1964 Paper E

THE ELECTROSCANNER® - AUTOMATIC WELL CHART DIGITIZER Author: J. T. Cotton

ABSTRACT

The techniques by which modern high speed computers may be used in the analysis of well data have been treated by many authors during the past three or four years. It has been conceded, almost without exception, that the major obstacle to the wider use of these techniques has been the high cost of obtaining raw data from the well in a form which would be readable by a computer system. Various approaches to the solution of this problem have been proposed including magnetic digital recording at the well site. This method is expensive and does not provide for the retrieval of historical data. The manual and semi-automatic conversion devices for translating graphical data are even more costly. The optimum solution to the problem would be a device which is capable of digitizing a well chart, either current or historical, at a cost per record far below any of the current methods.

This paper describes a system for digitizing well logs which utilizes an optical scanning system and a magnetic tape recorder. The field of optical scanning of chart records has been extensively explored by United Gas Corporation in connection with the automatic reading of flow meter charts. The scanning system which has been proven in this application has been adapted to read strip paper charts and, working with a transistorized control system, to produce the digital coordinates of each trace at selected intervals.

The optical scanning system is sensitive to abrupt changes in the reflectivity of the chart surface. As a result, digital coordinates will be recorded for traces, grid lines, pencil marks, depth scale numbers and a variety of other extraneous points. The novelty of this approach lies in the use of a high speed computer to pick out the trace data and discard the trash thereby performing automatically what has heretofore been a manual function. The input data requirements and the operating details of the edit program are discussed from the point of view of the system user, avoiding program details. The major emphasis is placed on the manner in which editing decisions are made to produce the final output record.

The techniques by which modern high speed computers may be used in the analysis of well data have been treated by convention speakers and authors of technical articles in various publications over the last several years. Some computer manufacturers furnish complete programs for their hardware to assist the analysts of the petroleum industry in the use of their equipment. Special representatives are available from the same sources for individual assistance on specific problems. This points out the fact that the trend is definitely toward automatic processing of data from all phases of the industry.