pressure transient analysis

[vibhore]

Hi all,

I'm currently doing a PTA in a slanted development well completed in gas cap of a near critical reservoir. The well was first cleaned up and then ramped up when it was connected to the production facility and then well was closed for pressure build.
During the well clean-up on successive chokes for a total production of 46 MMSCF a drop of 7 psia was observed in the permanent gauge installed. The well produced at a CGR of about 40 bbl/MMSCF. Also pressure had dropped by 15 psia when compared to start of clean-up and start of ramp-up. There is also one well about 300 m away from this well completed in the gas-cap. The present well has a stand-off of about 120m from the GOC.
some of the points are
1. When I make an IPR from C&n and Forchheimer, there is a difference by a factor of about 2.5 times.
2. When I make my IPR of multi-rate during clean-up, does taking pressure at equal time-steps would give a better result?
3. What to expect from a PTA of slant-well?
4. How do I incorporate the decreasing pressure and how it would affect my analysis?
5. The permanent gauges are about 60 m above the reservoir entry point. How will falling liquid level would affect my BU response?

Sorry for my long post.

[shiv_gupta]

please send details about this.

[mapo367]

1. When I make an IPR from C&n and Forchheimer, there is a difference by a factor of about 2.5 times.

Difference in what? AOF?

2. When I make my IPR of multi-rate during clean-up, does taking pressure at equal time-steps would give a better result?

No, it is important that rate and pressure are quite stabilized for each choke.

3. What to expect from a PTA of slant-well?

The impact on the IPR is in a skin reduction due to the geometrical effect.

4. How do I incorporate the decreasing pressure and how it would affect my analysis?

If you mean that the flowing pressure is lower than the initial after the ramp up, this is normal.
If it is the static pressure this should be an indication of depletion (if we compare quite stabilized BU pressures).

5. The permanent gauges are about 60 m above the reservoir entry point. How will falling liquid level would affect my BU response?

If you are doing a well test interpretation, it is better to consider the presence of more phases in the wellbore in the analysis software and enter also the condensate rates. If you have indication of flowing pressure under the dew point (I understood the fluid is a retrograde condensate) you have to set the fluid as biphase in the reservoir and you should see a condensate banking effect in the derivative curve.