| Popis: |
The objective in any perforated completion is to maximize the productivity index in a cost effective manner, which is to increase the flow rate for a given driving force (draw down) or to minimize the draw down for a given rate that could be achieved through minimizing the total well skin effect. Underbalance perforation through Tubing Conveyed Perforating (TCP) system is one of the best practices to ensure less damage to the perforation tunnels (perforating skin) leading to increased well productivity. However, it is very challenging in cases of completions using Electrical Submersible Pump's (ESP) to maintain productivity with undamaged reservoir by preventing any contact between reservoir and completion fluid and achieve the above simultaneously with safe well control during ESP deployment. Otherwise, the alternative solution is to perforate over balance using casing guns or run TCP string in single run then kill the well after perforation in order to install the ESP completion meanwhile both alternative ways lead to damage in the perforated tunnels. As reducing operating costs is a must, maximizing well productivity, and minimizing wellbore clean-up time, an innovative solution was designed and successfully implemented for perforating artificially lifted wells in static underbalanced condition meanwhile installing ESP completion in single run without killing the well. It combines the use of TCP system containing special hydraulic firing head (delaying technique with orifice and chamber filled with oil) equipped with hydraulic packer with on-off tool. TCP gun string with the hydraulic packer has been run by tubing and set hydraulically against the required intervals, then the ESP has been separately installed and the guns has been activated through a hydraulic firing head for a shoot-and-stay operation. The static underbalance condition has been created by the ESP thanks to the delayed firing time. After this operation, the well has been directly lined up to production flow-line with minimal wellbore clean-up time. The combination of static underbalanced perforation with deep penetration charges which is able to bypass invasion zone with depth of penetration more than 65 inch, can create a clean perforation tunnel, and significantly reduce the post-perforating damage by killing fluid, and finally maximize the well productivity. Despite the challenging reservoir conditions (Depth= 10200 FT, Pressure=3850 Psi, Temperature= 28544 deg. F), the Productivity Index (PI) of the wells were three times compared to the offset wells. This job has been performed by Agiba Petroleum Company, one of the main operators in Western Desert of Egypt, employing this combined TCP-ESP technique which has resulted in significant savings in cost as well as rig time and increased operating efficiency. This paper summarizes the practical experiences gained during the development and deployment of this integrated technique, in addition to an evaluation of the impact compared to the conventional perforation techniques through ESP downhole sensor data and well modelling. |
