Blowout preventer protector and method of using same

#The present invention relates to equipment for servicing oil and gas wells and, in particular, to an apparatus and method for protecting blowout preventers from exposure to high pressure and abrasive or corrosive fluids during well fracturing and stimulation procedures while providing direct access to production tubing in the well and permitting production tubing to be run in or out of the well.

#Most oil and gas wells eventually require some form of stimulation to enhance hydrocarbon flow to make or keep them economically viable. The servicing of oil and gas wells to stimulate production requires the pumping of fluids under high pressure. The fluids are generally corrosive and abrasive because they are frequently laden with corrosive acids and abrasive proppants such as sharp sand.

#The components which make up the wellhead such as the valves, tubing hanger, casing hanger, casing head and the blowout preventer equipment are generally selected for the characteristics of the well and not capable of withstanding the fluid pressures required for well fracturing and stimulation procedures. Wellhead components are available that are able to withstand high pressures but it is not economical to equip every well with them.

#The invention will now be further described by way of illustration only and with reference to the accompanying drawings, in which:

#FIG. 1 is a cross-sectional view of a preferred embodiment of the BOP protector in accordance with the invention, showing the mandrel in an exploded view;

#FIG. 2 is a cross-sectional view of the embodiment shown in FIG. 1 illustrating the BOP protector in a condition ready to be mounted to a wellhead;

#FIG. 1 shows a cross-sectional view of the apparatus for protecting the blowout preventers (hereinafter referred to as a BOP protector) in accordance with the invention, generally indicated by reference numeral 10. The apparatus includes a lockdown mechanism 12 which includes a base member 14, a mandrel head 16 and a lockdown nut 18 that detachably interconnects the base member 14 and the mandrel head 16. The base member 14 includes a flange and an integral sleeve 20 that is perpendicular to the flange of the base member 14. A spiral thread 22 is provided on an exterior of the integral sleeve 20. The spiral thread 22 is engageable by a complimentary spiral thread 24 on an interior surface of the lockdown nut 18. The flange of the base member 14 with the integral sleeve 20 form a passage 26 that permits a mandrel 28 to pass therethrough. The mandrel head 16 includes an annular flange, having a central passage 30 defined by an interior wall 32. A top flange 34 is adapted for connection to a fracturing head 35. A lower flange 36 retains a top flange 38 of the lockdown nut 18. The lockdown nut 18 secures the mandrel head 16 from upward movement with respect to the base member 14 when the lockdown nut 18 engages the spiral thread 22 on the integral sleeve 20.

#The mandrel 28 has a mandrel top end 40 and a mandrel bottom end 42. Complimentary spiral threads 43 are provided on the exterior of the mandrel top end 40 and on a lower end of the interior wall 32 of the mandrel head 16 so that the mandrel top end 40 may be securely attached to the mandrel head 16. One or more O-rings (not shown) provide a fluid-tight seal between the mandrel head 34 and the mandrel 28. The passage 26 through the base member 14 has a recessed region at the lower end for receiving a steel spacer 44 and packing rings 46 preferably constructed of brass, rubber and fabric. The steel spacer 44 and packing rings 46 define a passage of the same diameter as the periphery of the mandrel 28. The packing rings 46 are removable and may be interchanged to accommodate different sizes of mandrel 28. The steel spacer 44 and packing rings 46 are retained in the passage 26 by a retainer nut 48. The combination of the steel spacer 44, packing rings 46 and the retainer nut, provide a fluid seal to prevent passage to the atmosphere of well fluids from an exterior of the mandrel 28 and the interior of the BOP when the mandrel 28 is inserted into the BOP, as will be described below with reference to FIGS. 3-5.

#An internal threaded connector 50 on the mandrel bottom end 42 is adapted for the connection of mandrel extension sections of the same diameter. The extension sections permit the mandrel 28 to be lengthened, as required by different wellhead configurations. An optional mandrel extension 52, has a threaded connector 54 at a top end 56 adapted to be threadedly connected to the mandrel bottom end 42. An extension bottom end 58, includes a threaded connector 60 that is used to connect a sealing assembly 62, which will be described below with reference to FIG. 7. High pressure O-ring seals 64, well known in the art, provide a high pressure fluid seal in the threaded connectors between the mandrel 28, the optional mandrel extension(s) 52 and the sealing assembly 62.