Real-Time Fiber Optic Integrated System Provides Precision and Confidence in a Coiled-Tubing-Conveyed Perforating Operation: A Case Study from the Eastern Foothills in Colombia

Abstract

Underbalanced perforating with conventional cable operations involves several risks associated with well tortuosity, cable tension capacity, gun lifting, and the capability of achieving the optimum underbalance for effective tunnel cleanup (Graeme et al. 2008). Because of these risks, an operator in Colombia elected to perform a perforating operation using a coiled tubing (CT) real-time fiber optic (RTFO) integrated system in a newly drilled development well. CT-conveyed perforating is ideal for this type of wellbore. To achieve the proper underbalance and depth correlation to perforate the target interval, an RTFO CT system provides the most accurate and reliable depth correlation process, in addition to real-time pressure and temperature monitoring inside the CT and the outer annulus. Using the RTFO CT system, only two runs were necessary to complete the perforating program, in accordance with the operator design, rather than performing an additional run needed for pickling and to generate underbalanced conditions. The use of the RTFO CT system can help to prevent correlation errors resulting from CT elongation. A CT structure was not necessary to deploy the guns based on the finite model analysis that calculates maximum stress and flange bending, including a safety factor. A hydraulic firing head can be used with an RTFO CT system to activate the guns without affecting the integrity of the fiber optics or the downhole sensor tool after detonation. The RTFO CT system enabled the operator to evaluate the reservoir potential. The evaluation results indicated that one of the zones is a low producer, which avoided the pumping of unnecessary nitrogen to induce the specific zone. The use of a downhole pressure sensor enabled the identification of the time at which the guns were detonated. Improvement to the rigup was evidenced and enabled time optimization without affecting the operation. The casing collar locator (CCL), used for depth correlation, was a crucial factor in reducing operational costs because it helped to optimize placement accuracy and gun detonation and to prevent misfiring (Newman 2003). The guns were successfully activated without nonproductive time (NPT) or health, safety, or environmental (HSE) incidents during operations. A successful perforating operation was completed with 4,000 psi underbalance in a new formation using hydraulic detonation with continuous real-time downhole condition monitoring before and after detonation, enabling the operating company to make decisions in real time. This new approach of using an RTFO CT system combined with the hydraulic firing head can be used to perforate new formations in these crucial scenarios (wells with production greater than 20 MMscf/D and zones with continued sand production).