The geology beneath the seafloor is known primarily from rock samples, either cores or cuttings, that are obtained during drilling of an offshore borehole. In the Scotian Basin, which occupies an area of 300,000 square kilometres (roughly five times the area of Nova Scotia), only 140 wells have been drilled. Reflection seismic data provide the best means of correlating the geology from one borehole to another.

A problem arises, however, because the reflection seismic method records two-way travel time for acoustic energy to travel into the earth and be reflected back to the surface. To convert the travel times to depth, it is necessary to know the velocity at which the energy travels through every layer of rock. Generally this is known accurately only at boreholes, where sonic velocity and also the rock density can be measured directly using geophysical tools in the borehole. Thus, correlation of the well information with the seismic data is crucial.

For the Scotian Margin Project, 11 wells were selected for detailed correlations. The sonic and density logs were carefully edited to remove spurious data, and were then filtered to approximate the lower vertical resolution of the reflection seismic data. The edited and filtered data were used to calculate the proportion of acoustic energy that would be reflected to the surface at every significant layer penetrated by each borehole. This, combined with an estimate of the frequency and phase characteristics of each seismic survey, allowed us to model the theoretical seismic response that should be observed at each well location. The results, known as synthetic seismograms, can be seen by clicking on the desired well in the map below.

Well to Seismic Correlation

Map of Nova Scotia showing the location of the well correlations (see map below for detail)

Pick a well to view recent well correlation images

• Sable Island C-67
• Cohasset L-97
• Onondaga E-84
• Intrepid L-80
• Wenonah J-75
• Marmora C-34
• Eagle D-21
• South Venture O-59
• Venture D-23
• Louisbourg J-47
• South Griffin J-13