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The Gippsland Basin in South-Eastern Australia has been producing hydrocarbons since the early 1960’s when several giant oil and gas fields were discovered. It can therefore be considered to be a mature area, where production rates have been declining for the last twenty years and, with diminishing reserves, new reservoirs are being sought to meet the energy supply needs in this region. Since the initial discoveries there has been limited seismic exploration in this area and recent developments in broadband imaging technology, tomography and Full-Waveform Inversion mean that the existing data sets can be significantly improved by reprocessing to help to regenerate this basin.

In deep-water depositional systems such as the slope canyon-turbidite channel system encountered on the continental slope, offshore West Nile Delta Basin, deterministic prestack seismic inversion followed by facies classification delineated thick-bedded and thin-bedded gas-sand reservoirs encased in bypassed stratigraphic traps and also delineated prospective areas for development.

Below is a case study of the ongoing work on the Monarb and Seagull reprocessing projects in the Central North Sea, with a focus on the use of legacy near field hydrophone recordings, 3D recursive MWD, wave equation deconvolution and AVO QC (In particular Vp/Vs and Lambda Rho QC attributes)

We show how to separate the seismic image into specular reflections and diffractions using dip-angle gathers. A North Sea example and a 4D example are used to show the efficacy of the algorithm. The 4D example shows a significant reduction in imaging noise.

While the benefits of vertical particle velocity measurements are well known for towed streamer receiver deghosting, in many cases high noise levels can cause practical issues. We describe an inversion-driven receiver deghosting approach which is jointly constrained by hydrophone data and prior wavefield separated data. Prior wavefield separated data can relate to an up-going or down-going wavefield, obtained by combining hydrophone and particle velocity data. Use of prior wavefield separation data provides the joint inversion with signal at hydrophone notch frequencies, as well as making it less sensitive to variations in the free surface datum than hydrophone-only inversion methods. The use of data domain sparseness constraints makes the approach practical as it may be applied to data without prior denoise. The proposed method is validated on synthetic and real data examples.

We evaluate how two-dimensional (2D) seismic and controlled source electromagnetic (CSEM) imaging, both vintage and modern, might help improve geological understanding of, and exploration for, SMS deposits along part of the Mohns Ridge segment of the ultraslow-spreading Arctic Mid-Ocean Ridge. Mohns Ridge has been the subject of academic studies for the past 60 years. These have revealed that the plate boundary has a complex morphology, rifting and spreading history. Mohns Ridge is in deep water (2000-3500 m) and is an ultraslow-spreading ridge which contains significant proven resources of seafloor massive sulfide (SMS) mineral deposits.

Offshore Cameroon is a proven petroleum province with commercial production from the Douala Kribi-Campo Basin (DKC) and the prolific Rio del Rey Basin (RDR). The recent joint cooperation agreement between Cameroon and Equatorial Guinea will lead to the development of the Yoyo and Yolanda discoveries and open up the underexplored deep-water DKC Basin. CGG, together with Société Nationale des Hydrocarbures (SNH), has completed a basin-wide PSDM reprocessing project, which, coupled with favourable government terms, provides the opportunity to accelerate exploration in Cameroon.

A Rayleigh surface wave tomography with optimal coverage approach based on the creation of virtual raypaths by interferometry is proposed. The array based conventional surface wave picking methods often provides inhomogeneous or sparse coverage for high-resolution tomography. The delivered inversion result can suffer from acquisition pattern imprints or poor lateral resolution. We propose to create new optimally chosen virtual raypaths that better conditions the information. Rayleigh wave Green’s functions kinematics is then analyzed by a direct inversion of the phase interference pattern. Proof of concept on synthetics then illustrated on 3D real data are shown.

Ocean Bottom Node acquisition is known to improve seismic velocity model building and imaging, especially for deep and complex targets. Due to cost considerations, OBN surveys are typically only acquired around the production field, using a relatively dense receiver grid. At the exploration phase, the industry often has to rely on Narrow-Azimuth Towed Streamer data sets that are not always adequate to properly image deeper prospects, resulting in increased uncertainty and risk. Recently, hybrid blended acquisition combining towed-streamer and sparse node has emerged as a potential cost-effective solution to reduce exploration risk for larger areas. From the Norwegian North Sea to the challenging Nordkapp basin in the Barents Sea, we will illustrate how, by leveraging sparse node data combining Interferometry, Acoustic and Elastic full waveform inversion, we can enhance the streamer seismic image and deliver a high-resolution velocity field, reducing exploration risk and pushing the boundaries of imaging technologies one step further.