Interactive Digital Wellsite Formation Evaluation - The Prolog System

The advent of digital well logging equipment and associated interpretive software allows sophisticated handling of sonde calibrations, trouble-free logging operations, and accurate wellsite log interpretation analysis. Prolog, an interpretive computerized wellsite log analysis package incorporated into our computerized logging service (CLS) units, facilitates reliable, on-thespot decisions in a minimum of time. Prolog is based on two basic analysis packages. Wellsite CRA for complex reservoir analysis and Wellsite SAND for clastic sediment sequences. Both CRA and SAND present detailed formation evaluation in a four-track format supported by depth shift routines, a true vertical depth option, data-edit routines including borehole (washout) and environmental (invasion) log response corrections, and crossplot routines (frequency, Pickett, Hingle, etc.). This paper outlines the basic philosophy of the interactive Prolog system, presents flow charts and pertinent equations for both the CRA and SAND programs, illustrates the edit options based on comparative log response studies, and discusses the data format of wellsite Prolog analyses based on field examples from Texas.