The present invention relates to a downhole well system for producing hydrocarbon-containing fluid from a reservoir downhole, comprising a well tubular structure having an inside, a first and a second annular barrier for isolating an annulus outside the well tubular structure, each annular barrier comprising a tubular part adapted to be mounted as part of the well tubular structure, the tubular part having an outer face, an expandable metal sleeve surrounding the tubular part and having an inner sleeve face facing the tubular part and an outer sleeve face facing a wall of a borehole, each end of the expandable sleeve being connected with the tubular part, and an annular space between the inner sleeve face of the expandable sleeve and the tubular part, the first and second annular barriers being adapted to isolate a production zone when expanded, and an inflow valve assembly arranged between the first and the second annular barriers opposite the production zone for providing fluid communication between the production zone and the inside of the well tubular structure through a passage in the inflow valve assembly by adjusting a closing member in relation to the passage, wherein the inflow valve assembly comprises a sensor unit comprising a sensor adapted to measure at least one property of the fluid, a power supply for powering at least the sensor, and a control unit for activating the adjustment of the closing member based upon the measurement of the sensor. Furthermore, the present invention relates to an inflow regulation method for adjusting the inflow of fluid in the downhole well system according to the invention.