Abstract: A drilling fluid analyzing apparatus has at least two sensors is used to analyze drilling fluid that contains cuttings. The sensors are mounted vertically spaced in a well riser and in communication with well return fluid. The sensors convert the pressure exerted by the return fluid to signals that are then conveyed to a processor. The processor determines the density of the return fluid, and the fluid density is indicative of borehole cleaning efficiency. Two additional sensors may be added to the drilling fluid input mud pipe to sense the pressure exerted by the drilling mud before it is contaminated with cuttings.

Abstract: The present invention provides a fluid flow measurement system for an oil well drilling system that includes a supply of drilling fluid to a wellbore under pressure and a return line carrying fluid leaving the wellbore during drilling of the wellbore. The system includes at least one floating sensor in the return line that provides a measure of the velocity of the fluid in the return line. The sensor may be a thermal sensor, an electromagnetic sensor or an ultrasonic sensor. A height sensor provides the fluid level in the return line and a density sensor provides the density of the returning fluid. A controller determines the inflow rate and out flow rate of the drilling fluid and further determines the presence of a kick and wash out from the flow rates. The system also determines the operating condition of the pumps supplying fluid to the wellbore.