Modeling of Azimuthal Gamma-Ray Tools for Use in Geosteering in Unconventional Reservoirs

摘要: Abstract In recent years, more horizontal well targets in unconventional reservoirs are being designed to stay within narrow stratigraphic-target windows. These narrow windows can be as thin as 10 feet and require active geosteering to keep the wellbores within the target. It is a difficult challenge to meet the target objectives when steering with a standard omnidirectional gamma-ray (GR) tool alone. The lack of azimuthal sensitivity in these tools makes it difficult to determine whether the wellbore is approaching the top or bottom of the target window while using real-time data during drilling, or using memory log data even after drilling the lateral section. To solve this problem, the industry is beginning to turn to azimuthal GR tools. GR tools assist in determining the relative stratigraphic position of the drilling assembly. This is done as it cuts up-section or down-section, when approaching or crossing …