Abstract
In the Midway Sunset Oil Field in Central California, operators inject steam into the shallow diatomite formation to enhance heavy oil recovery through imbibition, wettability alteration, and viscosity reduction, among other mechanisms. The injected steam, however, does not always remain in the reservoir or return through the wells. In two zones in the study area, the steam comes out at the surface, creating sinkholes, seeps, and steam outlets. These phenomena, called “surface expressions,” pose safety and environmental hazards. Even though these surface expressions are a widespread problem in Central California, they are not well documented and understood. Possible causes of the surface expressions include: high injection pressure, structurally controlled flow patterns, leakage of steam through old improperly abandoned wells, high injection volumes, or flow along naturally occurring faults, among other possible factors. This study examines attributes of the zones with surface expressions in order to determine factors that may contribute to their occurrence. Spatial statistical analysis using logistic regression, random forests, and classification trees is used to explore the relationship between the surface expressions and geological and production-related attributes. The results point to a significant spatial correlation between the surface expressions and two predictors: concentration of plugged wells and geologic seal thickness. The results guide follow-up studies to further investigate the role of well abandonment and seal thickness in the occurrence of surface expressions.
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References
Alberta Energy Regulator (2014) Summary of conclusions from the reservoir containment project for steam-assisted gravity drainage schemes in the shallow thermal area. Technical report
Alberta Energy Regulator (2016) Root cause and regulatory response report canadian natural resources ltd. primrose bitumen emulsion releases, 2013. https://www.aer.ca/documents/reports/IR_20160321-CNRL.pdf
Ali SMF (2003) Heavy oil evermore mobile. J Pet Sci Eng 37:5–9
Alvarez J, Han S (2013) Current overview of cyclic steam injection process. J Pet Sci Res 2(3):116–127. https://doi.org/10.1190/1.1444903
Breiman L (2001) Random forests. Mach Learn 45(1):5–32. https://doi.org/10.1023/a:1010933404324
Breiman L, Friedman J, Stone CJ, Olshen RA (1984) Classification and regression trees. Chapman & Hall, Boca Raton
Byington CB (2003) An integrated structural analysis defining structural and geochemical controls of petroleum migration near the 38 and 44 fault systems in the midway-sunset oil field, Kern County, California. Ph.D. thesis
Carlson MR (2015) A review of caprock issues in thermal recovery in Canada. SPE Bergen one day seminar, (April), pp 1–13. https://doi.org/10.2118/173854-ms. URL https://www.onepetro.org/conference-paper/SPE-173854-MS
Denblna E, Boberg T, Rotter M (1991) Evaluation of key reservoir drive mechanisms in the early cycles of steam stimulation at Cold Lake. SPE Reserv Eng 6:207–211
Division of Oil Gas and Geothermal Resources (1998) Surface expressions database. Technical report
Division of Oil Gas and Geothermal Resources (2015) Well history report 02925159. Technical report, California Department of Conservation. URL https://secure.conservation.ca.gov/WellRecord/029/02925159/02925159{_}DATA{_}2015-04-27.pdf
Division of Oil Gas and Geothermal Resources (2018) Well search. URL https://secure.conservation.ca.gov/WellSearch/
Dusseault MB (1998) Casing shear: causes, cases, cures. In: SPE international conference and exhibition
Elias R, Wilson M, Pacific SM, Vassilellis GD, Bust V (2010) Successful thermal recovery of heavy oil from an ultra tight reservoir renews development of the 100-year-old Orcutt oil field. In: SPE annual technical conference and exhibition, pp 1–18
Fong W, Lederhos L, Skow L, Evola G, Choi J (2001) Analysis of a successful cyclic steam process at Cymric field, California. In: SPE international thermal operations and heavy oil symposium. https://doi.org/10.2118/69702-ms. URL http://www.onepetro.org/
Fu P, Settgast RR, Hao Y, Wang W, Ryerson FJ, Nelson D, Toland M, Bartling W (2017) Thermo-hydro-mechanical responses of fractured diatomite formation to steam injection. In: US rock mechanics/geomechanics symposium. URL https://www.onepetro.org/conference-paper/ARMA-2017-1049
Gareth J, Witten D, Hastie T (2017) An introduction to statistical learning with applications in R, 8th edn. New York, ISBN 9780387781884. https://doi.org/10.1016/j.peva.2007.06.006
Green D, Willhite G (1998) Enhanced oil recovery. Society of Petroleum Engineers, Richardson
James G, Witten D, Hastie T, Tibshirani R (2017) An introduction to statistical learning: with applications in R, 8th edn. Springer, New York
Jones J, Cawthon GJ (1990) Sequential steam: an engineered cyclic steaming method. J Pet Technol 42:848–901
Kovscek AR (2012) Emerging challenges and potential futures for thermally enhanced oil recovery. J Pet Sci Eng 98–99:130–143. https://doi.org/10.1016/j.petrol.2012.08.004
Kumar M, Beatty FD (1995) Cyclic steaming in heavy oil diatomite. In: SPE western regional meeting, pp 109–123. https://doi.org/10.2118/29623-ms. URL http://www.scopus.com/inward/record.url?eid=2-s2.0-0029207628{&}partnerID=40{&}md5=177df0cea462d6d39a166b4e82074fdb
Lawson AB (2013) Bayesian disease mapping: hierarchical modeling in spatial epidemiology, 2nd edn. Chapman and Hall, Boca Raton
Lee S, Min K (2001) Statistical analyses of landslide susceptibility at Yongin, Korea. Environ Geol 40(9):1095–1113. https://doi.org/10.1007/s002540100310
LeSage J, Pace RK (2009) Spatial econometrics. Chapman and Hall, New York. https://doi.org/10.1007/978-3-642-40340-8
Li Z, You C, Gonzales M, Wendt AK, Wu F, Brantley SL (2016) Searching for anomalous methane in shallow groundwater near shale gas wells. J Contam Hydrol 195:23–30. https://doi.org/10.1016/j.jconhyd.2016.10.005
Murer A, McClennen K, Ellison T, Larson D, Timmer R, Thomsen M, Wolcott K (2000) Steam injection project in heavy-oil diatomite. SPE Reserv Eval Eng 3(1):25–27. https://doi.org/10.2118/60853-pa
Nelson D, Klins M, Manrique J, Dozier G, Minner W (1996) Optimizing hydraulic fracture design in the diatomite formation, Lost Hills field. In: Proceedings of SPE annual technical conference and exhibition, pp 601–612. ISBN 9781555634230. https://doi.org/10.2118/36474-ms. URL https://www.onepetro.org/conference-paper/SPE-36474-MS
Pedregosa F, Varoquaux G, Gramfort A, Michel V, Thirion B, Grisel O, Blondel M, Prettenhofer P, Weiss R, Dubourg V, Vanderplas J, Passos A, Cournapeau D, Brucher M, Perrot M, Duchesnay E (2011) Scikit-learn: machine learning in python. J Mach Learn Res 12:2825–2830
Peng J, Kovscek AR (2011) Temperature-induced fracture reconsolidation of diatomaceous rock during forced water imbibition. SPE Reserv Eval Eng 14(01):45–59. https://doi.org/10.2118/132411-pa
Pollack A (2017) Statistical investigation of surface expressions in the midway sunset oil field. Stanford University, Stanford
Pollack A (2018) Spatial statistical investigation of surface expressions in the midway sunset oil field. In: SPE annual technical conference and exhibition. Society of Petroleum Engineers
Pollack A (2019) Data repository: investigation of surface expressions in the midway sunset oil field.. http://dx.doi.org/10.17632/gfdbj6s23r.1
Pradhan B, Lee S (2010) Landslide susceptibility assessment and factor effect analysis: backpropagation artificial neural networks and their comparison with frequency ratio and bivariate logistic regression modelling. Environ Model Softw 25(6):747–759. https://doi.org/10.1016/j.envsoft.2009.10.016
Schembre JM, Tang GQ, Kovscek AR (2006) Wettability alteration and oil recovery by water imbibition at elevated temperatures. J Pet Sci Eng 52(1–4):131–148. https://doi.org/10.1016/j.petrol.2006.03.017
Schultz RA (2017) Causes and mitigation strategies of surface hydrocarbon leaks at heavy-oil fields: examples from Alberta and California. Pet Geosci 23:231–237
Therneau T, Atkinson B, Ripley B (2015) rpart: Recursive Partitioning and Regression Trees
Toland M (2012) Report of occurrences: the Chevron fatality accident June 21, 2011 and area surface expression activity pre and post accident. technical report May, Division of Oil, Gas and Geothermal Resources. URL http://psbweb.co.kern.ca.us/UtilityPages/Planning/EIRS/mckittrick{_}landfill/Vol5/CADOCDOGGRWell20–ReportreChevronFatality6-21-11(5-4-2012).pdf
Acknowledgements
We gratefully appreciate financial support from the California Department of Conservation, Geologic Energy Management Division (formely known as the Division of Oil, Gas, and Geothermal Resources) as well as amazing help from the wonderful employees of DOGGR’s Inland District, including Cameron Campbell, Matt Van Grinsven, Rohit Sharma, Max Solanki, Glenn Muggelberg, and many others. We would like to thank Prof. Bob Lindblom for his help in creating the geological model. This work was partly performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 with Lawrence Livermore National Security, LLC. This document is Lawrence Livermore National Lab report LLNL-JRNL-759295. Earth models built for this study and related data are available at https://data.mendeley.com/datasets/gfdbj6s23r/1.
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Appendix 1: Sensitivity analysis on the grid size and search radius
Appendix 1: Sensitivity analysis on the grid size and search radius
A sensitivity analysis was performed to test the influence of the search radius on the predictive power of the different attributes. The predictive power was measured by the F1 score of a logistic regression model trained on one parameter at a time to predict surface expressions. The search radius of 61 m (200 ft) used in the paper is based upon a field observation indicating that injected steam can travel a distance of 61 m. The results in Fig. 14a show that the predictive power of the “plugged well density” attribute plateaus at a search radius of slightly more than 61 m (200 ft) and the predictive power of the “maximum normalized injection bottom hole pressure” reaches a maximum F1 score at a search radius that is slightly lower than 61 m. A sensitivity analysis on the influence of the grid size in Fig. 14b shows that the grid size has little influence on the predictive power. A middle value of 75 ft (23 m) was chosen for the grid size.
The mean influence of a the search radius size and b grid size on the predictive power of the different attributes. The predictive power was measured by the F1 score of a logistic regression model trained on one parameter at a time to predict surface expressions. The faded colors surrounding the lines indicate the standard deviation of the F1 score at different search radii and grid sizes. For a given constant radius, there are different F1 scores due to varying grid size and vice versa
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Pollack, A., Mukerji, T., Fu, P. et al. A spatial-statistical investigation of surface expressions associated with cyclic steaming in the Midway-Sunset Oil Field, California. Geomech. Geophys. Geo-energ. Geo-resour. 6, 20 (2020). https://doi.org/10.1007/s40948-020-00142-4
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DOI: https://doi.org/10.1007/s40948-020-00142-4