A density meter for measuring the density of a fluid, having a base plate, wherein a spring element is clamped to the base plate; a torpedo, wherein the torpedo comprises a known weight, and wherein the torpedo is attached or coupled to the spring element; and a sensor, wherein the sensor measures a deflection of the spring element, as the torpedo displaces a volume of fluid.

A device for monitoring liquid includes an apparatus for measuring a parameter representative of the density of the liquid to be monitored. This measurement apparatus includes at least one floating structure, at least one member for determining the position of at least a part of the floating structure, and at least one transmitter for transmitting data. The device includes an enclosure accommodating the floating structure and a system for hanging the enclosure. The enclosure has a first end and extends from the first end in the direction of the opposite second end, forming a chamber delimited by a solid wall and a porous wall so as to form inside the chamber, in the manner of a diving bell, with a first space in which air is able to be trapped in the submerged state of the enclosure and a second space inside which the liquid to be monitored can circulate. The hanging system includes a suspension rod connected at one end to the enclosure and equipped at its opposite end with a hanging member for keeping the enclosure in the suspended state.

A device for monitoring liquid includes an apparatus for measuring a parameter representative of the density of the liquid to be monitored. This measurement apparatus includes at least one floating structure, at least one member for determining the position of at least a part of the floating structure, and at least one transmitter for transmitting data. The device includes an enclosure accommodating the floating structure and a system for hanging the enclosure. The enclosure has a first end and extends from the first end in the direction of the opposite second end, forming a chamber delimited by a solid wall and a porous wall so as to form inside the chamber, in the manner of a diving bell, with a first space in which air is able to be trapped in the submerged state of the enclosure and a second space inside which the liquid to be monitored can circulate. The hanging system includes a suspension rod connected at one end to the enclosure and equipped at its opposite end with a hanging member for keeping the enclosure in the suspended state.

Provided is a downhole tool and a well system. The downhole tool, in one aspect, includes a tubular providing one or more production fluid flow paths for a production fluid. The downhole tool, according to this aspect, further includes one or more float chambers located within the tubular, and two or more floats located within the one or more float chambers. In one aspect, a first of the two or more floats has a first density (.sub.1) between a density of gas (.sub.g) and a density of oil (.sub.o), and a second of the two or more floats has a second density (.sub.2) between the density of oil (.sub.o) and a density of water (.sub.w). The downhole tool, according to this aspect, further includes two or more non-contact proximity sensors configured to sense a radial location of the two or more floats to determine a gas:oil ratio and oil:water ratio.

Provided is a downhole tool and a well system. The downhole tool, in one aspect, includes a tubular providing one or more production fluid flow paths for a production fluid. The downhole tool, according to this aspect, further includes one or more float chambers located within the tubular, and two or more floats located within the one or more float chambers. In one aspect, a first of the two or more floats has a first density (.sub.1) between a density of gas (.sub.g) and a density of oil (.sub.o), and a second of the two or more floats has a second density (.sub.2) between the density of oil (.sub.o) and a density of water (.sub.w). The downhole tool, according to this aspect, further includes two or more non-contact proximity sensors configured to sense a radial location of the two or more floats to determine a gas:oil ratio and oil:water ratio.

A method of measuring liquid level in a tank. An electromechanical liquid level gauge (ESG) is provided including a processor, a displacer suspended on a wire from a grooved drum having a servo motor coupled thereto to rotate the drum for balancing the displacer. A change in liquid level causes a change in a counterforce to move the ESG out of balance. The processor monitors a torque sensor output, and controls movement of the motor using a programmed apparent weight (AW) setpoint to raise or lower the displacer based on an AW derived from the torque. An associated memory stores a density compensated fixed immersion depth level gauging algorithm. The algorithm implements obtaining a density reading for the liquid, continuously corrects an immersion depth of the displacer for changes in density to provide an essentially fixed immersion depth, and calculates the liquid level from the density reading and immersion depth.

Provided is a downhole tool and a well system. The downhole tool, in one aspect, includes a tubular providing one or more production fluid flow paths for a production fluid. The downhole tool, according to this aspect, further includes one or more float chambers located within the tubular, and two or more floats located within the one or more float chambers. In one aspect, a first of the two or more floats has a first density (.sub.1) between a density of gas (.sub.g) and a density of oil (.sub.o), and a second of the two or more floats has a second density (.sub.2) between the density of oil (.sub.o) and a density of water (.sub.w). The downhole tool, according to this aspect, further includes two or more non-contact proximity sensors configured to sense a radial location of the two or more floats to determine a gas:oil ratio and oil:water ratio.

Provided is a downhole tool and a well system. The downhole tool, in one aspect, includes a tubular providing one or more production fluid flow paths for a production fluid. The downhole tool, according to this aspect, further includes one or more float chambers located within the tubular, and two or more floats located within the one or more float chambers. In one aspect, a first of the two or more floats has a first density (.sub.1) between a density of gas (.sub.g) and a density of oil (.sub.o), and a second of the two or more floats has a second density (.sub.2) between the density of oil (.sub.o) and a density of water (.sub.w). The downhole tool, according to this aspect, further includes two or more non-contact proximity sensors configured to sense a radial location of the two or more floats to determine a gas:oil ratio and oil:water ratio.

A concentration measuring apparatus of the present invention includes: an acquiring unit that acquires a height position of a float which floats in a liquid and whose floating height changes in accordance with a concentration of the liquid, the height position being measured using a radio wave; and a measuring unit that measures the concentration of the liquid based on the height position.