An Operator in Oklahoma had a requirement to identify the location of a specific bed boundary and stay in a particular zone of interest just above that boundary in a horizontal well. Cathedral Energy Services elected to use the APS SureLog™ AZG sensor along with the APS SureLog™ DG MWD system to meet their customer’s reservoir positioning challenges. The 4 ¾” SureLog™ AZG employs 3 shielded gamma ray detectors that are used to attain a 24-bin high resolution gamma ray image in memory while providing 4-bin image data in real-time for well bore positioning.
The image below illustrates a comparison of memory and real-time images as the well is drilled down dip then, later, identifies position of the zone of interest and confirms that the wellbore was positioned above the boundary. This “bounce off the bottom” ensured the Operator that they were in the desired part of the reservoir.
The high-resolution 24 bin memory log is on the top image with the lower resolution telemetered data in the bottom image. The lower resolution 4 bin real-time data were used to indicate the wellbore’s relative position to the bottom bed during drilling. The “ ( “ shapes in the image indicate that the wellbore is going down dip, deeper, into formation. When the “ ( ) ” shape is logged the wellbore is changing direction relative to the formation boundary and is then drilling up dip away from the bottom boundary which they desired to stay above.