WorldWide Drilling Resource

44 JULY 2022 WorldWide Drilling Resource® Frequently-Used Geological Terms Part 94 Glossary Adapted from the Dictionary of Geological Terms S Show - 1. A trace of gas or oil detected in a core, cuttings, or circulated drilling fluid, or interpreted from the electrical or geophysical logs run in a well. 2. A small particle of gold found in panning a gravel deposit. Siderosphere - Central iron core of the earth. Sidetracking - Intentionally deflecting and redrilling the lower part of a borehole away from a previous course; e.g. drilling to the side of and beyond a piece of drilling equipment permanently lost in the hole. Sidewall Core - A core or rock sample extracted from the wall of a drill hole, either by shooting a retractable hollow projectile, or by mechanically removing a sample. Sidewall Sampling - The process of obtaining sidewall cores, usually by percussion (shooting hollow retractable cylindrical bullets into the walls). Siltstone - A hardened silt having the texture and composition of shale, but lacking its fine lamination or fissility; a massive mudstone in which silt predominates over clay. It tends to be flaggy, containing hard thin layers, and often showing primary current structures. Silurian - A period of the Paleozoic, thought to have covered the span of time between 440 and 400 million years ago; also, the corresponding system of rocks. The Silurian follows the Ordovician and precedes the Devonian. It is named after the Silures, a Celtic tribe. Sima - A petrologic name for the lower layer of the earth’s crust, composed of rocks that are rich in silica and magnesia. It is equivalent to the oceanic crust and to the lower portion of the continental crust, underlying the sial. Sitting on a Well - Working at a well location when the well is being drilled. The geologist examines cuttings and cores to determine which formations are penetrated, and to look for signs of hydrocarbons. Skin Friction - 1. The frictional resistance developed between soil and an engineering structure. 2. The shearing resistance of the ground developed on the sides of a pile, pipe, or probing rod. 3. The friction between a fluid and the surface of a solid moving through it. EXB Look for more terms SOON! Booth 1808