Difference between revisions of "DFIT"

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[[File:fracture linear flow.png|thumb|right|300px| Stimulated well drainage]]
 
[[File:fracture linear flow.png|thumb|right|300px| Stimulated well drainage]]
  
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[[DFIT]] is the diagnostic fracture injection test or the fracture calibration injection falloff test performed to estimate fluid efficiency, leak off coefficient, formation permeability and pressure before the main hydraulic fracture treatment.
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[[DFIT]] is the diagnostic fracture injection test or the fracture calibration injection falloff test performed to estimate ISIP, fracture closure pressure, fluid efficiency, leak off coefficient, formation permeability and pressure before the main hydraulic fracture treatment.
  
 
==Math & Physics==
 
==Math & Physics==

Revision as of 07:18, 17 February 2022

Brief

Stimulated well drainage

DFIT is the diagnostic fracture injection test or the fracture calibration injection falloff test performed to estimate ISIP, fracture closure pressure, fluid efficiency, leak off coefficient, formation permeability and pressure before the main hydraulic fracture treatment.

Math & Physics

Steady state flow boundary conditions:

P |_{x=x_e/2} = P |_{x=-x_e/2} = P_i
\frac{dP}{dt} =0\ for \ \forall x

From Darcy's law:

\frac{q}{2}=\frac{kA}{\mu}\ \frac{dP}{dx}
A =y_e*h
dP=\frac{q \mu}{2ky_eh} dx

Integration gives: P-P_{wf}=\frac{q \mu}{2ky_eh} x

Since average pressure is: \bar P = \frac{\int P dx}{\int dx}

\bar P = \frac{ \int \limits_{0}^{x_e/2} \left ( \frac{q \mu}{2ky_eh} x + P_{wf} \right ) dx}{\int dx} = \left. \frac{q \mu}{2ky_eh} \frac{x}{2} \right|_{x=0}^{x=x_e/2} + P_{wf} = \frac{q \mu x_e}{8ky_eh} + P_{wf}
J_D=\frac{q \mu}{2 \pi k h} \frac{1}{( \bar P - P_{wf})} =\frac{q \mu}{2 \pi k h} \frac{8ky_eh}{q \mu x_e} = \frac{4y_e}{\pi x_e}=\frac{4}{\pi}

See also

6/π stimulated well potential
JD
optiFrac
fracDesign
Production Potential

Nomenclature

A = cross-sectional area, cm2
h = thickness, m
J_D = dimensionless productivity index, dimensionless
k = permeability, d
P = pressure, atm
P_i = initial pressure, atm
\bar P = average pressure, atm
q = flow rate, cm3/sec
x = length, m
x_e = drinage area length, m
y_e = drinage area width, m

Greek symbols

\mu =viscosity, cp
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