1964 Paper H

FIELD DIGITAL RECORDING OF WELL LOG DATA

Guy O. Buckner Lane-Wells Company Houston, Texas

ABSTRACT

A special BCD code and output format are described which were developed for field digital recording of well log data. The code and format are discussed and compared with the IBM BCD code and with the true 8421 BCD code. This code and format were developed for magnetic tape recording and computer playback but can be used for other forms of recording or for telemetering. A reel of magnetic tape is subdivided into logs and records. Logs begin with a prefix one record long and end with a suffix one record long. The prefix contains a service company identification number, a log type code number and a well identification log number. Any number of different types of logs may be recorded on the same reel of tape and identified on a computer by the numbers in the prefix. The suffix identifies end of log or end of log and tape. The main sequence between prefix and suffix may be a number of short records taken at given depth intervals in the borehole; or a number of long records where length is chosen to fit the computer that is expected to play back the tape; or one long record for continuous or gapless recording. Log data in the sequence may be recorded with depth to the nearest foot, interval depth to the nearest 1/10 foot, event timing mark to the nearest millisecond and eight channels of log data to the nearest 0.1 percent.

An experimental field magnetic tape digital recorder is described. Early results of this recorder as used for Focus-Minifocus, for Acoustic-Gamma-Focus, and for Diplog are discussed. Notes on programming the IBM 1401 and the CDC 1604 for reading and computing the above logs are given.