Performance evaluation of a high‐freqency borehole seismic source

1991 ◽  
Author(s):  
R. F. Ballard ◽  
R. D. Rechtien ◽  
K. L. Hambacker
Keyword(s):  
Performance Evaluation ◽  
Seismic Source ◽  
Borehole Seismic

Crosswell seismic imaging in a contaminated basalt aquifer

Geophysics ◽  
2004 ◽  
Vol 69 (1) ◽  
pp. 16-24 ◽  
Author(s):  
Thomas M. Daley ◽  
Ernest L. Majer ◽  
John E. Peterson
Keyword(s):  
Seismic Source ◽  
P Wave ◽  
Low Velocity ◽  
S Waves ◽  
High Attenuation ◽  
Well Spacing ◽  
Simultaneous Acquisition ◽  
Environmental Laboratory ◽  
New Type ◽  
Borehole Seismic

Multiple seismic crosswell surveys have been acquired and analyzed in a fractured basalt aquifer at Idaho National Engineering and Environmental Laboratory. Most of these surveys used a high‐frequency (1000–10,000 Hz) piezoelectric seismic source to obtain P‐wave velocity tomograms. The P‐wave velocities range from less than 3200 m/s to more than 5000 m/s. Additionally, a new type of borehole seismic source was deployed as part of the subsurface characterization program at this contaminated groundwater site. This source, known as an orbital vibrator, allows simultaneous acquisition of P‐ and S‐waves at frequencies of 100 to 400 Hz, and acquisition over larger distances. The velocity tomograms show a relationship to contaminant transport in the groundwater; zones of high contaminant concentration are coincident with zones of low velocity and high attenuation and are interpreted to be fracture zones at the boundaries between basalt flows. The orbital vibrator data show high Vp/Vs values, from 1.8 to 2.8. In spite of the lower resolution of orbital vibrator data, these data were sufficient for constraining hydrologic models at this site while achieving imaging over large interwell distances. The combination of piezoelectric data for closer well spacing and orbital vibrator data for larger well spacings has provided optimal imaging capability and has been instrumental in our understanding of the site aquifer's hydrologic properties and its scale of heterogeneity.

scholarly journals Next Generation Borehole Seismic Source: Dual-Wavefield Downhole Vibrator System

2012 ◽  
Vol 2012 (1) ◽  
pp. 1-#
Author(s):  
Jim Minto ◽  
Bruce Marion ◽  
Muhammad Shafiq ◽  
Ajay Nalonnil
Keyword(s):  
Seismic Source ◽  
Next Generation ◽  
Borehole Seismic

Orbital vibrator seismic source for simultaneous P‐ and S‐wave crosswell acquisition

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1471-1480 ◽  
Author(s):  
Thomas M. Daley ◽  
Dale Cox
Keyword(s):  
Seismic Energy ◽  
Seismic Source ◽  
P Wave ◽  
S Wave ◽  
Circularly Polarized ◽  
S Waves ◽  
Polarized Waves ◽  
Coordinate Rotation ◽  
Processing Algorithms ◽  
Borehole Seismic

A recently developed borehole seismic source, the orbital vibrator, was successfully deployed in a crosswell survey in a fractured basalt aquifer. This seismic source uses a rotating eccentric mass to generate seismic energy. Source sweeps with clockwise and counter‐clockwise rotations are recorded at each source location. Because this source generates circularly polarized waves, unique processing algorithms are used to decompose the recordings into two equivalent linearly oscillating, orthogonally oriented seismic sources. The orbital vibrator therefore generates P‐ and S‐waves simultaneously for all azimuths. A coordinate rotation based on P‐wave particle motion is used to align the source components from various depths. In a field experiment, both P‐ and S‐wave arrivals were recorded using fluid‐coupled hydrophone sensors. The processed field data show clear separation of P‐ and S‐wave arrivals for in‐line and crossline source components, respectively. A tensor convolutional description of the decomposition process allows for extension to multicomponent sensors.

Borehole seismic‐source radiation pattern in transversely isotropic media

Geophysics ◽  
1995 ◽  
Vol 60 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Wenjie Dong ◽  
M. Nafi Toksöz
Keyword(s):  
Radiation Effects ◽  
Low Frequency ◽  
Transversely Isotropic ◽  
Seismic Source ◽  
Wave Pattern ◽  
Radiation Patterns ◽  
S Wave ◽  
Source Radiation ◽  
Air Gun ◽  
Borehole Seismic

We extend previous discussions on crosswell tomography in anisotropic formations by deriving the radiation patterns of three typical downhole seismic sources (impulsive air gun or dynamite, wall‐clamped vertical vibrators, and cylindrical bender) inside a fluid‐filled borehole embedded in a transversely isotropic (TI) formation. The method of steepest descents, in conjuncture with the low‐frequency and far‐field assumptions, is applied to the exact displacement integrals of these sources to obtain their radiation patterns asymptotically. In spite of complications caused by quasi‐P‐ and quasi‐SV‐wave coupling and wavefront triplication in homogeneous TI media, the final results can still be expressed in slowness components determined by a ray direction, which is desired when source radiation effects are to be accounted for by ray‐based tomography techniques. Tests with the radiation patterns show that while the effect of anisotropy on P‐waves is moderate, its effect on the S‐wave pattern is significant even for slightly anisotropic formations. One can predict the S‐wave pattern from the sign of the Thomsen’s measure δ*.

The use of drill‐bit energy as a downhole seismic source

Geophysics ◽  
1991 ◽  
Vol 56 (5) ◽  
pp. 628-634 ◽  
Author(s):  
J. W. Rector ◽  
B. P. Marion
Keyword(s):  
Seismic Energy ◽  
Seismic Source ◽  
Drilling Process ◽  
Drill Bit ◽  
Data Set ◽  
Pilot Signal ◽  
Data Volume ◽  
Vsp Data ◽  
Borehole Seismic ◽  
Incoherent Noise

A new wellbore seismic technique uses the vibrations produced by a drill bit while drilling as a downhole seismic energy source. The technique is described as “inverse” VSP because the source and receiver positions of conventional VSP are reversed. No downhole instrumentation is required to obtain the data and the data recording does not interfere with the drilling process. These characteristics offer a method by which borehole seismic data can be acquired, processed, and interpreted while drilling. Interchanging the conventional VSP source and receiver positions improves the efficiency of recording multioffset surveys for imaging a 3-D data volume in the borehole vicinity. The continuous signals generated by the drill bit are recorded by a pilot sensor attached to the top of the drillstring and by receivers located at selected positions around the borehole. The pilot signal is crosscorrelated with the receiver signals to compute traveltimes of the arrivals and to attenuate incoherent noise. Deconvolution and time shifts of the pilot signal compensate for the effects of propagation from the drill bit to the top of the drillstring. By repeating this process for an interval of the well, a VSP‐equivalent data set is generated. Results from a test well demonstrate that the processed drill‐bit data are comparable to conventional VSP data.

A field test of an electrodeless arc discharge, borehole seismic source

Geophysics ◽  
1993 ◽  
Vol 58 (11) ◽  
pp. 1558-1564 ◽  
Author(s):  
Kenneth D. Mahrer ◽  
Brian J. Zook
Keyword(s):  
Field Test ◽  
Arc Discharge ◽  
Sensor Arrays ◽  
Seismic Source ◽  
Test Site ◽  
Near Surface ◽  
Single Firing ◽  
Borehole Seismic ◽  
High Degree ◽  
Repeatability Test

Waveforms generated by an impulsive, 1.2 kJ, seven‐conductor wireline electrodeless arc discharge borehole seismic source or sparker at Texaco’s Humble, TX field test site were recorded by three borehole sensor arrays: two free‐hanging hydrophone streamers in in‐line boreholes at 82 m and 170 m from the source well and a grouted, three‐component geophone string in a borehole 110 m from the source well. A repeatability test of the source, consisting of single firings of the source at a rate of 1 firing per 5 s, showed very clean, very strong, Ricker‐like wavelets. Despite a high‐degree of attenuation (exact value of Q is not known), the useful frequency passband of the wavelets was from 200 Hz to 1200 Hz for the data recorded by the 82-m offset hydrophones and 200 Hz to 500 Hz for the 170-m hydrophones. Using 62 single‐firing wavelets recorded in the 82-m offset well gave mean and median crosscorrelations greater than 0.96 with standard deviations less than 0.02. A stack test, consisting of 1, 2, 4, 8, 16, and 32-stacked waveforms, confirmed the shape, strong S/N ratio, and high correlation of the sparker output. The 32-stack, which took less than 3 minutes to generate, was recorded by the noisy, near-surface geophones at a raypath distance of nearly 300m.

Seismic data acquired with a novel, permanently-installed borehole seismic source

2019 ◽  
Author(s):  
Tyler W. Spackman ◽  
Donald C. Lawton ◽  
Malcolm Bertram
Keyword(s):  
Seismic Data ◽  
Seismic Source ◽  
Borehole Seismic

The use of an active drill bit for inverse VSP measurements

1989 ◽  
Vol 20 (2) ◽  
pp. 343 ◽  
Author(s):  
J.W. Rector III ◽  
B.P. Marion ◽  
R.A. Hardage
Keyword(s):  
Seismic Energy ◽  
Seismic Source ◽  
Drilling Process ◽  
Drill Bit ◽  
Seismic Surveys ◽  
Reference Trace ◽  
Vsp Data ◽  
Sensor Signals ◽  
Borehole Seismic ◽  
Reference Sensor

Vertical Seismic Profiling (VSP) is often used to provide high resolution seismic images near a wellbore. A new borehole seismic technique, the TOMEX� survey (Rector, et al., 1988), uses the vibrations produced by a drill bit as a downhole seismic energy source to produce inverse VSP data. No downhole instrumentation is required to acquire the data, and the data recording does not interfere with or delay the drilling process. Hence, there is no loss of rig time in performing the survey. These characteristics offer a method to acquire SWD (seismic-while-drilling) borehole seismic surveys. In addition, 3-D imaging around a well can be obtained at significant savings compared to conventional offset VSP imaging. The continuous signals generated by the bit during drilling are monitored with a reference sensor attached to the top of the drillstring, and the reference sensor signals are crosscorrelated with signals from surface-positioned geophones to produce inverse VSP data. Deconvolution and time shifts are then performed to remove the effects of recording the source reference trace at a location that is a considerable distance from the source. Results from tests demonstrate that these processed drill-bit source data are virtually identical to conventional forward VSP data. In using the drill bit as a downhole seismic source for inverse VSP, many of the limitations of conventional VSP are overcome. Several applications for VSP that were previously considered to be prohibitively expensive are now feasible. Furthermore, this seismic-while-drilling technique offers the potential for the explorationist to make real-time drilling decisions at the well site.

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