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The Central North Sea is a mature petroleum exploration province, with over 50 years of exploration to date. With increased maturity, recent exploration efforts have focused on the deeper targets below the Base Cretaceous Unconformity (BCU), where there is increased risk and often high-pressure, high-temperature (HP-HT) conditions. The key to de-risking these plays is high quality seismic data with good frequency content and high signal-to-noise ratio at depth. With Cornerstone Evolution, CGG has utilised the latest seismic processing technologies to achieve these goals, producing the best-quality regional imaging in the area to date.

While the subsurface geoscience skills required for geothermal exploration and development differ from those required for oil and gas, there are existing skills and technologies that are highly transferable. Moreover, as the shift for geothermal resources moves away from high-enthalpy areas and towards sedimentary basins, the transfer of oil and gas industry techniques, skills and data will be beneficial to the geothermal industry by providing a fresh subsurface technical perspective and the adoption of new drilling and completion techniques.

GeoVerse is CGG’s flagship geological multi-client database. Through a combination of advanced data organization and machine-learning processes, GeoVerse enables a step-change in data analytics and data interrogation.

This article discusses the importance of performing rock physics diagnostics in the context of rock texture and geological processes that lead to rock formation. This makes it possible to select the right physical rock physics model to perform the modeling and set the parameters intelligently to produce superior results, and at the same time, a good understanding of the uncertainties involved in the outputs.

Despite continuous improvements in seismic acquisition and processing technology, imaging under the salt remains very challenging, specifically because of the difficulty to update the complex salt geometries and the velocity under them. Synthetic studies show that when certain conditions are met, full waveform inversion (FWI) can recover very complex velocity models, including the geometry of the salt and the sub-salt velocity. Unfortunately, the current available seismic data fall short of meeting the requirements needed to replicate what can be achieved on synthetic data. We first use a typical wide-azimuth (WAZ) dataset from the Mexican side of the Gulf of Mexico (GoM) to show what FWI can do to help improve the imaging in the sub-salt. Besides utilizing the diving wave energy to derive a reliable model in the shallow sediment overburden, we present a Reflection FWI (RFWI) workflow to update the velocity model in the deep area. We then use an ultra-long offsets, full-azimuth (FAZ) dataset from the U.S. side of the GoM to show that, with better data, FWI and RFWI can be combined to help recover the velocity in and around complex salt bodies, providing significant uplift to sub-salt images.

Well planning is one of the most demanding aspects of drilling engineering for hydrocarbons. Hence, seismic exploration objectives often require the interpretation of the seismic image as early as possible to facilitate well planning. This task becomes challenging when one needs to employ advanced acquisition to image complex geological structures. Ocean Bottom Seismic (OBS) surveys, especially high density OBS ones, are gaining attention in modern marine acquisition for the recording of wide azimuths, long offsets and data with high fold to address complicated imaging problems. However, the increase in data volume and processing complexity (due to the nature of multicomponent data) from high-density OBS surveys magnifies the turnaround issue of obtaining the seismic image for early well planning. Cases where the surveys are performed over challenging areas, such as shallow water environments, further complicate the processing and hence lengthen the turnaround. In this paper, we describe a targeted P-wave only processing flow, using advanced methods of deghosting, demultiple, velocity model building and migration. The flow can provide an optimal solution that meets both the drilling program’s needs and the complex processing requirements for shallow water OBN surveys that aim to image structures with large velocity contrasts. This approach is described using data acquired utilizing state-of-the-art ISS® ocean-bottom nodes deployed in relatively shallow (20-80 m) water over the Tangguh gas field, Indonesia.

Risto Siliqi, CGG, France, explains how the largest multi-client ocean bottom node survey in the UK Central North Sea will deliver unprecedented seismic data quality to identify remaining reservoir potential.

This article is related new pyrolysis method developed by CGG. This new method is called “unconventional pyrolysis method” for bitumen-rich source rock samples from shale oil plays. This novel technique applies a different temperature program to the Rock-Eval pyrolysis 6 equipment, using the multi-heating temperature program option. This method significantly improves the peak resolution of the hydrocarbons carried over into the S2 peak and resolves the issue of the S1 peak being underestimated. Moreover, it significantly improves interpretation and evaluation of the organic matter properties and productive trends in shale oil plays.

The Cornerstone OBN data set delivers subsurface images of unprecedented quality in the most challenging areas of the UK Central North Sea, de-risking field development and near-field exploration.