Application of mass balance of kick fluid in well control

Abstract

A material balance equation of kick fluid in the annulus is derived. This equation can be used to determine the pressure head of the kick, whether or not the kick is intermittent or a continuous slug, the volume (or length) of the kick, the rate of rise of the kick fluid, the maximum casing pressure that will be encountered during the well control operation and the annular pressure as the kick reaches critical points of interest such as the casing seat. When integrated with transient surface shut-in drill stem test analysis techniques, pertinent formation characteristics can be evaluated. These can be useful for optimizing the planning, design and drilling of subsequent wells within the particular field. The model requires a minimum of assumptions and it is dynamic as it is based on the well control process. With speedy and accurate acquisition of the kick data, well control can become more efficient. The major limitations of the model include possible leakages in the flow system and high gas solubility in the drilling fluid. The procedure for the application is discussed and examples of a gas kick and a saltwater kick illustrate the applicability of the model. © 1991.