Glossary
| Term | Definition |
|---|---|
| Sandstone | A sedimentary rock composed primarily of sand sized grains, usually quartz. A common hydrocarbon reservoir rock. |
| SCF | Standard cubic feet. See MSCF |
| Seal | An impermeable rock unit that prevents hydrocarbons from escaping from the reservoir. |
| Sediment | Generally, water borne debris that settles out of suspension. |
| Sediment rock | A type of rock formed by aggregation of sediments. |
| Seismic reflection | An event observed on seismic data that corresponds to a given rock layer in the subsurface. |
| Seismic survey | A tool employing an energy source, such as dynamite, and recording devices used to measure the travel time from a rock layer to the surface. The primary tool used to detect hydrocarbon traps. |
| Shale | A very fine grained rock often thinly layered. An important seal rock. |
| Show | An indication while drilling that hydrocarbons are present in the well. |
| Silt/siltstone | A rock whose grain size is intermediate between sand and shale. |
| Source/source rock | An organic rich rock (typically shale) capable of generating hydrocarbons under certain conditions of temperature and pressure. |
| STB | Stock tank barrel, the volume of a barrel of oil at the earth's surface as opposed to the corresponding volume in the subsurface. |
| Stratigraphy | The study of the vertical and horizontal distribution of stratified rocks, with respect to their age, lateral equivalence, and environment of deposition. |
| Structural trap | Generally, a hydrocarbon trap formed by dipping rock layers and/or faults. |
| Structure | A geological feature usually higher in elevation than the surrounding rock, formed by local deformation of the rock layers. |