Unlocking Reservoirs

To drill successfully for oil and natural gas, you need to have a good idea of what's beneath the surface. Two-dimensional (2D) and three-dimensional (3D) seismic are crucial tools in the toolkit that exploration and development teams use to drill new wells with confidence, achieving a high rate of technical success and commercial viability.

Seismic was first used to explore for hydrocarbons in the Western Canada Sedimentary Basin (WCSB) in the early 1940s. Before seismic was invented, producers looked for surface oil seeps or attempted to map the subsurface by examining surface outcrops and extrapolating from these physical indicators. But if you wanted to examine the real underlying geology in a prospective area, you had to drill a well. This worked to a degree, especially when drilling costs were lower the basin's easiest, largest undiscovered fields lay waiting. Nowadays, with each new well costing several million dollars and typical oil and natural gas targets much smaller and more challenging than in the past, seismic has become an essential tool for oil and natural gas exploration.

Raw seismic data can be reused many times and over a long period. Thanks to modern reprocessing through computer software that "sharpens" the data, some seismic data recorded as far back as the 1960s is still being used for exploration in western Canada. A major milestone in seismic's development was the switch to digital recording in the 1970s. This gave exploration and production companies a much clearer picture of the underlying geology, and significantly improved the data's reusability under modern reprocessing.

The key to seismic quality is the "fold." High-fold data is recorded at shorter physical intervals on the surface, picking up more of the subtle changes in sound frequency and interval necessary for precise geological mapping and seismic modelling. High-fold seismic also collects data from the full range of prospective geological zones, from shallow through deep. Low-fold seismic focused on narrower zones of interest to the original user of the seismic data, omitting large portions of the geological column. Low-fold can also overlook details even within its zones of interest, analogous to a grainy or fuzzy photo. Pulse focuses on acquiring high-fold data wherever possible. Lower-quality data sets, targeting only a few horizons, are purchased when they are the only seismic data available for a region.

Seismic technology is continuously improving. Recent developments in seismic technology include the use of three-component geophones, which measure both the reflected S and P sound waves, producing a much sharper picture of the underlying formations. Three-component geophones are particularly useful for heavy oil plays.

The majority of the WCSB, with the exceptions of the Foothills belt along the eastern slopes of the Rocky Mountains and the sub-Artic, is covered by existing lines of 2D seismic data. However, only an estimated 15-20 percent of the Basin is covered by 3D surveys. Pulse continues to acquire both types of data, and to participate in new 3D seismic surveys covering active exploration areas in the WCSB.