First Break - Volume 29, Issue 9, 2011

Organizational learning can boost the intelligence of energy companies but slow learners may lag behind and experience a decline in their IQs. That follows from a new conceptual framework and test that allow companies to routinely monitor their Corporate IQ. Ruud Weijermars explains.

Matt Hall and Evan Bianco have ventured into the more or less virgin territory of developing geoscience ‘apps’ for mobile devices. Here they explain the possibilities and why geoscientists should not dismiss the idea out of hand.

Dechun Lin, Ronan Sablon, Yan Gao, Damien Russier, Danny Hardouin, Bruno Gratacos, Robert Soubaras and Peter Whiting, CGGVeritas, explain some of the issues in processing variable-depth solid streamer data acquired as part of the company’s newly introduced BroadSeis broadband acquisition solution.

John Brittan, Tony Martin, Maiza Bekara and Konstantin Koch explain how 3D multiple techniques in seismic processing can be adapted relatively easily for application to shallow water environments.

Alex Berkovitch, Kostya Deev and Evgeny Landa, reveal how MultiFocusing technology can dramatically improve the quality of seismic imaging especially in cases of low fold data, poor signal-to-noise ratio and sparse 3D acquisition. They show the implementation of two applications: a signal enhancement scheme and velocity model construction by prestack stereotomography.

Håkon Haugvaldstad, Bjarne Lyngnes, Patrick Smith and Andrew Thompson describe the seismic acquisition and processing techniques that have steadily enhanced the quality and reliability of the time-lapse data on the Ekofisk field, offshore Norway, and anticipate further improvements in the future.

In the 2009 licensing round for predefined areas on the Norwegian Continental Shelf, three oil companies were awarded stakes in licence PL 559 in the Norwegian Sea. An interesting aspect of this award is that the area had previously been derisked by another oil company using, among other data types, controlled source electromagnetic (CSEM) data. This led to the drilling of a dry well and subsequent relinquishment of the area. The negative result was perceived as a failure of the CSEM technology in terms of being a false positive. However, a preliminary revised interpretation of the area provided an alternative explanation for the dry well, suggesting that the observed EM anomaly was positioned outside the dry well location. After a successful licence application, new CSEM data were acquired. The alternative explanation was strengthened after detailed analyses of the new data provided support for the presence of hydrocarbons as the most likely explanation for the observed CSEM anomaly. The revised interpretation will be tested by the drilling of an exploration well during the autumn of 2011, and the results will be important in order to better understand the potential of CSEM technology for hydrocarbon exploration.

We performed forward basin modelling along a profile in the south-eastern Caribbean to evaluate the effect of an evolving island arc on the evolution of petroleum systems in adjacent sedimentary basins. The geological model used is a published interpretation of a NW-SE regional 2D seismic line across the Lesser Antilles island arc, in which the Grenada and Tobago basins are interpreted as a single large basin during the Eocene that was split by the developing Lesser Antilles arc, north of the Caribbean-South America collision zone, during the middle Miocene. South of the collision zone, the eastern offshore Trinidad region has developed as a foreland basin since the middle Miocene. Basin modelling shows that formation of the Lesser Antilles arc caused an increase in temperature that subsequently decayed in space and time. Heating had a major impact on the maturation of Palaeogene source rocks adjacent to the arc, which became mature and over-mature. The heating also affected reservoir rocks that were deposited before and during arc formation, but not after the arc was formed. No temperature effects are observed in the eastern offshore Trinidad–Columbus Basin region.

Dual tow-depth acquisition configurations are used to mitigate the band-limiting effect of the sea-surface ghost in marine streamer surveys. Here we report on the analysis of a 2D broadband marine seismic project acquired offshore China. The deployment configuration included over/under sources and three streamers towed at different depths (5, 17, and 23 m). This configuration allowed not only for analysis of dual tow depth as a method for increasing bandwidth, but also for evaluation of two distinct dual tow-depth combinations, over/under and sparse-under. The project provided the first opportunity to make this comparison. Evaluation of reflection images, filter panels, amplitude spectra, and signal/noise separations demonstrates that both techniques are effective at compensating for the filtering effect of the ghost response, but also suggest that the improved results from each dual tow-depth technique are very comparable. Given the operational advantages of the sparse-under technique, due to the reduced streamer requirements, we conclude that the sparse-under technique is an attractive option for 3D deployments.