Type-log selection and preparation for a more accurate geosteering model

Abstract

Selection of an optimum type log for modeling a horizontal well lateral is arguably the most critical decision made to deliver the best geosteering interpretation. When selecting one or more type logs, complications with data quality are often misunderstood or overlooked. The result of a poor type log match or an errant depth correction can lead to undesirable effects. Important considerations include: poor data quality, stratigraphic variability, structural variability, errant survey data, and improper depth correction. Hindsight can be costly and detrimental effects may include: landing the well out of zone, incorrect formation dip estimates, drilling into undesirable zones, and poor zone thickness estimates. All of these decrease economic returns via slower drill times, high dogleg severity leading to completion issues, incorrect reserve calculations, less wellbore interface with the targeted reservoir rock, or worst of all, a lost hole. Fortunately, most of these issues can be accounted for when determining if your type logs are optimal for the best geosteering interpretation. We will overview potential type log sources and consider techniques for selecting and correcting them for modeling purposes. Additionally, the presentation will illustrate differences in geosteering interpretations where the type logs were and were not properly selected and prepared. The best wells are drilled in the best rock, so make sure your type log is optimized for the task.

AAPG Datapages/Search and Discovery Article #90221 © 2015 Mid-Continent Section, Tulsa, Oklahoma, October 4-6, 2015