Real-Time Rig Less Intervention with a Catenary Coiled Tubing System to Perforate the Long Horizontal Section of a Well, Offshore Brunei

Abstract

A horizontal oil development well offshore Brunei had unwanted gas zones needing to be isolated and its oil zones reperforated. Limited deck space, riser length, long gun length, and a long horizontal section posed many challenges for executing the operation using conventional methods. To overcome these, a customized perforation and detonation gun system was used for efficient and safe deployment into a live well with Coiled Tubing (CT) to reach the target depth along with a Real-Time (RT) CT system, allowing more accurate depth correlation for the plug setting and perforation. A Solution to the limited deck space was developed using an integrated RT catenary CT unit, pumping, and flowback package. This setup allows most of the equipment to remain on the vessel while transferring only minimal items to the platform and keeping the capability of pumping and safely managing the flowback from a live well. An adjustment to the injector jacking frame was also made by designing an extension that would safely increase the height for the gun length to be deployed while remaining able to withstand any strong weather. Additionally, software simulations were performed to verify that the longest perforating gun could successfully be deployed in and out of the live well. Due to the long target interval needing perforated, a gun deployment system was selected to reduce tripping time instead of a more traditional section-by-section method. With a ninety-meter gun length deployment in a single trip for the longest interval, this deployment method saved twelves trips compared to the more conventional approach. Overall, considering three intervals to be perforated, this system eliminated a significant number of trips for the whole project. RT CT integrated with sophisticated and reliable sensors guaranteed depth accuracy during the correlation process. These sensors delivered RT Gamma Ray (GR), Casing Collar Locator (CCL), pressures, compression, tension, torque, inclination, and temperature, fulfilling the requirement of achieving accurate depth control and overall RT monitoring of downhole conditions. The electrical firing mechanism allowed a more straightforward and safer firing process than the alternative of circulating a ball. This project marked the first successful operation to perforate more than two hundred and fifty meters of target horizontal interval with three long perforating guns. This approach saved twelve runs compared to the more conventional method, which also needs additional correlation runs. The customized solution demonstrates that critical operations in long horizontal wells in challenging offshore environments can be successfully and safely executed.