Methods of Well Killing
When drilling and operating wells, it is necessary to use methods of well killing, in connection with the situations, caused by the release of drilling mud, or lack of ability to extract oil and gas because of damage to underground or wellhead equipment.
In the event of showings of oil, gas and water, struggle against them begins with the implementation of some methods.
The most common methods of well killing are:
- wait-and-weight method;
- flushing-out of well until the termination of formation fluid entry from the reservoir itself under constant pressure in the drill pipe;
- flushing-out of well, controlling the pressure before the throttle valve, and circulation withdrawal with the use of throttle device;
- driller’s method, etc.
These methods of gas and oil fountains killing are based on the level of formation pressure, or it is determined immediately before the killing.
This requires a continuous bottom-hole pressure in the well (for the entire circulation), which may be some higher than the formation pressure.
There are several methods of well killing due to the constant supervision during the elimination of BHP:
Method of Indirect Control
Method of Direct Control
Deviation of pressure or fluid density in the annulus during washing, which is reflected in the pressure in the pipe. In continuous pump output, the pressure in the pipes will always be maintained by adjusting the valve pressure in the column, and during the process of a complete killing of well bottom-hole pressure is maintained constant. This method allows you to control bottom-hole pressure and control it with the washing-out of formation fluids, changing the fluid in the well and other operations. Its advantages are the simple mathematical calculations and easily accessible training.
Measurements directly in the well annulus. This happens according to pre-planned program and calculations, and with the help of valves the pressure in the column is varied, ensuring the stability of the desired bottom-hole pressure. The advantage of this method is its accuracy of pressure changes in the boundaries of the annulus. Its disadvantage is the inability to build an accurate curve backpressure due to the variability of the annulus shape and other factors. This method is impractical.
“SNK” company is aimed at achieving the exceeded BHP over the formation pressure.