Seeing seismic in 3D

Shell’s GeoSigns has helped the company find reservoirs like the pre-salt West Boreas field in the Gulf of Mexico and there is more to come. Elaine Maslin reports.

Shell’s iScope facilities enable the company to collaborate with colleagues around the world in real time and see seismic in 3D. Photos from Shell.

Four years ago, Shell decided to take a new approach to its seismic imaging. The supermajor wanted to bring a plethora of applications—seismic and non-seismic—together under one platform, incorporating state of the art visualization technologies.

The outcome was GeoSigns, a constantly-developing suite of applications incorporating subsurface interpretation software and visualization technologies, which “visualize and extract information from data rather than simply averaging it through various processing steps into a single data point.”

For Shell, it is all about technology and novel IP and the possibilities breakthrough innovation can offer in the subsurface. The opportunities have already been demonstrated. Bettina Bachmann, Shell’s Vice President, Subsurface and Wells Software, has been involved in GeoSigns from its inception. An early indicator of its use was on the US Gulf of Mexico Deimos field.

“We drilled a well in 2004 (on Deimos) on the basis of very good seismic,” she says. “It was in the Tertiary Gulf of Mexico where we understand the plays. The quality of the seismic was very good, but the imaging around salt domes has always been difficult and is an ongoing challenge for all companies operating in this space.” The well showed no sign of oil or gas and the exploration program was suspended.

But Shell didn’t give up. It re-surveyed the area using wide-azimuth seismic acquisition, with ocean bottom sensors, which helped to illuminate the area under the Deimos salt structure from all directions. “Shell has been pushing the limits around that space for a while,” Bachmann continues. “We used wide azimuth, processed the data in a different way, and used some of the functionality that is unique in GeoSigns, in terms of displaying this information and giving the user access to better imaging under the salt dome. In 2009, we re-drilled the well in a different location, much deeper, under the neck of the salt dome, and it was a discovery, confirming the existence of the West Boreas field.” Soon after another field, South Deimos, was discovered based on the same data. Together, the two discoveries added more than 150MMboe to Shell’s resources.

“The discoveries were clearly attributed to the improved imaging and interpretation capability,” Bachmann says. Two specific areas helped. First, the use of wide azimuth seismic. Now common practice and widely used, it was not so at the time Shell drilled Deimos. “Shell was one of the first,” Bachmann says. “We used ocean bottom seismic so you can record the waves from the seismic and avoid disturbance, and having the experience of how to do that helped.”

The second issue is handling the “enormous” amount of data received, processing it properly and interpreting it correctly using high-performance computer power. This is where GeoSigns comes into its own, Bachmann says. “The challenge for us is the sheer amount of data, which is difficult to handle. An awful lot of it you don’t even want to look at because it doesn’t add any value.” Through processing, about 60-70% of the seismic data is discarded, with the remainder worked into a final processed picture to hand over to the seismic interpreters.

Shell’s iScope facility. Photos from Shell.

Selecting what data you want and then utilizing it and displaying it is key, Bachmann says. For example, GeoSigns is able to display butterfly gathers so that a viewer can look at different azimuths while keeping the view of the gathers intact, she says, giving the viewer access to five dimensions.

The principle behind GeoSigns was initially called an exploration integrated workspace, or EIW. The idea was to bring all the applications together in one space, e.g. they can be accessed from a common point from multiple locations. This would also bring data, which may have been stored separately and used in different ways, through different workflows together under one workflow.

GeoSigns includes 29 of Shell’s major proprietary technologies, as well as applications bought from the marketplace. “Two-hundred different applications were pulled together in to the different product lines and we simplified the way they are operating and the way they are accessed. This meant there was much more data but it also integrated, so 2D and 3D data can be integrated,” Bachmann says.

GeoSigns incorporates subsurface interpretation software based on seismic data, but it also integrates non-seismic methods, such as gravity and magnetic survey data, as well as “search engines.” The Trap Search Engine automatically and rapidly scans large seismic datasets and finds suitable traps that interpreters might miss. The Seismic Well Tie fits seismic to well logs, aiding more accurate drilling predictions.

When GeoSigns was introduced, a new, Windows-based operating environment was introduced as well, which, it was felt, many people use and can interact with in an easier way. New hardware was also brought in, which meant applications, processing power and data are stored centrally. “We moved away from people having all the computer power under their desks, and instead we are using shared and centralized computer power, which means data and applications are stored and held somewhere so you can utilize and leverage much more shared hardware capability,” Bachmann says. “It also means individual users have greater computing power as and when they need it.”

GeoSigns is not a finished system, however. It is constantly being upgraded. For example, Shell is working with NVIDIA and Intel to develop and improve the processing and visualization of data for its subsurface applications. It is working with such companies to extend the amount of data that can be displayed in real time.

The amount of data itself is also a moving target—how much is being stored and used, Bachmann says. “We see data increasing and becoming a bigger challenge,” she says. “It is still an acceptable challenge in areas like the offshore Gulf of Mexico, where you have very high-pressured fields, deep underneath the ground, so you find substantial volumes of hydrocarbons in a small space. When you start to go on land, [they are] very different fields you are looking at in order to make the economics work. They are bigger, cover a larger area, and you have to acquire more seismic. It is a completely different challenge to offshore.”

But, while a large amount of the seismic data is currently thrown away, thanks to increased computing power, Bachmann suggests more will be used. “In the future we expect we will want to keep more and more of this data. Acquisition methods will probably, at least in the immediate future, not necessarily increase the data we have. But we will want to utilize a lot more of that data in the processing. Software is constantly operating at the limit of what it can do. But there is always more ground to cover. The trick for us is in the extraction and making sense of it.

“There is still a long way to go. The industry is still drilling dry wells. The industry’s understanding of the subsurface is still very incomplete and there are still a lot of uncertainties. This is where investing in computer power gives us the ability to solve equations that comes out of physics to solve this much better.”

Integrating and utilizing different data sets, handling big data and improving processing, using techniques such as elastic and full wave form inversion, will play a key role in the future, Bachmann says, with GeoSigns as the hub of it, for Shell.

“GeoSigns is an integration of a number of different exploration technologies and software that existed but were fragmented before,” she says. “We have leveraged IT capability much more than ever. We have new applications and a new operating environment and new hardware.”