Difference between revisions of "Decline Curve Analysis"

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<td>Hyperbolic decline, 0 < b < 1 and b > 1<ref name = DDA/></td>
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<td>Hyperbolic decline, 0 < b < 1, b > 1<ref name = DDA/></td>
 
<td><math>q(t) = \frac{q_i}{(1+b\ D_i\ t)^{1/b}}</math></td>
 
<td><math>q(t) = \frac{q_i}{(1+b\ D_i\ t)^{1/b}}</math></td>
 
<td><math> Q = \frac{q_i}{D_i\ (b-1)} \left ( (1+b\ D_i\ t)^ \left ( 1-\frac{1}{b} \right ) -1 \right )</math></td>
 
<td><math> Q = \frac{q_i}{D_i\ (b-1)} \left ( (1+b\ D_i\ t)^ \left ( 1-\frac{1}{b} \right ) -1 \right )</math></td>

Revision as of 14:42, 9 July 2018

Brief

Decline Curve Analysis (DCA) is an empirical method for rate decline analysis and rate forecasting published by Arps in 1945 [1].

DCA is applied for Wells and Reservoirs production forecasting.

E&P Portal has DCA available as one of it's engineering tools.

DCA.gif

DCA in the E&P Portal

Math & Physics

Note Rate Cumulative
Hyperbolic decline, 0 < b < 1, b > 1[2] q(t) = \frac{q_i}{(1+b\ D_i\ t)^{1/b}} Q = \frac{q_i}{D_i\ (b-1)} \left ( (1+b\ D_i\ t)^ \left ( 1-\frac{1}{b} \right ) -1 \right )
Exponential decline, b = 0 q(t) = {q_i}\ e^{-D_i\ t} Q = \frac{q_i}{D_i}(1-e^{-D_i\ t})
Harmonic decline, b = 1 q(t) = \frac{q_i}{1+D_i\ t} Q = \frac{q_i}{D_i} ln{(1+D_i\ t)}

Discussion

If one has a need to convert decline factor Di to the actual annual decline in %:

if\ b > 0, a = (1 - (1 + b\ D_i)^{- 1 / b}) \times 100
if\ b = 0, a = (1 - e^{-D_i}) \times 100

Workflow

  1. Upload the data required
  2. Open the DCA tool here
  3. For a single well
    1. Select a well in a filter
    2. Input the initial rate, q_i
    3. Drag the Navigation Point to match the actual data
    4. Correct the model parameters manually if needed
    5. Check the difference in cumulative production of actual cure vs decline curve
    6. Check the Rate vs Cumulaive Plot in linear and log scale
    7. Save the decline curve model
    8. Move to the next well
  4. For a multiple wells
    1. Select the wells in the filter
    2. DCA tool will automatically normalize the wells data to zero time and then averages it
    3. Input the initial rate, q_i
    4. Drag the Navigation Point to match the actual data
    5. Correct the model parameters manually if needed
    6. Check the difference in cumulative production of average cure vs decline curve
    7. Check the Rate vs Cumulaive Plot in linear and log scale
    8. Export the type curve if needed
DCA tool at the E&P Portal

Data required

Nomenclature

a = annual decline, %
b = decline curve parametr, dimensionless
D_i = decline factor per time t, dimensionless
q_i = initial rate, any rate units applies
q(t) = rate at time t, any rate units applies
Q = cumulatve rate at time t, any rate units applies
t = forecast time, days

References

  1. ↑ Arps, J. J. (1945). "Analysis of Decline Curves"Paid subscription required. Transactions of the AIME. Society of Petroleum Engineers. 160 (01). 
  2. ↑ "KAPPA Dynamic Data Analysis (DDA) book"Paid subscription required. 
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