Evaluation of Alternative Initial Responses to Kicks Taken During Managed-Pressure Drilling

Abstract

Summary An industry-supported research project has completed its evaluation of alternative initial responses to kicks taken during the constant-bottomhole-pressure (CBHP) method of managed-pressure-drilling (MPD) operations. The evaluation is the first phase of a study that is intended to provide a basis for comprehensive, reliable well-control procedures for MPD operations. The evaluation was based primarily on computer simulations of multiple alternative initial responses to several causes and severities of kicks in different well geometries. Three responses were concluded to have general application: increasing casing pressure until flow out equals flow in, shutting the well in, and using an adaptation of an MPD pump-shutdown schedule to detect and shut in low- rate kicks. A simple shut-in was concluded to be the most generally applicable response because it stops formation flow without requiring any special equipment. However, it also causes an increased risk of exceeding the formation fracture pressure for most situations vs. a response that maintains continuous circulation. Increasing casing pressure while maintaining a constant pump rate until flow out equals flow in was concluded to be the most applicable response that avoids the disadvantages of shutting in the well. However, it requires accurate metering of return flow as a basis for determining whether formation flow has stopped. The adaptation of an MPD pump-shutdown schedule can be used to determine whether questionable kick indications are caused by a kick more conclusively than the other responses. It ends with the well being shut in. A fourth response, increasing the pump rate, also has important but very limited application. The selection of which response is the most practical is shown to depend on well conditions and the equipment being used. Potential advantages of and constraints on the use of these responses are also explained.