1. Chevron Carbonates Shell GOM Sands Phillips Chalk Kerr McGee
Lumped Parameter Matrix Injection Evaluations Matrix Injection Case Studies
Chevron Carbonates
Shell GOM Sands
Phillips Chalk
Kerr McGee

2. Chevron Methodology
A method is presented whereby the injection history of a well may be interpreted in terms of the quality of the injected water.
Coreflooding and/or membrane measurements
Effective history matching and monitoring methodology

3. Water Quality Ratio RWQ ….. water quality index (darcies)
rc ….. density of filter cake formed from the suspended solids,
kc ….. permeability of filter cake formed from the suspended solids (darcies),
r ….. water density,
W ….. suspended solids concentration

4. For Internal and External Cake
V throughput,
VTC core volume
kF formation baseline permeability (darcies),
k plugged permeability (darcies),
a fraction of the total particulates in the external cake, and,
b fraction of the total particulates in the internal cake.

5. Coreflooding
McCune advised not
to do tests this way.

6. Theory:
"According to this parameter [Water Quality Ratio] the greater the water quality ratio, the less is the tendency of the water to damage by suspended solids plugging. Through a series of coreflood tests the water quality ratio is related to the filtration level, which in turn provides a guide for choosing the filtration equipment needed in the field under construction."

7. Theory:
"It is shown that waters with ratios less than 10 would be expected to cause extreme plugging. Above 100 only minor plugging is expected."

8. Using for Matrix Injection
Lumping parameters
Numerous assumptions
Water quality ratio often used for monitoring
An effective wellbore is used to avoid inputting diameters, perforations, permeability, porosity variations, etc.
“The effective or equivalent properties are simply those that fit the mathematical description of the injection well performance.”

9. Effective Parameters
For an overall time, T, the volume of water injected is:
where:
VW is the injection wellbore volume
l is the ratio of rates at time T and time 0,
kF is the effective/equivalent reservoir permeability,
re is the outer radius, and,
r*W is the effective or equivalent wellbore radius.

10. Effective Parameters
A plot of the reciprocal term versus the total volume is a straight line with intercept 1 and its slope is a measure of the injection water quality. With some assumptions and units conversions:

11. 200 md, wellbore volume of 88.4 ft3
1/l vs. Water Injected
200 md, wellbore volume of 88.4 ft3

12. 200 md, wellbore volume of 88.4 ft3
1/l vs. Water Injected
200 md, wellbore volume of 88.4 ft3

13. Saudi ARAMCO Examples Saudi Aramco seawater floods.
In this particular situation, the injection pressure and the differential pressure were relatively constant.

16. Saudi Aramco Two injectors, monitored over seven years
1/IIT plotted versus VT.
For both wells the slopes decrease with time.
Injection water quality generally was improving through better corrosion and bacteria control.
“On the assumption that GII0 did not change, the improvement in water quality (i.e., increasing RWQ) would account for the slope decrease. The improvement in water quality is not evident in the plots of injectivity index versus volume injected.”

17. Merit in the Concept
Lumped parameters not requiring an explicit knowledge of plugging mechanics
Poor track record of micro-level plugging models
With assumptions of Gaussian distributions of particle deposition and various other simplifications, reduce complicated formulae to:

18. Merit in the Concept
a governs magnitude of rate and b governs temporal flow rate profiles.
Take injectivity ratio as:

19. Potential Fracture Diagnostic

20. Lumping
Is not a purely empirical one even though the method appears to be so simple that imitates a curve-fitting approach.
The field injectivity decline profiles appear to replicate a stochastic Gaussian distribution.
The present simplification is mainly reflected in selecting a single and a collective distribution, which is equivalent to choosing the path of a representative particle migration.

21. Well A36

22. Well A42

23. Phillips Chalk 2
Dump Flood

29. Kerr McGee
G Field