Method and apparatus for orienting perforating devices
The present invention provides an apparatus and method of orienting perforating gun strings conveyed on a tool string. One embodiment of the present invention provides an orienting weight provided in a portion of the perforating device, such as the shaped charge, the loading tube or the gun housing. An adapter is provided intermediate the tool string that facilitates conveyance of the gun string downhole. Additionally, the adapter enables the gun string to rotate independent of the tool string.
1. An oriented perforating gun affixed to a tool string, comprising:
one or more eccentrically weighted gun string components;
a swivel intermediate the one or more gun string components and the tool string, the swivel enabling the one or more gun string components to rotate independently from the tool string, the swivel comprising:
a thrust bearing;
a bearing floater adapted to cooperate in reducing the load applied to the thrust bearing upon application of a sufficient axial load to the swivel;
a shaft; and
a collar, the bearing floater being positioned between the shaft and the collar such that an axial movement of the shaft relative to the collar under axial loading compresses the bearing floater, the bearing floater compressing until further axial movement of the shaft is prevented and any increased axial loading is transferred directly from the shaft to the collar without passing through the thrust bearing.
2. The oriented perforating gun of claim 1 , wherein the bearing floater comprises a spring device.
3. The oriented perforating gun of claim 1 , wherein the bearing floater comprises a slotted cylinder capable of deflection under a high load.
4. The oriented perforating gun of claim 1 , wherein the thrust bearing is a roller bearing.
5. The oriented perforating gun of claim 1 , wherein the swivel further comprises a split ring positioned to transfer axial loading directly from the shaft to the collar once the further axial movement of the shaft relative to the collar is prevented.
6. A system for use in a wellbore, comprising:
a tool string;
a perforating gun having at least one eccentrically weighted gun string component; and
a swivel coupled between the perforating gun and the tool string, the swivel comprising a collar, a thrust bearing, and a bearing isolation device to limit the potential load acting on the thrust bearing, the bearing isolation device allowing tensile loading to pass through the thrust bearing until a threshold level, the bearing isolation device then directly transferring any further tensile loading directly to the collar instead of the thrust bearing.
7. The system as recited in claim 6 , further comprising a roller adapter having a plurality of roller wheels to facilitate movement of the perforating gun and the tool string along the wellbore.
8. The system as recited in claim 7 , wherein the plurality of roller wheels are housed within a roller cage.
9. The system as recited in claim 8 , wherein the roller cage is mounted between the tool string and the perforating gun to rotate independently of the perforating gun and the tool string.
10. The system as recited in claim 7 , wherein the plurality of roller wheels are aligned along a longitudinal axis of the roller adapter.
11. The system as recited in claim 6 , wherein the bearing isolation device comprises a bearing floater adapted to reduce the load applied to the thrust bearing under high tensile loading.
12. The system as recited in claim 11 , wherein the bearing isolation device comprises a shaft within the collar, the bearing floater being deployed between the shaft and the collar such that under sufficient tensile load, the bearing floater is compressed until any additional tensile loading is transferred from the shaft to the collar without passing through the thrust bearing.