Flapper lock open apparatus

#The field of this invention is mechanisms that can hold open a subsurface safety valve (SSSV) that has malfunctioned so that another valve can be installed to take its place.

#SSSVs are normally closed valves that are used primarily in offshore and gas wells to prevent uncontrollable flow of fluid to the surface, in the event the surface safety equipment fails to properly operate. If the SSSV malfunctions or for any other reason requires replacement with a backup SSSV, the well operator will normally want the old SSSV locked in the open position so it does not interfere with well operations after the old SSV has been taken out of service. Typically, to avoid undue complication in the design and operation of an SSSV, the lock open assembly is not installed with the SSSV but is subsequently run in when needed on an accessory tool known as a flapper lock open (FLO) tool.

#One known design of an FLO tool is U.S. Pat. No. 4,577,694, which illustrates the use of a scroll of wound spring steel that is allowed to spring out after being delivered to the SSSV to keep the flapper from rotating back to a closed position. The downside of this design and several others is that flow through the locked open SSSV could and did, at times, dislodge the lock open device, allowing the flapper to close off the well. In this particular patent, the ring of steel was coiled, like a watch spring and held at opposite ends until properly positioned. When the delivery tool released the ring, it sprang outwardly to contact the flapper. This tool was complicated and required stocking of various sizes of rings as well as an installation method that involved two wireline trips with jar down/jar up activation.

#FIG. 1 is a perspective view of a slotted sleeve in the unexpanded position;

#FIG. 2 is the view of FIG. 1 with the sleeve in the expanded position;

#FIG. 3 is an alternative sleeve having longitudinal flutes before expansion;

#The present invention deals with ways of holding an SSSV in an open position. This can be done by holding open the flapper, as illustrated in FIGS. 13-15 or holding the flow tube when the flow tube pushes the flapper into an open position, as shown in FIGS. 5-8, for example.

#The preferred device for holding the SSSV open is a tube 10 that has slots 12 or any other shaped openings on it to facilitate expansion but at the same time to retain sufficient structural integrity after expansion to avoid collapse or simple breakage. Shown in FIG. 1, the slots 12 are rectangular and are in alignment with the longitudinal axis of the tube 10. Other arrangements and orientations are envisioned. As shown in FIG. 2, the slots 12 turn from a rectangular shape to a diamond shape after expansion. The tube 10 is permanently deformed so that it will not spring back to its run in dimension. The deformation results in a residual holding force to keep the tube 10 in place against the velocity of flowing fluid. The expansion can be carried out using a variety of techniques such as a swage, a mechanically compressed resilient sleeve, or an inflatable, to mention a few possibilities.

#FIG. 3 shows a tube 14 having longitudinal folds or corrugations 16 to give it a small enough diameter to allow it to be positioned properly inside the SSV. In the expanded position it is rounded and preferably deformed into contact with a flapper or the flow tube or both to hold the SSSV in the closed position. Once again, many expansion techniques can be used to fixate tube 14 in the chosen position.