Hydrocarbon influxes into the wellbore while drilling are typically caused by over-pressured formations, where mud weight is insufficient to control the pore pressure of the formation drilled. Formation permeability and over-pressure determine the intensity of the kick. Well kill procedures in such situations are standard industry wide. Shut in drillpipe pressure is used to determine the pore pressure of the formation, and the driller's or weight and wait method is used to remove the hydrocarbon influx from the well. Hydrocarbon influxes associated with fracture breathing are much less common, and methods to deal with such influxes are not taught within the drilling industry. This paper describes two case studies: the first, Bard–1, an exploration well in the Timor Sea, offshore Australia, describes a well control situation that was initially interpreted as over-pressure. The well could only be killed by pumping cement. Investigation showed that the influx mechanism was a fracture breathing and hydrocarbon swap out mechanism. The high mud weights used in the attempt to kill the well actually exacerbated the situation. The second case study, Jura-1 which was located nearby Bard-1, describes design and procedures used to manage a similar influx mechanism. These were implemented successfully enabling the well to achieve its objectives.

You can access this article if you purchase or spend a download.