Transport and Fate of Natural Gas and Brine Escaping from a Hydrocarbon Reservoir Through a Failed Deepwater Well in the Oceanic Subsurface of the Gulf of Mexico
- 61 Downloads
The possibility of broaching, or the release of fluids at the seafloor due to a damaged or faulty well, is a hazard that must be assessed in the well permitting process. This paper describes a numerical simulation study of a real-life scenario where a complex, permeable sandy formation, connected to the seafloor via known chimneys/seeps, is intersected by a damaged production well that drains another deeper, gas-bearing formation. The objective of the study is to determine the transport and fate of hydrocarbon reservoir fluids (gas and brines) escaping into the sandy formation through the casing shoe of the failed well, and to determine the time it takes for these contaminants to reach the ocean floor. We conducted a detailed simulation study to represent the conditions, properties, and behavior of the system under such failure conditions, and we investigated the migration of gas and brine for a range of reservoir and chimney properties. A key conclusion is that, for such complex systems, modeling the three-dimensional geometry of the system in detail is the key to describing transport and assessing the time and magnitude of potential releases. For the system studied here, transport times range from under 2 years (highest permeabilities) to many decades, ensuring significant time to respond to potential broaching hazards. Under the conditions investigated in this study, we also determine that gas-dominated releases associated with low rates of water flow into the sandy formation are likely to cause hydrate formation that can reduce permeabilities in the colder, upper regions of the chimneys and possibly mitigate releases.
KeywordsBroaching Hydrate formation Well failure Hazard assessment Reservoir simulation
This work was carried out under Interagency Agreement M14PG00044 between the Bureau of Ocean Energy Management and Lawrence Berkeley National Laboratory. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
- Forrest, J., Marcucci, E., Scott, P.: Geothermal Gradients and Subsurface Temperatures in the Northern Gulf of Mexico, Search and Discovery Article #30048, 2007, adapted from paper published in GCAGS Transactions, 55, 233–248 (2005)Google Scholar
- Gallaway, B.J., Cole, J.G., Martin, L.R.: The Deep Sea Gulf of Mexico: An Overview and Guide, OCS Study MMS 2001-065. U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region (2001)Google Scholar
- Moridis, G.J.: User’s Manual for the HYDRATE V1.5 Option of TOUGH + V1.5: A Code for the Simulation of System Behavior in Hydrate-Bearing Geologic Media, Report LBNL-6869E, Lawrence Berkeley National Laboratory, Berkeley, CA. https://pubarchive.lbl.gov/islandora/object/ir%3A1005569 (2014)
- Moridis, G.J.: User’s Manual of the MeshMaker V1.5 Code: A Mesh Generator for Domain Discretization in Simulations of the TOUGH + and TOUGH2 Families of Codes, Report LBNL-1005134, Lawrence Berkeley National Laboratory, Berkeley, CA (2016)Google Scholar
- Moridis, G.J., Keen, N.: MeshMaker V2.0S And V2.0P: New Grid Generators For Complex Heterogeneous Domains in TOUGH2/TOUGH + Simulations, Proceedings, TOUGH Symposium 2015, Lawrence Berkeley National Laboratory, Berkeley, California, Sept 28–30 (2015)Google Scholar
- Moridis, G.J., Pruess, K.: User’s Manual of the TOUGH + v1.5 Core Code: A General Purpose Simulator of Non-Isothermal Flow and Transport Through Porous and Fractured Media, Lawrence Berkeley National Laboratory Report LBNL-6869E. https://pubarchive.lbl.gov/islandora/object/ir%3A1005566 (2014)
- Moridis, G.J., Reagan, M.T.: Gas Production From Oceanic Class 2 Hydrate Accumulations, OTC 18866, 2007 Offshore Technology Conference, Houston, Texas, USA, 30 April–3 May 2007Google Scholar
- Moridis, G.J., Kowalsky, M.B., Pruess, K.: TOUGH + HYDRATE v1.0 User’s Manual: A Code for the Simulation of System Behavior in Hydrate-Bearing Geologic Media, Report LBNL-0149E, Lawrence Berkeley National Laboratory, Berkeley, CA (2008)Google Scholar
- Pruess, K.: The TOUGH Codes—A Family of Simulation Tools for Multiphase Flow and Transport Processes in Permeable Media, LBNL Report 53630. https://pubarchive.lbl.gov/islandora/object/ir%3A121930 (2003)
- Queiruga, A.F., Reagan, M.T.: tough_convert: Version 1.0. Zenodo. https://doi.org/10.5281/zenodo.1164418 (2018)
- Zhang, K., Moridis, G.J., Wu, Y.S., Pruess, K.: A domain decomposition approach for large-scale simulations of flow processes in hydrate-bearing geologic media. In: Proceedings of the 6th International Conference on Gas Hydrates (ICGH 2008), Vancouver, British Columbia, Canada, July 6–10 (2008)Google Scholar