A well tool for use with a subterranean well can include an elongated passageway and a plug which prevents fluid communication through the passageway for a predetermined period of time. The plug can including an anhydrous boron compound, whereby the predetermined period of time is determined by a length of the anhydrous boron compound. A method of operating a well tool in conjunction with a subterranean well can include exposing an anhydrous boron compound to an aqueous fluid, with the anhydrous boron compound being included in a plug which prevents fluid communication through a passageway of the well tool. The well tool can be operated in response to fluid communication being permitted through the passageway a predetermined period of time after the exposing step.

well tools are provided which although pressure responsive, may be maintained by a hydraulic lockout in a nonresponsive condition until a threshold actuation step is performed. This lockout may be achieved by a hydraulic mechanism (130) which controls the rate at which pressure is transmitted to a fluid spring during periods of increased pressure at the pressure source. When the tool is desired to be responsive to pressure cycles, a valve may be opened by establishing a differential between the pressure in the fluid spring and the pressure source. Communication of pressure in the fluid spring to a movable mandrel will then allow operation of the well tool in response to pressure cycles at the pressure source in accordance with the established design of the well tool.

Sliding sleeve mechanisms including protective sheaths for debris protection are disclosed. Protective sheaths can be formed from materials such as composites, metal, foil, rubber, plastic, glass, ceramic, wire mesh, tape, etc. The protective sheaths can be substantially cylindrical shells (having one or more pieces), plugs in the flow ports, and/or tape or wire wrappings. The protective sheaths can be retained by recesses in the sliding sleeve or mechanical fasteners such as screws, pins, rivets, snap rings, bands, and buckles. The protective sheath can be outside or inside the sliding sleeve. The protective sheath can protect the sliding sleeve from debris by retaining grease that has been packed into the sliding sleeve for that purpose or positively preventing entry of debris into the sliding sleeve. The protective sheath can be cleared by permitting fluid flow through the sliding sleeve, which can act to destroy and/or wash away the protective sheath.

There is disclosed a fillup and circulating tool, comprising:

a body (10) having a passage therethrough (12);

a telescoping assembly (34) mounted to said body having a seal adjacent a lower end thereof;

a valve (16) in said passage operable by said telescoping assembly.

There is disclosed a tubular fillup and circulating tool, comprising:

a body (10) having a passage therethrough (12);

a telescoping member (34) mounted to said body for selective engagement with the tubular;

said telescoping member further comprising a seal (48) to engage the outside of the tubular.

Multiple embodiments of a system for capturing displaced fluid or adding fluid to tubulars (20) being run into or out of the wellbore are described. Several embodiments are supported by a top drive (54) with telescoping features to rapidly seal over a tubular (20) to connect to a mudline. A flapper valve (18) in one embodiment is described to keep fluid from spilling when the apparatus is removed from the tubular (20). In the event of a well kick, the valve (18) can be shattered with pressure from the mudline. In another embodiment, the apparatus can be placed in sealing contact with the tubular (20) and can incorporate a valve (84) which can be manually closed in the event of a well kick. In yet another alternative, the incorporated valve (84) can be automatically actuated to open as the apparatus sits on the tubular (20) and closed as the apparatus lifts from the tubular (20).

There is disclosed a tubular fillup and circulating tool, comprising:

a body (10) having a passage therethrough (12);

a telescoping member (34) mounted to said body for selective engagement with the tubular;

said telescoping member further comprising a seal (48) to engage the outside of the tubular.

A well completion tool (10) operatively positionable within a subterranean well (12). The tool (10) comprises a fluid delivery flowpath (56) configured for delivering fluid into the well (12), a fluid return flowpath (62) configured for returning fluid from the well (12) and a pressure relief device (64) in fluid communication with the fluid delivery and fluid return flowpaths (56,62). The pressure relief device (66) is operative to provide fluid communication between the fluid delivery and fluid return flowpaths (56,62) upon application of a first predetermined fluid pressure differential between the fluid delivery flowpath (56) and the fluid return flowpath (62).