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4100 Level



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EGS Collab Daily Shift Report

Date:  10/31/19

Written by:  Patrick Dobson (pfdobson@lbl.gov; 510-486-5373) 10/31/19

SURF Personnel: George Vandine

Location(s): 4100 Level Battery Alcove



1.     We (Paul Cook, LBNL; Florian Soom, LBNL, Patrick Dobson, LBNL, and George Vandine, SURF) took the 7:00 am cage down to the 4100 Level to continue the Step Rate Injections for Fracture In-situ Properties (SIMFIP) in the TV4100 borehole.

2.     A toolbox talk was initiated and the day’s activities were discussed along with mitigations.

3.     We restarted Test 7 at [12.29 m - 14.7 m, Fig. 1]. We had previously conducted a test where the pressure was increased rapidly until it reached a peak value of 3370 psi with the chamber at elevated pressure for 10 minutes, and then had a planned shut-in overnight. When we arrived in the morning, we noticed that the packers had held, and the chamber pressure was at 2298 psi. We began a slow bleed-off at around 0.2 L/m, and the system pressure bled out within 3 minutes. The compass was still oriented at 129.5 degrees. We then shut in the chamber, and observed that the pressure rebounded back to 2001 psi after 12 minutes. We then did another bleed-off of the chamber.  We then started another leak-off test, starting at 8:03 by raising the pressure quickly, and we observed some fracture opening with a potential shear component. The chamber conditions were 3245 psi and 2.67 L/m flow at 8:04, and at 3286 psi and 2.78 L/m at 8:06 – we then shut in the system at 8:08, followed quickly by a Tom Doe bleed-off. We bled off the system at a rate of around 0.4-0.5 L/m – the system had bled off by 8:21. After the bleed-off was completed, we then started a test at 8:29 where we increased pressure step-wise using the bypass valve – with pressure intervals of 500, 1000, 1500, 2000, 2500, 3000 (where flow increased, and a drop in Z followed by a rise in Z was observed, suggesting possible fracture opening – Fig. 2), 3254 (bypass shut off, with maximum flow of around 2.82 L/m), 3000, 2500, 2000, 1500, 1000, and 500 psi – each step lasted 4 minutes. We then completed the test by bleeding off at 9:21, and declamped, deflated the packers, and prepared to move to zone 8.

4.     We then moved to Test 8 at [7.89 - 10.3m, Fig. 3] (a relatively intact zone with no major fractures). We inflated the packers, deployed the clamps, and noted the compass reading of 150.5 degrees. We then did a low-pressure step rate test (Fig. 4) with ~300 psi pressure steps (bottom section closed) with steps of 450, 600, 900, 1200, 1500, 1100, 900, and 600 psi (the duration of each step was about 1 minute). We then bled off the pressure, and repeated this test two more times. We then did a high-pressure test, raising the pressure and flow rate quickly. Right at the start of the test, we got a response from the SIMFIP that suggested that a hydrofracture was created and opened (Fig. 5). We maintained elevated pressure for 12 minutes, and then proceeded to shut in the system for 24 minutes, and then did a Tom Doe bleed-off with a leak-off rate of ~0.4 L/m. We continued the controlled bleed-off for 15 minutes before bleeding off the system completely. We then decided to repeat this test. Upon starting, we observed a very weird response to elevated pressure – we then bled the system and restarted the high-pressure test, and observed the same signature (Fig. 6). We had two possible explanations for this changed response – one was that the method that we started this second test was slightly different – we began it with the bypass valve, because there was quite a bit of built up pressure in the rock from prior injections; the other idea was that because of all of the prior injections in the borehole, the bottom pressure was elevated, and this might be causing the packers to shift in the borehole. We went ahead with running this test for 6 minutes, then shut it in and did the Tom Doe bleed-off method with a rate of ~0.4 L/m. As the bleed-off proceeded and the chamber pressure dropped, we started noticing strange behavior in the SIMFIP, with cyclic oscillating shifts in all of the fiber signals (Fig. 7). Paul suggested that this might be due to packer slip caused by the elevated bottom pressure in the borehole (~800 psi). We bled off the bottom hole pressure, didn’t see much of an effect, and then checked the compass orientation (149.2 degrees). We bled off the system, bled off the bottom again, repeated the venting, and decided to repeat the previous test to see if what we observed was reproducible.  Upon starting the high-pressure test, we again observed the strange initial fiber response, with a signal that suggested fracture opening that might have y-direction shear. We maintained elevated pressures for 6 minutes, then shut in the chamber and initiated the Tom Doe bleed-off at about 0.4 L/m. After about 15 minutes, the same strange oscillating fiber response seen in the previous test reappeared. We again released the bottom hole pressure, then closed it, and continued the slow bleed-off for 7 more minutes before venting the chamber. We decided to test the hypothesis of packer slip due to elevated bottom hole pressures by venting and reinflating the packers, reclamping, and then running the test again with the bottom hole valve open throughout the test. Upon resetting the packers, the new compass reading was 151.5 degrees. We raised the pressure quickly (using the bypass setup to start the test), and saw more normal fiber responses, with opening and perhaps some shear. We maintained elevated pressure for 5 minutes, then shut in the chamber and initiated the Tom Doe controlled bleed-off at a rate of ~0.4 L/m. During the slow bleed-off, we saw none of the strange oscillating signals in the fiber that were observed in the previous two tests, suggesting that the elevated bottom pressures were responsible for packer slip in the previous tests. We did the controlled bleed-off for 20 minutes, then vented the system.  We decided to run the final pressure step test also with the bottom interval open to avoid the same complications. We did 4 minute steps at 500, 1000, 1500, 2000, 2500, 3000 (shear observed), 3232 (fracture opening observed, with a flow of 2.86 L/m), 3000, 2500, 2000, 1500, 1000, and 500 psi. We then bled off the system, declamped, and depressurized the packers.

5.     We moved the SIMFIP so that it was positioned inside of the cased portion of the well (tape reading of 1.85 m) to do some low-pressure step tests for diagnostics of the SIMFIP tool. We inflated the packers and set the clamps – the compass registered an orientation of 156.5 degrees. We then did short (~1 minute) pressure steps, going from 300, 600, 900, 1200, 1500, 1800, and 2100 psi – at that point, the casing appeared to be leaking, so the system was bled off. We repeated the same test, with the second test ending at 1800 psi due to the casing leak. We then unclamped the SIMFIP, deflated the packers, and manually rotated the SIMFIP tool counterclockwise 180 degrees in the borehole, and then reinflated the packers and clamped the tool. The new compass reading was 326 degrees. We then attempted a similar suite of tests – 1 minute pressure steps starting at 300, 600, and 900 psi, where the casing leak prevented higher pressures. We tested this setup again, going to 300 and then 600 psi – the casing leak ended the test at that point. Paul plans to repeat these diagnostic tests back at the lab using a vertical cased borehole. We then unclamped the tool and deflated the packers. Florian saved and downloaded all of the data onto a memory stick.

6.     We spent our remaining time tidying up the site. We raised the SIMFIP tool so that it was partially out of the borehole, and then spooled up the fiber cable, the pressure gauge cable, the compass cable, and the tape measure. We covered up the wireline winch, and did general housekeeping of the site.

7.     We took the 5:30 cage back to the surface.


Lead Researcher:  Patrick Dobson (pfdobson@lbl.gov; 510-486-5373)


Documents or Procedures:  JHA: EGS-024


Inspections: general site layout and boreholes.


Materials Receiving/Shipping: None



Recommendations:  N/A

Irregularities:  N/A


Acts of Safety Florian Soom used a zip tie to secure metal tubing against the drift rib, removing a potential tripping hazard. We spooled up all of the loose cable prior to leaving the drift (Fig. 8).


Near Misses or Incidents:  N/A


(Name of Science Group) Personnel Hours (Surface and Underground):




Surface Hours

Underground Hours

Time In

Time Out

Time In

Time Out


Paul Cook (LBNL)






Florian Soom (LBNL)






Patrick Dobson (LBNL)






George Vandine (SDSTA)








<img width=485 height=291 id="Picture 2" src="DailyShiftReport-Collab-2019_10_31_4100L.fld/image001.png">

Fig 1: Schematic of Test 7 SIMFIP interval overlaid on televiewer logs.


<img width=478 height=291 id="Picture 3" src="DailyShiftReport-Collab-2019_10_31_4100L.fld/image002.jpg">

Fig 2: Screen shot of ~3000 psi pressure step for Test interval 7.


<img width=454 height=273 id="Picture 1" src="DailyShiftReport-Collab-2019_10_31_4100L.fld/image003.png">

Fig 3: Schematic of Test 8 SIMFIP interval overlaid on televiewer logs.


<img width=349 height=349 id="Picture 10" src="DailyShiftReport-Collab-2019_10_31_4100L.fld/image004.png">

Fig 4: Paul Cook conducting low-P step test for Test 8 zone.

Fig. 5: First high-P stimulation of Test 8 interval.


10 31 6.jpg

Fig. 6: Second high-P stimulation of Test 8 interval.


10 31 7.jpg

Fig. 7: Cyclic oscillations during controlled bleed-off of second high-P stimulation of Test 8 interval.

10 31 8.png

Fig.8: Site following completion of SIMFIP tests.

10 31 9.png