Exploring new technology

Exploration is a risky game but the potential rewards are just too good to ignore, which is why companies are moving further afield into deeper and more inhospitable terrains in the hope of striking it rich.

The Society of Exploration Geophysics (SEG), which celebrated its 75th anniversary last year, strives to be the best society for geophysicists. The executive committee is elected from active members each year, who work with society staff to develop and generate courses and publications in geophysics, organize large conventions and smaller workshops and forums on specialized topics, and encourage students of geophysics through education and scholarships through the SEG Foundation. With active sections throughout the world and a total membership close to 25,000, more than half the current membership of the society resides outside of its base in North America, including Moscow, Norway, India, Egypt and West Africa..

O&G caught up with David Monk, 1st Vice President of SEG, to get his thoughts on current trends in exploration. Monk is also Director of Geophysics at Apache Corporation, where he has worked since 2000, and has technical responsibility for worldwide seismic activity. After obtaining his PhD in Physics, in 1979, Dr Monk worked for two years in West Africa and was involved in all aspects of seismic acquisition in Land and Swamp environments. Since then he has lived in England, Norway and the USA, and worked across the globe. He has been awarded six US patents, and has published over 60 papers.

O&G. Seabed exploration is particularly challenging because surveying comprises of both seismic and sampling techniques. What key technologies are now helping to make this process more accurate and efficient compared to a few years ago?

DM. Controlled Source EM (CSEM) has exploded as a commercially viable methodology in the last couple of years having been in restricted to academia before then. While currently restricted to deep water, there are technical developments that will make this a viable technique for shallow water soon.

The barrier to shallow water EM work is the presence of the sea surface and the ‘air wave’ arrival that interferes with the measurements of arrivals from below the source and receivers. Methods which are utilised onshore are now being used in shallow water, and other methods of processing the data are being developed to separate out the unwanted signals.

O&G. When will these CSEM techniques be commercially available for shallow water exploration?

Some would claim that CSEM methods are commercially available for shallow water already, and there have certainly been tests during the last 12 months, but it is certainly not yet ‘routine’. My best guess would be that the technology will mature within the next five years to a level where industry would not accept that shallow water CSEM is viable for a technical standpoint.

O&G. How do techniques differ in acquiring multi-component data from the seabed and what are the advantages?

DM. Multi-component data is seismic data acquired through generation of an acoustic signal (not usually at the sea floor, but close to the sea surface), and detection of the subsequent reflections of the acoustic energy from the subsurface using devices which are sensitive to sound. Because sound can travel in two different ways through the subsurface, but not through water, MC detectors can be used to detect both types of energy. EM exploration utilizes electromagnet energy rather than sound, and allows remote measurement of an entirely different rock property.

O&G. How can better data results be achieved by combining seismic and electromagnetic surveying techniques?

DM. Seismic data (P or MC) images the structure of the subsurface and potentially with MC, some of the lithology. From this, we can infer the possible presence of hydrocarbon but there is absolutely no guarantee, so there is risk before drilling unless it was been previously drilled. EM data adds another aspect because it measures a different attribute of the subsurface. We know that in general when reservoir rock contains hydrocarbon there is a change in the resistivity of the rock. If we can see structure, lithology and resistivity generally associated with hydrocarbon, then we have additional risk reduction prior to an initial well. However, they are still no guarantees as resistivity changes are not only associated with the presence of hydrocarbon.

O&G. You say that there are no guarantees that this technology will identify hydrocarbon, but can you estimate how much more accurate this technology makes predictions? Do you have any anecdotal examples of this technology being used to make drilling decisions/non decisions?

DM. That’s a difficult question. At Apache we have yet to make a drilling decision based on EM work. However, we have considered it as a method to lower the risk on some exploration wells. Unfortunately, some of our most critical wells in the last couple of years haven’t fitted with the current limits (in terms of water depth) of the technology.

O&G. How expensive are these advances in technology to deploy? Does the cost mean they need to be targeted on exploring existing prospects, or can the technology be used to investigate shallow water environments generally?

DM. The capital involved in building and deploying EM technology is not cheap, but then nothing offshore is inexpensive. The value is dependent only on the size of the reservoirs found, or the expensive wells that are not drilled if the technique can demonstrate that there is no hydrocarbon potential. While deepwater wells are more expensive than those in shallow waters, I don’t think that this means that there is no value to EM work in shallow water.

O&G. Do environmental factors such as icy or rough seas affect the viability of using any of these techniques? Could they be used in sea environments around the arctic circle for example?

DM. I’m not sure that the technology is limited by these conditions, but the operation of the technology certainly is. Deployment of equipment is difficult in rough seas and towing a deep source in rough seas is also a challenge.

O&G. With technology now making more raw data available, what kind of functions should solutions comprise to offer the best tools for interpreting and utilising captured information?

DM. Multi-attribute interpretation systems that allow simultaneous interpretation of many different attributes of the subsurface will become required. We have seen some of this with different mode seismic data but, as yet, there is no simultaneous seismic EM interpretation capability. Current techniques are crude, being limited to co-rendered visualisation of the different attributes of the data.

O&G. Do you think there is likely to be a bigger surge in seabed exploration and seismic technology in the near future? What challenges still lie ahead?

DM. Yes. Integration of both methods and the application of EM to shallow water are the current big challenges. All of the commercial companies involved in CSEM are working towards a shallow water implementation and, as I indicated previously, I expect this will become accepted in less than five years.

For more information visit more information at www.seg.org .