Editing Well logging (section)

==Coring==
{{See also|Core sample}}
[[File:Rochovce granite01.JPG|thumb|An example of a granite core]]
Coring is the process of obtaining an actual sample of a rock formation from the borehole.  There are two main types of coring: 'full coring', in which a sample of rock is obtained using a specialised drill-bit as the borehole is first penetrating the formation and 'sidewall coring', in which multiple samples are obtained from the side of the borehole after it has penetrated through a formation.  The main advantage of sidewall coring over full coring are that it is cheaper (drilling doesn't have to be stopped) and multiple samples can be easily acquired, with the main disadvantages being that there can be uncertainty in the depth at which the sample was acquired and the tool can fail to acquire the sample.<ref>{{Cite web|url=http://www.halliburton.com/ps/default.aspx?navid=1831&pageid=1141&prodgrpid=PRG%3a%3aJCFUH1E8Z|archiveurl=https://web.archive.org/web/20111011073101/http://www.halliburton.com/ps/default.aspx?navid=1831&pageid=1141&prodgrpid=PRG%3a%3aJCFUH1E8Z|url-status=dead|title=Halliburton. Sidewall Coring|archivedate=October 11, 2011}}</ref><ref>{{Cite web|url=http://www.glossary.oilfield.slb.com/Display.cfm?Term=core|title=Schlumberger Oilfield Glossary. Core}}</ref>