Evaluation of drilling events in the Haynesville and Bossier Shale, Magnolia, NW Louisiana

Luis G. Montalvo, University of Puerto Rico Department of Geology

Conclusion The distribution of drilling events on the geohazard maps did not appear to be related to the EUR’s of Shell and Encana wells. Circulation losses are prevented once casing for the well is set and the amount of gas shows reported while drilling is not a direct representation of how much gas will be obtained from the subsurface. The larger amount of circulation losses was found on the Upper Bossier and the larger amount of gas shows are found at the Lower Bossier. A change of facies on the Lower Bossier makes it more permeable and thus larger gas shows are encountered in this interval. Few drilling events were found at the Haynesville production target. As new well data is loaded to these maps it will increase their usefulness for further drilling plans. Selected Referencee •  Bomer, P., 2008 A Primer of Oil Well Drilling, Seventh Edition, The University of Texas at Austin •  Horkowitz, K., Yahi, N., Chauvin, P., Ma, L., Eoff, J., Kornakci, A., O’Neil, P., Novosel, I., Manzano Karerah, K., 2009, Magnolia Regional Framework Study – Haynesville/Bossier Shale Gas N. Louisiana and E. Texas, Shell International exploration and production, Shell Global EP Library •  Mudlogs and HSI Reports •  Personal Communications at Shell Exploration and Production Woodcreek Campus, Houston, Texas:

•  David Velez (PG) •  Scott Rivet (Petrophysicist) •  Barret Summers (Petrophysicist) •  Mohammed Asgharzdeh (Geophysicist) •  Alex Summit (Drilling Engineer) •  Shawn Holzhauser (Reservoir Engineer) •  Christopher Klug (Geologist) •  Jolyn Gisclard (Geologist) •  Alan Rolph (Geologist) •  Sada Iyer

Acknowledgements I would like to thank my supervisor David Velez and my mentor Kelly Hutchings for their support, guidance and for the motivation I received to complete this research. Thanks to all the professionals in science and engineering at Shell Exploration and Production for sharing a vast amount of knowledge in oil industry technologies. Special thanks to my fellow interns: Eric Avalos, Najeeb Alharthy and Elaine Wong for sharing ideas and feedback. I also like to thank RESESS and UNAVCO for guiding me throughout my professional development and giving the motivation and help to complete this research. Thanks to the UPR faculty for providing me with all the education requirements and all the knowledge shared during my bachelors degree, without it this research would have never been completed. The RESESS Program is administered by UNAVCO, a NSF funded research consortium. Funding for the RESESS program is provided by the NSF Grant GEO-OEDG # 0914704.

Introduction The Haynesville gas play in NW Louisiana, known as the Magnolia field, has been a potential target for drilling wells by Shell Exploration and Production and Encana since 2007. The upper Jurassic Haynesville/Bossier shales are found at over 10,000 ft on the subsurface. Natural gas is found on a tight unconventional reservoir in which wells are drilled to produce gas obtained from the Haynesville formation. Drilling wells is an expensive task and drilling events such as circulation losses, LOT (failed formation integrity tests) and gas shows can cause equipment damage, wasted drilling time and economic loss. Is important to understand the changes in the subsurface and how this correlates with drilling events to prevent them. Therefore, creating geohazard maps of drilling events will enhance the production of natural gas in the Magnolia field.

Results •  Gas shows are very common on the Lower Bossier •  Circulation losses and LOT are more common on the Upper Bossier •  Drilling events in the Haynesville are rare •  3 zones of high permeability and high occurrence of gas shows where identified in the Lower Bossier:

• Laffite hazard zone • Joseph hazard zone • Minerals hazard zone

•  The larger amounts of gas was found at the Lower Bossier and the Haynesville •  The amount of Silt and Sand decreases southward which is consistent with the depositional history (prodelta) of the Bossier and Haynesville shales Methods

An evaluation for the origin of 140 drilling events was done based on mudlogs and HSI drilling reports data in the Haynesville and Bossier shales. Each event was classified into 3 categories: lithology related, fracture related (Includes faults), unknown (missing information). Geohazard maps were created using Petrel 2009.2 and ArcGIS 9.2 by plotting each event in the Magnolia field to analyze the areal distribution of drilling events. The purpose is to find if there exist any relations between drilling events and lithological or structural changes within the Haynesville and Bossier Shales. Geohazard maps were compared with EUR’s (estimate ultimate recovery) to determine if there exist a relation to drilling events.

High TOC Low Pore

High Pore Low TOC

>Water

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LOUISIANA

TEXAS

MAGNOLIA AMI

HOUSTON