The relationships used in these operations are established by means of calibration procedures and then stored in the computer memory. To obtain graphic logs, these raw measurements must first be converted into the desired parameters, such as ohm-m, bulk density, etc., by means of exact mathematical relationships. The basic measurements of the CSU are raw quantities such as millivolts, count rates etc. With the advent of CSU, this method has become obsolete. In the past, most of the steps were to record the calibration of galvanometers and other surface apparatus for processing and recording the measured signals. They provide, in particular, a control of the quality and an evaluation of the accuracy of the measurement. These summaries are an integral part of modern measurements. These can take the form of a film, which records galvanometer readings under suitable calibration conditions, or of a tabular summary in the case of Schlumberger Cyber Service Unit (CSU). Quality control starts with checks on the calibrations. This chapter discusses the quality control of logging tools.

The log analyst must have at his disposal quick, reliable, and proven methods so that he can answer these questions confidently and in the shortest possible time. In view of the high cost of operating drilling equipment, in particular in the offshore environment, it is of the greatest importance to minimize down-time by being able to make key decisions quickly.

Quick look over the shoulder