**4. Developments in early kick detection for conventional drilling**

The following criteria have been set for assessing the success of a kick detection system—how early kicks are detected, how the system is able to eliminate or minimize the number of false alarms, the sensitivity and accuracy of the sensor(s), and its ease of installation [19]. An early kick detection (EKD) system has been described as a system of hardware, Intelligent Control Unit (ICU) and control software with the capability to detect an influx of formation fluids into the borehole during well operations. An advanced EKD system utilizes high precision equipment with ICU/software providing advanced models and algorithms for greater automation and comparison to controlled well conditions. As with simple EKD systems, audio and visual alarms are an integral part of any EKD system to provide real-time assessment [20]. Advances in EKD systems will be considered in terms of sensor function and sensitivity, sensor location (surface versus downhole measurement), and algorithms for efficient kick detection. Each of the previously mentioned primary kick indicators (increase in flow rate while pumping at a constant rate, pit gain and flow from the well when the pumps are off) are measured with different sensors with differing physical principles.
