Prediction ahead of the bit by using drill‐bit pilot signals and reverse vertical seismic profiling (RVSP)

Geophysics ◽  
2002 ◽  
Vol 67 (4) ◽  
pp. 1169-1176 ◽  
Author(s):  
Massimo Malusa ◽  
Flavio Poletto ◽  
Francesco Miranda
Keyword(s):  
Numerical Model ◽  
Low Cost ◽  
Drill Bit ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling ◽  
Zero Offset

Surface drillstring axial pilot signals are used to predict reflections ahead of the drill bit. We show that part of the drill‐bit signal propagates downward in the formation, reflects upward by a seismic interface, and is then transmitted to the drillstring and the surface pilot sensors. These reflections are interpreted in drill‐bit pilot signals by means of a numerical model of the drillstring coupled to the formation at the bit–rock contact. The result is an additional, low‐cost, reverse VSP (RVSP) in the zero‐offset approximation. These while‐drilling results are integrated with conventional drill‐bit RVSP measurements and compared with other geophysical and well results.

Salt/sediment proximity to delineate salt boundaries using seismic while drilling in the Gulf of Mexico

2019 ◽  
Vol 38 (11) ◽  
pp. 833-842
Author(s):  
Jacob Bayer ◽  
Bryce Jensen ◽  
Yingping Li ◽  
Tianrun Chen ◽  
Ken Matson
Keyword(s):  
Gulf Of Mexico ◽  
Comprehensive Analysis ◽  
Processing Method ◽  
P Wave ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling ◽  
Degree Of Confidence ◽  
Zero Offset ◽  
Optimization Efficiency ◽  
High Degree

Between July 2018 and January 2019, Shell acquired two vertical seismic profiling (VSP) surveys in two deepwater wells in the Gulf of Mexico by using a seismic while drilling (SWD) tool. Each survey included a rig source zero-offset VSP and a boat source offset VSP. The main objective of the surveys is to delineate the salt-sediment boundary at the salt base and flank. We design and execute the complex VSP surveys with emphasis on optimization, efficiency, and integration. We develop a comprehensive analysis and processing method to integrate P-wave sediment and salt proximities with converted PS salt proximity. We use SWD-VSP surveys to demonstrate how we define the salt boundary with the integrated results. Our results show that we can delineate the salt boundary with better accuracy and with a high degree of confidence. These successful VSP surveys provide significant business and technical value.

Identification of structures inside basement at Soultz-sous-Foret (France) by triaxial drill-bit vertical seismic profiling

Geothermics ◽  
1999 ◽  
Vol 28 (3) ◽  
pp. 355-376 ◽  
Author(s):  
Hiroshi Asanuma ◽  
Hakusei Liu ◽  
Hiroaki Niitsuma ◽  
Roy Baria
Keyword(s):  
Drill Bit ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling

A new approach to offshore drill‐bit reverse vertical seismic profiling (RVSP)

Geophysics ◽  
2002 ◽  
Vol 67 (4) ◽  
pp. 1071-1075 ◽  
Author(s):  
Flavio Poletto ◽  
Giuliano Dordolo
Keyword(s):  
Drill Bit ◽  
New Approach ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling

Application of Gabor deconvolution to zero-offset VSP data

Geophysics ◽  
2013 ◽  
Vol 78 (2) ◽  
pp. D85-D91 ◽  
Author(s):  
A. Ahadi ◽  
M. A. Riahi
Keyword(s):  
Real Data ◽  
Frequency Spectra ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling ◽  
Anelastic Attenuation ◽  
Vsp Data ◽  
High Resolution Images ◽  
Seismic Sections ◽  
Zero Offset ◽  
Hyperbolic Smoothing

The aim of designing deconvolution operators is to extract the reflectivity series from seismic sections. Due to the noise, source signature inconsistency, reflection/transmission, anelastic attenuation, and multiples, the amplitude of a propagating seismic wave varies as a function of time. Because of these factors the frequency spectra of seismic signals narrow with time. Recognition of reflectors using upgoing waves is one of the notable properties of vertical seismic profiling (VSP) data. Designing a deconvolution operator for VSP data based on downgoing waves is considered to be one of the most ideal deconvolution methods intended to produce high-resolution images in routine processing of zero-offset VSP data. For such an analysis, the Gabor deconvolution operator has been designed using the downgoing wavefield and then was applied to the upgoing wavefield, and hyperbolic smoothing was used to estimate the wavelet. The final result of applying the deconvolution operator is a VSP section with superior resolution. To compare this method with customary methods of deconvolution, the Wiener deconvolution was applied to the synthetic and real data, and the results were compared with those of the Gabor deconvolution.

Positioning drill-bit and look-ahead events using seismic traveltime data

Geophysics ◽  
2006 ◽  
Vol 71 (4) ◽  
pp. F79-F90 ◽  
Author(s):  
Jo Eidsvik ◽  
Ketil Hokstad
Keyword(s):  
Velocity Model ◽  
Drill Bit ◽  
Surface Sampling ◽  
Data Set ◽  
Norwegian Sea ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling ◽  
Look Ahead ◽  
Sampling Locations ◽  
Dense Sampling

We study seismic traveltime measurements acquired in the borehole, including vertical seismic profiling, seismic measurements while drilling, and drill-bit noise generated data. These traveltime data are used to assess informative parameters, including drill-bit position, distance to drilling target, and parameters of the velocity model. First, we analyze seismic traveltime data using a simple hyperbolic traveltime equation for rays between surface sampling locations and the drill bit. Second, we describe a model for estimating both the position of the drill bit and the relative distance to geologic interfaces ahead of the bit. Finally, we present a dynamic Bayesian strategy for real-time prediction of drill-bit positions, velocity parameters, and distances to geologic markers. Walk-away vertical seismic profiling data from the Norwegian Sea are used to demonstrate our methods. For this data set, we pick five key reflectors ahead of the drill bit. The deepest reflector is estimated to be [Formula: see text] ahead of the drill bit, using seismic traveltime data alone. The effects of aperture and surface sampling locations are large on our estimates and their associated uncertainties, and we observe that large offset is preferable to dense sampling in terms of positioning accuracy.

A blind interpretation of drill‐bit signals

Geophysics ◽  
2000 ◽  
Vol 65 (3) ◽  
pp. 970-978 ◽  
Author(s):  
Flavio Poletto
Keyword(s):  
Seismic Signal ◽  
Dominant Frequency ◽  
Drill Bit ◽  
Coherent Noise ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling ◽  
Vsp Data ◽  
First Arrival

The role of kurtosis in evaluating the quality of vertical seismic profiling (VSP) drill‐bit data is investigated. The calculations show how kurtosis depends on the dominant frequency, bandwidth, and phase content of a seismic signal. This analysis is applied to synthetic and real common‐offset and common‐shot drill‐bit seismograms to evaluate the prominence and quality of the first arrival and other coherent events. High values of kurtosis correspond to an isolated first arrival or to a compressed coherent noise event, while low values are typical of low S/N (distributed) ratio traces. Kurtosis analysis applied to drill‐bit VSP data while drilling proved to be successful at identifying high‐quality traces with little interpretational input.

Comparison of seismic attenuation models using zero-offset vertical seismic profiling (VSP) data

Geophysics ◽  
2005 ◽  
Vol 70 (2) ◽  
pp. F17-F25 ◽  
Author(s):  
Tommy Toverud ◽  
Bjørn Ursin
Keyword(s):  
Model Fitting ◽  
Seismic Attenuation ◽  
Data Set ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling ◽  
Vsp Data ◽  
Seismic Frequencies ◽  
Standard Linear Solid ◽  
Attenuation Models ◽  
Zero Offset

For seismic frequencies it is common to use an empirical equation to model attenuation. Usually the attenuation coefficient is modeled with linear frequency dependence, a model referred to as the Kolsky-Futterman model. Other models have been suggested in the geophysical literature. We compare eight of these models on a zero-offset vertical seismic profiling (VSP) data set: the Kolsky-Futterman, the power law, the Kjartansson, the Müller, the Azimi second, the Azimi third, the Cole-Cole, and the standard linear solid (SLS) models. For three separate depth zones we estimate velocities and Q-values for all eight models. A least-squares model-fitting algorithm gives almost the same normalized misfit for all models. Thus, none of the models can be preferred or rejected based on the given data set. Slightly better overall results are obtained for the Kolsky-Futterman model; for one depth zone, the SLS model gave the best result.

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