GB2117815A - Subsea wellhead and orienting apparatus - Google Patents

Abstract

A subsea wellhead with suitable orienting means 26 including a conductor pipe 16 having an internal mule shoe 22 ending in a slot 24, a downhole well member 28, a collar 30 secured around said member, a key ring 34 having an external key 40 and being rotatable about the collar 30 and means 38 for securing the key ring to said collar in a preselected oriented position whereby engagement of the key on the mule shoe helical shoulder and in the slot provides the preselected orientation of the downhole member. <IMAGE>

Description

SPECIFICATION Subsea welihead and orienting apparatus A subsea wellhead tree may require relatively fine alignment of the production lines with the flowlines connecting thereto. With a guidelineassisted completion, the tree orientation usually has included running the 30 inch conductor housing and drilling guidebase in approximate orientation; rotating the guidebase and conductor housing to the exact heading with a torque tool; and orienting the tubing hanger within a vertical slot machined in the interior of the blowout preventer wellhead connector.

Such orientation has been used with success in shallow water but in deeper water and with bottom conditions which make rotating the guidebase and conductor housing difficult, success is not readily achieved particularly where a fine alignment (+2 or 30) is needed.

Additionally alignment becomes a problem in those subsea completions which are without guidelines (guidelineless).

The present invention provides an improved subsea wellhead which is used to provide fine alignment of the production lines with the connecting flowlines and is particularly suitable for deep water completion, guidelineless completions and completion in difficult bottom conditions. The wellhead includes an internal mule shoe in the conductor pipe, a collar secured to a downhole member and a key is secured to the collar in a selected position whereby on running of the downhole member the key coacts with the mule shoe to orient the member and the production tubing to a preselected position.

An object of the present invention is to provide an improved subsea wellhead which provides simple and accurate orientation of the welihead completion equipment.

Another object is to provide an improved subsea wellhead which provides orientation of the production lines with the flowlines in a guidelineless completion.

Another object is to provide a wellhead system which requires no operations to orient the blowout preventer stack.

A further object is to provide an improved subsea well head which does not require high torque orientation even in deep water with difficult bottom conditions.

These and other objects, features and advantages of the present invention are hereinafter set forth and explained with reference to the drawings wherein: FIGURE 1 is a vertical section view of subsea well showing the conductor housing with the internal mule shoe. FIGURES 1 A and 1 B are the upper and lower portions thereof respectively.

FIGURE 2 is a partial plan view and partial sectional view taken along line 2-2 and FIGURE 1.

FIGURE 3 is a detailed sectional view of one form of the improved orienting ring of the present invention.

FIGURE 4 is a view taken along line 4-4 in FIGURE 3.

FIGURE 5 is a sectional view of a modified form of improved orienting ring.

As shown in FIGURES 1A and 1 B subsea wellhead 10 is shown with production tubing 12 extending from well bore 14 which is lined by conductor pipe 1 6 and has upwardly facing funnel 1 8 supported on base 20. Mule shoe 22 is positioned on the interior of conductor pipe 1 6 and ends in slot 24.

Orienting means 26 hereinafter described is secured connected to downhole well member 28 such as a flowline extension spool, a completion riser or a tieback spool. Orienting means 26 includes collar 30 which is secured to well member 28 as by welding or other suitable means as shown in FIGURE 3. Collar 30 includes outer downwardly facing shoulder 32. Key ring 34 surrounds collar 30 and has its upwardly facing shoulder 36 in engagement with shoulder 32 on collar 30. Set screws 38 are used to retain key ring 34 in position on collar 30. Key 40 is secured on the exterior of key ring 34 and is of a proper size to pass into slot 24. The upper surface of collar 30 is marked as shown in FIGURE 4 so that the relative position of key ring 34 with respect to production tubing 12 is easily read.When key ring 34 is properly positioned with respect to collar 30 set screws 38 are set and they are welded together around their top and bottom adjacent surfaces as shown by welds 46 and 48.

FIGURE 5 illustrates a modified form of orienting means 26a which includes collar 50 secured to downhole member 28a as by welding or other suitable means. Key ring 52 is threaded onto the exterior of collar 50. It is preferred that such threads be close fitting stub Acme threads.

Key ring 52 includes key 54 secured on its exterior. Key 54 is suitable for riding mule shoe 22 onto slot 24 to provide the desired orientation for downhole member 28a. When key ring 52 has been positioned as hereinafter explained it is secured to collar 50 as by welding.

The improved orienting apparatus of the present invention is useful for subsea completions when the conductor pipe has been cemented. A well survey, generally called a single shot, is run to determine the exact position of slot 24 with respect to a compass. Since the position of the flowlines is known the correct position of key 40 or 54 is determined and the key ring being used is secured in such predetermined position. This position aligns production tubing with the flowlines. This does not require orienting the blowout preventer stack. It does, however, provide the proper orientation for the drilling tieback spool, the downhole master valve assembly and the above mudline structures which can be keyed to the shallow angle mule shoe helix and slot.

Thus, by providing the adjustable orienting key rings all of this subsea equipment is automatically landed in its preferred orientation.

Claims (12)

1. A subsea wellhead comprising a downhole conductor pipe having a shallow angle internal helical mule shoe, a downhole well member, a collar secured around the exterior of said downhole well member, a key, and means for securing said key to the exterior of said collar in selected orientation to coact with said mule shoe on running of said well member to provide a preselected orientation of said well member when landed.

2. A subsea wellhead according to claim 1 wherein said key securing means includes a key ring having said key secured to the exterior thereof, said key ring surrounding the exterior of said collar.

3. A subsea wellhead according to claim 2 wherein said key ring is welded to said collar with said key in its preselected orientation with respect to said downhole well member.

4. A subsea wellhead according to claim 2 wherein said key ring is threaded on the exterior of said collar

5. A subsea wellhead according to claim 2 wherein said collar has an external shoulder, and said key ring has an internal shoulder engaging said collar shoulder.

6. In combination with a subsea wellhead having a conductor pipe with an internal low angle helix mule shoe ending in a slot, an orienting apparatus comprising a collar suitable for securing to a downhole well member, a key, and means for securing said key in a preselected orientated position to said collar.

7. An orienting apparatus according to claim 6 wherein said securing means includes a key ring having said key secured to its exterior, said key ring surrounding the exterior of said collar.

8. An orienting apparatus according to claim 7 wherein said key ring is welded to said collar with said key in its preselected orientation with respect to said downhole well member.

9. An orienting apparatus according to claim 7 wherein said key ring is threaded on the exterior of said collar.

1 0. An orienting apparatus according to claim 7 wherein said collar has an external shoulder, and said key ring has an internal shoulder engaging said collar shoulder.

11. A subsea wellhead substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

12. An orienting apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.