Challenges in perforating multiple zones

BHP Billiton wanted to improve the efficiency, safety, and reliability of its CT perforating operations in Eagleville field, South Texas. Conventionally perforating multiple zones in a well required using extra gun spacers between the loaded guns but could not provide the flexibility of perforating designated zones at separate times.

Highly accurate delay timing for efficient, safer perforating

The Schlumberger ballistic delay fuse reliably provides a 4- to 8-min delay time. The delay is temperature dependent, increasing as the bottomhole temperature decreases. Incorporating the ballistic delay fuse in CT perforating operations eliminates the need for installing extra spacers between guns. Instead, each zone is perforated at a separate time during a single run by simply moving the string to position the loaded guns.

Successful perforating at up to 327 degF

Using the delay fuse streamlined multizone CT perforating operations for BHP Billiton to one run in each of eight Eagleville field wells. Rig-up and -down time was lessened because only one firing head was necessary and no spacers had to be installed. Despite experiencing pressures from 9,000 to 16,000 psi and estimated temperatures of 321 to 327 degF, the delay fuses functioned reliably, with a maximum timing error of only 6%, which was well within expectations. As shown on the table, the second shot by the delay fuse indicated a 6-min delay, which was exactly the predicted time at 321 degF.