Design and Dynamic Characterization of an Orientation Insensitive Microwave Water-Cut Sensor

Modern reservoir management in oil and gas industry relies on accurate water fraction measurement which is produced as a by-product with oil. This paper presents a novel and contactless water fraction (also known as water-cut) measurement technique which is independent of geometric distribution of oil and water inside the pipe. The sensor is based on a modified T-resonator implemented directly on the pipe's outer surface and whose resonance frequency decreases by increasing the water content in oil. The E-fields have been made to rotate and distribute well inside the pipe, despite having narrow and curved ground plane. It makes the sensor's reading dependent only on the water fraction and not on the mixture distribution inside the pipe. That is why, the presented design does not require any flow conditioner to homogenize the oil/water mixture unlike many commercial water-cut (WC) sensors. The presented sensor has been realized by using extremely low-cost methods of screen printing and reusable 3-D printed mask. Complete characterization of the proposed WC sensor, both in horizontal and vertical orientations, has been carried out in an industrial flow loop. Excellent repeatability of the sensor's response has been observed in 'dispersed bubble' as well as in 'stratified wavy' flow regimes. The performance test of the sensor confirms that the water fraction measurement is independent of the flow pattern, flow rate or orientation. The measured performance results of the sensor show full range accuracy of $ ± $2%-3% while tested under random orientations and wide range of flow rates.