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Well logging, also known as borehole logging is the practice of making a detailed record (a well log) of the geologic formations penetrated by a borehole.The log may be based either on visual inspection of samples brought to the surface (geological logs) or on physical measurements made by instruments lowered into the hole (geophysical logs).
Logging while drilling (LWD) is a technique of conveying well logging tools into the well borehole downhole as part of the bottom hole assembly (BHA).. Although the terms Measurement while drilling (MWD) and LWD are related, within the context of this section, the term MWD refers to directional-drilling measurements, e.g., for decision support for the smooth operation of the drilling, while ...
For example, if the tool fails at 1,500 ft (460 m) while drilling with a triple rig (able to trip 3 joints of pipe, or about 90 ft (30 m) feet, at a time), then it would generally be faster to pull the tool out of the hole than it would be to rig up wireline and retrieve the tool, especially if the wireline unit must be transported to the rig.
The tools can be categorized in a number of ways: simple optical borehole imaging (OBI) systems, energy source (electrical, acoustic, or nuclear with gamma rays or neutron); conveyance (wireline or logging while drilling); and type of drilling mud (water-based mud or oil-based mud).
Free to use software to digitize geological cross-sections, and display and edit borehole logs Geoscience ANALYST [30] Free 3D visualization and communication software for integrated, multi-disciplinary geoscience and mining data and models, which also connects to Python through geoh5py, its open-source API Mira Geoscience Ltd. Free / Proprietary
Spontaneous potential log, commonly called the self potential log or SP log, is a passive measurement taken by oil industry well loggers to characterise rock formation properties. The log works by measuring small electric potentials (measured in millivolts) between depths with in the borehole and a grounded electrode at the surface.
Mud logging is usually performed by a third-party mud logging company. This provides well owners and producers with information about the lithology and fluid content of the borehole while drilling. Historically it is the earliest type of well log. Under some circumstances compressed air is employed as a circulating fluid, rather than mud.
Density logging is a well logging tool that can provide a continuous record of a formation's bulk density along the length of a borehole.In geology, bulk density is a function of the density of the minerals forming a rock (i.e. matrix) and the fluid enclosed in the pore spaces.