Unique Solution to a Challenging Multilateral Well Intervention Using an Electric Multilateral Tool and Distributed Temperature Diagnostics on Coiled Tubing in a West Kuwait Field

Abstract

Multilateral wells offer multiple benefits to oil and gas operators, including lowering the field development cost by minimizing wellsite construction work and increasing reservoir contact leading to enhanced reservoir production. They also present challenges, with each leg requiring separate intervention and uniform stimulation to gain full advantage of these complex wells. An operator in Kuwait drilled a 2-leg level 1 multilateral well to enhance production from the Mishref formation. Mishref is a fast-depleting reservoir requiring an extended contact area to drain the reservoir uniformly and efficiently. The main challenges with multilateral intervention include identifying the junction depths, gaining lateral entry, and confirming the correct lateral entry. To overcome these challenges, the operator identified the unique technology of utilizing Real-Time Hybrid Coiled Tubing (RTHCT) with an Electric Multilateral Tool (EMLT). Diagnostics using Distributed Temperature Sensing (DTS) were also used to compare pre and post-stimulation effectiveness. Intervention into a level 1 multilateral well presented several challenges, and RTHCT with the EMLT were successfully used to overcome these. The solution includes a hybrid fiber optic and electrical cable installed in the CT string and a Modular Bottom Hole Assembly (MBHA) equipped with various sensors. An electrically controlled indexing tool, inclination sensor, tool-face sensor, downhole camera, hydraulic knuckle joint, and pulsating stimulation tool were used as part of the BHA to enable real-time diagnostics and dynamic controls from the surface to successfully enter and stimulate both the lateral legs. This customized solution helped identify each different lateral without the need to tag the bottom of each lateral. This paper focuses on applications, strategies, and benefits of specific tool configurations developed for multilateral well intervention, which enabled the stimulation of both the Mishref laterals. Also discussed are the DTS diagnostics used to identify any thief and impermeable zones. Pre and post-stimulation diagnostics were performed to identify the effectiveness of the stimulation treatment. This paper includes strategies that address proper tool selection, confirmation of lateral entry, hydrostatic pressure balance, borehole stability, and acid design. It also explores the potential of new, synergistic strategies and work processes planned for stimulation of the Mishref reservoir.