Type of Document Master's Thesis Author Davoudi, Majid Author's Email Address firstname.lastname@example.org URN etd-11132009-105045 Title A Simulation-Based Evaluation of Alternative Initial Responses to Gas Kicks During Managed Pressure Drilling OPERATIONS Degree Master of Science in Petroleum Engineering (M.S.P.E.) Department Petroleum Engineering Advisory Committee
Advisor Name Title Smith, John Rogers Committee Chair Bourgoyne, Adam T. Committee Member Langlinais, Julius Committee Member Keywords
- Well control
Date of Defense 2009-11-09 Availability unrestricted AbstractManaged pressure drilling (MPD) is an adaptation of conventional drilling that has been developed to manage and control subsurface pressures in the well in order to minimize specific drilling problems. The constant bottom hole pressure approach (CBHP) is a versatile method of MPD, where a closed annulus allows initial responses to kicks other than simply shutting in the well. The objective of this research was to identify and evaluate the best initial response to gas kicks taken during drilling as a basis for developing reliable well control procedures for CBHP operations.
Nine non-circulating and circulating responses (NCRs and CRs) were defined, and their application to kicks in two different wellbore geometries was studied through the use of computer simulations. Two different kick sizes, two different formation permeabilities, and three different kick intensities were considered. NCRs included a rapid shut in (SI) and four different MPD pump shut down schedules ending in SI. CRs included stepwise and rapidly increasing the casing pressure until the mud flow out equaled mud flow in, increasing casing pressure to a pre-defined limit and increasing the ECD by increasing mud pump rates. The initial responses were compared, based on the ability to stop an influx, determine whether the influx was stopped assuming intact wellbore, minimize risk of lost returns, minimize additional kick influx, and minimize excessive pressure at the surface and casing shoe.
The results of over 150 simulations revealed that no single best initial response to all kicks could be identified. Three initial responses showing broad applicability include a rapid increase of casing pressure until flow rates are equal, shutting the well in and an adaptation of the MPD pump shut down schedule that allowed confirmation of a low rate kick. Increasing mud pump rate also showed advantages, but has limited application. Potential advantages and limitations of each were also explained. A method to confirm that the influx stopped during the application of CRs was also proposed. The best initial response was dependent on well conditions and the equipment used. Therefore, a simple decision tree was developed to plan an appropriate response.
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