Definition - What does Logbook mean?
A Logbook is a detailed record of a geological formation during the drilling of a borehole. It can simply be defined as a log of oil or a gas well. A well log is prepared by either taking samples through visual inspections or with the aid of measuring instruments lowered into the borehole. Logs prepared using visual inspections are called geological logs whereas logs prepared with the help of inspection instruments are called geophysical Logs.
Petropedia explains Logbook
Logbooks generally hold multiple well logs, i.e., the detailed progress reports of all the individual wells in an E&P organization vicinity. These records are important as they help an organization in analysis and strategic decision making.
Logs are generally prepared in order to evaluate hydrocarbon deposits. In order to perform this evaluation, testing of rock and fluid formations at different locations is conducted and the data is recorded on the logs. The device that is used to conduct well testing is called logging tool and it can be attached to a thin wire known as wireline. The wireline carries this tool to the necessary depth within the borehole to conduct testing on quantity and location of hydrocarbons beneath the earth’s surface. This tool gathers all data and sends it to the control room where the well logs are prepared.