DRILLING RIG WITH SHIFTABLE CROWN BLOCKS

• US 3,658,298 A
• Filed: 10/14/1969
• Issued: 04/25/1972
• Est. Priority Date: 10/14/1969
• Status: Expired due to Term

• Current Assignee: National Oilwell LP (National Oilwell Varco Incorporated)
• Original Assignee: Fletcher H. Redwine, Wesley W. Moore
• Inventors: Moore, Wesley W., Redwine, Fletcher H.
• Primary Examiner(s): Blunk, Evon C.
• Assistant Examiner(s): Maffei, Merle F.
• Application Number:
  US04/866,259
• Time in Patent Office: 924 Days
• Field of Search: 254/190,19B,192 214/2,5,1P
• US Class Current: 254/286
• CPC Class Codes: E21B 15/00 Supports for the drilling machine, e.g. derricks or masts

Abstract

A drilling rig equipped with two sets of hoisting mechanisms. The two crown blocks are shiftable to enable either block to be positioned over the drill hole. The crown blocks carry depending guides for the two traveling blocks. The guides move horizontally and vertically as the crown blocks are shifted, but are constrained to remain vertical.

Claims

1. In a well-drilling rig which is equipped with two sets of hoisting mechanisms used with a single derrick, said mechanisms including two crown blocks supported at the top of the derrick, means operatively connected with said blocks for shifting them horizontally with respect to the derrick, two traveling blocks, and drilling cables suspending said traveling blocks from the respective crown blocks, the combination therewith of:

respective vertically extending guides beneath said crown blocks;

means connecting said guides with said crown blocks for shifting said guides uniformly horizontally and vertically as said crown blocks shift horizontally;

means connected to said guides and said derrick below said crown blocks constraining said guides to remain vertical as they shift; and

means connected to said traveling blocks and riding on the respective guides, whereby the traveling blocks always move in vertical paths as they are raised or lowered without swaying.

2. A combination as defined in claim 1 in which said crown blocks form part of an assembly which includes shiftable carriers and rotatable elements journaled to the respective carriers, and in which the means connecting said guides with said crown blocks includes flexible members anchored at one of their ends to the top of said derrick, running over the respective rotatable elements;

and anchored at their opposite ends to said guides, whereby said guides move equal distances horizontally and vertically as said crown blocks are shifted horizontally.

3. A combination as defined in claim 1 in which the means constraining said guides to remain vertical include a plurality of links pivoted to said derrick and to said guides.

4. In a well drilling rig which is equipped with two sets of hoisting mechanisms used with a single derrick, said mechanisms including two crown blocks supported at the top of the derrick, means operatively connected with said blocks for shifting them horizontally with respect to the derrick, two traveling blocks, and drilling cables suspending said traveling blocks from the respective crown blocks, said crown blocks being part of an assembly which comprises:

a pair of linear roller bearings, each of which includes a respective lower race fixed to the top of the derrick, rollers riding in said lower race, and a respective upper race riding on said rollers;

base members on said crown blocks fixed across said upper races;

respective carriers fixed to the undersides of said base members;

sprockets journaled to each of said carriers; and

power means connected to said carriers for shifting said crown blocks horizontally as a unit;

said rig also including;

chains having one end anchored with respect to the top of the derrick and running over said sprockets; and

a pair of guides for said traveling blocks depending from said chains and movable uniformly horizontally and vertically as said crown blocks are shifted.

5. An aSsembly as defined in claim 4 comprising in addition links pivoted to said guides and to the derrick constraining the guides to a vertical position as they move.

6. An assembly as defined in claim 4 in which the upper races are of sectional construction bolted end-to-end to enable either crown block and its upper races and carrier to be removed without disturbing the other.

7. An assembly as defined in claim 4 in which said power means includes a movable fluid-pressure cylinder extending through said carriers and attached thereto, hollow piston rods fixed to the top of the derrick and extending into each end of said cylinder, and pistons on said piston rods within said cylinder.