Cementing systems for wellbores

摘要

A new wellbore cementing system has been developed which includes, in certain embodiments, a plug container with a flow diverter for diverting a portion of flowing fluid away from plugs in the plug container; a plug set system with internal sleeves or dart receivers with shearable parts for shearing to selectively release plugs-all in certain embodiments made of non-metal material and/or plastic; a swivel equalizer with internal valving to isolate a plug set (or any other item) from torque and to relieve pressure below the swivel equalizer; and unique burst tube systems for selectively controlling fluid flow and plug system operation. In one aspect a plug nose is tapered to correspond to a taper of a landing ring so that wedge-locking of the nose and ring effects desired non-rotation of the plug during drilling. In one aspect plug fin bending is facilitated by reducing plug body thickness so that an alternate fluid flow path is provided for cementing. In one aspect a new float valve system is provided with a top baffle that prevents debris etc. from shutting off fluid flow to a float valve.