Beware – the technologies are coming!

The thirst for energy continues to push the boundaries of science in the oil and gas sector. Spanning drilling and completions to remote sensing, we are seeing numerous advances in all scientific disciplines. On the geo side, seismic technology is moving forward with the rest of the industry, with new marine equipment and technologies as well as frac monitoring on the surface and downhole. Let’s take a closer look at some of these emerging technologies.

On the marine side, the need for a broader frequency spectrum continues to grow. With the requirement of lower frequencies for subsalt exploration and full waveform inversion to higher frequencies for identification of subtler traps, new technologies are increasing in use. One of the main limitations in the marine seismic quest for broader bandwidth is the mirror-like reflection of seismic energy from the sea surface. This relection, called a “ghost,” eliminates frequencies at both the high and low end of the frequency spectrum and is a function of the streamer depth. Two technologies are helping to recover the frequencies in those ghost notches. New equipment that employs multicomponent cables with hydrophones, geophones, and accelerometers is one approach, while a variable tow depth along the length of conventional seismic streamers is the second technique. These advances come not only from new equipment and operations but also from new seismic processing algorithms that can begin to recover the frequencies in the ghost notches on existing marine seismic data. Look for the use of these technologies, coupled with other seismic processing techniques, to grow in the coming year.

Meanwhile, at the bottom of the ocean, marine node technology continues to develop and increase in utilization. Better and longer-life batteries allow for improved spatial sampling, especially wide-azimuth spatial sampling, which has proven critical for subsalt illumination and imaging. The use of marine nodes will continue to increase, especially in field development and 4-D field monitoring in both deep and shallow water and around infrastructure. And while those autonomous nodes sit on the seafloor, look for seismic receivers that independently sail near the surface of the sea, recording both active and passive seismic signals – that one may be a little further down the timeline.

Back on terra firma, shale exploration and exploitation continues to drive the industry in North America. Surface monitoring of fracing is growing, and there is still a lot to learn. Understanding the earth stress field’s subtle variations over time, combined with passive seismic and active frac monitoring, will continue to push the boundaries in shale exploitation. The role of conventional 3-D seismic will continue to provide information on structures and depositional environments, but look for more detailed subsurface information on lithologies, fluids, and porosities to continue to be pulled from high-quality 3-D seismic in combination with good well logs and core analysis.

Conventional seismic is compared to broadband seismic offshore Australia. (Image courtesy of Apache Corp.)

In both conventional and unconventional seismic, land data often suffered from noise, both source-generated and environmental. In the coming year, source-generated ground roll will begin to play a larger role in understanding and compensating for the near surface. The near-surface weathered layer often causes problems with seismic data, particularly the higher frequencies that are needed for delineation of stratigraphic details in the subsurface. Ground roll, that troublesome noise that hides reflections while traveling in the near surface, can provide additional insight into the physical properties of the weathered layer. With this knowledge it is possible to better attenuate the ground roll “noise” while gaining a better understanding of near-surface seismic properties. This additional knowledge will increase the ability to handle other near-surface effects (like statics) and allow for improved imaging of the deeper structural and stratigraphic features in the subsurface.

Covering both onshore and offshore, vertical seismic profiles (VSPs) are often used to gain a better understanding of the subsurface near the wellbore. These have typically come at a high cost for a number of reasons, most notably the deployment of seismic receivers in the well. But new technology using fiber-optic cable allows a continuous measurement of acoustic seismic energy along the entire cable/wellbore. Existing wells with fiber-optic cables may already be “instrumented” for VSPs at a much finer spatial sampling than has ever been done with conventional downhole receiver arrays. Imagine measuring the wave field at 1-m (3-ft) intervals along the entire wellbore. There are still limitations on the surface seismic source and the earth’s attenuation, but spatial sampling along the wellbore might no longer be a limitation. Another piece of information that has historically been omitted due to cost constraints will be available.

Look for these and other technologies in the coming year.