In injectors one can use short-live tracers to assess the infectivity profile.
If one looks for cross-well connectivity then there are only three teqniue to assess:
1) Pressure interference and pressure--pulse testing
2) Chemical or long-term radioactive tracers
3) Cross-well seismic
|Cross-well pressure survey||Among those the pressure pulsation is the cheapest, fastest and the most accurate.|
The main advantage of tracers is that they show flow connectivity rather than pressure connectivity.
The radioactive tracer can be coupled with GR-loigging in receiving wells and can assess the vertical flow profile which pressure surveys can not do.
The advantage of cross-well seismic is that it can assess saturation in cross-well interval.
How do you determine the location and nature of a fault (sealing or no sealing) from pulse test ?
I know we can say there is a barrier in between two wells, if we don’t get a pressure response from the pulsed well in the observation well.
How can we conclude that it is due to a barrier?
Also, how do we calculate at what distance from the generator well is the fault/barrier?
We call these transient pressure responses:
DTR (a drawdown or self-response)
CTR (a cross-well interference or cross-well response).
All TRs are easy to simulate in numerical softwares: 2D or 3D (for example Eclipse or tNavigator).
The meaning of this excercise is to adjust property distribution and barriers to decomposed DTRs/CTRs.
Since single DTR or CTR is taking very short time to calculate in 2D/3D solver we have opportunity to calibrate 2D/3D model step by step (each TR separately).
This would not be the case if we tried calibrating the 2D/3D model using original contaminated data without PCD deciphering -- the processing time will be huge and the calibration process would be highly ambiguous.
We call these exercises : 2D-express test and 3D-express test (3D is only needed for bottom water or gas cap scenarios)