Pressure Related Questions

Q: What is the maximum pressure on surface?

There are 3 different pressure regimes:
1) Testing pressure is 7500 psi for 1 minute.
2) Working pressure is 5000 psi for the entire job.
3) Special case pressure is 6000 psi.

Q: What is the max surface pressure required to be able to cut multiple casing strings at say ~ 15,000 ft?

Typically 5000 psi is the maximum surface pressure required and in special cases 6000 psi.

Q: How about the effect on the DP’s and surface equipment from the erosion of the DP’s.

No impact on DP’s or surface equipment. There are two main reasons for this.

1. Maximum working pressure at surface of 5000 psi never exceeds burst pressure.

2. Generally abrasives must impact a material to be cut at an angle to cause erosion. When abrasives flow down the drill or tubing string to the DHA, the abrasives more or less flow in a path parallel to the drill string or CT. This leads to little or no erosion.

3. Generally PowerSlottingTM does not use harsh corrosive chemicals.

Q: How can we assure this pressure will not be exposed to the formation?

Formation pressure must always exceed hydrostatic head so no hydraulic pressure can ever be applied against formation. High working pressure in DP or tubing is converted to exit velocity at nozzles used in the cutting process, thus there is never exposure or application of hydraulic pressure against formation. As a result, the formation is always exposed to under-balanced pressure.

Q: How we are filling the DP’s while RIH and how we can establish circulation while RIH if need it or in case of well control issue?

PowerSlottingTM BHA is designed for flow and reverse flow at various pressures and follows industry standard circulation procedure. The equipment is designed on two principles:
1) The equipment has standard API “thru-tubing” design (and fits standard cross-over fitting – generally 2 3/8” or 2 7/8”)
2) The equipment is not live (operating) during RIH and POOH.

Q: Will 5000 PSI be the maximum required pressure ratings of the pumps or more pressure could/will be required?

Practically speaking, 5000 PSI is the maximum. At the beginning of the procedure, we conduct a safety pressure test wherein we raise pressure to 1.5x the working pressure, but below the burst pressure of the work string, for one minute, to test for safety purposes. Generally, we use 4000-5500 psi working pressures. The highest commercial job we have been involved in is 7000 psi, but technology is capable of pressures up to 10,000 psi.