1962 Paper I

A PROGRESS REPORT ON MACHINE INTERPRETATION OF WELL LOGS

J. H. Moran and W. Hoyle Schlumberger Well Surveying Corporation Ridgefield, Connecticut and E. E. Finklea and J. L. Dumanoir Schlumberger Limited New York, New York

ABSTRACT

The use of computer techniques to assist the log analyst in transforming recorded logging information into more usable data for evaluating formation characteristics is of considerable interest. The possible scope of such endeavors is so broad that it is impracticable to cover all of them in any one paper. Therefore, this paper is offered as a progress report on one such application, the interpretation of the Grand Slam suite of logs - which consists of a deep-investigation induction log, a medium-investigation induction log, a shallow-investigation laterolog, and a proximity log, as well as a recording o the SP curve.

The interpretation of the Grand Slam provides values of Rt and Rxo after accounting for the effects of invasion conditions varying from a transition zone in water-bearing formations to the possible presence of an annulus in oil-bearing formations. Recognizing that the interpretation over large numbers of zones is time-consuming when performed manually, it has been programmed for use with the IBM 704 and 7090, and 1620.

Since the presence of displaceable hydrocarbons in recognized by comparing Rxo/Rt to Rmf/R-wsp , and since Rmf/Rwsp is directly obtained from the SP curve, the programs for the large computers also include a method for correcting the SP for bed thickness and invasion where necessary. The data are entered into the computer on cards into which are punched the readings obtained visually from film logs.

The Grand Slam programs are outlined, and examples of the use of the method are shown.

Rwsp is the apparent resistivity of the formation water as derived from the SP.