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.
In the current cost-constrained oil field environment, operators must complete their wells while minimizing capital expenditure. Operators respond to these challenges by utilizing customized diagnostic services and specialized tools in a single run to save on rig costs. Coiled Tubing (CT) deployed fiber- optics assist in taking Distributed Temperature Sensing (DTS) during acid stimulations to estimate fluid volume distribution in the horizontal openhole with a specialized jetting tool to create wormholes and complex microfractures. This paper discusses an acid stimulation process using dynamic fluid energy to divert flow into a specific sweet spot in the well to initiate and accurately pinpoint acid stimulation. The treatment efficiency was monitored and visualized in Real Time (RT) with CT-conveyed fiber-optic DTS. This acid stimulation process, named Integrated Dynamic Diversion (IDD), often uses two independent fluid streams: the acid phase down the treating string and other liquids or foamed fluid down the annulus. Two different fluids mix downhole with high energy to form a homogenous mixture. Pre-job DTS injection profile diagnostics identified a non-permeable zone, and the stimulation pumping schedule was adjusted accordingly. Using the IDD process, this was done in RT by changing the depths and increasing the number of stages across the non-permeable zone. Post-job injection profile DTS diagnostics confirmed an increase in injectivity across the non-permeable zone with a uniform injection across the entire openhole. This proved the value of combining RT CT with IDD using a dual pumping process and the specialized jetting tool. Post-job production results also indicate a sustainable production with an oil gain of +500 BOPD. Applying the IDD methodology with DTS services is the most appropriate solution to address the unique challenges of openhole operations, formation technical difficulties, high-stakes economics, and untapped high potential from intermittent reservoirs. This paper presents post-job results obtained from stimulating multiple zones along the lateral and describes the lessons learned in implementing this methodology, which can now be considered best practice for applications with similar challenges in other fields.
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