Prediction of lateral variability in fracture intensity using multicomponent shear-wave surface seismic as a precursor to horizontal drilling in the Austin Chalk

Mueller, Mike

doi:10.1111/j.1365-246x.1991.tb01402.x

Cited by 97 publications

(48 citation statements)

References 16 publications

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“…5,7,9,15,16 This is not to say that the use of Alford in acoustic logging is never appropriate; it is simply that the azimuth computation is prone to error in the context of unconventional exploration and production. For acoustic processing, Alford rotation results are valid, or have negligible error, for ray paths that deviate at most twenty degrees from the vertical.…”

Section: Deviated Well Azimuth Computationmentioning

confidence: 99%

Seismic Methodologies Adapted For Use In Acoustic Logging

Biswas

Ley

2015

Day 1 Tue, October 20, 2015

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If we are to continue to use acoustic logging as a viable method for characterizing wellbore formation characteristics, such as natural fractures, then logging techniques developed for conventional reservoirs and vertical wells should be updated and adapted for use in today's unconventional and directional drilling applications. Unlike seismic processes, which have undergone research and changes to adapt to the more complex characterization needs of today's wells, acoustic logging techniques have stayed relatively stagnant. In order to stay relevant, acoustic logging processes must adapt for use in unconventionals as well. The following discussion focuses on four seismic techniques adapted for acoustic logging processes, the process for choosing these particular techniques to adapt, and the results achieved.We have based new acoustic logging algorithms and routines on these four seismic techniques and adapted the research into proprietary software for processing raw, acoustic waveform data. First, we have adapted the use of compressional waves to map drops in energy across natural fractures which allows industry to move away from many of the limitations imposed by more widely used techniques. Second, as part of the workflow presented in the compressional fracture identification methodology, we have adapted stacking to improve results and amplify anomalies. Third, in order to provide a broad available toolsets and usable data, we have incorporated advanced filtering routines based on predictive deconvolution, which can be used to process acoustic data from alternative tools or to enhance data collected using measurement-while-drilling or logging-while-drilling tools. Fourth and last, applicable to both shear and compressional waveform processing, we have chosen to move away from Alford-based azimuth computations, or at least correct for assumptions in Alford-based azimuth computations that are not relevant in unconventionals, so that borehole deviation does not adversely affect the processing.The use of compressional waves to map natural fracture patterns has found great success in both vertical and lateral wells and has been used in the field in the Permian, Eagle Ford, the Bakken, and in various international fields. Comparisons against image and core results demonstrate an 80-85% correlation rate. The following discussion will go over two case studies, the evaluation method used to study the correlation, briefly discuss the workflow used, and also provide an example of how the advanced filtering produces much cleaner waveforms for processing than relying solely on frequency filtered waveforms.These new processes allow acoustic processing to enter the modern age of exploration and create a new, more direct process for finding the fracture density in the well bore. Furthermore, they may be incorporated in to new and old processing techniques, making the most of the modern tools available.

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Section: Deviated Well Azimuth Computationmentioning

confidence: 99%

Seismic Methodologies Adapted For Use In Acoustic Logging

Biswas

Ley

2015

Day 1 Tue, October 20, 2015

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“…A rather general approach tries to solve a broad range of hard‐fracture anisotropic‐media problems using multicomponent data [ Mueller , 1991; Stewart , 1991; Michelena et al , 2001; Stewart et al , 2002; Simmons , 2009]. However, due to difficulties in acquiring accurate information about S‐wave polarizations, misinterpretation of S‐wave splitting effects can occur in converted wave (P to S) data.…”

Section: Introductionmentioning

confidence: 99%

Estimating fracture orientation from elastic‐wave propagation: An ultrasonic experimental approach

et al. 2012

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Elastic‐wave propagation in fractured and cracked media depends on the dominant spatial orientation of the discontinuities. Consequently, compressional and shear‐wave velocities can give valuable information about the orientation of the cracks. The main goal of this work is to estimate the preferential fracture orientation based on an analysis of cross‐correlated S‐wave seismograms and Thomsen parameters. For this purpose, we analyzed ultrasonic measurements of elastic (P and S) waves in a physical‐modeling experiment with an artificially anisotropic cracked model. The solid matrix of the model consisted of epoxy‐resin; small rubber strips simulate cracks with a compliant fill. The anisotropic cracked model consists of three regions, each with a different fracture orientation. We used the rotation of the S‐wave polarizations for a cross‐correlation analysis of the orientations, and P‐ and S‐wave measurements to evaluate the weak anisotropic parametersγ and ε.The shear and compressional wave sources had dominant frequencies of 90 kHz and 120 kHz. These frequencies correspond to long wavelengths compared to the spacing between layers, indicating a nearly effective‐media behavior. Integrating the results from cross‐correlation with anisotropic parameter analysis, we were able to estimate the fracture orientation in our anisotropic cracked physical model. Theγparameter showed good agreement with the cross‐correlation analysis and, beyond that, provided additional information about the crack orientation that cross‐correlation alone did not fully resolve. Moreover, our results show that the shear waves are much more strongly influenced by, and can thus contain more information about, crack orientation than compressional waves.

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“…Differences in the level of anisotropy reflect differences in the productivity of a reservoir which can be explained by the quantity of subvertical fractures. Crampin 1985;Schoenberg and Douma 1988;Wang and Sun 1990;Muller 1991;Yardley and Crampin 1993). Backus 1962;Crampin, Chesnokov and Hipkin 1984;Crampin et al 1990).…”

Section: Introductionmentioning

confidence: 99%

The effect of orthorhombic anisotropy and its implication for oil recovery and reservoir exploitation

Ass'ad¹

2004

Geophysical Prospecting

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Results of an experimental study of shear‐ and compressional‐wave propagation in an orthorhombically anisotropic medium are presented. The experiments were performed on a physical model consisting of two sets of fractures. The first set consisted of orientated rubber inclusions simulating weak material‐filled cracks. The second set consisted of a system of closely spaced parallel fractures simulated by thin plates of epoxy resin, superimposed orthogonally on the first set. Three cases of fracture orientations within the model were identified and studied. Case 1 is analogous to a jointed fracture reservoir with one vertical set of fluid‐filled cracks or fractures and one non‐filled horizontal set. This case is referred to as JFV. Case 2 is analogous to a double fracture reservoir with one horizontal set of fluid‐filled fractures or cracks and one non‐filled vertical set. This is referred to as DFH. Case 3 is analogous to a double fracture reservoir with two vertical sets of fractures or cracks, with only one fluid‐filled. Case 3 is referred to as DFV. A pulse transmission method was performed on all three modelled cases along the three principal axes. A directional variation in the compressional‐ and shear‐wave velocities, as well as distinct shear‐wave splitting, was observed. The elastic constants for each case were determined and differences between them were noted and compared with the controlled results of both layered (transverse isotropy, TI) and vertically fractured (azimuthally anisotropic models, VF) media. The differences in elastic moduli and velocities indicate the potential of recognizing the different fracture orientations and suggest an approach to designing a method of drilling to further enhance oil recovery and reservoir exploitation.

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Prediction of lateral variability in fracture intensity using multicomponent shear-wave surface seismic as a precursor to horizontal drilling in the Austin Chalk

Cited by 97 publications

References 16 publications

Seismic Methodologies Adapted For Use In Acoustic Logging

Seismic Methodologies Adapted For Use In Acoustic Logging

Estimating fracture orientation from elastic‐wave propagation: An ultrasonic experimental approach

The effect of orthorhombic anisotropy and its implication for oil recovery and reservoir exploitation

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