Claims
- 1. A method for completing an underwater well having a weak formation extending below the conductor casing, which formation cannot otherwise withstand the pressure of the drilling mud required to contain the downhole pressure of the well, comprising the steps of:
- (a) locating drilling means at an underwater well site above the weak formation;
- (b) installing conductor casing in the floor of a body of water with a wellhead, blowout preventer stack, and riser attached thereto at a point near the floor, the riser extending upwardly to the drilling means;
- (c) running a drill string and standard drill bit through the wellhead and conductor casing;
- (d) drilling a hole for suspending an intermediate-sized formation support casing within said wellhead and conductor casing;
- (e) lowering a hanger-support member having the intermediate-sized formation support casing string attached thereto into the well until the hanger-support member lands in the wellhead, said intermediate-sized formation support casing string extending below the conductor casing and through the weak formation;
- (f) rotating the hanger-support member less than 360.degree. to connect the hanger-support member within the wellhead;
- (g) latching the hanger-support member within the wellhead;
- (h) drilling a hole for suspending the outermost surface casing within the wellhead and conductor casing and the intermediate-sized formation support casing;
- (i) running a casing hanger with such outermost surface casing string attached thereto through the riser and into the wellhead; and
- (j) landing the casing hanger with such outermost surface casing string attached thereto on the hanger-support member.
- 2. Method according to claim 1, wherein the step (e) includes prior to the landing of the hanger-support member in the wellhead, passing a plurality of circumferentially spaced apart groupings of tooth segments on the outer periphery of the hanger-support member downwardly along spaces between a plurality of circumferentially spaced apart groupings of tooth segments on the inner periphery of the wellhead.
- 3. Method according to claim 2, wherein the step (f) includes engaging the tooth segments on the hanger-support member with the tooth segments on the wellhead.
- 4. Method according to claim 2, wherein the step (e) includes prior to passing the groupings of tooth segments on the hanger-support member downwardly along spaces between the groupings of tooth segments on the wellhead, engaging the tops of the uppermost tooth segments on the wellhead with the bottoms of the lowermost tooth segments on the hanger-support member, and rotating the hanger-support member less than one revolution to align the groupings of tooth segments on the hanger-support member with the spaces between the groupings of tooth segments on the wellhead.
- 5. Method according to claim 4, wherein the step (f) includes engaging the tooth segments on the hanger-support member with the tooth segments on the wellhead.
- 6. Method according to claim 1, wherein the step (f) includes engaging circumferentially spaced apart groupings of breech block teeth on the outer periphery of the hanger-support member with correlative circumferentially spaced apart groupings of breech block teeth in the wellhead bore.
- 7. Method according to claim 1, wherein the step (f) includes both holding down and supporting of said hanger-support member within said wellhead by said connection resulting from rotating said hanger-support member less than 360.degree..
- 8. Method according to claim 1, wherein there is included a step (gg) after step (g) and before step (h), including:
- (gg) cementing the intermediate-sized formation support casing string in place below the conductor casing through passageways along the exterior surface of the hanger-support member.
- 9. Method according to claim 8, wherein there is included a step (ggg) after step (gg) and before step (h), including:
- (ggg) installing a packoff ring on the hanger-support member for sealing between the packoff ring and the bore wall of the wellhead and between the packoff ring and the interior bore of the hanger-support member to seal off the upper annulus of the well.
- 10. A method for completing an underwater oil or gas well having a working pressure in the 15,000 psi range and extending through a weak subsurface formation below the conductor casing of the well, the borehole through which is otherwise unable to support, without rupturing, the pressure of the weight of the drilling mud used to contain the bottom hole pressure, comprising the steps of:
- (a) locating drilling means at an underwater well site above the weak subsurface formation;
- (b) installing and cementing a 20 inch conductor casing in the floor of a body of water with a wellhead, blowout preventer stack, and riser attached thereto at a point near the floor, the riser extending upwardly to the drilling means;
- (c) running a drill string and standard 171/2 inch drill bit through the wellhead and 20 inch conductor casing;
- (d) drilling a hole for suspending a 16 inch casing within said wellhead and 20 inch conductor casing;
- (e) lowering a hanger-support member having an upwardly facing support shoulder on its upper end and a 16 inch casing string attached to its lower end into the well until the hanger-support member lands in the wellhead, said 16 inch casing string extending below the 20 inch conductor casing and through the weak formation;
- (f) rotating the hanger-support member less than 360.degree. to connect the hanger-support member within the wellhead;
- (g) latching the hanger-support member within the wellhead;
- (h) cementing the 16 inch casing string in place below the 20 inch conductor casing through passageways along the exterior surface of the hanger-support member;
- (i) installing a packoff ring having an upwardly facing support shoulder on its upper end on the support shoulder of the hanger-support member for sealing between the packoff ring and the bore wall of the wellhead and between the packoff ring and the interior bore of the hanger-support member to seal off the upper annulus of the well;
- (j) drilling a hole for suspending another casing string within the wellhead;
- (k) running a casing hanger with such other casing string attached thereto through the riser and into the wellhead; and
- (l) landing the casing hanger on the support shoulder of the packoff ring.
Parent Case Info
This is a division of application Ser. No. 350,374, filed on Feb. 19, 1982.
US Referenced Citations (11)
Divisions (1)
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Number |
Date |
Country |
Parent |
350374 |
Feb 1982 |
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