Multilateral Completion Technology to Improve Reservoir Management

Abstract Effective well completion design is crucial to optimize well and field performance, with many operators utilizing different techniques to achieve this important objective. However, the conventional means of designating wells for reservoir monitoring and standalone wells for production presents challenges to cost-effective reservoir management. Vertical observation wells are usually drilled in different locations to monitor the reservoir and assist with planning and intervention decisions by running periodic logs to obtain subsurface information. However, these wells can be costly and occupy valuable space that could be utilized for production. An alternate technique is to drill a pilot hole, perform all the necessary logging, and obtain the required reservoir information. The pilot hole is then plugged and sidetracked to a producer well. Nevertheless, the collected data only remains valid for a limited period due to potential changes to the reservoir. The demand for cost-effective, optimized drilling of production and observation wells has led to a paradigm shift in multilateral well technology that achieves both production and monitoring objectives for both laterals at the same time. Using this enhanced technology, wells can be completed with a pilot hole (vertical) drilled for reservoir evaluation throughout the life of the well, with permanent downhole gauges (PDHGs) installed for pressure and temperature monitoring, while the horizontal lateral functions as an oil and gas producer. Combining the observation and producer wells into one well results in cost savings and enhanced reservoir production and surveillance programs. In addition, the capability to access the lateral allows for intervention in both the motherbore and lateral at any time. Well intervention operations for a well completed with this multilateral technology involve slickline runs to gain access to the horizontal lateral, retrieve an isolation sleeve, and install a tubing exit whipstock (TEW) for lateral re-entry. Later, coiled tubing (CT) or wireline tractor can be run through the window into the lateral to perform the logging and intervention necessary. Upon completion, the TEW is retrieved from the window, the isolation sleeve is reinstalled, and the well is returned to production. Well intervention through such multilateral completion demonstrates the ease and efficiency of accessing both the vertical and horizontal lateral, without requiring a rig or completion retrieval. This paper will highlight the multilateral completion technology for accessing both laterals, which includes real-time monitoring capabilities that provide more reliable data for optimum well and field performance.