First Break - Volume 30, Issue 1, 2012

After a lustrum of economic turmoil, how have the oil majors come through, and what comes next? Ruud Weijermars analyzed a time series of corporate performance indicators and suspects a future playfield where innovation rates may be slowing.

John Archer, Lee Bell, Mike Hall, Gary Margrave, Kevin Hall and Malcolm Bertram report on a field study to show that many benefits of low frequency information from seismic in land and OBC environments can be obtained without excessive difficulty, additional cost and issues with the transition zone environment being the only limitations.

Christopher T. Usher foresees emerging role for land seismic data in a more integrated approach by geoscientists and engineers to meet the challenge of exploiting unconventional resources such as shale oil and gas. This is illustrated by a case study of the Eagle Ford shale play in southwest Texas.

Malcolm Lansley offers some insight into the land seismic survey dilemma of whether to use cable, cable-less or a combination of the two in order to achieve the optimum results. Three case studies support his analysis.

Ron McWhorter, Gehrig Schultz, Andrew Clark, Tim Branch and Malcolm Lansley discuss the challenges of an operationally problematic 3D seismic survey carried out in Western Portugal where the solution was found in careful planning plus the use of multiple sources and a cable-free recording system.

The flexibility of 3D ocean bottom cable (OBC) seismic survey design allows a variety of survey geometries. Among the infinite variations, we naturally seek higher survey efficiency within operational constraints whilst satisfying the geophysical requirements. We have analysed several geometry and shooting options, such as zippers between panels, source line interleave, flip-flop shooting, outboard shooting, and distance-separated simultaneous shooting (DS3), to show how the survey geometry may be optimized to yield higher productivity within the limitations of the available equipment.

An analysis of the rifting history of the Central Atlantic focused on Nova Scotia and Morocco reveals new plays potentially charged from an Early Jurassic source system. The revised rift model is based on newly acquired seismic refraction data, reprocessing of existing refraction and multi-channel seismic data, and integration of potential fields data from the conjugate margins. We infer from the geophysical evidence that there was volcanic rifting from south-west Nova Scotia to the Newfoundland fracture zone during the Early Jurassic, with a restricted, shallow marine environment for sediment deposition. We have integrated plate tectonics, geochemistry, and sequence stratigraphic interpretation with the aim of identifying new plays. Analysis and integration of geochemical evidence has led to a new paradigm for the exploration potential offshore Nova Scotia. In particular, there is now good evidence for deposition of a source rock in restricted marine conditions during the Early Jurassic. This source rock is capable of providing charge to an oil play in the south-western half of the Scotian margin, which is a new concept for this area.