Posted on September 15, 2017
A new method for deghosting data collected on a depth-variable acquisition surface by combining Green’s theorem wave separation followed by a Stolt extended Claerbout III wave prediction for one-way propagating waves
3D source and receiver deghosting in the space-frequency domain using a depth-variable measurement surface: An initial offshore synthetic data study with anticipated onshore and ocean-bottom application
A wedge resolution comparison between RTM and the first migration method that is equally effective at all frequencies at the target: Tests and analysis with both conventional and broadband data
Impact of the shape of the acquisition surface on the effectiveness of the ISS internal multiple attenuation and elimination algorithms: Analyzing the problem and providing a response to the challenge
An opening overview and perspective on seismic multiples in exploration seismology
The first multi-dimensional internal-multiple-elimination method: a new toolbox option for removing internal multiples that interfere with other events, for example, a target primary, without damaging the primary, and : (1) without energy minimization adaptive subtraction and (2) without a priori or a posteriori knowledge of subsurface properties Yanglei Zou, Chao Ma and Arthur B. Weglein, M-OSRP, Physics Department, University of Houston 10:05 am - 10:20 am (Poster session: Removal of Multiples)
The first multi-dimensional internal-multiple-elimination method: A new toolbox option for removing internal multiples that interfere with primaries, without damaging the primary, and without any knowledge of, and need for, subsurface information. Yanglei Zou, Chao Ma, and Arthur B. Weglein, M-OSRP, Physics Department, University of Houston
We begin with a brief overview of M-OSRP projects and their approach to identifying and addressing pressing and prioritized seismic challenges. Within that broad perspective we focus on the project that progresses and delivers new and necessary capability and effectiveness for the removal of multiples. In seismic exploration, migration and migration-inversion are the methods to locate and identify targets and hydrocarbon reservoirs. Only primaries are migrated and migration-inverted. And primaries come in two varieties: those that are recorded and those that are not recorded. There are circumstances where a recorded multiple can be used to provide an approximate image of an unrecorded primary, where the latter is a subevent of the recorded multiple. The removal and using of multiples are not adversarial positions and viewpoints, but rather are addressing different issues and circumstances, and represent different levels of ambition, capability and effectiveness, as options within the seismic processing toolbox.
However, only recorded primaries can provide specular and non-specular structural imaging (e.g., for curved reflectors and pinch-outs) and subsequent amplitude analysis using the most effective and interpretable imaging and inversion method, Stolt CIII migration. The new Stolt CIII migration for heterogeneous media is the first migration method that is equally effective at all frequencies at the target and reservoir, and provides resolution benefits and added value (at the target and reservoir) that is beyond the intrinsic resolution capability of RTM and all variants and extensions of RTM. Stolt CIII migration inputs recorded primaries. For a smooth velocity model and Stolt CIII migration, multiples will produce false images and artifacts; therefore multiples must first be removed prior to migration and migration-inversion. Hence removing multiples remains a significant and important E&P objective, and obstacles to the effective removal of multiples are a prioritized and pressing challenge in many offshore and onshore plays.
This presentation will focus on certain serious obstacles and challenges to current multiple removal capability, and recent advances to address those challenges in removing internal-multiples. The Inverse-Scattering-Series (ISS) internal-multiple-attenuation algorithm (Araújo et al. (1994), Weglein et al. (1997) and Weglein et al. (2003)) has stand-alone capability since it is the only method that can predict all internal multiples with correct time and approximate amplitude without requiring any subsurface information. It makes none of the assumptions of other methods (e.g. stacking, FK filter, Radon transform, deconvolution and Feedback loop etc.) and is especially effective when the subsurface is complicated, complex and unknown. When internal multiples and primaries are isolated, the ISS internal multiple-attenuation algorithm is usually combined with an energy minimization adaptive subtraction to remove internal multiples. When internal multiples are proximal to and/or interfering with primaries or other events, the criteria of energy-minimization adaptive subtraction can fail. With interfering events, this failure of energy-minimization adaptive subtraction can lead to removing/damaging the target primary which is the worst possible outcome.
In this presentation, we provide the first multi-dimensional ISS internal-multiple-elimination algorithm that can predict both the correct time and the correct amplitude of internal multiples without any subsurface information. This is an important part of a three-pronged strategy proposed by (Weglein 2014). That provides an effective response to this challenge while retaining and adding to the strengths of the current ISS internal-multiple-attenuation algorithm. We provide this method as a new capability in the multiple-removal toolbox and a new option for circumstances when this type of capability is called for, indicated and necessary. 1-D and 2-D acoustic and elastic model data are used to examine, analyze and evaluate the new internal multiple removal capability. We will discuss open issues, significant remaining challenges and future plans.