Four decades ago, ExxonMobil pioneered an exploration technology called 3-D seismic, which uses sound waves to form sharp three-dimensional images of underground formations, facilitating the location of oil and gas deposits. ExxonMobil employs the latest generation of 3-D technology, coupled with advanced computing, to create detailed images of the world’s oil and gas reservoirs. Today, four-dimensional seismic technology, which compares 3-D seismic surveys from the same field over different points in time, is extending our reach, and optimizing thermal recovery in heavy-oil reservoirs.