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Stimulation. Increasing Fracture Pressure. RII. Gained Injection Area. Date. Fracture Damage. Fracture Plugging and Ballooning. Fracture Plugged. RII. Fracture Growth. Date. Fracture Damage. Existing Fracture. Solid Deposition. Fracture Growth. Fracture Plugged. Determining Slope.
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Increasing Fracture Pressure RII Gained Injection Area Date Fracture Damage
Fracture Plugging and Ballooning Fracture Plugged RII Fracture Growth Date Fracture Damage
Determining Slope f(temperature, damage, pore pressure) RII f(fracture pressure) Date
Determining Slope F(Water Quality) RII F(Fracture Pressure) Date
Mechanism • Blue lines • Top line - fracturing pressure • Bottom line - gain area from fracture • Red lines • Positive gradient - matrix (stationary fracture) injection • Drop caused by the gain in area
Stimulation Flag • Frac. Pressure line intersects Gain: • Fracture completely filled • Dramatic rise in pressure • Stimulation: • Establish trend • Predict Intersection • Stimulate in advance
Progressive Increase in the plugging slope RII vs. Date Phillips Chalk Field
RII vs. Cumulative Injection Increasing Fracture Pressure Maersk A Field
Modes of Injection Red - Fracture Blue - Stationary Fracture Yellow - Plugged Maersk A Field
Modes of Injection Red - Fracture Blue - Stationary Fracture Yellow - Plugged Increasing Fracture Pressure Maersk A Field
Modes of Injection • Strong correlation from previous 2 plots • Change of injection mode between fracturing & matrix
Constant Fracture Pressure Sandstone Example BP PB Unit
Correlation with PEA 23 • PB Unit • PB Unit the gradient of bounding lines = 0 • Both mechanisms work together to create relatively constant RII • Both theories seem to correlate well
Correlation with PEA 23 • Maersk A Field • Account for increasing fracture pressure • Recalculate RII with increasing F.P. • Should see constant RII
RII From Fracture Pressure Maintained Injection Maersk A Field
Side Benefit • Predict/Estimate - Fracture pressure • Correlate to Step Rate Test
Stimulation Evaluation Stimulation RII RII Baseline Date
Definition • Baseline - best performance • RII - current performance • Stimulation - commonly acidizing
Stimulation Evaluation Slope Before RII DRII Before Date
Stimulation Evaluation Slope After RII DRII After Date
Factors • DRII - measure of damage • Slope - rate of damage accumulation
Example Elf Field 3
Example 2 Maersk Field A
Improvement Ratio Ideal Case Hall Plot Examination RII Field Data Stimulation Date
Ideal Hall Plot • Ideal or initial injectivity immediately following stimulation
Improvement Ratio • Shows the gain in injectivity
Hall Plot Elf Field 3
Hall Plot Maersk Field A