[CCoE Notice] Thesis Defense: Technical Evaluation of Managed Pressure Drilling Methods For Deepwater Drilling Application

[Grayson, Audrey A]

Technical Evaluation of Managed Pressure Drilling Methods

For Deepwater Drilling Application

Joseph W. Lollini Dissertation



Defense Date: Wednesday, April 13th 2016 Time: 10:30 am Location Room: UH-ERP Building 9, 104

Committee Members: Dr. Christine Ehlig-Economides, Dr. Thomas Holley, Dr. JJ Azar,

 and Mr. Hal Edwards



                       The upstream industry has been venturing into fields and horizons that are increasingly difficult to successfully drill, complete, and produce. Managed pressure drilling (MPD) is one of the technologies that have been called upon to assist with the well construction process in scenarios such as narrow or tight margin drilling environments. MPD was first utilized in land based applications that typically involved a rotating control device that was used to hold backpressure during various well operations (Rehm, 2008). This type of MPD can assist by safely drilling with losses in the case of pressurized mud cap drilling or drilling with a fluid that is of low enough density to prevent fracturing the formation while holding backpressure as necessary to maintain a bottom hole pressure greater than that of pore pressure. During the past several decades the industry has seen possible value of utilizing managed pressure drilling in the offshore environment.

                       The presence of a riser in the circulating system of a floating drilling vessel provides the opportunity to vary the bottom hole pressure by other means. Primarily this type of pressure management involves utilizing a different gradient in the riser than what you are drilling with or lowering the level in the riser to offset the equivalent circulating density. This dual gradient type of MPD is accomplished by additional subsea hardware that, at a minimum, includes an additional pumping system which can require a substantial investment to develop and bring into operation. These types of systems also require new equipment design and trial, new procedures, and new training and competency issues to be addressed in a high stakes offshore environment. In addition to these systems the more traditional MPD systems that are utilized on land and platforms can be utilized from a floating vessel. However, there are new challenges with incorporating a rotating control device (RCD) into the riser. These can include pressure fluctuations while off bottom making a connection in an enclosed environment and dealing with the length of riser between the MPD equipment and drilling units traditional well control equipment. The separation of the blowout preventer (BOP) stack and MPD equipment requires clear specification of the low pressure drilling riser (not specified as part of the well control system for traditional operations) and fully understanding how different scenarios will be handled with this added complexity. These new system challenges have slowed the progression of MPD applications into deep water drilling.

                       The primary intent of this dissertation is centered around providing a framework for selecting and justifying an MPD application that could be incorporated on a floating vessel for two different deep water well types. This will include performing hydraulic analysis utilizing Schlumberger SPT Drillbench software to determine the applicability and associated risks of MPD using Applied Back Pressure, Controlled Mud Level, and Sea Floor Dual Gradient MPD. The analysis will include aspects of well design optimization, well control or process safety considerations, and operational efficiencies. Integration of any of the MPD systems onto a floating vessel and the associated day rate of the service make the incorporation of the MPD into a business plan a very large investment decision. The study has the intent to understand the value proposition of the three MPD types with respect to enabling narrow margin wells, design gains, operational efficiency, and ease of integrating each technology on a rig.
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