Scaling of Hydraulic Fracturing Operations to Lab Experiments
Saied Mighani, Jianhua GongGraduate student, EAPS
Under supervision of Brian Evans
MIT Earth Resources Laboratory2017 Annual Founding Members MeetingJune 1st, 2017
2016 Annual Founding Members Meeting 2
Scaling Hydraulic Fracturing Operations Lab Experiments
Field operation HF
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 3
1400 m3!
Garcia et al., 2013
Governing equations for propagation of a fluid-filled fracture
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 4
𝐾" = 42𝜋
�𝐾 )*
1- Conservation of mass.
2- Elastic deformation 𝐾" =8𝜋
2𝑅
�-
𝑝 𝑟"
𝑅0 − 𝑟"0� 𝑑𝑟"
3
4
3- Fracture criterion
Detournay, 2016
R fracture length𝛔o min. (lith.) prin. stress E’ Plane strain modulus𝑅6 fluid-filled frac. length H sample lengthw frac. width KIC frac. toughnessQo fl. injection rate K’ stress Intensityp fl. net pressure 𝐾"7 Fluid leak-off constant𝛍 fl. viscosity
𝑄4𝑡 = 2𝜋- 𝑤𝑟" 𝑑𝑟"3<
4+ 𝜋-
𝐾"7𝑅60 𝑡"
𝑡 − 𝑡"� 𝑑𝑡" >
4
Dimensionless Time Constants
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 5
𝜓@ =�̅� C𝑞4
C𝐸"@C
𝐻C𝐾"04
@ 0⁄
𝜓0 =𝐾"C
𝜎4 C𝐻C 0⁄ 𝜓I =𝐾"@4𝑞4
@4
𝐾"704𝐻@C𝐸"@4
@ J⁄
Bunger et al., 2005; Detournay, 2016
𝛔o min. (lith.) prin. stress E’ Plane strain modulusqo fl. injection rate K’ modified mode I fracture toughnessH desired fracture length 𝐾"7 Fluid leak-off constant
Symbols, variables, and constants
viscosity Fluid lag Leak-off
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 6
Bunger et al., 2005; Detournay, 2016
𝜓I>>1 𝜓I<<1 (leakoff)𝜓@<<1 𝜓@>>1 𝜓@<<1 𝜓@>>1
𝜓0<<1 Toughness Viscosity Toughness Viscosity
𝜓0>>1 Toughness Viscosity and Fluid lag Toughness Viscosity and Fluid lag
Dimensionless Time Constants
𝜓@ =�̅� C𝑞4
C𝐸"@C
𝐻C𝐾"04
@ 0⁄
𝜓0 =𝐾"C
𝜎4 C𝐻C 0⁄ 𝜓I =𝐾"@4𝑞4
@4
𝐾"704𝐻@C𝐸"@4
@ J⁄
viscosity Fluid lag Leak-off
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 7
𝜓@ = 960 𝜓0 = 6 ×10P@4 𝜓I = 1.7×10J
Bunger et al., 2005; Detournay, 2016
Operations Parameters
𝜓I>>1 𝜓I<<1 (leakoff)𝜓@<<1 𝜓@>>1 𝜓@<<1 𝜓@>>1
𝜓0<<1 Toughness Viscosity Toughness Viscosity
𝜓0>>1 Toughness Viscosity and Fluid lag Toughness Viscosity and Fluid lag
Injection rate Fluid viscosity
Min. in-‐situstress
Tensile strength
Young’s modulus
Fracture toughness
Leakoff constant
10 m3/min 1 cp 40 MPa 15 MPa 40 GPa 1.8 MPa.m0.5 10-‐06 m.s-‐0.5
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 8Experiment Design
Fluid name: Silicone oil A B C DFluid Viscosity (P·s) 0.1 1 5 12.5
Injection rate (m3/sec) 3.6×10-06 4×10-8 7×10-9 3×10-9
Viscosity
Toughness
Fluid lag
No fluid lag
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 9ExperimentsExp. # Specimen 𝝈𝟑, 𝝈𝟏(M
Pa)Fluid Viscosity (cp) Injection rate
(ml/sec)𝝍𝟏 𝝍𝟐 𝝍𝟑
1 Solnhofen limestone
5/10 Argon 0.02 4.9 1 e-‐6 3.5 e4 9 e9
2 Solnhofen limestone
5/10 Silicone Oil
100 3.6 970 3.5 e4 9 e9
3 PMMA 5/10 Silicone Oil
100 3.6 2e-‐4 4 e4 3 e11
𝜓I>>1 𝜓I<<1 (leakoff)𝜓@<<1 𝜓@>>1 𝜓@<<1 𝜓@>>1
𝜓0<<1 Toughness Viscosity Toughness Viscosity
𝜓0>>1 Toughness Viscosity and Fluid lag Toughness Viscosity and Fluid lag
Tough
Vis & lag
Tough
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 10Experiment Configuration
Strain gauge
notch
Pressure transducer
Radial LVDT
Axial LVDT
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 11Experiment Configuration
Radial LVDT Axial LVDT
Pressure transducer
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 12Experiment3- PMMA (Toughness-dominated regime)Fluid: silicone oil 100 cp
Axial LVDT: Compression +Radial LVDT: Compression +
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 13Experiment3- PMMA (Toughness-dominated regime)Fluid: silicone oil 100 cp
1 mv ~ 0.005 m/secSheibani, 2017
AE event for 2 msecs!
5.4 5.5 5.6 5.7 5.8 5.9
x 10-3
10
20
30
40
50
60
70
80
90
100
time, sec
Volta
ge, m
volts
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 14Experiment3- PMMA (Toughness-dominated regime)Fluid: silicone oil 100 cp
Blue early red latePoint size corresponds to event magnitude (first motion)
We were able to locate 32 out of 50 events.
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 15Experiment3- PMMA (Toughness-dominated regime)Fluid: silicone oil 100 cp
Amplitu
de, m
v
Dry borehole Sat. borehole After HF-‐frac open After HF-‐frac closed
Time, µsec
Amplitu
de, m
v
Sensor 11
Vp before HF: 2696 m/secVp after HF: 2287 m/sec (15% decrease = generated pathway for hydrocarbon flow)
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 16Experiment2- Solnhofen limestone (Viscosity-dominated regime)Fluid: silicone oil 100 cp
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 17Experiment2- Solnhofen limestone (Viscosity-dominated regime)Fluid: silicone oil 100 cp
We could not detect any AE’s for experiment 2!
Testing a hypothesis:Is this because the rock specimen can not generate AE events or
the HF in viscosity-regime behaves differently?
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 18Experiment2- Solnhofen limestone (Viscosity-dominated regime)Fluid: silicone oil 100 cp
Fracture propagation velocity: (500-‐200 m/s)Based on experimental parameters: the experiment was in
toughness-‐dominated regime
So, we could register AE events in Solnhofen limestone but in a different regime!
Gu, 2016
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 19Energy budget anlaysis
𝐸7 + ∆𝑊 = 𝐸[\ + 𝐸] + 𝑙 + 𝐸3
Energy budget analysis:
Goodfellow et al. (2015)
Injection system +Δ(Elastic potential)= Griffith release+ crack deformation + Losses+ seismic
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 20Energy budget analysis
0.3 Hz
∆𝑊 = 4.7585𝑒 − 04 J 𝐸3 = 3.3449𝑒 − 05 J
So, 99. 99 % of the input energy turns non-‐seismic!
MIT Earth Resources Laboratory2017 Annual Founding Members Meeting
Slide 21Summary
• Field operations were in the viscosity-‐dominated regime
• We can conduct experiments in different regimes by changing the pumping rate, fluid viscosity and confining stress.
• Toughness-‐dominated regime in PMMA and earlier Solnhofen tests:
AE occurrence over 2 ms interval and 15% reduction in velocity.Very rough estimate indicates 99. 99 % of the input energy is non-‐seismic
• No AE generated in viscosity-‐dominated regime in Solnhofen limestone