Case Study of Autonomous Inflow Control Devices (AICD) to Control Water Production in Fractured Carbonate Reservoir in Eastern Montana

Autonomous Inflow Control Devices (AICD) have been commercially available since 2010 and there are many published case studies of wells in sandstone reservoirs, encompassing a wide variety of water and gas control scenarios. There are, however, relatively few documented studies of AICD for water control in fractured carbonate reservoirs. This paper will discuss and compare two trial wells that were completed with AICD in Eastern Montana in late 2022. Mission Canyon is a limestone formation of the Mississippian age and is associated with the Williston Basin of the North Central United States. It is composed primarily of oolitic calcarenite consisting of sedimentary carbonate grains. Depending on the grain size, matrix permeability can be relatively low, and a complex network of natural fractures is what dominates fluid flow. These fractures can be good or bad; they can deliver a good oil rate, or they can be direct conduit to the reservoir’s natural bottom-water drive. Consequently, most wells start with 50% water cut and reach 90%+ within a few months. Water volumes can be as high a 3000 barrels of water per day, per well, requiring large-volume pumps and significant water handling & disposal infrastructure. This field trial of AICD technology was designed to reduce water production rates, and then evaluate the impact on additional oil recovery. The technology tested was an AICV (autonomous inflow control valve) that utilizes the fluid viscosity and density to autonomously restrict water. The AICV devices were installed in two wells; the first was an existing horizontal producer (retrofit installation) and the second was a newly drilled horizontal well. AICV were installed on 3-1/2" liners in the open-hole horizontal section, compartmentalized into stages by swellable packers. Each compartment of the well was approximately 150 ft long and was controlled by a dual AICV flow screen. Nodal analysis predicted a 50% reduction in produced water, with an increase of 20-30% oil rate versus the standard open-hole laterals. This field study documents the world’s first application of the AICV technology for light oil, water control in a fractured carbonate reservoir. Many valuable lessons were learned on how to best complete and operate the wells. Preliminary results show effective water control, regardless of pressure drawdown. The paper will share production results for each well and attempt to estimate the net effect on oil production and well economics.