A Simulation Study of Factors that Affect Pressure Control During Kick Circulation in Managed Pressure Drilling Operations

Abstract

An university-industry consortium has been studying alternative well control procedures to be used for kicks taken during managed pressure drilling (MPD) operations using the constant bottom hole pressure (CBHP) method. The CBHP method of MPD allows more precise control of wellbore pressure than conventional drilling. MPD surface equipment allows more alternatives for controlling a kick and may support faster detection of kicks and losses which can reduce the severity of a well control event. Nevertheless, the elimination of well control incidents cannot be guaranteed, and the uncertainty in downhole drilling margins are not reduced by adopting MPD methods. The primary objective of this research was to evaluate pressure variation and maximum pressure during kick circulation to properly design and conduct a MPD operation. Three specific objectives were addressed in this project. First, a pump start up method to keep bottomhole pressure approximately constant when beginning kick circulation after shut in is presented. Second, since formation pressure cannot be calculated by using shut in drillpipe pressure during typical MPD operations, a procedure to estimate kick zone formation pressure based on circulating pressure was documented. And third, a simple and practical method to estimate maximum expected casing pressure during well control operations was developed. This method was also used as part of a method for selecting kick circulating rate. Methods for making calculations to achieve each of these objectives were developed. Computer simulations were used for comparison to a range of realistic well conditions. Full-scale gas kicks experiments were done to confirm applicability to a limited range of real situations. The applicability and accuracy of the method developed in this research were tested based on actual drilling practices reproduced in computer simulations and LSU well facility experiments.