Drill and Remove Fill and Seal Formation at Perforations
Well Data example:
payzone depth |
+/- 6500 ft tvd |
formation pressure |
0.50 psi |
perforated section |
50 ft of 7" liner |
rathole |
+/- 400 ft |
length of sand fill |
+/- 500 ft |
bottom hole temp |
< then 250°F |
permeability |
< then 2 darcies |
The 7" wellbore is filled with sand with about
100 ft above perforated section. A fluid system is required
to drill out the fill and temporarily seal the perforations
as the drill bit passes them. The well volume is +/- 245
bbls. need to mix at surface for circulation +/- 350 bbls
- 400 bbls.
A Bridgesal-Ultra fluid system at 10.4
ppg containing sized salt bridging material in the range
of 1-75 micro will efficiently seal the formation and
possess excellent rheology to remove the sand fill.
The same formulation has been used on a number of similar
applications in the North Sea for Shell-Bp-Amoco, Mobil,
Statoil in Norway. All these wells were successfully removed
of fill with the perforations sealed and no loss of fluid
to the formations. All the wells were subsequently cleaned
up and production recommenced.
{ Bridgesal-Ultra was used as a pill or
as a circulating system as needed }
System Formulation:
Saturated NaCl brine @ 10.0 ppg |
0.94 bbl |
Defoam-2 |
0.35 lit/bbl |
Bridgesal-Ultra |
40.0 ppb |
Ph-Buffer |
1.0 ppb |
Thixsal-Ultra |
2.0 ppb |
Pill formulation:
Saturated NaCl brine @ 10.0 ppg |
0.89 bbl |
Defoam-2 |
1/2 lit/bbl |
Bridgesal-Ultra |
60.0 ppb |
Plugsal |
40.0 ppb |
Ph-Buffer |
1.0 ppb |
Thixsal-ultra as viscous carrier
ahead & behind total 20 bbls |
6.0 ppb |
Note: Due to depleted reservoir & or
presence of vugs, the system itself may not seal losses
completely, thus a pill as formulated above need to be mixed
@ surface and displaced downhole to completely cure the
losses & seal at formation face. The pill volume has
to be calculated at 2 bbls for each ft of open perfs.
e.g.: for 50 ft of perfs, you need to mix & displace
100 bbls of pill.
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