Introduction to well logs & subsurface maps / Введение в документацию скважин и карты погребенного рельефа

After a well is drilled, a string of geophysical instruments (called a sonde) is placed into the borehole to record the geophysical properties of the subsurface strata. The data are digitally recorded in a nearby logging facility (commonly a logging vehicle for land-based rigs) and transferred to a paper log and/or saved as a digital .las data file. It is very common to get both a digital and paper copy of the well. Paper logs give interpreters the extra advantage of being able to quickly view and shift logs to make quick correlations. Digital files, however, are more useful in deriving specific values and can be quickly rescaled and electronically transferred. Logging can also take place while drilling. This requires the geophysical logging instruments to be operated behind the drill bit, which can be highly advantageous in horizontal or highly deviated wells because it is difficult to properly log these wells after drilling is complete. Logging while drilling also enables almost instantaneous data transfer between the bottom of the borehole and the drillers or interpreters on the rig or in the office. <...>