ConocoPhillips
SETTING A CEMENT PLUG

Abstract:

The invention relates to a cementing tool (1) and method for setting a cement plug. Instead of the conventional "balanced plug", the technique involves pumping cement whilst pulling and rotating the tool. The cementing tool (1) includes nozzles (9) for jetting cement which are located in a relatively narrow region (8) of the tool and a larger diameter choke region (5) proximal of the nozzles (9). The end of the tool (11) is closed off and tapered. The tool is passed down the well to a location where it is desired to set a plug, then cement is injected whilst rotating and withdrawing the tool. The jets of cement help displace existing fluid in the well thereby reducing mixing of the existing fluid with the cement, The choke region (5) increases the flow energy, whilst the tapered end (11) helps prevent disruption to the cement as the tool is withdrawn. The choke region (5) may be expandable to allow the tool to pass through a cased part of the well and then set a plug in an under-reamed open hole part of the well.