A mechanised process for proximity survey interpretation

Proximity surveys have been used for many years to define the shape of salt domes. A travel time is measured from a source through the salt to each of several downhole sensor locations. From prior knowledge of salt velocities, velocities of formations encountered by the well, and at least one salt tie point, distances from salt to sensor positions can be calculated; thus, the shape of the salt flank can be determined. Recent developments have entirely mechanised the interpretation process, increasing its speed. Three-axis data recording enhances the measurement of the necessary travel times, improving the accuracy of the technique. The results agree with those obtained using conventional interpretation techniques, with a considerable saving in time.