Designing Methodology for Identifying Different Types of Influx Entering in a Well Bore during Drilling and Study of Influx Behavior

Abstract

Drillers frequently encounter kick in drilling operations. Kick refers to the unwanted entry of formation fluid into the well bore. Primary well control and secondary well control are used to control influx entry into a well during drilling operations. Primary well control refers to making the overbalance by the hydrostatic pressure exerted by drilling fluid on the formation pressure. Secondary well control refers to controlling the kick through the use of BOPs. BOPs consist of annular preventers, pipe ram, shear ram and blind ram. Reservoir fluid entering the well bore during drilling or tripping is called influx. Influx encountered in a well bore could be oil, water and gas or their mixture. Behavior of all the influxes is different. For example, if a gas influx is encountered, it percolates upwards in the annulus while if water it there it just mixes with the drilling fluid and causes a reduction in its density. The behavior of gas influx in open well and closed well condition is different and complex. In this paper, the behavior of different types of influxes encountered in a well bore has been thoroughly studied and a methodology for understanding the type of well influx that has entered the well bore has been designed. Keywords: Kick, influx behavior, influx identification, well control