The Perfobur technical system is intended for quality improvement of the connectivity between the pay zone and the drilled well at the final stage of well construction or workover by deep perforation of the producing zone of oil and gas wells. The system enables to increase the flow rate of producers and the injection capacity of injectors.
|Diameter of perforation channels, mm||58 /60|
|**Channel deviation from the main hole, m||5 - 10|
|Length of perforation channel, m||up to 50|
|Number of channels on one layer, ea.||up to 4|
|* Curvature radius of channel, m||3,5 - 12|
|**Length of assembly, m||35 - 45|
|**Weight of assembly, kg||600 - 800|
|Circulation rate,l/sec.||0,5 - 2|
|ROP, m/h||5 -7|
|Motor shaft torque, Nm||200 - 400|
|Pressure differential in Perfobur BHA, MPa||4 - 8|
|Axial load on bit, kN||2 - 6|
|*Build-up rate at a radius of 10.5 m makes 5.5 deg./m
** Channel length being 14 meters
Formation depth – up to 3000 meters, casing diameter – 146 mm, wall thickness (steel of any grade) - 7-9 mm.
The target is wells with a potential ability of flow rate (injection rate) increase by making perforation channels with a sufficient deviation from the main hole, including:
- wells with low-permeability reservoirs for drainage improvement;
- wells with a bottom-hole area with a low skin-factor as a result of wall packing;
- wells, in which applied stimulation methods (for example, acid treatment) do not achieve the planned efficiency;
- wells with pay zones of a small thickness (if the formation section is very much wall-packed);
- wells with close occurrence of water-bearing and producing horizons.
Perfobur enables to:
- penetrate into thin formations with weak boundary lines;
- go through deposits of paraffin films and asphaltens in the bottom-hole area that reduce the pressure differential in the “hole-formation” system.
- Wells with a carbonate reservoir / wells planned for interventions with transition to a higher producing carbonate layer.
- Build-up rate – not more than 3 deg. / 10 m.
- Sump from the low perforation channel to the plugback depth – not less than 7…10 meters (for channels of 14-meter length).
- Cement bond of sufficient reliability behind the production casing is mandatory in the interval of perforation.
- The interval of perforation channel drilling cannot contain centralizers of the production casing.
- Density of holes from the previous perforation – not more than 60 holes per running meter.
- Bottomhole temperature – not to exceed 100 deg.C.