the subsurface and the lack of accurate representations for both heterogeneity and spatial distribution of water bearing bodies. This notwithstanding, highly-resolved geophysical investigations bring new images of the subsurface. This is exemplified over a fractured limestone aquifer at the site scale (for example, that of the radius of influence of an extraction well). On an experimental site, situated in the Cher region (France), two boreholes have been drilled for field experiments. Full Waveform Acoustic Logging (FWAL) and seismic experiments were conducted. Hybrid seismic imaging, which consists in combining refraction and reflection seismic results, has been carried out. Based on a four-step procedure, the processing of refracted and reflected waves provided two sections. After assemblage, these sections produced in a first step an extended time reflectivity section starting from the surface and, in a second step, a section over depth after calibration with Vertical Seismic Profile (VSP) and acoustic data. However, even the Very High Resolution (VHR) seismic methods do not have a sufficient vertical resolution to describe accurately the geological formation. The acoustic sections were processed to separate the different wave fields, to extract the criss-cross events and to build a criss-cross index log. A log of fracturation index, based on both criss-cross index and P-wave velocity measurements, was computed to detect the presence of fractures. After calibration, and under the assumption that the slower the P-wave velocity, the higher the permeability – porosity, a 3D seismic block of reflection can inform on preferential areas where flow should occur. At the scale of an open wellbore, acoustic loggings that measure wave velocities over a short distance within the well also inform on open features crosscut by the well. Finally, flow log measurements confirm the occurrence of flowing horizons that were previously marked by both seismic and acoustic data. Seismic and acoustic data are therefore suited to image contrasted hydraulic properties over fractured subsurface systems usually poorly documented.

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Secondary porosity classification in heterogeneous carbonate reservoirs based on the sonic log data

Markova,

Markov

2023

Journal of Applied Geophysics

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Energy of acoustic signals in a borehole

Cited by 3 publications

References 14 publications

Contribution of Full Wave Acoustic Logging to the Detection and Prediction of Karstic Bodies

Contribution of Full Wave Acoustic Logging to the Detection and Prediction of Karstic Bodies

Characterizing flow in the first hundred-meter depth of a fractured aquifer using hybrid seismic methods, acoustic logging, and flow-log measurements

Secondary porosity classification in heterogeneous carbonate reservoirs based on the sonic log data

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