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Haldorsen J.B.U.,Schlumberger | Haldorsen J.B.U.,READ ASA | Scott Leaney W.,Schlumberger | Coates R.T.,Schlumberger | And 3 more authors.
Geophysics | Year: 2013

We evaluated a method for using 3C vertical seismic profile data to image acoustic interfaces located between the surface source and a downhole receiver array. The approach was based on simple concepts adapted from whole-earth seismology, in which observed compressional and shear wavefields are traced back to a common origin. However, unlike wholeearth and passive seismology, in which physical sources are imaged, we used the observed compressional and shear wavefields to image secondary sources (scatterers) situated between the surface source and the downhole receiver array. The algorithm consisted of the following steps: first, estimating the receiver compressional wavefield; second, using polarization to estimating the shear wavefield; third, deconvolving the shear wavefield using estimates of the source wavelet obtained from the direct compressional wave; fourth, the compressional and shear wavefields were back projected into the volume between the source and receivers; where, finally, an imaging condition was applied. When applied to rig-source VSP data acquired in an extended-reach horizontal well, this process was demonstrated to give images of formation features in the overburden, consistent with surface- seismic images obtained from the same area. © 2013 Society of Exploration Geophysicists.


Haldorsen J.B.U.,READ AS | Stensrud E.,READ AS | Merciu I.-A.,Statoil | Miller D.E.,Miller Applied Science
Geophysics | Year: 2015

The objective of this study is to establish whether sonic data acquired in a cased hole can be used to estimate the material behind a second casing when the annulus between the two sets of casings is fluid filled. We have analyzed full-waveform data acquired using the Schlumberger tool Sonic Scanner for a double casing with a fluid between them, and where the outer annulus, outside the outer casing, might be cement filled or fluid filled. The sonic tool uses a cylindrical array of 104 omnidirectional receivers. The cylindrical array - approximately 4 in. in diameter and 1.8 m (6 ft) long - allows a formal decomposition of the acquired data into quasi-plane waves. Analyzing these plane waves, we have identified subtle but distinct changes in the waveforms. These changes appear to be dependent on the material filling the outer annulus, allowing for the determination of the fill material. The most significant changes relate to the propagating Stoneley waves. The identifications made are confirmed by cement bond log (CBL) analysis done on the exposed outer pipe after pulling the inner pipe. In one instance, for single-casing logging and a clean top-ofcement, like with conventional CBL analysis, we were able to confidently and accurately identify the cement/fluid boundary. In another instance, we were able to identify it as a nondistinct/ smooth transition zone. For double-casing logging, we could confidently and accurately identify the cement/fluid boundary behind the second casing. For one case, we have substantiated that this zone has a longer interval of smooth transition from cement to consolidated/unconsolidated barite to a fluidfilled annulus. © 2016 Society of Exploration Geophysicists. All rights reserved.


Haldorsen J.B.U.,READ AS | Stensrud E.,READ AS | Merciu I.-A.,Statoil | Miller D.E.,Miller Applied Science
Geophysics | Year: 2015

We have analyzed ultrasonic flexural data acquired in a North Sea well using a commercial tool optimized for generating such data, and found how one might separate refractions along successive layers of casings, and from these separated refractions, characterize successive pipes and annuli. From the timing of refracted events, we determined the shape of a pipe, and by examining the amplitudes of these refracted events - a measure of the conductance of a pipe wall to transverse movement - we characterized the material in the annuli around a pipe. Data from two separate depth intervals were analyzed, demonstrating that a well plan might not give a sufficiently accurate description of the well. In the deeper interval in which the inner pipe was supposed to be free, we found that the annulus was most likely filled with sedimentation and debris. We could also see that the inner 7 in tubing was touching, or nearly touching, the outer 95/8 in casing over the entire interval. For the shallower interval, below a certain depth, we saw that the 7 in tubing appeared to be touching the 95/8 in casing approximately every 7-8 m. From measurements inside the 7 in tubing, we estimated the deformation of the outer 95/8 in casing to be up to a maximum of nearly 5 cm, meaning that the minimum inner diameter of the outer pipe was close to the outer diameter of the inner pipe. Whereas some features revealed by the analyses were "good-to-know" - such as minor pipe deficiencies and deformations - other features might be critical for planned overhaul, or for operations related to abandonment, e.g., touching points were potential sticking points. Knowing where they were may be critical in determining the best depth to cut a pipe before pulling. © 2016 Society of Exploration Geophysicists.


O'Brien J.,Anadarko Petroleum Co. | Farmani B.,READ AS | Atkinson B.,READ ASA
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

We present a case study from the deepwater Gulf of Mexico, USA, where two orthogonal 2-D profiles are imaged using free-surface P-wave multiples recorded in a VSP survey. We compare VSP surface multiple imaging with primary VSP P-P imaging and 3-D seismic imaging. This demonstrates the expanded zone of illumination and the excellent image quality that can be obtained with the technique. However it also demonstrates the impact that 3-D subsurface geometry can have: we observe high quality imaging in the dip direction but significantly poorer imaging in the strike direction which we attribute to 3-D geometry and which is supported by ray-trace modelling studies. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.


Haldorsen J.B.U.,READ AS | Brooks N.J.,READ Wireline Services LLC | Milenkovic M.,READ AS
Geophysics | Year: 2013

We have developed a method for finding microseismic hypocenters from data recorded by arrays of triaxial motion sensors. The method reconstructs the elastic time-series signatures for possible microseismic sources at any point in 3D space, using full-waveform migration of the recorded vector wavefield. The imaging condition for the migration is based on a semblance-weighted deconvolution between two or more reconstructed source signatures, requiring similarity and simultaneity of the reconstructed signatures. This imaging condition eliminates the need for an absolute timing of the data, gives optimum resolution for the location of the microseismic sources - better than correlation-based approaches - and ensures numerical stability by adapting to the signal and noise conditions of the data. Because the method eliminates time-consuming phase picking and traditional event association, it should be well suited for fully or semiautomated data processing. The method was tested by an application to field data acquired with arrays of three-component receivers in two deep wells. Nevertheless, the formulation is equally applicable to data acquired by a distribution of single three-component receivers, or local arrays of these, deployed at the surface or in one or several shallow wells. © 2013 Society of Exploration Geophysicists.


A method for estimating parameters of a propagating wave field, such as the direction of propagation in 3D space of an acoustic wave from borehole-acoustic data. The estimation technique uses phase delays between recordings made by the individual receivers related to a plane wave travelling across the receiver array. The estimated plane waves include the wave field generated directly by the acoustic source, as well as refracted and reflected components of these fields. The technique can be used with overlapping wave fields. This will provide significant improvements in the quality of formation properties estimated from full-waveform data that are obtained either from wireline or from while-drilling sonic data. The inventive method enables characterization of abnormalities outside multiple casing strings where acoustic signals are transmitted from a source located inside said multiple casing string.


A seismic sensor cable 10 for lowering into a subterranean well 15 for acquiring information about seismic, microseismic and mechanical vibration incidents in the subterranean well 15, where the device comprises a first portion 20 that is elongate and has a first length with a proximal end and a distal end that are to be lowered down into a lower part of the subterranean well 15, the first portion 20 having a plurality of electric or electromechanical multicomponent seismic sensors 25 that are connected and distributed over large parts of its first length, and wherein the seismic profiling device 10 further comprises a second portion 30 that is elongate and has a second length with a proximal end that is to be held above the subterranean well 15 and a distal end that is to be lowered down into the upper part of the subterranean well 15, said second portion 30 comprising an optical fibre 35 that runs along large parts of said second portion 30, and an electric cable 40 for conducting electric power from the proximal end to said seismic sensors in the first portion 20, and a connector 45 for connecting the proximal end of the first portion 20 to the distal end of the second portion 30. The invention also comprises a system and a method for acquiring information about seismic, microseismic and mechanical vibration incidents in the subterranean well 15.

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