Increasing water cut and well integrity are currently major concerns, particularly in mature fields. Excessive water production can detrimentally affect the profitability of hydrocarbon-producing wells if not controlled properly. This paper describes a successful zonal isolation case study in a dual-string completion well with well integrity challenges and variable permeability intervals using a modified organically crosslinked polymer (m-OCP) and coiled tubing (CT)-assisted real-time temperature sensing for effective placement and post-operation evaluation. The m-OCP system is a combination of a thermally activated, organically crosslinked polymer and particulate material for leakoff control to help ensure shallow matrix penetration. It is acid resistant, H2S tolerant, has controlled penetration, and is easy to clean up using a rotating wash nozzle. The setting time can be accurately predicted with simple laboratory tests. These characteristics make this system the preferred choice compared to the traditional cement squeeze method that is both time consuming and exorbitant. Diagnostic services delivered by CT-conveyed fiber-optic distributed temperature sensing (DTS) that add real-time capabilities to monitor well integrity assess reservoir performance and visualize treatment efficiency. Using real-time diagnostic services, tubing integrity was confirmed, and the treatment was placed in the same run, helping eliminate the possibility of an undesired leakoff. After allowing the setting time, a successful pressure test or post-cleanout DTS (in case pressure test is not feasible) was used to establish the reliability of this method. The first attempt was made on Well A of the field; however, isolation was successful using m-OCP and conventional CT. Operation execution and production recovery took more time than planned because of the uncertainty concerning well integrity in the dual-string completion and lost circulation in the depleted reservoir, which affected the economic deliverability of the operation. The major challenges with Well B of the same type in the same field remain the same. Thus, as part of lessons learned from the previous intervention, diagnostic services were chosen for a real-time evaluation of the completion to review well integrity and accurately place the optimized treatment, thereby helping improve overall results in the most time-saving and lucrative manner. The successful isolation of the water-producing zone/perforations in the southeast Kuwait field using m-OCP and CT-assisted real-time DTS to review well integrity can be considered a best practice for addressing similar challenges globally.

Multilateral technology offers 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. To gain full advantage of these complex wells, they must be stimulated properly. The operator in Kuwait drilled, cased, and cemented a six-leg, level IV multilateral well targeting two different formations, the upper and lower Tuba. This provided various production options and the flexibility of taking production from either the lower or upper laterals or even all six laterals to help mitigate the risks of drilling horizontal or directional wells. As such, multilateral technology can positively transform the economic viability of reserves in marginal fields. Exploiting the advantages of multilateral technology requires a multi-disciplinary approach to select appropriate well structure, completion design, re-entry flexibility, and production longevity. Intervention in this level IV multilateral well presented several challenges, such as Oil Based Mud (OBM) in all the laterals, encountering a fault in one of the laterals while drilling, and high shale content that can lead to stuck Coiled Tubing (CT) and the loss of fluid returns. Real-time hybrid cable CT was chosen along with an electric multilateral tool to mitigate the various risks involved. This solution includes a hybrid fiber optic and electrical cable installed in the CT string and a modular Bottom Hole Assembly (BHA) 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 all the lateral legs. This configuration helped identify each different lateral without the need to tag the bottom of each lateral. The paper focuses on applications, strategies, and benefits of specific tool configurations developed for multilateral well intervention, enabling the stimulation of all the lower Tuba laterals. This was a particularly challenging operation due to shale in one of the laterals causing several instances of stuck CT with the possibility of a collapsed hole mitigated by using the real-time camera in the BHA. 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 upper Tuba field.