How a New On-Command Downhole Control System is Breaking the Efficiency and Sustainability Paradigm in Multilateral Stimulations

Abstract Over the past two decades, coiled tubing (CT) has been the preferred intervention method in multilateral wells, given its ability for deeper reach, smaller displacement volumes, more controlled placement, and flexibility on the scope of work. Nonetheless, as the lateral mapping and entry processes have relied on hydraulically actuated downhole tools, interventions tend to be lengthy and fluid consuming, requiring more than 400 bbl of water per lateral just for mapping purposes. Stimulation treatments in multilateral wells are usually preceded by wellbore conditioning on each lateral. The placement of the treating fluids is conducted through a high-pressure jetting module that, when activated permanently, isolates the multilateral entry components of the hydraulically actuated toolstring. Therefore, interventions with cleanout and stimulation scope of work cannot be conducted in a single run, extending the overall intervention time. The recent introduction of an acid-resistant, electrical multilateral entry tool with direction and inclination measurements allows lateral entry on the first attempt. The system also features a downhole on-command, electrically actuated circulation valve (EACV), which redirects fluid to either exit jetting nozzles or to downhole tools, thus avoiding isolation of any toolstring component. A dual-lateral carbonate water injector well, completed as a 6 1/8-in. open hole, was selected for the first implementation of the acid-resistant, multilateral entry assembly. The CT string was equipped with a hybrid electro-optical cable that provides continuous downhole power and enables dual telemetry (optical and electrical) capabilities for a virtually unlimited operational time. Following cleanout work on the main lateral (L-0), entry into the second lateral (L-1) was completed on the first attempt. In both cases, the wellbore conditioning stage was conducted by circulating fluids through the jetting nozzles of the EACV. Before the matrix stimulation of each lateral, the flow path of the EACV was switched, redirecting the flow through a high-pressure jetting tool. Close to 5,000 bbl of reactive fluids were pumped throughout the stimulation stage with an average pumping rate of 3.5 bbl/min. The entire scope of work was completed in a single CT run, saving more than 48 hours of operating time. The optimized intervention workflow saved more than 1,000 bbl of water and reduced CO2 emissions by nearly 25%. The experience gained from the first implementation of the acid-resistant, multilateral entry assembly validates the technology as a step-change for enhanced CT multilateral intervention. This technology paves the road for new intervention workflows leveraging optical and electrical CT downhole telemetry with the EACV acting as the key building block to provide full control of the selective actuation of part of the hydraulic bottomhole assembly.