Liner Drilling Technology as a Mitigation to Wellbore Ballooning - A Successful Case Study in the Gulf of Mexico Shelf
- Steven Michael Rosenberg (Weatherford International) | Deepak M. Manilal Gala (Weatherford International)
- Document ID
- Society of Petroleum Engineers
- SPE/IADC Drilling Conference and Exhibition, 1-3 March, Amsterdam, The Netherlands
- Publication Date
- Document Type
- Conference Paper
- 2011. SPE/IADC Drilling Conference and Exhibition
- 3 Production and Well Operations, 1.5 Drill Bits, 1.10 Drilling Equipment, 2.1.7 Deepwater Completions Design, 1.7.5 Well Control, 1.6.1 Drilling Operation Management, 1.6.6 Directional Drilling, 2 Well Completion, 1.7.6 Wellbore Pressure Management, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 1.14 Casing and Cementing, 1.6.10 Running and Setting Casing, 1.11 Drilling Fluids and Materials, 2.4.3 Sand/Solids Control, 1.11.2 Drilling Fluid Selection and Formulation (Chemistry, Properties), 1.6 Drilling Operations, 1.6.2 Technical Limit Drilling
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Conventional drilling techniques proved problematic when employed in a well in the Gulf of Mexico shelf, causing the well to exhibit severe lost circulation (~25 barrels per hour) and wellbore ballooning in the interval at 10,700 ft MD. After a detailed review of the situation liner drilling technology was identified as the most appropriate technique for reaching the well objective and setting the liner at planned depth without losing hole size because of the following advantages that this technology provides:
• Documented lost circulation problems have been minimized or eliminated through prior use of liner drilling technology, largely attributed to the "smear effect?? phenomenon.
• The liner system selected provided for high torsional capability as well as requiring both a mechanical and pressure event to release the setting tool, minimizing chances for premature release.
• The 7-in liner drilling system can help to minimize or even eliminate non-productive time in case of induced fluid losses while drilling hazards are experienced in the well.
• This technology has a proven track record as an effective solution to lost circulation in the Gulf of Mexico shelf.
Ultimately, the correct application of liner drilling technology on this well allowed the operator to reach the intended drilling depth and completion objective and to set the 7-in liner in place. This despite the fact that a drillable casing bit with displaceable PDC cutting structure, which was used to drill the 8-1/2 in hole section, could not be displaced as planned.
In this paper the authors will review the benefits of liner drilling technology successfully to drill the operator's 7-inch liner in place and describe in detail the equipment selection. They will go on to provide a detailed description of the liner drilling process which resulted in the wells objective being realized despite the fluid loss and wellbore ballooning that was experienced and discuss the reasons for the failure of the PDC displacement sequence.
While drilling an 8-1/2-in. sidetrack hole from 10,357 ft MD to 10, 982 ft MD in a development well located in the central Gulf of Mexico shelf, severe wellbore ballooning was encountered. 9-5/8?? casing had been set at 9,816 ft MD, a whipstock was then set in it with its top at 9,516 ft MD and an 8-1/2-in sidetrack hole drilled to 10,357 ft MD, but the wellbore ballooning phenomenon that was encountered prevented the well from being drilled to its objective of 11,500 ft MD, in much the same way as two previous attempts to drill the problematic shale and sand interval had failed. Wellbore ballooning is usually identified with deepwater drilling operations and can be seen during connections when mud flow back is observed.
When the pumps are switched on, pressure applied to the formation can open fractures, which then take fluid and then shutting the pumps off relieves the down hole pressure, allowing the fractures to close, subsequently displacing the same volume of fluid back into the wellbore. This situation, known as wellbore breathing or ballooning, can often cause serious confusion, resulting in a breathing well being incorrectly diagnosed as a flowing well. In that case a response such as increasing mud weight can serve to worsen the problem leading to lost circulation and, when drilling with oil or synthetic-based drilling fluids, compressibility can lead to further confusion (Weisenger 2000).
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