BEYOND THE HORIZON - Into the reservoir: New direction of geophysics

"Reservoir management of the future will depend on geophysics," said Gustavo Inciarte, past president of SPE.

Apr 1st, 2001

"Reservoir management of the future will depend on geophysics," said Gustavo Inciarte, past president of SPE. This statement is remarkable, considering that just a decade ago, most reservoir engineers did not even think of geophysics as a component in their toolkit.

Now, as we progress toward active reservoir management through geosteered re-entry drilling, intelligent completions, and downhole oil/water separation, it is increasingly clear that seismic imaging is the technology that will serve as the guiding light.

Success in the oilfield has always been dependent on managing uncertainty and risk. That dependence will grow as the pursuit of additional energy resources challenges the industry further. Preserving precious profit margins in the face of highly variable oil and gas prices will demand continuous improvement in capital efficiencies and a dramatic increase in recovery factors.

In this context, seismic, once viewed only as a precursor to oil and gas development, is expected to play an ever-increasing role as a reservoir development and management tool.

3D seismic

The introduction of 3D in the 1980s improved seismic imaging dramatically, and together with 4D time-lapse seismic, paved the way for geophysics to move deeper into the reservoir and closer to the heart of upstream operations. Just as 3D seismic was becoming an established part of the offshore exploration process, it is now being re-invented in a much higher resolution form to serve the needs of the reservoir engineer.

The consolidation of the geophysical industry has also brought seismic much closer to the rest of the upstream oilfield technology services. Dedicated seismic companies now often form part of a much larger multidisciplinary organization. Geoscientists are learning to speak the language of reservoir and petroleum engineers to ensure delivery of the information and services needed to meet clients' objectives. As a result, seismic technology now offers immense value-adding opportunities, not only for explorationists, but also for appraisal and production teams.

Efforts to deliver higher fidelity, higher resolution 3D seismic data have led to breakthroughs (Q technology, for example, uses single-sensors to produce a higher-resolution image of the subsurface, which decouples acquisition and geophysics, providing the explorationist with the tools required to achieve new levels of image fidelity).

4D seismic

In the future, 4D seismic will allow us to monitor the movement of fluids as we produce them and will also help locate bypassed hydrocarbons. Prospects and fields will be imaged frequently for time-lapse reservoir monitoring by the integration of seismic, petrophysical and production data sets. Streaming (continuous recording) will be developed for passive seismic monitoring and optimization of reservoir performance.

Somewhat more of a challenge is the active management of oil reservoirs using 4D, which implies a much shorter period between successive samples if reservoir management is going to be truly optimized. For this application, highly "calibrated" 4D surveys are needed to capture the much more subtle effects of oil/water movements.

Multi-component

Another key reservoir technology is multicomponent seismic - the acquisition of both pressure and shear waves from the same volume of rock. In certain conditions, this allows us to differentiate between fluid and lithology changes, a differentiation we often cannot make with pressure-wave seismic data alone.

As we build the number of case studies, new sorts of knowledge and new applications to exploit this will appear. Multi-component technology has had a slow start, despite promising technical performance, particularly in the offshore environment.

Applications of seismic-while-drilling and repeat 3D or 4D seismic for reservoir monitoring are extensions of success in the exploration phase. Seismic-while-drilling is emerging as a valuable process and is a key driver for active integration of borehole and surface seismic data.

Future

So, is there a bright future for the oil and gas industry? Maybe. Despite the unprecedented benefits these technological advances provide, the seismic industry has struggled in an environment of low pricing for high-value services. It is not a sustainable condition.

Terms and conditions of proprietary work must improve in order to reduce risk and ensure returns to contractors, especially those with significant investments in key research.

From its inception, seismic technology has been an illuminator. Now, as it moves from the surface into the reservoir and becomes integrated with other geoscience and engineering technologies, its ability to illuminate and add value to upstream operations is greater than ever. The critical factor in this equation is that we are able to sustain the levels of research that enable this progress and ultimately ensure a healthy industry for us all.

Gary Jones
President
WesternGeco

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