DATA MINING THE KNOWN UNKNOWNS OF OKLAHOMA S CLASS II UIC DATA TO IMPROVE INJECTION INDUCED SEISMICITY STUDIES

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1 Groundwater Protection Council (GWPC) Underground Injection Control Conference Tulsa, OK Feb 13, 2018 DATA MINING THE KNOWN UNKNOWNS OF OKLAHOMA S CLASS II UIC DATA TO IMPROVE INJECTION INDUCED SEISMICITY STUDIES Kyle E. Murray, Kyle.Murray@ou.edu Iason Grigoratos, igrigoratos@utexas.edu Univ School of Advanced Studies IUSS, Pavia, Italy

2 It is Like a Riddle What is the message there? The message is: That there are known knowns. There are things we know that we know. There are known unknowns, that is to say that there are things that we now know we don t know. But there are also unknown unknowns. There are things we do not know, we don t know. So, when we do the best we can and pull all of this information together and we then say well that s basically what we see as the situation. That is really only the known knowns and the known unknowns and each year we discover a few more of those unknown unknowns. It sounds like a riddle. 2

3 Studies of Seismicity versus Fluid Injection

4 Problem: INCREASE Seismicity (# M3.0+) history: 2/yr, 2015: 907/yr M5.7 Prague M5.1 Fairview M5.8 Pawnee M5.0 Cushing

5 Granite Wash Zones for Production, Injection, & Disposal Producing Zones Wells that Started Producing from Predominant Disposal Zone, avg of 2 km depth Earthquakes Down Here, avg of 5.5 km depth

6 What is Known? and What is Unknown? Known knowns Number of M3.0+ earthquakes occurring in Oklahoma Locations of permitted Class II SWD wells (2D) Known unknowns Accuracy of reported SWD rates vs. actual SWD rates Accuracy of injection depths relative to basement Discrepancy between sources of data (e.g., OCC Data Files vs. Imaging) Effect of volume reductions vs. market conditions Effect of SWD vs. HF vs. Hydrologic Cycle vs. Natural Seismicity, etc. Unknown unknowns Remember that these are things we do not know, we don t know 6

7 OCC Data Files versus OCC Imaging of 1012A, 1002A, etc. Forms Known Unkowns Known Knowns

8 Data Quality & Limitations, OCC Data Files vs. OCC Imaging OCC Data Files OCC Imaging monthly data only available from 2011 to 2016 monthly data available from 2009 to 2016 annual data 2006 to 2010 monthly data inconsistently available back to about 1998 many duplicate records from 2011 to 2016 many missing 1012As from 2009 to 2011 may include CO2 injection volumes (MCF) fluid type is differentiated presumably some BPD instead of BPM some BPD instead of BPM documented typographical errors cannot be resolved typographical errors may be documented

9 SWD in Oklahoma, OCC Data Files vs. OCC Imaging

10 Known Unknowns & Unknown Unkowns Cherokee Data Bust corrected by OCC in 2017 (Murray, 2018 in preparation) max about 40 MMBPM (Walsh and Zoback, 2015) max about 20 MMBPM 2015

11 Statistics of SWD Well Variables vs. Seismicity (M3.0+ w/in 15km ) Over 600 wells completed in basement? (Scanlon, Weingarten, Murray, et al., 2018 in review)

12 Plug-back Program, ~250 SWD wells

13 Closing Remarks All Models are Wrong, Some are Useful George Box Conceptual models must change w/ new info Iterative process 1. Rectify Data Quality Issues 2. Define Uncertainties and Limitations 3. Analyze & Make Decisions 4. Repeat 1 3 Kyle.Murray@ou.edu

14 Background seismicity in Oklahoma, for 2008 and the prior historical record, equates to about two M3.0+ earthquakes per annum statewide. From 2009 through 2017, the Oklahoma Geological Survey seismic network recorded between 20 (2009) and 903 (2015) M3.0+ earthquakes per annum. The number of M3.0+ earthquakes occurring in Oklahoma represents a known known. Numerous scientific studies have correlated saltwater disposal (SWD) rates and seismicity in Oklahoma because SWD rates increased from about 2.24 million barrels per day (MMBPD) in Oct 2009 to more than 4.54 MMBPD in Oct However, investigations that rely on SWD data have numerous fundamental flaws, Rumsfeldian known unknowns and unknown unknowns. These include the accuracy of the SWD volumes and the completeness of the SWD volume data. Our study attempts to define the known unknowns for SWD volumes from 2009 to 2016 period by cross-validating Oklahoma Corporation Commission (OCC) compiled records with individual electronic Annual Fluid Injection Reports (1012A Forms). We also use database methods to detect outliers and optical character recognition (OCR) to identify typographical or human errors on 1012A Forms, specifically targeting incorrect reports of barrels per day (BPD) rather than the 1012A required barrel per month (BPM). For some SWD wells, rates compiled by OCC are about one-thirtieth of the actual rate because of this common error. However, the unknown unknown is how much do the reported rates vary from actual SWD rates each year? Preliminary results indicate that records for recent years (2015 and 2016) are very accurate (<5% underestimated rates), but rates for former years (2009 to 2012) could be underestimated by as much as 20%. Our project goal is to 14 produce a complete and accurate SWD database for 2009 to 2016, but also to fill in the unknown unknowns for years prior to Abstract