Managed 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.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-11132009-105045 |
| Date | 13 November 2009 |
| Creators | Davoudi, Majid |
| Contributors | Langlinais, Julius, Bourgoyne, Adam T., Smith, John Rogers |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-11132009-105045/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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