Microdeformation: combining direct fracture height measurement with microseismic response Natalia Verkhovtseva, Greg Stanley

Microdeformation: combining direct fracture height measurement with microseismic response Natalia Verkhovtseva, Greg Stanley Principal Geophysicist Pinnacle a Halliburton service

Outline Introduction Microseismic processing background Downhole (Hybrid) Microdeformation Mapping Integrated Diagnostics: FracHeight Tool Real Data Examples Summary and Conclusion 2014 HALLIBURTON. ALL RIGHTS RESERVED. 2

Shallow Microseismicity What is it? Bakken example Dohmen et al. SPE 166274 Side view of zones of microseismicity in two wells in the Bakken Large amount of activity 800 to 1,000 ft above the Bakken 2014 HALLIBURTON. ALL RIGHTS RESERVED. 3

Fracture Height Interpretation How do we interpret the isolated shallow events? Fracturing & fluid movement Hydraulically connected? Stress effects above fracture Shear slippage along interfaces Shear slippage on faults/fractures 2014 HALLIBURTON. ALL RIGHTS RESERVED. 4

What is a Microseismic Event? Microseisms are micro-earthquakes that originate in an envelope surrounding the hydraulic fracture Increase in pore pressure reduces net effective stress causing preexisting flaws to undergo shear slippage Looking down WELLBORE MICROSEISMS INDUCED BY LEAKOFF MICROSEISMS INDUCED BY STRESS CHANGES NEAR TIP ENVELOPE NATURAL FRACTURES 2014 HALLIBURTON. ALL RIGHTS RESERVED. 7

Offset-Well Microseismic Mapping Microseismic Monitoring is Applied Earthquake Seismology Based on principles known for decades Has been used since Mid-1970 s (Hot Dry Rock) Primary difference is the use of a Downhole Array Treatment Well Observation Distance Depends on Seismic Attenuation and Event Magnitudes Typically 20 3C Levels @ 15M Observation Well Recorded Events Perforated Interval 2014 HALLIBURTON. ALL RIGHTS RESERVED. 9

Locating Microseisms P S Side View Distance Depth P-S Separation P Moveout S Moveout Receivers Event Distance Obtained Primarily From P-S Separation Event Depth Obtained Primarily From Moveout Event Direction Obtained From Wave Particle Motion (Vibration) P-Wave: Always Pointed In Direction Of Wave Propagation (Back To Source) S-Wave: Orthogonal To P Wave Monitor Well P-Wave Particle Motion Microseism 2014 HALLIBURTON. ALL RIGHTS RESERVED. 10

Principle of Microdeformation Fracture Mapping Induced volumetric changes will produce a measurable deformation of the earth. For a hydraulic fracture, this deformation field is not isotropic. The gradient of the deformation is easily measured with tiltmeters. On the surface or offset well. 2014 HALLIBURTON. ALL RIGHTS RESERVED. 12

4600 4700 2556(A) Site: downhole Fracture Perforation interval 4800 4900 5000 2510(A) 552(A) 2552 Fracture Top (TVD): 5543 Fracture Bottom (TVD): 5912 Fracture Height (ft): 369 Depth Relative to Injection Well (feet) 5100 5200 5300 5400 5500 5600 25232523(A) 2529(A) 2539(A) 2539 2551(A) 2551 5700 2505 2505(A) 5800 2517(A) 5900 2502(A) 2502 6000 25192519(A) 6100 0 1 2 3 4 5 6 7 8 9 10 11 12 2014 HALLIBURTON. ALL RIGHTS RESERVED. Tilt(uR) 13

Hybrid (Downhole) Offset Well Technology Deformation (in) -0.1 0 0.1 0.2 2800 Tilt (micro-radian) -150-50 50 150 2800 Fracture covering pay zone 2900 2900 Maximum tilt at Fracture top and Bottom 3000 3000 1000 bbl fracture 100 ft tall 0.5 in wide 3100 3100 Cross-section Absolute tilt magnitude (shown in following figures) frac 100 ft observation well 3200 Rock deformation at 100 ft 3200 Tilt at 100 ft Actual tilt magnitude 2014 HALLIBURTON. ALL RIGHTS RESERVED. 15

Changes in Theoretical Tilt Well with DH tilt array 4000 4200 4400 Half-length = 200 ft Half-length = 300 ft Half-length = 400 ft Half-length = 500 ft 4600 4800 600 ft Depth (ft) 5000 Height 5200 5400 Frac well 300 ft 5600 5800 6000 0 2 4 6 8 10 12 14 Tilt magnitude (microradians) 2014 HALLIBURTON. ALL RIGHTS RESERVED. 16

Changes in Theoretical Tilt 4000 Height = 100 ft 4200 Height = 200 ft Height = 300 ft 4400 Height = 400 ft 4600 4800 Well with DH tilt array Depth (ft) 5000 5200 Frac well 5400 5600 300 ft 5800 6000 0 10 20 30 40 50 60 Tilt magnitude (microradians) 2014 HALLIBURTON. ALL RIGHTS RESERVED. 17

Downhole Microdeformation Mapping -400 0 H=200ft H=200ft -600 H=400ft -400 H=400ft -800 Depth (feet) -1000 Distance=200 ft Distance=400 ft Depth (feet) -800-1200 Distance=360ft Distance=480 ft -1200-1400 -1600 X=100 ft X=400 ft -1600-200 -150-100 -50 0 50 100 150 200 Tilt(microradians) -2000-20 -15-10 -5 0 5 10 15 20 Tilt(microradians) Half-Length (L=400 ft) Width (W=0.05 ft) X The distance between two DH tilt peaks is mostly a function of fracture height and the distance between fracture and DH tilt array Well with DH tilt array 2014 HALLIBURTON. ALL RIGHTS RESERVED. 18

Downhole Microdeformation Mapping Well with DH tilt array 8000 8500 HalfLength=1000 HalfLength=1100 HalfLength=1200 9000 1300 ft Depth (ft) 9500 10000 10500 11000 Frac well 300 ft 11500 12000 Dip=90 0 4 8 12 16 Tilt (microradians) 2014 HALLIBURTON. ALL RIGHTS RESERVED. 19

Downhole Tiltmeters: Large Signal Responses X Tilt -106 Movement during breakdown Fracture treatment Y Tilt 178-108 177 176-110 175 microradians -112 Difference in slope Tilt magnitude 174 173 microradians -114 172 171-116 170-118 5/30 9:40 5/30 9:50 5/30 10:00 5/30 10:10 5/30 10:20 5/30 10:30 5/30 10:40 5/30 10:50 5/30 11:00 5/30 11:10 169 5/30 11:20 2014 HALLIBURTON. ALL RIGHTS RESERVED. 22

Integrated Diagnostics: FracHeight Tool (DHT + MSM) microseismic Tiltmeters are deployed in a nearby observation well on single conductor wireline (hybrid fiber) Standard oilfield centralizers or magnetic decentralizers (hybrid decentralizers) Move tiltmeter string to capture multiple stages Data can be acquired in real time to provide results during injection 2014 HALLIBURTON. ALL RIGHTS RESERVED. 28

Fracture Height Versus Downhole Tiltmeter Data 4400 M-Site Comparison of tiltmeter and microseismic data DEPTH (ft) 4500 4600 B SAND 4700-300 -100 100 300 500 ALONG FRACTURE LENGTH (ft) Linear gel minifracs 2 identical injections 400 bbl 22 bpm DEPTH (ft) 4200 4300 4400 4500 FE -- 67 ft 5B data 6B data Inverted tilt fracture height 4200 4300 4400 4500 Microseismic depth histogram 4600 4600 2014 HALLIBURTON. ALL RIGHTS RESERVED. 29 4700-10 -5 0 5 10 TILT (microradians) 4700 0 20 40 60 Frequency

Microdeformation Principle of a Tiltmeter A tiltmeter is like an extremely sensitive carpenter s level When the sensor tilts the resistance between the electrodes changes excitation electrodes gas bubble glass case conductive liquid pick-up electrode It can measure tilt down to approx 1 nanoradian. 1 billionth of a radian or approximately one thousandth of a millimeter per km 2014 HALLIBURTON. ALL RIGHTS RESERVED. 30

Integrating Diagnostics Microseismic Monitoring + Microdefomation Monitoring Plan View Two unique views of the fracturing process Downhole microseismic array Downhole tiltmeter array Observation Well Microseismic & Tilt Value Proposition See where actual deformation is occurring relative to microseismic activity Obtain actual fracture height Sensitive to volume % (i.e. multi-zone fracs) Potential indicator of fracture half-length Observe deformation time history Calibrate fracture and reservoir Model Side View 2014 HALLIBURTON. ALL RIGHTS RESERVED. 32

Downhole Tiltmeter Assessment of Height Growth Hybrid tools with both microseismic and tiltmeter monitoring provide additional information Where actual deformation is occurring Likelihood of hydraulic connectivity Possibility of horizontal shear displacement Hybrid tools Side view Microseisms Tilt Plan view 2014 HALLIBURTON. ALL RIGHTS RESERVED. 33

Real Data Examples: Magnitude Bias 750 from the toolstring 500 from the toolstring Mismatch between MS and Tilt Good correlation between MS and Tilt *Small magnitude events are not detected at 750 from the toolstring: wrong interpretation about fracture height can be made 2014 HALLIBURTON. ALL RIGHTS RESERVED. 37

Microdeformation & Microseismic Microdeformation responds to a fundamentally different mechanical process than does Microseismic. Microseismic Locates and characterizes small shear displacements liberated by a reduction in normal stress or induced by frac related strains. This is often a secondary process often associated with fracture growth. Microdeformation Characterizes the deformation field directly produced by fracture growth. It is relatively unaffected by fluid motion that is not parting rock. It s the differences that can produce a more complete understanding of treatment behavior. 2014 HALLIBURTON. ALL RIGHTS RESERVED. 40

Microdeformation Summary Tilt observes a unique geomechanical response to fracturing See where the fluid is going Powerful independent diagnostic and microseismiccompliment Complex & horizontal fracturing Aseismic fracturing detection Volumetric placement (aerial w/ STM, vertical w/ DHT) See where deformation is occurring relative to microseismicity Indicative of fracture dilation Fracture height determination Higher probability of proppant placement 2014 HALLIBURTON. ALL RIGHTS RESERVED. 41

Microdeformation/MS Conclusion Microdeformation confirms fluid placements within formation Fracture geometries based only on MS data are only valid for the most representative/closer stages Gaps in the MS data can be related to lack of MS events not the lack of fluid 2014 HALLIBURTON. ALL RIGHTS RESERVED. 42