A new automated method of detecting an influx or losses using standpipe pressure (SPP) and annular discharge pressure (ADP) has been tested while drilling a tight gas well in Canada with approximately 200 hours of operational time being logged. While tight gas reservoirs may seemingly pose a low well control risk, they are typically drilled underbalanced to increase the rate of penetration and to eliminate a casing string which is required when using a higher mud density in order to protect upper formations due to low kick margin tolerance. The operator’s experience was that previous kicks went undetected until a significant volume had been produced due to the closed loop system having fluid retention without accurate flow measurement, resulting in slower pit volume measurement, extended well control time and requiring the casing to be set deep enough to protect the weaker formations from high shut-in pressures. Delta flow using flow meters has been in use for over 15 years for early kick detection (Haeusler et al 1995), however for tight gas drilling this method has not proven suitable due to cost, complexity and measurement disruption due to high gas fractions in the drilling fluid. A comparison of using a high resolution flow meter and pressure sensors prior to the field test will be discussed in addition to the field trial results. Benefits of using this new system, what was learned during the trial and improvements to the system will also be discussed along with how the system can be applied to Managed Pressure Drilling applications where the system is augmented using choke position and with conventional drilling applications.

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