Expendable borehole pressure generators (hereinafter referred to as GDS) of the “Plast-BK” series are used for fracturing and thermo-gas-chemical treatment of oil and gas bearing formations to restore and improve filtration properties of the near-wellbore zone when working on wireline. Technology of gas-dynamic fracturing includes creation of excess pressure in a well by the impact of combustion products of propellant charges on a productive formation. At the same time, the boom-hole zone is exposed to mechanical, heat and physical-chemical impact. The main impact factor is mechanical. Rock loading rate is about 10⁴ MPa/s. With such a high-rate deformation, the rock residual deformation prevents fracturing closure after pressure release.
Operating Principle:
The generators present a unique design having no analogues. The propellant charges are initiated simultaneously by two blasting cartridges installed at the top and at the bottom of the assembly. Combustion pulses converge at the assembly midpoint providing maximum pressure directly to the required target interval without exposing the casing and cement stone to excessive explosive action outside the target interval.
Safety:
Using the method of converging pulses reduces the impact on the casing and cement stone during generator operation.
Main Technology Components:
- Mulpurpose soware "Plast" based on the well data to calculate the generator layout and the pressure it creates;
- GDS "Plast-BK";
- High-speed pressure gauge running in hole together with the generator to confirm the design pressure.
Technology Specific Features:
- Convergence of pressure pulses (iniang from both sides) provides predominant impact on the target interval;
- Specified fracturing pressure is achieved by a smaller number of propellant charges due to the cumulative impact at superposition of converging pressure pulses;
- Reduction of high-explosive impact on the production casing outside the target interval due to dynamic balancing of the generator assembly under the influence of converging pressure pulses;
- Possibility of adjustment of the pressure rise rate by using active and basic propellant charges;
- Possibility of through-tubing operations by non-team method using a small-size GDS “Plast-42BK”
- Scientific approach to every perforation process, control of each well by the developer;
- Design and impact method are protected by the patent №2645313 and №2643533.
GDS "Plast-BK" Technical Characteriscs
| Parameter | Value | |
|---|---|---|
| GDS «Plast-42BK» | GDS «Plast-65BK» | |
| Overall diameter, mm | 42 | 65 |
| Minimum casing drift diameter, mm | 50 | 73 |
| Maximum allowable hydrostatic pressure, MPa | 100* | |
| Minimum allowable hydrostatic pressure, MPa | 5 | |
| Maximum allowable temperature, °C | 150 | |
| Propellant charge name | ShGD-42PP | ShGD-65PP |
| Propellant charge weight, kg | 0,9 | 2,2 |
| Specific volume of gaseous combustion products of propellant charges, l/kg, not less | 700 | |
| Max interval length perforated per trip | Limited by maximum lifting height of the hanging roller | |
| * Depending on the initiation means used. | ||