Laser Scan Gives Lay of the Land

Getting the lay of the land is the most basic building block for virtually any oil and gas operation, but mapping the terrain isn't always easy — particularly in hostile, remote and ever shifting places like the Sahara Desert.

This is a story of how one project dealt with the challenge — and how getting a little distance up and away from the problem provided positive results.

Infoterra, an airborne laser scanning company, was asked to tackle a challenging survey in Algeria's Sahara Desert region to prove the worth of laser scanning applications for the petroleum business.

Despite some logistical nightmares, sandstorms, massive sand dunes and a remote location over seven hours from the nearest village, the project team — along with the vital support of WesternGeco — successfully gathered geographic information that will aid the service company and its clients operating in the hostile desert landscape.

The story starts in 2000, when WesternGeco, on behalf of several oil companies, hired Infoterra to acquire digital elevation and terrain models over a large area of the Sahara using airborne laser scanning, also known as lidar.

"This was a huge survey area covering about 1,500 square kilometers — about the size of Houston," said John Murtagh with Infoterra, "and to acquire data via traditional means over that large an area, which is also extremely inaccessible, would have been very difficult.

"You can't even get a 4X4 vehicle into much of the survey area," he continued. "Also, the sand dunes in this region of the Sahara are the highest in the world, and conducting ground surveys would have been too time consuming and costly.

"Lidar offered a safer, easier and more cost effective solution."

First Steps

The project was designed to provide geographic data for detailed engineering development planning, well site locations and general infrastructure design. The survey's initial objectives were to test the method and technology under these difficult desert conditions — and if successful, use the results to survey the entire area.

A secondary application of the data was for access planning and identification of problematic high gradient regions, which would be inaccessible for seismic source vehicles. The survey was a success, providing WesternGeco with a dataset useful for many applications.

But about those obstacles ...