Notes

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Outline

Challenges in Predicting and Monitoring Injection in Layered Media
Outcome of the Workshop?
| Clarification of Problems Encountered
| Delineation of Solutions and Precautions
| Delineation of Tools Required
| Recommendations on Presentation of Information for Greatest Utility
Radial Matrix Flow
Issues
| Plugging Criterion
| From available data for radial flow
| Time and throughput dependence
| Pressure Signature
| Thermal effects
| Poroelastic effects
| Best Practices
| Recognition
| Persistence
Matrix
| But what if there is crossflow?
Challenges
| Monitoring and measurement methodologies
| Newer technologies
Matrix and Vertical Crossflow
| Analytical representation?
| Are there any serious consequences
| Recognition
Challenges
| Interlayer vertical crossflow
| Horizontal crossflow on shut-in
| Methodologies for minimizing horizontal crossflow (Completions Spreadsheet)
| Pressure transient interpretation
| Can mimic a fractured reservoir if there is a fairly large permeability contrast or can appear to be homogeneous if contrast is not as strong
Commingled Reservoirs
A Lesson From Production Analysis
| “The rapid depletion of the high permeability layer(s) implies that the deliverability of the well will diminish with time. Thus, contractual agreements made on the basis of short duration tests will not be met.”
| “If the commingled layers consist of one high permeability layer while all the others are low permeability, then the test will only give the kh of the high permeability layer.”
| Time to reach pseudo-steady state can be diagnostic - longer if there is no crossflow (from injection test).
"If k1 >> k2,"
| If k1 >> k2, the radial pressure gradient is higher in k1 than in k2.
| Spreading pressure increase in k1 creates a vertical pressure gradient in k2.
| If k2/k1 £ 0.01 direction of flow in k2 would be almost vertical.
| You may not like it, but the best (technical) solution is to test zones individually!
Methods Available
| Ehlig-Economides and Joseph (1987) requires accurate measurement of pressure and rate in individual zones and two rates.
| Methods were also developed by Kucuk et al. 1986 (multi-rate analysis, early transient state). Implication is bottomhole measurements.
| Flow rate and pressure survey with depth for each rate
| Similar concept presented by Nelson and Economides (1996) for fractured wells.
Fracturing
Issues/Challenges
| Stabilized plugging criteria are available
| Thermo- and poroelastic components
| Pressure signatures
| Remediation and control