GOHFER Variable Sensitivity
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Transcript of GOHFER Variable Sensitivity
8/10/2019 GOHFER Variable Sensitivity
http://slidepdf.com/reader/full/gohfer-variable-sensitivity 1/27
8/10/2019 GOHFER Variable Sensitivity
http://slidepdf.com/reader/full/gohfer-variable-sensitivity 2/27
BASE MATCH OF SIMULATED DATA
Actual Data – Dashed Lines
Simulated Data – Solid Lines
35# HPG w/ 20/40 Badger Sand
8/10/2019 GOHFER Variable Sensitivity
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8/10/2019 GOHFER Variable Sensitivity
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PRESSURE COMPARISON - WIDTH EXPONENT = 2.8
Less pressure gain because of higher flow capacity in fracture.
Lower pressure drop down the fracture makes the final ISIP lower
than the base case. (appropriate for gelled treatments)
Actual Data – Dashed Lines
Simulated Data – Solid Lines
8/10/2019 GOHFER Variable Sensitivity
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FRACTURE GEOMETRY COMPARISON – DECREASE IN WIDTH EXPONENT
Base Fracture Geometry
The created fracture geometry has less width because of the lower net pressure, and
generates longer length as the fluid can move more easily.
8/10/2019 GOHFER Variable Sensitivity
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PRESSURE COMPARISON - WIDTH EXPONENT = 3.2
Increased pressure drop down the fracture makes the
pressure trend upward through the job and results in a
higher ISIP. (appropriate for slickwater treatments)
Actual Data – Dashed Lines
Simulated Data – Solid Lines
8/10/2019 GOHFER Variable Sensitivity
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FRACTURE GEOMETRY COMPARISON – INCREASE IN WIDTH EXPONENT
Base Fracture Geometry
The higher net pressure increases the fracture width and reduces length.
8/10/2019 GOHFER Variable Sensitivity
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PRESSURE COMPARISON – TORTUOSITY = 100
Increase in observed treating pressure due to high near wellbore
pressure loss. Tortuosity erodes linearly with the mass of proppant
pumped. Early time treating pressure is more affected. ISIP has nochange as the tortuosity pressure drop disappears on shut-in.
Actual Data – Dashed Lines
Simulated Data – Solid Lines
8/10/2019 GOHFER Variable Sensitivity
http://slidepdf.com/reader/full/gohfer-variable-sensitivity 9/27
FRACTURE GEOMETRY COMPARISON – INCREASE IN TORTUOSITY
Base Fracture Geometry
No impact on fracture geometry
8/10/2019 GOHFER Variable Sensitivity
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PRESSURE COMPARISON – CD = 0.5
Lower perforation entry coefficients (less efficient perforations)
leads to early increase in observed treating pressure. Addition of
proppant through perfs will increase coefficient. No change in ISIP.A much lower CD will generate a more rapid and almost exponential
decrease in treating pressure.
Actual Data – Dashed Lines
Simulated Data – Solid Lines
8/10/2019 GOHFER Variable Sensitivity
http://slidepdf.com/reader/full/gohfer-variable-sensitivity 11/27
FRACTURE GEOMETRY COMPARISON – DECREASE IN COEFFICIENT OF
DISCHARGE
Base Fracture Geometry
No impact on fracture geometry
8/10/2019 GOHFER Variable Sensitivity
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PRESSURE COMPARISON – CD = 0.9
Higher perforation entry coefficients (more efficient perforations)
leads to early decrease in observed treating pressure. Addition of
proppant through perfs will increase coefficient. No change in ISIP.
Actual Data – Dashed Lines
Simulated Data – Solid Lines
8/10/2019 GOHFER Variable Sensitivity
http://slidepdf.com/reader/full/gohfer-variable-sensitivity 13/27
FRACTURE GEOMETRY COMPARISON – INCREASE IN COEFFICIENT OF
DISCHARGE
Base Fracture Geometry
No impact on fracture geometry
8/10/2019 GOHFER Variable Sensitivity
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PRESSURE COMPARISON – MODULUS STIFFNESS = 0.001
Increase in the rate of modulus change when the rock yields non-
linearly results in an increase in the slope of the treating
pressure with time, once CFOP is exceeded. .
Actual Data – Dashed Lines
Simulated Data – Solid Lines
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FRACTURE GEOMETRY COMPARISON – INCREASE IN MODULUS STIFFNESS
Base Fracture Geometry
Higher modulus leads to higher stress and fracture pressure. Fracture may grow out of
zone resulting in lower average width and proppant concentration.
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PRESSURE COMPARISON – MODULUS STIFFNESS = -0.001
Decrease in the rate of modulus change when the rock yields
non-linearly results in an decrease in the slope of the treating
pressure with time, once CFOP is exceeded.
Actual Data – Dashed Lines
Simulated Data – Solid Lines
8/10/2019 GOHFER Variable Sensitivity
http://slidepdf.com/reader/full/gohfer-variable-sensitivity 17/27
FRACTURE GEOMETRY COMPARISON – DECREASE IN MODULUS
STIFFNESS
Base Fracture Geometry
Lower modulus leads to lower stress and fracture pressure. Fracture width grows larger
and possibly shorter resulting in higher average proppant concentration.
8/10/2019 GOHFER Variable Sensitivity
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PRESSURE COMPARISON – CXSP = 4 (DEFAULT - 2)
Higher pipe friction associated with the addition of proppant in
the pipe leads to increase in observed treating pressure. No
change in ISIP.
Actual Data – Dashed Lines
Simulated Data – Solid Lines
8/10/2019 GOHFER Variable Sensitivity
http://slidepdf.com/reader/full/gohfer-variable-sensitivity 19/27
FRACTURE GEOMETRY COMPARISON – INCREASE IN SAND EXPONENT
Base Fracture Geometry
No impact on fracture geometry
8/10/2019 GOHFER Variable Sensitivity
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PRESSURE COMPARISON – PHOLD = 1.7 (DEFAULT – 1.2)
Increase in proppant holdup proppant results in additional proppant
being held-up by interference with the fracture walls. Proppant is
traveling at a slower velocity compared to the fluid. Increase in
observed treating pressure but no screenout in this case.
Actual Data – Dashed Lines
Simulated Data – Solid Lines
8/10/2019 GOHFER Variable Sensitivity
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FRACTURE GEOMETRY COMPARISON – INCREASE IN PHOLD
Base Fracture Geometry
Higher PHOLD results in shorter fracture and higher average proppant concentration due to
more proppant being deposited near the wellbore.
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PRESSURE COMPARISON – PHOLD = 2.2
Additional increase in proppant holdup proppant results in
earlier pressure increase and premature screenout (all
perforations blocked with proppant).
Actual Data – Dashed Lines
Simulated Data – Solid Lines
8/10/2019 GOHFER Variable Sensitivity
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FRACTURE GEOMETRY COMPARISON – LARGER INCREASE IN PHOLD
Base Fracture Geometry
Larger increase in PHOLD results in shorter fracture and higher average proppant
concentration due to more proppant being deposited near the wellbore and a screenout.
8/10/2019 GOHFER Variable Sensitivity
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PRESSURE COMPARISON – PHOLD V/H FACTOR = 1.5
Increase in PHOLD vertical to horizontal anisotropy (V/H)
increases the proppant holdup vertically across layers resulting
in early pressure increase and premature screenout.
Actual Data – Dashed Lines
Simulated Data – Solid Lines
8/10/2019 GOHFER Variable Sensitivity
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FRACTURE GEOMETRY COMPARISON – INCREASE IN PHOLD V/H FACTOR
Base Fracture Geometry
Increase in PHOLD V/H Factor results in shorter fracture and higher average proppant
concentration due to more proppant being deposited (and distributed vertically) near the
wellbore and a screenout.
8/10/2019 GOHFER Variable Sensitivity
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PRESSURE COMPARISON – PZS V/H FACTOR = 1.2
Increase in PZS vertical to horizontal anisotropy increases the net
fluid pressure over the PZS to grow vertically compared to
horizontally. May result in increased observed treating pressure
due to higher fracture pressure.
Actual Data – Dashed Lines
Simulated Data – Solid Lines
8/10/2019 GOHFER Variable Sensitivity
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FRACTURE GEOMETRY COMPARISON – INCREASE IN PZS V/H FACTOR
Base Fracture Geometry
Increase in PZS V/H Factor may result in longer more contained fracture. Negligible affect
on this example.