Imaging vertical structures using Marchenko methods with vertical seismic-profile data

Abstract

Marchenko methods use seismic data acquired at or near the surface of the earth to estimate seismic signals as if the receiver (now a virtual receiver) was at an arbitrary point inside the subsurface of the earth. This process is called redatuming, and it is central to subsurface imaging. Marchenko methods estimate the multiply scattered components of these redatumed signals, which is not the case for most other redatuming techniques that are based on single-scattering assumptions. As a result, images created using Marchenko redatumed signals contain a reduction in the artifacts that usually contaminate migrated seismic images due to improper handling of internal multiples. We exploit recent theoretical advances that enable virtual sources and virtual receivers to be placed at arbitrary points inside the subsurface as a means to incorporate vertical seismic profile (VSP) data into Marchenko methods. The advantage of including this type of data is that the additional acquisition boundary increases subsurface illumination, which in turn enables vertical interfaces and steeply dipping structures to be imaged. We develop this methodology using two synthetic data sets. The first is created using a simple variable density but constant velocity subsurface model. In this example, we find that our newly devised VSP Marchenko imaging methodology enables imaging of horizontal and vertical structures and that optimal results are achieved by combining these images with those created using standard Marchenko imaging. A second example demonstrates that the method can be applied to more realistic subsurface structures, in this case a modified version of the Marmousi 2 model. We determine the applicability of the methods to image fault structures with the final imaging result containing reduced contamination due to internal multiples and an improvement in the imaging of fault structures when compared to other standard imaging methods alone.

On the benefits of auxiliary transmission data for Marchenko-based Green’s function retrieval

“…Recently, some novel applications of the Marchenko methodology have emerged in which auxiliary transmission data are available. We mention for instance: Marchenko imaging of joint VSP and reflection data (Liu et al, 2016;Lomas et al, 2020), laboratory experiments (Cui et al, 2018) and transcranial wavefield focusing (Meles et al, 2019). Since transmission data include forward-scattered waveforms, we reason that these data might be used to improve Marchenkobased Green's function retrieval.…”

Marchenko Green’s Function Retrieval in Layered Elastic Media from Two-Sided Reflection and Transmission Data

“…In this paper, we show that the conditions for elastodynamic Green's function retrieval are significantly better when an elastic volume can be accessed from two sides, as is the case in particular laboratory experiments [20], non-destructive testing [21,22], brain imaging [23,24], transcranial ultrasound focusing [25,26], transcranial photoacoustics [27,28] and when using auxiliary downhole receivers in seismic data acquisition [29,30]. Although the underlying representations of our work could be extended to account for lateral variations [19], the presence of a free surface [31,32] and intrinsic attenuation [33,34], we restrict ourselves to a layered lossless medium for simplicity.…”

Marchenko Green's Function Retrieval in Layered Elastic Media from Two-Sided Reflection and Transmission Data

“…In this paper, we show that the conditions for elastodynamic Green's function retrieval are significantly better when an elastic volume can be accessed from two sides, as is the case in particular laboratory experiments [12], non-destructive testing [13,14], brain imaging [15,16], transcranial ultrasound focusing [17,18], transcranial photoacoustics [19,20], or by using auxiliary downhole receivers in seismic data acquisition [21,22]. Although the underlying representations of our work could be extended to account for lateral variations [11], the presence of a free surface [23,24] and intrinsic attenuation [25,26], we restrict ourselves to a layered lossless medium for simplicity.…”