A new high-precision timely monitoring and metering system for early kick and loss

Abstract

Kick and loss are two complicated incidents that affect the construction safety in oil and gas well drilling. The commonly-used kick/loss monitoring methods are disadvantageous with monitoring lag and low metering precision, which may cause well collapse, pipe sticking and well blowouts due to untimely detection and improper treatment. In this paper, a new type of kick/loss monitoring and metering system was designed based upon a comparative analysis of several kick/loss monitoring methods commonly used on rig sites. This new system has the functions of early monitoring and alarm, kick/loss velocity metering, total loss metering and automatic filling, and its feasibility was verified through laboratory experiments. And the following research results were obtained. First, the monitoring tank of this new system is divided into two chambers, i.e., a main chamber and a secondary chamber. The return of drilling fluid partially flows back to the shale shaker through the main chamber, and the rest overflows into the secondary chamber. Second, the internal cross section area of the secondary chamber is small, which increases the response sensitivity to liquid level change, so kick/loss can be detected in time. Third, the water head of the outlet pipeline of the main chamber remains constant and the outlet flow is stable, so kick/loss velocity and total kick/loss can be calculated quantitatively based on the change of liquid level in the secondary chamber. And the monitoring error of kick/loss velocity is less than 8%. Fourth, in the process of tripping out, the drilling fluid in the monitoring tank flows into the wellbore under the action of self weight to keep the full liquid level of the wellbore all the time. As a result, lagged filling and partial filling are eliminated. In conclusion, this new kick/loss monitoring system is economical and practical, and giving a full play to the advantages of ground survey and alarm timely and accurately.