APPARATUS FOR PROTECTING A RISER STRING The present invention relates to an apparatus for protecting a riser string used with offshore rigs and vessels, and particularly, but not exclusively, an apparatus for protecting a keel joint and a hull through of the offshore rig through which it passes.

Wellbore operations from floating vessels typically utilize risers or tendons in a string that extends from the vessel to the sea floor. Such floating vessels include tension buoyant towers , compliant towers , and spars in which the structures extend well below the sea surface and are subjected to heave, pitch, and roll motion at the surface and also may be subjected to yaw, sway and surge . The risers and tendons are connected to the sea floor and pass through openings in the keel or bottom portion of the vessels. The openings in the vessels constrain the pipe forming the risers or tendons when the vessel is moved laterally with respect to the sea floor connection.

In many prior systems a special section of riser called a "keel joint" is used adjacent the keel of the hull : to accommodate the bending loads where the riser leaves the support of the platform; to accommodate the relative vertical movement between the riser and the hull; and to protect the riser string and the hull from damage. Several prior keel joints are reinforced to carry the bending loads imposed on the riser by the pitch/heel motions of the hull relative to the riser as well as the bearing and wear loads imposed on the riser by the vertical and lateral motions of the hull relative to the riser. Lateral movement can produce bending of the riser pipe at the hull opening, or rotation of the riser

pipe about the contact of the riser pipe with the edges of the opening. Bending of the pipe, which is normally under tension, can result in fatigue and wear at the opening. The prior art includes a variety of patents directed to vessels, risers and keel joints, including, but not limited to, U.S. Patents 4,634,314; 5,377,763; 5,628,586; 5,683,205; 6,422,791; 6,739,395; 6,746,182; 7,013,824; 7,144,048; and 7,217,067 - all incorporated fully herein for all purposes. Certain prior systems include the use of thick walled pipes with tapered ends. These thick, tapered wall sections have been machined from heavy forgings and can be relatively expensive. Another solution utilizes a sleeve member centralized within the vessel opening and a mud line or sea floor connection to receive the lower end of the pipe. The pipe is centralized within the sleeve but otherwise unattached to the sleeve. Other approaches use a centralizing, ring like device and/or a ball joint, located between the side walls of the vessel opening and the pipe.

U.S. Patent 5,683,205 discloses a joint that passes through the vessel opening and is connected to the sea floor with the pipe centralized within an outer sleeve with large elastomeric rings located at each axial end of the sleeve. U.S. Patent 6,422,791 discloses a sleeve positioned around a riser pipe where the pipe penetrates the keel of the platform. The riser-to-sleeve attachment provides a load carrying capacity in both the axial and lateral direction (or reduced capacity in one of these directions) and permits flexibility for angular offsets between an outer sleeve and a riser pipe.

U.S. Patent 7,217,067 discloses a riser joint keel assembly in which a tapered riser joint is connected to a

larger diameter outer sleeve through a connection that allows the tapered section and outer sleeve to function as one unit. In the combined design, the outer sleeve provides the required sliding interface between the riser and the guide at the keel of the hull while also providing some of the bending compliance needed to transition from the riser supported in the hull to the riser unsupported below the hull. The tapered section also provides the remaining bending compliance needed for the transition. The connection between the tapered and sleeve sections is a forged, machined ring plate welded to the bottom end of the sleeve, which provides a base for either bolted or threaded type attachment points for the tapered riser joint below the ring plate and the internal riser joint that continues to the surface. In one aspect such an assembly for a floating offshore structure with a top tensioned riser arrangement, includes a compliant riser keel joint assembly, including: a. an outer sleeve positioned inside two keel guides in the hull structure; b. an internal riser joint positioned in said sleeve and having a flange attached at the lower end; c. a centralizer mounted inside said outer sleeve adjacent the upper end and sized to receive said internal riser joint; d. a single, tapered riser joint positioned below said internal riser joint; and e. means for connecting the lower end of said internal riser joint to the upper end of said single tapered riser joint, including i. said internal riser joint having a threaded lower end; ii . a flange attached to the upper end of said tapered riser joint; and iii . a machined ring attached to said sleeve, said ring having a threaded bore sized to threadably receive the internal riser joint and providing the attachment point for the flange on the tapered riser

joint .

U.S. Patent 7,013,824 discloses a riser centralizer for transferring lateral loads from the riser to a platform hull with a keel centralizer mounted on a keel joint. The keel centralizer is received within a keel guide sleeve secured in a support mounted at the lower end of the platform hull . The keel centralizer includes a non-metallic composite bearing ring having a radiused peripheral profile for minimizing contact stresses between the keel centralizer and the keel guide sleeve in extremes of riser and platform motion. The internal surface of the keel guide sleeve is clad with a corrosion resistant alloy and coated with a wear resistant ceramic rich coating. In one aspect, there is keel centralizer that includes: a. a flat keel centralizer body having a central bore extending through said body; b. the keel centralizer body including a circumferential flange member defining the perimeter thereof; c. at least one opening extending through the keel centralizer body; d) a bearing ring mounted on the flange member; and e) a keel sleeve mounted in a keel support frame, the keel sleeve being adapted for slidably receiving the keel centralizer body, and wherein the keel sleeve is clad with a corrosion resistant material. U.S. Patent 6,746,182 discloses keel joint assemblies that permit a degree of rotational movement of a riser within the keel of a floating vessel and greatly reduce the amount of stress and strain that is placed upon the riser, as well. Keel joint assemblies described provide a limiting joint between the riser and the keel opening that permits some angular rotation of the riser with respect to the floating vessel. Additionally, the limiting joint permits the riser to move upwardly and

downwardly within the keel opening, but centralizes the riser with respect to the keel opening so that the riser cannot move horizontally with respect to the keel opening. In certain embodiments, the limiting joint is provided by a single annular joint that allows that riser to move angularly with respect to the can. In some embodiments, the keel joint assembly incorporates a cylindrical stiffening can that radially surrounds a portion of the riser and is disposed within the keel opening. In these embodiments, a flexible joint is provided between the can and the riser. Supports or guides may be used to retain the can within the keel opening. In one aspect, in floating platform, there is: a hull having a bottom and a deck spaced above the bottom; a riser opening extending generally vertically through the hull from the bottom to the deck; a riser extending through the riser opening; a landing profile in the riser opening adjacent to the bottom of the hull; a guide sleeve having an engagement profile that lands and locks on the landing profile for movement with the hull; and a collar being located with the guide sleeve and having a flex member having a central passage through which the riser extends , the flex member being supported by the guide sleeve adjacent to the bottom of the hull, the flex member being movable axially relative to an axis of the riser and allowing angular movement of the guide sleeve relative to the riser.

U.S. Patent 6,422,791 discloses an attachment that extends between an outer sleeve and an inner riser pipe where the pipe penetrates the keel of a platform. In one version, the attachment is a conically shaped with a small diameter ring that engages the riser pipe and a large diameter ring that engages the outer sleeve. This

attachment has elements that are very flexible in bending but relatively stiff and strong in axial load. Other versions include flat rings where lateral load is taken directly into tension and compression in the beams, allowing for relatively high lateral load transfer. Both the conically shaped attachment and the flat ring have a number of variations that provide low bending stiffness but high axial stiffness of the elements. Depending on whether resistance to axial loads, lateral loads, or resistance to combination of both loads is desired, the attachment and the flat ring may be used alone or in combination. Other variations of the device provide two opposing conical shaped attachments or a conical and flat ring attachment installed together to provide load capability in both axial and lateral directions while still providing angular flexibility. In one aspect there is a riser joint for a riser extending between a floating vessel and a sea floor, the riser joint including: a tubular member having an axis ; a sleeve surrounding a portion of the tubular member and having an upper end, a lower end, and a sleeve axis that substantially aligns with the axis of the tubular member; a metal upper element adjacent to the upper end of the sleeve, and having a first portion mounted to the sleeve, and a second portion mounted to the tubular member, wherein the first and second portions of the upper element are axially spaced apart; a metal lower element adjacent to the lower end of the sleeve, and having a first portion mounted to the sleeve, and a second portion mounted to the tubular member, wherein the first and second portions of the lower element are axially spaced apart; and wherein the upper and lower elements have apertures therein between the first and second portions to allow

angular and radial flexibility of the tubular member relative to the sleeve and resist axial motion of the tubular member relative to the sleeve.

U.S. Patent 4,634,314 discloses composite marine riser system which, in certain aspects, include tubular marine riser sections formed by a wound or woven filament resin matrix tubular body having a modulus of elasticity in tension of about 27,000,000 psi or greater utilizing carbon or boron for the filament material . The riser sections may be provided with end couplings secured to the tubular body for forming a riser system wherein the tensile strength or load bearing capacity of each section and its hydrostatic collapse resistance may be selectively determined by its position in the riser system. The riser sections may be provided with cylindrical collapse resisting ribs defining spaced buoyancy chambers filled with low density material contained by an outer shell formed of a glass or aramid fiber resin matrix composite having a lower modulus of elasticity in tension than the primary load bearing tubular member. An inner abrasion and fluid impervious sleeve is disposed within the tubular body but is not bonded thereto. Multiple conduit riser sections may be utilized as anchoring members for a floating platform and the like. In one aspect there is a marine riser for use in drilling or production of hydrocarbons from a subsea formation including: elongated tubular body means constructed of a composite of elongated filaments of a material in a resin matrix having a modulus of elasticity not less than about 27. times .10. sup.6 psi, said filaments being bonded in a resin matrix to form a load bearing member of the tubular body means having an elastic elongation strain characteristic under stress in tension

not substantially greater than steel; and coupling means at opposite ends of the tubular body means for coupling the riser to a member for transmission of tensile loads through the tubular body means between said ends . In accordance with the present invention, there is provided an apparatus for protecting a keel joint, the apparatus comprising a body made of flexible material, a central open bore through the body, characterised in that the body comprises a plurality of spaced-apart energy management zones therein for diffusing a force applied to a particular part of the body.

A force or load that encounters an energy management zone in an apparatus in accordance with the present invention is defocused in the sense that the force or load goes around the zone . Thus a concentrated or point- applied force or load is diffused and distributed.

Preferably, the flexible material is polyurethane . Advantageously, the apparatus further comprises an inner support arranged between the body and the central open bore. Preferably, the inner support comprises at least two parts, one for each of a segmented body, each part having a lip and a hole therein for facilitating connection of the parts to form the inner support.

Advantageously, the apparatus further comprises an outer support arranged external said body. Preferably, the outer support comprises at least two parts, one for each of a segmented body, each part having a lip and a hole therein for facilitating connection of the parts to form the outer support. Advantageously, the body is moulded onto the inner support and/or the outer support. Preferably, the inner support has a plurality of spaced-apart openings (12Op) therethrough, said openings containing a portion of said

flexible material that makes the body. Advantageously, the apparatus as further comprises at least one bracket projecting into and embedded in said flexible material of said body. Preferably, the bracket is a retaining bracket or an anchoring bracket. Advantageously, each bracket is a discrete bracket which has a length which is substantially shorter than the axial length of the body.

Preferably, the body has a first primary body part having a first plurality of spaced apart energy management zones projecting inwardly of the body from the first primary body part. Advantageously, said body has a second primary body part having a second plurality of spaced apart energy management zones projecting inwardly of the body from the second primary body part . Preferably, said body has a third primary body part having a third plurality of spaced apart energy management zones projecting inwardly of the body from the third primary body part. Advantageously, said body has a fourth primary body part having a fourth plurality of spaced apart energy management zones projecting inwardly of the body from the fourth primary body part .

Advantageously, the body has a primary part and a secondary part, the primary part about the central open bore comprising a continuous rib thereabout, the secondary part spaced therefrom comprising a continuous rib, said energy management zones arranged between said primary part and said secondary part.

Preferably, the body comprises at least two segments. Advantageously, said body has a primary part and a secondary part, the primary part about the central open bore comprising a continuous rib along the segment, the secondary part spaced therefrom comprising a continuous rib, said energy management zones arranged between said

primary part and said secondary part. Preferably, the energy management zones each have a floor. Advantageously, each of the energy management zones extend down into the body to different depths . Preferably, each of the energy management zones has portions extending to different depths .

Advantageously, the apparatus further comprises at least one ring and a sleeve enclosing said body and said ring. The present invention also provides a riser comprising a keel joint having an apparatus of the present invention thereabout .

The present invention also provides a method for protecting a keel joint of a rig with respect to a hull of the rig, the keel joint extending through an opening in the hull, the method comprising the steps of positioning a keel joint with respect to a hull, the keel joint extending through an opening in the hull, the keel joint comprising a body made of flexible material, a central open bore through the body, the body having a plurality of spaced-apart energy management zones therein for diffusing a force applied to a particular part of the body, further comprising the step of contacting the hull with the keel joint so that a force is applied to the body of the keel joint and said force is diffused in the body.

The present invention also provides a centralizer for centralizing a tubular, the centralizer comprising a body made of flexible material , a central open bore through the body, and the body having a plurality of spaced-apart energy management zones therein for diffusing a force applied to a particular part of the body. Preferably, the centralizer is for centralizing a

tubular in the drilling of an oil or gas well . Advantageously, the centralizer is for centralizing casing in a cased or open borehole and preferably for centralizing drill pipe in a cased or open borehole. In certain aspects , the present invention provides a keel with: a riser pipe; a plurality of keel joint protectors on the riser pipe including at least one pair of keel joint protectors,; each of the plurality of keel joint protectors having a body made of flexible material, a central open bore through the body, the body having a plurality of spaced-apart energy management zones ; a support ring between each pair of keel joint protectors; and, optionally, a protective shell over the keel joint protectors and support rings . In certain aspects , the present invention teaches methods for protecting a hull of a rig adjacent a keel joint, the keel joint extending through an opening in the hull, the methods including: positioning a keel joint with respect to a hull, the keel joint extending through an opening in the hull, the keel joint like any disclosed herein in accordance with the present invention, for example , one having a body made of flexible material , a central open bore through the body, the body having a plurality of spaced-apart energy management zones, and contacting the hull with the keel joint so that a force is applied to the body of the keel joint and the force's effects on the hull is diffused.

For a better understanding of the present invention, reference will now be made, by way of example, to the accompanying drawings , in which :

Figure 1 is a side schematic view of a system in accordance with the present invention;

Figure 2A is a perspective view of a pipe used in the keel joint in accordance with the present invention shown in Figure 2B;

Figure 2B is a perspective view of a keel joint in accordance with the present invention.

Figure 2C is an exploded perspective view of the keel joint shown in Figure 2B;

Figure 3A is a side view of a protector in accordance with the present invention; Figure 3B is a top view of the protector shown in Figure 3A;

Figure 4A is a side view of an inner support of the protector shown in Figure 3A;

Figure 4B is a top view of the inner support shown in Figure 4A;

Figure 5A is a side view of an outer support of the protector shown in Figure 3A;

Figure 5B is a top view of the outer support shown in Figure 5A; Figure 6A is a side view of an eyebolt mounting block of the protector shown in Figure 3A;

Figure 6B is a front view of the eyebolt mounting block shown in Figure 6A;

Figure 7A is a side view of a safety cable mounting block of the protector shown in Figure 3A;

Figure 7B is a front view of the safety cable mounting block shown in Figure 6A;

Figure 8A is a top view of a mounting bracket of the

protector shown in Figure 3A;

Figure 8B is a side view of the mounting bracket shown in Figure 8A;

Figure 8C illustrates top views of various shapes of brackets for supports in accordance with the present invention;

Figure 9A is a side view of a mounting block of the protector shown in Figure 3A;

Figure 9B is a top view of the mounting block shown in Figure 9A.

Figure 10 is a perspective view of a body part of a protector in accordance with the present invention;

Figure 1OA illustrates top views of various shapes for an energy management zone in accordance with the present invention;

Figure HA is a side view of a protector in accordance with the present invention, with some hidden parts shown in dashed line;

Figure HB is a side view of locking bars in accordance with the present invention for securing together two protectors in accordance with the present invention;

Figure HC is a side view of a protector in accordance with the present invention, with some hidden parts shown in dashed line;

Figure HD is a top view (or bottom view) of the protectors shown in Figures HA and HC;

Figure HE is an end view of half of one of the protectors of Figure HD; Figure HF is a schematic view of the protector half shown in Figure HE;

Figure HG is a schematic view of the protector half shown in Figure HE;

Figure HH is a schematic view of the protector half shown in Figure HE;

Figure 12A is a perspective view of a protector in accordance with the present invention; Figure 12B is a cross-sectional view of the protector shown in Figure 12A;

Figure 13A is a perspective view of a protector in accordance with the present invention;

Figure 13B is a cross-sectional view of the protector shown in Figure 13A;

Figure 14A is a top view of a protector in accordance with the present invention;

Figure 14B is a side cross-sectional view of the protector shown in Figure 14A; Figure 14C is a side view of supports of the protector shown in Figure 14A;

Figure 14D is a top view of the supports shown in Figure 14C; and

Figure 15 is a side view of a centralizer in accordance with the present invention on a tubular member .

Figure 1 illustrates a floating drilling vessel 10 in accordance with the present invention which has a hull

12 in water up to a waterline 14. A riser string 20 extends from a deck 16 into the water. A derrick 18, shown partially, on the deck 16 is a typical wellbore operations derrick. Typical well operations equipment

El, E2 , E3, E4 , E5 is used with the riser string (any suitable known equipment for any wellbore operations) . The riser string pivot 22 permits the riser string 20 to pivot .

A keel joint 30 in accordance with the present invention is located in the riser string 20 for

contacting sides 24 of a moonpool of the hull 12. The keel joint 30 may be any keel joint in accordance with the present invention disclosed herein.

Figures 2A and 2B shows a keel joint 40 in accordance with the present invention which has a plurality of protectors 50 in accordance with the present invention on a riser 44 covered by a shell 42. The shell 42 has two halves, 42a and 42b (one shown in Figures 2B, 2C) , which are bolted, fastened, welded, and/or glued in place. Optionally, the shell 42 is a single hollow cylinder. Rings 54 between the protectors 50 axially hold together two halves, 50a, and 50b, of each protector 50. In one aspect, each pair of halves 50a, 50b are bolted together on the riser 44. The rings 54 (which may be split rings secured together) carry the weight of the protectors and hold them in position.

The protectors 50 may be any protector disclosed herein in accordance with the present invention. Any desired number of protectors 50 may be used on the riser 44 (as is true for the number of protectors for any keel joint in accordance with the present invention) . In certain aspects in accordance with the present invention, a riser or pipe of a keel joint is completely covered with protectors (for example as in Figure 2B) , while in other aspects only one protector is used or two or more spaced-apart protectors are used. In certain aspects the protectors are two-piece with the two pieces installed around the riser and secured together. When connected together, the protectors have a central open bore through which the riser passes. Additionally or alternatively the two-pieces are held together by the shell 42. In other aspects, the protectors are a single integral item with a central bore in one aspect, moulded in place on a

tubular such as a riser.

As is true of any keel joint in accordance with the present invention, the protectors 50, the rings 54, inner and outer supports, and/or the shells 42 may be made of plastic, foam, rubber, wood, metal (including, but not limited to, brass, bronze, steel, stainless steel, aluminium, aluminium alloy, zinc, zinc alloy) , composite, fibreglass, nylon, and/or KEVLAR (TRADEMARK) material. In certain aspects the bodies of protectors like the protectors 50 (and any protector in accordance with the present invention) are made from flexible material, for example, but not limited to, flexible urethanes and polyurethanes . Optionally, the shell 42 may be moulded in place on a riser or formed of two (or more) parts secured together on a riser. Optionally a protector 50 (and any protector disclosed herein) can be a single integral item.

As shown in Figure 2C the protectors 50 each have a series of cells , holes , zones and/or openings 58. Any such zones, cells, etc. disclosed herein in accordance with the present invention may be used. The rings 54 may have grooves or recesses for receiving and radially holding a protector or part of a protector.

Figures 3A and 3B show a protector 100 in accordance with the present invention which may be used in any keel joint in accordance with the present invention. The protector 100 has a central open bore 100b therethrough. The protector 100 has two halves 101, 102 releasably secured together by securing together lips 120s with bolts 103, threadedly secured in corresponding holes 108a in nuts 108 each on an inner support 120. An outer support 140 is spaced-apart from the inner support 120. Optionally, the two halves 101, 102 are also releasably

held together by one, two, or more members 105 each secured by bolts 106 and nuts 107 to the outer support 140 through holes 140a in lips 14Op. The lips 14Op wrap around and are adjacent edges of the halves 101, 102. The members 105 may be any suitable rigid (for example but not limited to metal plates or bars) or flexible member (for example, but not limited to springs, corrugated metal, cables, etc.). As shown in Figure 3B, the members 105 are pieces of flexible stainless steel cable. Optionally, the bolts 103 are deleted. Optionally, the bolts 103 are deleted and bolts (not shown) at the location of the members 105 releasably hold the two halves 101, 102 together. The bolts 103 are accessible through channels 109. As is true of any keel joint disclosed herein in accordance with the present invention, the inner support 120 and any inner supports and outer supports) can be made of any suitable material, including, but not limited to, metal, plastic, composite or fibreglass. In certain aspects an optional interior ridge member 128 is provided on each inner support 120 for contacting a riser on which a protector with such inner supports is installed. In certain aspects, the ridge members 128 are made of non- conductive material that does not conduct electricity, for example, but not limited to fiberglass, plastic, foam, or polyurethane to reduce or inhibit galvanic corrosion. Optionally ridge members, with recesses 120, inhibits or prevents metal/metal contact between a riser (or other tubular) and metal of the protector 100 (especially in the event of corrosion of a metal part) . This also prevents metal/metal corrosion. Recesses 12Op provide space into which material under load can move .

Channels 109 provide access to bolts 103. Eyebolt

holes 111 are adjacent corresponding holes 112a in eyebolt mounting blocks 112. The eyebolt mounting blocks provide lift points and attachment points. The bolts 106 extend through the outer supports 140 and threadedly mate with corresponding holes 113a in mounting blocks 113 which are secured to the outer supports (for example with epoxy and/or welding) . Openings or gaps 12Op permit material flow during production process, for example a moulding process, to produce the halves 101, 102. Material can remain within the gaps following production.

Optionally, the halves 101, 102 are formed or made with one, two, three, four, five, six or more inner retaining brackets 114. The brackets 114 may be discrete brackets, having a length substantially less than the axial length of the inner or outer support 120, 140. The retaining brackets 114 are preferably made from bent strips of material or moulded and fixed to an outer surface of the inner support 120 and to an inner surface of the outer support 140. In one aspect, these brackets 114 are completely encased within material (for example plastic, rubber, foam, fiberglass or composite) that is used to make the halves 101, 102 or the inner support 120 or outer support 140. The inner support 120 may be connected to the outer support 140 or, as shown, the two are not connected together (other than by body material between them) ; thus desirable movement of the inner support with respect to the outer support is possible, which facilitates energy management. The mounting blocks 108 are shown in Figures 4A and 4B. Each half 101, 102 has a plurality of energy management zones 161, 162, 163, 164 within body halves 170, 172. Each energy management zone 161, 162, 163, 164 is defined by ribs 165, 166, 167, 174 and by parts 168,

169, 171, 172, 173 of the bodies 101a, 102a. It is within the scope of the present invention for the energy management zones to each have a floor Fl , F2 , F3 , F4 , i.e., these zones are not holes or channels which extend all the way through the bodies 101, 102 from one side to the other or from one end to the other. These floors Fl - F4 are below a surface of the bodies 101, 102. The depth of each energy management zone can be the same or, in accordance with the present invention, depths of different zones can be different. In one particular embodiment, the energy management zones 162 are 7.6cm

(three inches) deep with a two degree side taper in a body that is 71cm (28 inches) wide ("w", Figure 3A),

125cm (49.3 inches) long ("1," Figure 3A) and about 25cm (ten inches) thick ("t," Figure 3B). In such a body, the energy management zones 163 are 28cm (11 inches) deep, the energy management zones 161 and 164 are 33cm (13 inches) deep, the ribs 165, 167 are about 4.3cm (1.7 inches) thick, the ribs 174 are about 4.6cm (1.8 inches) thick.

The outer support 140 can be within the body half

170, 172 of the protector 100 or, as shown in Figure 3B, can be on the outside of the body half 170, 172. The inner support 120 can, as shown in Figure 3B, be within the body half 170, 172, or can be outside.

Figure 10 shows a protector half 200 in accordance with the present invention for use with any protector disclosed herein in accordance with the present invention. The half 200 has a body 202 with a plurality of energy management zones 211, 212, 213, 214; ribs 216, 217, 218; body parts 221, 222, 223, 224 and ends 225, 226. An inner support 238 (like any inner support disclosed herein) with or without brackets (like the

brackets 114) is spaced-apart from an outer support 240, like any outer support disclosed herein, with or without brackets (like the brackets 114) . The inner support 238 has lips 238a which are adjacent and wrap around edges of the body 202. The outer support 240 has lips 240a that are adjacent and wrap around edges of the body 202. Figure 10 shows the top of the body 202. The bottom (not shown) has corresponding energy management zones which are the same as the energy management zones , ribs , body parts and ends shown for the top. The energy management zones of top and bottom all have floors and, for example, the energy management zones 212 on the top are spaced- apart from the corresponding zones 212 on the bottom by part of the body 202 so that corresponding top and bottom zones are not in communication with each other (i.e., fluid cannot flow from a top zone to a corresponding bottom zone) . In one aspect the protector half 200 is made of polyurethane .

In use, the various energy management zones of the protector 200 (and of any protector in accordance with the present invention with a plurality of adjacent energy management zones) act as deformable crumple zones which absorb an impact and facilitate the distribution of the force of an impact from an impact point or area to other portions of the protector. In certain methods of use, in accordance with the present invention, of protectors in accordance with the present invention the protectors are secured to the riser adjacent moonpool sides with the protector seams (the plane at which ends of adjacent protector halves meet) perpendicular to the moonpool sides so that relatively large body parts (for example body parts 222, Figure 10) will abut the moonpool sides in the event of keel-joint/moonpool-side contact. In

certain aspects with such a positioning of a protector, force initially applied at such a body part (for example the body parts 222, 224, Figure 10) is distributed over a portion of the protector which includes additional parts of the body in addition to the body part at which the initial impact occurs . In certain aspects it is desirable that the protector be positioned so that a point of impact will be at or near a protector part at which protector material extends all the way from the protector outer surface to the protector inner surface (for example see adjacent body parts 222, 224; and rib 216 and part 221) . In one particular aspect such an initial impact is distributed over, about one fourth of the entire protector's body (for example, with a protector that has an outer circumference of about 400cm (one hundred fifty seven) inches, and a height of about 66cm (twenty-six inches) ) . Thus by using body parts (like the body parts 221, 222, 224, Figure 10) with ribs (like the ribs 217, 218, Figure 10) localized contact forces are distributed over a larger area than the area of initial contact. In certain particular cases in which a distribution to one-fourth of the protector is achieved, no brackets (like the optional brackets 114) are used. By using such brackets, it is believed greater and more efficient, force distribution will be achieved and separation of a body, for example separation of a urethane body from steel inner and outer supports, will be inhibited or reduced.

In one aspect of the protector 200, zone depth in inches is as follows: zones 211, 28cm (11 inches); zones 212, 33cm (13 inches); zones 213 13 inches; and zones 214, 3 or 28cm (11 inches).

It is within the scope of the present invention to

employ energy management zones which, viewed from above, are generally triangular (like the zones 211 - 214, Figure 10) with bases of adjacent zones adjacent each other, with apices of adjacent zones opposite each other (see apex a and apex b, Figure 10) . Optionally, each pair of generally triangular zones is spaced-apart from each other pair by a relatively large body part (for example see body parts 222, 224, Figure 10) or by a relatively large body part and a rib (for example, see body part 221 and rib 216, Figure 10) . Optionally, a relatively large body part has a plurality of spaced- apart ribs radiating from it (for example see ribs 217 and 218 with respect to body part 222, Figure 10; see, ribs 217, 216, 217 with respect to body part 221, Figure 10) . Optionally, at an area of expected impact energy management zones are adjacent a relatively large body mass (for example see zones 212, 211, 214, 213 adjacent a mass including body parts 222, 224, Figure 10), a relatively large mass which extends fro an outer surface of the body to an inner surface thereof. It is within the scope of the present invention for the shape of the energy management zones , as viewed from above , to be any suitable shape, including, but not limited to, square, rectangular, pentagonal, hexagonal, heptagonal, with or without rounded-off corners and with equal length sides or unequal length sides, for example, as those shown in Figure 1OA.

The brackets 114, shown in Figures 8A, 8B and 3B, serve as mechanical anchors for the body material of a protector half. It is within the scope of the present invention for these anchors to be any suitable shape or size so long as they protrude from their respective support sufficiently to anchor the body to the support.

Figure 8C shows several alternative shapes for these retaining brackets 114 as viewed from above. The retaining brackets 114 may be anchoring brackets. In use within a body of a protector, a portion, in some cases a substantial portion, of these anchoring brackets is encased in the material of the body of a protector.

Any energy management zone of any keel joint or centralizer in accordance with the present invention may extend all the way through the protector or centralizer body. For protectors in accordance with the present invention or centralizers in accordance with the present invention, halves thereof may be secured together by frangible members and/or shear bolts which break under a certain predetermined load. In certain aspects, a keel joint in accordance with the present invention has a body having a first primary body part, a second primary body part, a third primary body part, and a fourth primary body part (primary body parts like the parts 222, Figure 10); the plurality of spaced-apart energy management zones (for example as in the protector 200) including a plurality of first zones, a plurality of second zones , a plurality of third zones , and a plurality of fourth zones; the plurality of first zones projecting inwardly of the body from the first primary body part (for example the zones 211, 212, 213, 214, Figure 10) and the plurality of second zones projecting inwardly of the body from the second primary body part (for example the zones 211, 212, 213, 214, Figure 10) ; the plurality of third zones projecting inwardly of the body from the third primary body part (for example the zones 211, 212, 213, 214, Figure 10); and the plurality of fourth zones projecting inwardly of the body from the fourth primary body part (for example

the zones 211, 212, 213, 214, Figure 10). In such a keel joint the body has a central open bore therethrough (for example bore 100, Figure 3B or a bore formed between two halves as shown in Figure 10) ; an inner support (for example support 120, Figure 3B or support 238, Figure 10) ; an outer support (for example support 140, Figure 3B or support 240, Figure 10A); the inner support spaced- apart from the outer support; and a secondary body part extending from each primary body part to an inner support (for example the part 224, Figure 10 or the rib 166, Figure 3B) . In such a keel joint, in certain aspects, there is a bracket in each primary part and encased therein (for example a bracket 114 on the support 140, Figure 3B) ; and a bracket in each secondary part and encased therein (for example a bracket 114 on the support 120, Figure 3B) .

In certain aspects, a keel joint in accordance with the present invention h as a first half having a first inner support and a first outer support and a second half having a second inner support and a second outer support (for example, the two halves 101, 102, Figure 3B); each inner support having a first end and a second end; a first inner lip on the first end of the first inner support adjacent an edge of the first body half, a second inner lip on the second end of the first inner support each adjacent an edge of the first body half, a third inner lip on the second inner support adjacent an edge of the second body half, a fourth inner lip on the second inner support adjacent an edge of the second body half (see, for example, lips 120s, Figure 3B) ; a first outer lip on the first outer support adjacent an edge of the first body half, a second outer lip on the first outer support adjacent an edge of the first body half, a third

outer lip on the second outer support adjacent an edge of the second body half, and a fourth outer lip on the second outer support adjacent an edge of the second body half (outer lips for example the lips 14Op, Figure 3B) . In certain aspects, a keel joint in accordance with the present invention has a plurality of energy management zones , each energy management zone having a depth and a plurality of adjacent energy management zones having different depths (for example the zones from a one o ' clock to a three o ' clock position as viewed in Figure HF) . In certain aspects a keel joint in accordance with the present invention has a plurality of the spaced-apart energy management zones each having portions therein with different depths (for example the zones 321 with zones 326 therein, Figures HF and HG) .

Figures HA to HC show an exploded view of two protectors 300 , 302 in accordance with the present invention (which may be any protector in accordance with the present invention) which are joined together by pins 304 or bars which have portions that extend with a friction fit into holes 306, 308 of the adjacent protectors 300, 302.

Figure HD shows an end view of one embodiment of the protector 302. The protector 302 as shown in Figures HD and HE has two halves 311, 312 each with an inner support 313 and an outer support 314, each with a plurality of anchor brackets 315 and bodies 3Ha, 312a, respectively anchored to the brackets 315 and made, in one aspect, of polyurethane which is bonded to the inner surfaces of the supports 313, 314. A plurality of spaced-apart ridge members 316 made of polyurethane or some other non-electrical-conductor material encircle the circle formed by inner surfaces of the inner supports

313. The halves 311, 312 may be releasably secured together around a riser with any securement structure disclosed herein.

In one aspect the protector halves 311, 312 have a plurality of energy management zones, 321, 322, 323, 324 adjacent each other (with the zones 322, 323, 325, and 326 projecting further downwardly from a floor of zones 321) . As is true for any embodiment hereof, the zones may be of the same or of different depths , and/or as in certain aspects, the zone sides are tapered (as may be any zone of any protector disclosed herein), for example, but not limited to, with a two degree taper. Figures HF - HH provide a key for zone depth for one particular embodiment of the protector 300 (the end of the protector 300 opposite the end shown in Figures HD and HE has corresponding zones) . The zones blacked out in Figure HF are 7.6cm (three inches) deep; those in Figure HG, 32cm (twelve-and-a-half inches) deep; and those in Figure HH, 28CM (eleven inches) deep. Some (not all) of the corresponding zones are shown in Figure HC. As is true for any keel joint in accordance with the present invention or centralizer in accordance with the present invention, energy management zones reduce the amount of material in a body and facilitate the distribution of a focused or what is essentially a point load over a larger area and mass.

Figures 14A and 14B show a protector 400 in accordance with the present invention which has two halves 401, 402 each with a body 401a, 402a, respectively. Each half has an inner support 403 with body anchor brackets 404 and securement structure 405 for releasably securing the two halves 401, 402 together. Recesses 406 provide access to the securement structures

405. Each body half 401, 402 has a plurality of spaced- apart energy management zones 407 and 408. Corresponding top and bottom zones (as viewed in Figure 14B) have floors (for example see the floors 407f, 407g, Figure 14B) which are spaced-apart by a certain amount of the mass of the body of the protector. As shown the zones 407 are all of the same depth as are the zones 408 and the depth of all zones is the same. As with any protector in accordance with the present invention, the zone depth for any zone may be a percentage of the total height (height h as viewed in Figure 14B) which is, in certain aspects, between 10 and 45% of the height; in certain aspects with individual zones with depths of 10.7% of h, 39.2% of h, and 44.6% of h; and, in certain aspects, with at least two inches between the floors of corresponding zones .

Figures 12A and 12B show a keel joint 500 in accordance with the present invention which includes a plurality of spaced-apart protectors 502 on a riser pipe 504 with rings 506 between the protectors 502. A protective shell 508 (only half shown in Figure 12 A) is secured around the protectors 502. The rings 506, secured to the riser pipe 504, hold the protectors in place on the riser pipe 504 and support the weight of the protectors .

Figures 13A and 13B show a keel joint 600 in accordance with the present invention which includes a plurality of spaced-apart protectors 602 on a riser pipe 604 with spacers 606 between the protectors 602. A protective shell 608 (only half shown in Figure 13 A) is secured around the protectors 602. As is true for any embodiment herein, rings, like the rings 606 can be deleted either so the protectors have empty space between

them or so that protectors are positioned in contact with each other. Radially-oriented holes 610 extend through at least a portion of the protectors 602. Radially- oriented holes extend through at least a portion of the rings 606.

In certain particular aspects a structure in accordance with the present invention (any disclosed herein) is used as a centralizer on a wellbore tubular (pipe, casing, tubing) . Figure 15 shows a centralizer 700 in accordance with the present invention on a tubular member 702. The centralizer 700 may have the structure, materials, and details of any protector described above or disclosed herein.

A centralizer in accordance with the present invention may be used, for example, in place of centralizers as disclosed in U.S. patents 7,159,668; 6,435,275; 5,908,072; 5,881,810; 5,575,333; 5,261,488; 5,238,062; 5,095,981; 4,984,633; 4,794,986; 4,787,458; 3,963,075; 3,528,499; and 3,052,310. The present invention, therefore, provides in at least some, but necessarily all, embodiments: keel joint protector including: a body made of flexible material, a central open bore through the body, and the body having a plurality of spaced-apart energy management zones therein for diffusing a force applied to a particular part of the body. Such a system may include one or some, in any possible combination, of the following: wherein the flexible material is polyurethane ; the body having a central open bore therethrough, an inner support, an outer support, and the inner support spaced-apart from the outer support; wherein the body is molded onto the inner support and the outer support; wherein the inner support has a plurality of spaced-apart openings

therethrough, said openings containing a portion of the flexible material that makes the body; a plurality of brackets on the inner support projecting outwardly from the inner support into the body, a plurality of brackets on the outer support projecting inwardly from the outer support into the body, and a portion of each bracket encased in the flexible material of the body; the body having a first primary body part, a second primary body part, a third primary body part, and a fourth primary body part, the plurality of spaced-apart energy management zones including a plurality of first zones, a plurality of second zones , a plurality of third zones , and a plurality of fourth zones, the plurality of first zones projecting inwardly of the body from the first primary body part, the plurality of second zones projecting inwardly of the body from the second primary body part, the plurality of third zones projecting inwardly of the body from the third primary body part, and the plurality of fourth zones projecting inwardly of the body from the fourth primary body part; the body having a central open bore therethrough, an inner support, an outer support, the inner support spaced-apart from the outer support, and a secondary body part extending from each primary body part to an inner support; a bracket in each primary part and encased therein, and a bracket in each secondary part and encased therein; wherein the energy management zones extend down into the body at different depths ; an inner layer of flexible material on the inner support, and the central open bore defined by the inner layer; a plurality of spaced-apart gaps in the inner layer; the body made of two halves connected together including a first half and a second half; the first half having a first inner

support and a first outer support, the second half having a second inner support and a second outer support, each inner support having a first end and a second end, a first inner lip on the first end of the first inner support adjacent an edge of the first body half, a second inner lip on the second end of the first inner support each adjacent an edge of the first body half, a third inner lip on the second inner support adjacent an edge of the second body half, a fourth inner lip on the second inner support adjacent an edge of the second body half, a first outer lip on the first outer support adjacent an edge of the first body half, a second outer lip on the first outer support adjacent an edge of the first body half, a third outer lip on the second outer support adjacent an edge of the second body half, and a fourth outer lip on the second outer support adjacent an edge of the second body half; a first fastener connecting the first inner lip and the third inner lip, and a second fastener connecting the second inner lip and the fourth inner lip; a third fastener connecting the first outer lip and the third outer lip, and a fourth fastener connecting the second outer lip and the fourth outer lip; a first fastener connecting the first inner lip and the third inner lip, a second fastener connecting the second inner lip and the fourth inner lip, a third fastener connecting the first outer lip and the third outer lip, and a fourth fastener connecting the second outer lip and the fourth outer lip; each energy management zone having a depth; and a plurality of adjacent energy management zones having different depths ; and/or a plurality of the spaced-apart energy management zones each has portions therein with different depths .

The present invention, therefore, provides in at

least some, but necessarily all, embodiments: a keel joint protector including: a body made of flexible material , a central open bore through the body, the body having a plurality of spaced-apart energy management zones therein for diffusing a force applied to a particular part of the body, an inner support connected to the body, an outer support connected to the body, the inner support spaced-apart from the outer support, the inner support having a plurality of spaced-apart openings therethrough, said openings containing a portion of the flexible material, a plurality of brackets on the inner support projecting outwardly from the inner support into the body, a plurality of brackets on the outer support projecting inwardly from the outer support into the body, a portion of each bracket encased in the flexible material, the body made of two halves, including a first half and a second half, the first half connected to the second half with fasteners.

The present invention, therefore, provides in at least some, but necessarily all embodiments, a keel joint including: a riser pipe; a plurality of keel joint protectors on the riser pipe comprising at least one pair of keel joint protectors; each of the plurality of keel joint protectors comprising a body made of flexible material, a central open bore through the body, the body having a plurality of spaced-apart energy management zones therein for diffusing a force applied to a particular part of the body; a support ring between each pair of keel joint protectors; and a protective shell over the keel joint protectors and support rings.

The present invention, therefore, provides in at least some, but necessarily all embodiments, a method for protecting a hull of a rig with respect to a keel joint

adjacent the hull, the keel joint extending through an opening in the hull, the method including: positioning a keel joint with respect to a hull, the keel joint extending through an opening in the hull, the keel joint comprising a body made of flexible material, a central open bore through the body, the body having a plurality of spaced-apart energy management zones therein for diffusing a force applied to a particular part of the body; and contacting the hull with the keel joint so that a force is applied to the body of the keel joint and said force is diffused in the body.

The present invention, therefore, provides in at least some, but necessarily all embodiments, a centralizer for centralizing a tubular, the centralizer including: a body made of flexible material, a central open bore through the body, and the body having a plurality of spaced-apart energy management zones therein for diffusing a force applied to a particular part of the body.