Development of drilling fluid flowmeter for small diameter core drilling

Abstract:

During small-diameter core drilling， monitoring drilling fluid flow is challenging. To enable real-time and accurate monitoring of flow rate， promptly detect abnormal flow changes during drilling， facilitate timely adjustment and handling， ensure drill bit safety， and prevent downhole accidents such as bit burning and pipe sticking， an innovative flowmeter has been designed. Based on the fundamental structure of a float flowmeter and incorporating magnetic induction technology， this flowmeter can accurately measure drilling fluid flow in small-diameter drilling. Both linear and annular scale display schemes were designed for flow indication. Tests were conducted to address magnetic misalignment in the linear scale system， and parameter optimization experiments were carried out on key components such as the float and tapered tube. The results show that when eight magnets are used， no misalignment occurs between the active and passive magnetic assemblies. The flow measurement data exhibit a highly linear trend when using a float diameter of 33.8mm and a tapered tube with end diameters of 52mm and 34mm， making it more suitable for practical applications. Field tests in drilling operations demonstrate that this drilling fluid flowmeter offers high accuracy， sensitivity， adaptability， and reliability. It enables real-time monitoring of downhole drilling fluid flow， thereby helping to reduce the occurrence of downhole accidents.