Maximizing Reservoir Potential: Coiled Tubing Multilateral Extended Reach Intervention for Acid Stimulation

Abstract

Multilateral well designs have been gaining demand, aiming to expand the recovery of hydrocarbon or injection of recovered fluids, depending on application. The primary challenge in such well completion is accessing the unnatural laterals, followed by extending the coiled tubing (CT) depth reach at which the stimulation treatment can be delivered, which is normally restricted by the friction lock limit. This paper presents a solution for multilateral extended reach CT stimulation. The producing multilateral well was completed as dual open hole laterals, from completion to open hole, increasing the friction coefficient and reducing the maximum reach. The application of a reliable hydraulic multilateral entry tool (MLT) and an extended reach tool (ERT) was proposed, which provided a reliable option to access the un-natural lateral and extend the reachability of coiled tubing for stimulation. The BHA included a real time integrated sensor tool and casing collar locator (CCL), powered by a reliable single conductor system for telemetry. The use of real time data provided confirmation on accessing the correct lateral. The use of an MLT is mandatory to enable CT entry into the lateral leg. During intervention, the access depth to the lateral window was located with the use of CCL for depth accuracy, followed by pressurizing the MLT to a predetermined pressure for the tool to begin the search mode, indexing the wand section of the tool and enabling it to complete a mapping cycle by continuously rotating 360° in less than 2 minutes. A pressure drop signal will indicate that the window has been located and rotation will then stop with full kickoff achieved. If there is no pressure drop, the tool will complete full rotation and is reset to straight position by increasing pressure to a predetermined value. CT is then moved to next mapping depth and new cycle is started. Upon locating the window, the indexed wand section is run in hole (RIH) into the lateral past the access window and CT is stopped to reset the tool to extended position and allowing fluid to be continuously pumped through the ERT and the MLT. At this point, the ERT is activated, and it helps CT RIH past the default friction lock limit to perform stimulation at a deeper depth. The combination of these technologies, prove to be an effective option to increase the working envelope of smaller OD CT in multilateral extended reach interventions, challenged by the offshore work environment. This application translates to an increased footage of direct stimulation in the open hole section and maximizing the reservoir potential.