The science of searching
Forming an educated guess
There may be no more unexplored frontiers on earth, but deep inside the earth there is plenty that we don’t yet know.
Oil companies have a range of technologies to help them locate oil and gas reservoirs deep beneath land and sea. But the search remains a complex business. Success is never certain.
Improving the odds
In the early days of oil exploration, oil companies and prospectors really had no idea what they were looking for. They focused their search on areas near seepages, where oil bubbled up naturally in pools. Then they sunk a drill and hoped for the best.
The rate of success has improved greatly since those early discoveries, from 10% or less to more like 50%. New technologies developed by BP and others may improve the odds even further.
Drilling is still the only sure way to find out whether there’s oil or gas down there. But drilling is expensive. Each project can cost tens of millions of dollars or more. So before we drill, we do as much planning as possible. And that can take years.
The geologist’s eye
We start with what we can see. Both geologists and geophysicists provide crucial insights at this stage in the exploration process. Geologists look at what rocks are made of and the formations they make in the earth. Geophysicists use physical characteristics, such as magnetic and gravitational properties, to guess the type and shape of subsurface rocks.
Aerial photography from aircraft and satellites can be revealing. The same tectonic shifts that formed mountains and other topographical features above the earth’s surface also shaped the rock formations down below. To the trained eye, these photographs can say a lot about what lies beneath the soil.
Aircraft can measure the gravitational pull over an area. Even small gravitational differences can reveal large clues about the density of underlying rocks.
Using sound waves to get the picture
But the most powerful tool available to us is the acoustic survey. Geophysicists use air guns to fire acoustic pulses down through the rock. The sound waves bounce back like echoes, revealing different layers and depths.
This data gives our experts the information they need to map reservoirs and identify whether they’re filled with oil, gas or merely water.
Needless to say, this sort of seismic study is a lot less damaging to the environment than random drilling. But there are still environmental risks to consider. Before we begin a seismic study, we speak with marine biologists where appropriate, and look thoroughly at any environmental issues. For example, work might be delayed so that it doesn’t interfere with animals’ feeding times, breeding periods or migrating seasons.
Visualizing success in four dimensions
Anyone who has seen a 3D film on a large-format screen can imagine what the next stage in our exploration process is like.
In a special room called a highly immersive visual environment, or HIVE, our geologists, geophysicists, computer scientists, drilling engineers and others come together to view the seismic data – in four dimensions. (The fourth dimension is time.)
On a large, curved screen three projectors display sophisticated renderings of the reservoir’s oil and gas deposits, the surrounding rock structures and the earth or sea above it. Viewed through 3D glasses, these projections help us to more accurately plan our next step: drilling into soil and rock to find out for certain whether these visualisations were correct.