Autonomous Inflow Control Valve for Medium-Light Oil and its Effective Performance

Abstract

Most horizontal oil wells will after a time start producing unwanted fluids. Autonomous Inflow Control Valves (AICV) may help to choke these unwanted fluids and consequently improve the carbon efficiency. This paper publishes new experimental data describing how an AICV handles a medium-light oil (6 centipoise), water and gas at full reservoir conditions. A further objective is to evaluate how the AICV might impact well performance under various conditions. To verify the single and multi-phase flow behaviour of the AICV for medium-light oil viscosity, an extensive multi-phase flow loop campaign was performed. The test was performed under real reservoir conditions, i.e., with formation water, reservoir oil and hydrocarbon gas at the given reservoir temperature and pressure. Preceding the external and independent verification, internal laboratory studies were performed with model fluids. A simple conceptual reservoir model with realistic boundary conditions was built to explore and understand the impact of this AICV for various reservoir scenarios. At various differential pressures the single-phase oil, water, and gas rates were measured. Performance at varying water and gas fractions were measured to get improved understanding and knowledge of multi-phase flow occurring in a well. The results show clearly that the AICV will choke gas and water effectively, both at single and multi-phase flow conditions. The external and independent verification are consistent with the internal laboratory evaluations with model fluids. The AICV shows roughly a linear transition from 100% oil to 100% gas performance, and similar for 100% oil to 100% water, implying that the AICV will always prioritize sections with the largest oil fraction. A mathematical model match of the AICV performance is possible via the 10-parameter extended AICD equation, that enables practical evaluation of the AICV in industry standard reservoir simulators. Various scenarios are explored with a conceptual reservoir model and the AICV shows its capacity to reduce water production and enable more gradual and controlled increase in gas-oil-ratio for most scenarios. AICV used in segmented reservoirs shows the largest potential to reduce unwanted fluids and in addition increase oil recovery. In cases with uncertain aquifer and/or gas cap strength, or large variation in effective permeability, the AICV will make an infill well more robust as it autonomously adapts to reality and chokes unwanted fluids and consequently enables more carbon efficient reservoir management.