Evaluation of ultrasonic methods for in-situ real-time characterization of drilling mud

A real time multi-functional ultrasonic sensor system is proposed to provide automated drilling fluid monitoring that can improve the capability and development of slimhole and microhole drilling. This type of reliable, accurate, and affordable drilling fluid monitoring will reduce the overall costs in exploration and production. It will also allow more effective drilling process automation while providing rig personnel a safer and more efficient work environment. Accurate and timely measurements of drilling fluid properties such as flow rate, density, viscosity, and solid loading are key components for characterizing rate of drill penetration, providing early warning of lost circulation, and for use in real-time well control. Continuous drilling fluid monitoring enhances drilling economics by reducing the risk of costly drilling downtime, increasing production performance, and improving well control. Investigations conducted to characterize physical properties of drilling mud indicate that ultrasound can be used to provide real-time, in-situ process monitoring and control. Three types of ultrasonic measurements were evaluated which include analysis of in wall, through wall and direct contact signals. In wall measurements provide acoustic impedance (the slurry density and speed of sound product). Through wall and direct contact measurements provide speed of sound and attenuation. This information is combined to determine physical properties such as slurry density, solids concentration and can be used to detect particle size changes and the presence of low levels of gas. The measurements showed that for the frequency range investigated in-wall measurements were obtained over the slurry density range from 1500 to 2200 kg/m(3) (10 to 17 pounds solids per gallon of drilling fluid). Other measurements were obtained at densities in the 1500 to 1800 kg/m(3) range. These promising measurement results show that ultrasound can be used for real-time in-situ characterization of the drilling process by monitoring drilling mud characteristics.