Detection of guided waves between gas wells for reservoir characterization

Parra, Jorge O.; Hackert, Chris L.; Gorody, Anthony W.; Korneev, Valeri

doi:10.1190/1.1451322

Cited by 20 publications

(10 citation statements)

References 13 publications

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“…It is not clear why the Liu et al (2000) and Parra et al (2002) far‐offset crosswell seismic data do not appear to provide evidence for seismic‐waveguide action comparable to the 100 m offset data of Parra et al (1998) or the present 600 m offset Liaohe data. In the case of Liu et al (2000), perhaps the waveguide is simply not well enough defined; or perhaps the layer is, unknown to the investigators, offset or otherwise discontinuous.…”

Section: Waveguide Seismic Observations and Liaohe Oil Field Velocitymentioning

confidence: 66%

“…The difference in far‐offset (>500–600 m) waveguide signals between those recorded at Liaohe and those recorded by Liu et al (2000) and Parra et al (2002) may be due to different degrees of physical property heterogeneity in the waveguide structures. Numerical simulations of 3‐D fault‐zone waveguide phenomena conducted by Leary et al (1991) and Igel et al (1997) suggest that heterogeneity within a waveguide LVL can destroy a waveguide signal.…”

Section: Waveguide Seismic Observations and Liaohe Oil Field Velocitymentioning

confidence: 90%

“…A possible complication arises because the shale formations have strong layering anisotropy. In the case of Parra et al (2002), air‐gun source tube waves have contaminated the waveguide signal; processing the tube waves may have obscured waveguide energy localizations or otherwise perturbed the waveguide signal. The Parra et al (2002) data have apparent surface seismic control that has been interpreted to eliminate the possibility of lateral discontinuity.…”

Section: Waveguide Seismic Observations and Liaohe Oil Field Velocitymentioning

confidence: 99%

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Crosswell seismic waveguide phenomenology of reservoir sands & shales at offsets >600 m, Liaohe Oil Field, NE China

Leary¹,

Ayres²,

Yang

et al. 2005

Geophysical Journal International

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S U M M A R YCrosswell seismic data recorded at 620-650 m offsets in an oil-bearing sand/shale reservoir formation at the Liaohe Oil Field, northeast China, provide robust evidence for waveguide action by low-velocity reservoir layers. Crosswell-section velocity models derived from survey-well sonic logs and further constrained by observed waveguide seismic wavegroup amplitudes and phases yield plausible evidence for interwell reservoir-sand continuity and discontinuity. A pair of back-to-back Liaohe crosswell vector-seismic surveys were conducted using a source well between two sensor wells at 650 and 620 m offsets along a 200-m-thick reservoir formation dipping 7 • down-to-east between depths of 2.5 and 3 km. A downhole orbital vibrator generated seismic correlation wavelets with frequency range 50-350 Hz and signal/noise ratio up to 5:1 over local downhole ambient noise. The sensor wells were instrumented with a mobile 12-to 16-level string of clamped vector-motion sensor modules at 5 m intervals. Using 5 m source depth increments, crosswell Surveys 1 and 2 cover source/sensor well intervals above and through the reservoir of, respectively, 600 m/600 m (13 000 vector traces in 9 common sensor fans) and 300 m/560 m (7000 vector traces in 7 common sensor fans). Survey 1 common sensor gathers show clear, consistent high-amplitude 20 ms waveletgroup lags behind the first-arrival traveltime envelope. Such arrivals are diagnostic of seismic lowvelocity waveguides connecting the source and sensor wells. Observed Survey 1 retarded wavegroup depths tally with source and sensor depths in low-velocity layers identified in sonic well logs. Finite-difference acoustic model wavefields computed for waveguide acoustic layers constrained by well-log sonic velocity data match the observed waveguide traveltime and amplitude systematics. Model waveforms duplicate the observed m-scale and ms-scale sensitivity of waveguide spatio-temporal energy localization. Survey 2 crosswell data, in contrast, provide no comparable evidence for waveguide action despite a sensor-well sonic well log similar to that of Survey 1. Instead, acoustic wavefield modelling of Survey 2 data clearly favours an interpreted waveguide model with 10 • downdip interrupted by a 75-100 m throw downfault near the sensor well. The absence of clear waveguide arrivals is adequately explained by dispersal of waveguide energy at the fault discontinuity. Auxiliary well sonic velocity and lithologic logs confirm the model-implied 75-100 m of down-throw faulting near the sensor well.

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Section: Waveguide Seismic Observations and Liaohe Oil Field Velocitymentioning

confidence: 66%

Section: Waveguide Seismic Observations and Liaohe Oil Field Velocitymentioning

confidence: 90%

Section: Waveguide Seismic Observations and Liaohe Oil Field Velocitymentioning

confidence: 99%

See 1 more Smart Citation

Crosswell seismic waveguide phenomenology of reservoir sands & shales at offsets >600 m, Liaohe Oil Field, NE China

Leary¹,

Ayres²,

Yang

et al. 2005

Geophysical Journal International

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“…Compressional waves guided by impedance contrasts have been used in cross-well studies in oil-bearing sand -shale reservoirs (Leary et al 2005), coal seams (Buchanan et al 1983) and sandstone-shale formations (Parra et al 2002) for distances greater than 600 m for a frequency range of 50-350 Hz. To apply these techniques to fractured carbonate reservoir characterization requires an understanding that fractures can produce wave guiding, and the behaviour of the guided modes depends on contributions from the mechanical properties of both the fracture and the matrix.…”

Section: Resultsmentioning

confidence: 99%

Wave guiding in fractured layered media

Shao

Petrovitch

Pyrak‐Nolte

2014

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Many carbonate rocks are composed of layers and contain fracture sets that cause the hydraulic, mechanical and seismic properties to be anisotropic. Co-located fractures and layers in carbonate rock lead to competing wave-scattering mechanisms: both layers and parallel fractures generate compressional-wave (P-wave) guided modes. The guided modes generated by the fractures may obscure the presence of the layers. In this study, we examine compressional-wave guided modes for two cases: wave guiding by fractures in a layered medium with sub-wavelength layer thickness; and wave guiding in media with competing scattering mechanisms, namely layering (where the thickness is greater than a wavelength) and parallel sets of fractures. In both cases, the fracture spacing is greater than a wavelength. When the layer thickness is smaller than a wavelength, P-wave guiding is controlled by the spacing of the fractures, fracture specific stiffness, the frequency of the signal and the orientation of the layering relative to the fracture set. The orientation of the layering determines the directionally dependent P-wave velocity in the anisotropic matrix. When the layer thickness is greater than a wavelength and an explosive point source of a signal is located in the layer containing a fracture, the fracture either enhanced or suppressed compressional-mode wave guiding caused by the layering in the matrix.Carbonate reservoirs pose a scientific and engineering challenge to geophysical prediction and monitoring of fluid flow in the subsurface. This is particularly true for carbonate rocks, many of which form in spatially and temporally variable depositional environments, and are modified further by diagenesis and deformation during the subsequent rock history. Variations in primary depositional geometries (metre to kilometre scale), as influenced by factors such as their depositional environments, sealevel fluctuations and climate, are reflected by distinct stacking patterns of rock layers or bodies, and variations in their thickness and lateral continuity. Depositional and/or construction processes influence finer-scale (micron to centimetre scale) textural variations and the formation of sedimentary structures. The resulting pore systems in the rock matrix comprise pores that vary in scale from submicron to centimetres. Fossil and primary mineral content, as well as spatial and compositional variations in cements, introduce further heterogeneities to the rock texture. Both cements and pore structure can be modified multiple times by temporal variations in the compositions, temperatures and flow rates of fluids migrating through the rocks. Carbonate rocks that have been subjected to deformation in response to burial, tectonic and induced (e.g. during hydrocarbon production) stresses commonly develop arrays of fractures as well as stylolites. While the orientations of these features vary with the burial and deformation history, fracture arrays are commonly steeply dipping, while stylolites tend to be oriented parallel to bedding.Diffi...

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“…Due to shale's low velocity nature, head wave is very common in crosswell seismic (Dong and Toksöz, 1995;Parra et al, 2002;Parra et al, 2006) and microseismic survey (Maxwell, 2010;Zimmer, 2010;Zimmer, 2011) in shale operation. When the distance between geophones and source is relatively large, the head wave arrival can precede direct arrival.…”

Section: Introductionmentioning

confidence: 99%

Microseismic Event Location Using Multiple Arrivals: Demonstration of Uncertainty Reduction

Zhang¹,

Rector²,

Nava³

2015

Proceedings of the 3rd Unconventional Resources Technology Conference

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SummaryEvent location is the basis of hydraulic fracture characterization using microseismic data. However, the traditional method of using direct arrival times and Pwave polarizations leads to increased error due to the large uncertainty in polarization. Due to shale's low velocity nature and the configuration of horizontal stimulation and monitoring wells, the head wave can often be the first arrival rather than the direct arrival.Finite difference modeling was used to validate the character of head waves in field data gathered from the Marcellus shale and the situations under which a head wave can be the first arrival were carefully analyzed. With careful processing, we reveal the presence of high number of head waves in the Marcellus Shale. Head wave and direct arrivals were used instead of the conventional Pwave polarization to estimate microseismic event location. A Bayesian inference program was also developed for joint event location and velocity model calibration. Validation of the developed method was performed on perforation shots and shows that using head waves instead of polarization can achieve much better resolution in microseismic event location. The application of the developed method on field data shows a more reasonable result than that provided by contractor.Our results show that the head wave can be a contributor instead of a detractor in the process of accurate event location. This will eliminate the necessity for polarization which has large uncertainty due to poor geophoneborehole coupling, multiple arrivals, and low signal to noise ratio. The developed method can effectively improve the accuracy of microseismic event location and proposes a better acquisition geometry and strategy to reduce microseismic monitoring cost and improve event location accuracy.

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Detection of guided waves between gas wells for reservoir characterization

Cited by 20 publications

References 13 publications

Crosswell seismic waveguide phenomenology of reservoir sands & shales at offsets >600 m, Liaohe Oil Field, NE China

Crosswell seismic waveguide phenomenology of reservoir sands & shales at offsets >600 m, Liaohe Oil Field, NE China

Wave guiding in fractured layered media

Microseismic Event Location Using Multiple Arrivals: Demonstration of Uncertainty Reduction

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