Cementing Plug Method And Construction Steps
1. Cement plug method
According to the position of the cement plug, there are two kinds of solid cement plugs and suspended cement plugs. In order to save cement and facilitate construction, in general, the method of hanging suspended cement plug is adopted.
According to the pressure in the well and the construction process, it is divided into four methods: cementing plug for pouring method, cement plug for circulating method, cement plug for injection method (including circulation + extrusion), and cable/rope ashing method.
2, cement plug construction steps
(1) Recirculating cement plug
This is currently the most widely used method in oil fields. The cement slurry is pumped into the well for replacement to a predetermined position, and then solidified to form a plug. The construction steps are as follows:
1) Lower the cemented pipe column to the bottom of the expected cement plug and cycle it to the well for stability.
2) Prepare the cement slurry according to the design and then inject it into the well according to the previous isolation liquid, cement slurry, back isolation liquid, replacement liquid sequence and design amount.
3) Replace the cement slurry to the design position. At this time, the inside and outside of the pipe should be in balance, and the pipe string should be raised to 1-3m above the predetermined cement surface.
4) Reverse circulation to wash the well and wash out excess cement slurry.
5) Start the pipe column to a safe position, sit at the wellhead, fill the killing fluid, and shut down the well.
6) After a certain period of time, check the cement surface position (depth).
7) Test the cement plug seal according to the standard pressure test. The pressure test method adopts the corresponding method according to different well conditions.
(2) Squeeze cement plug operation procedure
The cement plug is used to seal the high pressure layer. The construction steps are as follows:
1) Plug the string or packer/bridge down to the design position.
2) Fully wash the well back of the well or the seat sealer.
3) Squeeze the absorbency with clean water to calculate the pressure, time and amount of squeeze.
4) According to the test data parameters, squeeze into the amount of cement slurry and the amount of replacement, and lift it up to the backwash position.
5) Backwashing or positive (reverse) squeezing into the killing fluid, shutting down the well.
6) After a certain period of time, check the cement surface position (depth).
7) Test the cement plug seal according to the standard pressure test. The pressure test method adopts the corresponding method according to different well conditions.
