Wells – Packers or plugs – With expanding anchor
Reexamination Certificate
1999-08-31
2001-03-20
Schoeppel, Roger (Department: 3672)
Wells
Packers or plugs
With expanding anchor
C166S322000, C166S323000
Reexamination Certificate
active
06202747
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to oil and gas well completion and production. In particular, the present invention relates to hydraulically controlled packer structures and associated methods utilized in well completion and production activities.
2. Description of the Prior Art
It is well known in the art to provide a well packer between the outer casing and the production tubing of an oil or gas well to isolate and seal off production fluids. It is also well known to set such packers hydraulically. Examples of hydraulically set packers can be found in U.S. Pat. Nos. 3,456,723, 3,603,388 and 4,263,968. In the hydraulic packers of the prior art, the setting of the packer would lock the packer in place within the outer casing of the well. To release the prior art packer required mechanical axial or rotational motion so that screws or other retaining means would shear and allow the packer to relax and be withdrawn from the well. In order to reuse the packer of the prior art, it was necessary to remove the packer completely from the well for reassembly with new shear screws or similar retaining means. Also, once set and locked, the packer could not be repositioned within the well bore. This made fine tuning of the packer's location relative to oil-bearing strata difficult.
The mechanical method for releasing prior art packers is particularly disadvantageous in wells containing multiple stacked packers. In these wells, the force required to shear the packers free requires the use of slip joints between packers set in close proximity to assure release of the packers individually. In addition, the modern trend toward intelligent completion components requires hydraulic and electrical conduits through packers. These conduits are easily damaged when mechanical releasing means are used.
Accordingly, there exists a need for a hydraulic packer that can be set, unset and reset prior to locking so that the packer location in relation to oil-bearing strata can be fine tuned and well completion components can be functionally checked. There is also a need for a hydraulic well packer that can be unset and reset without rendering the setting and locking mechanism inoperable so that the well packer can be easily relocated within the well casing without the need to retrieve and reassemble the well packer. Additionally, there is a need for a hydraulic well packer that can be released through application of hydraulic pressure rather than through mechanical axial or rotational motion to allow packer stacking and to protect hydraulic and electrical conduits. These needs are met by the present invention.
SUMMARY OF THE INVENTION
The present invention is directed to various embodiments of a hydraulic well packer. Like prior art hydraulic packers, the hydraulic packer of the present invention uses hydraulic pressure to set and lock within a well casing. In addition, one embodiment of the present invention is capable of unsetting and resetting prior to locking to allow fine tuning of the packer's position within a well. In other embodiments, the hydraulic packer of the present invention is capable of hydraulically unlocking and unsetting so that the packer can be reused in another location within a well without the need for withdrawal from the well for reassembly. The hydraulic unset and release features of the various embodiments also offer advantages in cases where multiple packers are closely stacked or where hydraulic and electrical conduits extending through the packer could be damaged by mechanical motion. The various embodiments of the present invention are summarily described below.
A first embodiment of the present invention is capable of being hydraulically set, unset and reset prior to locking. This embodiment uses three discrete sources of hydraulic pressure, a setting port, an unsetting port, and a locking port. The object of this embodiment is the ability to set and unset the packer multiple times without locking the packer in place. This embodiment features at least one double acting setting piston and at least one locking piston with a ratcheted surface. The setting piston operates slips and sealing elements in the conventional manner. Hydraulic pressure from the setting port actuates the double acting setting piston such that the slips and sealing elements engage the well casing wall. Conversely, hydraulic pressure from the unsetting port actuates the double acting setting piston in the opposite direction allowing the slips and sealing elements to return to their running positions. In this manner, the packer can be repositioned multiple times. When the packer is in the desired position and hydraulically set, hydraulic pressure from the locking port actuates the locking piston. The locking piston abuts the setting piston and the ratcheted surface of the locking piston engages matching ratchets on the mandrel thus locking the slips and sealing elements in place. Once locked in place, this packer can be removed in the conventional manner by axial movement that shears screws thus requiring removal and reassembly prior to further use. Alternatively, hydraulic pressure applied to a release port can shear screws to release the packer.
A second embodiment of the present invention is capable of being hydraulically set and locked as well as hydraulically unlocked and unset. This embodiment uses two distinct sources of hydraulic pressure, a setting port that sets and locks the packer and an unsetting port that unlocks and unsets the packer. A feature of this embodiment is the ability to set/lock and unlock/unset multiple times without being removed from the well. This embodiment uses at least one double acting piston with a cavity having a small section and a large section. The fingers of a collet are disposed within the cavity. The cavity is shaped such that when the fingers are within the small section they are held tightly against the mandrel. Conversely, when the fingers are within the large section the fingers can be readily lifted away from the mandrel. The interior surface of the fingers has ratchets that are designed to engage matching mandrel ratchets and lock the collet in place. The opposite end of the collet is fixed to actuating means that actuate the slips and seal elements in a conventional manner. Application of hydraulic pressure from the setting port forces the double acting piston to carry the fingers over the mandrel ratchets thus setting and locking the packer. Application of hydraulic pressure from the unsetting port forces the double acting piston in the opposite direction thus lifting the fingers away from the mandrel and unsetting the packer to a running configuration.
A third embodiment of the present invention is also capable of being hydraulically set and locked as well as hydraulically unlocked and unset. This embodiment uses two distinct sources of hydraulic pressure, a setting port that sets and locks the packer and an unsetting port that unlocks and unsets the packer. The hydraulic packer of this embodiment is capable of being set/locked and unlocked/unset multiple times without being removed from the well. This embodiment features at least one double acting piston disposed to move axially and capable of actuating slips and seal elements in a conventional manner. At least one locking piston is disposed within the double acting piston and oriented to actuate in a direction perpendicular to the longitudinal axis of the mandrel. The surface of the spring loaded locking piston adjacent to the mandrel is ratcheted and designed to engage matching ratchets on the mandrel. The locking piston is spring loaded so that it naturally presses against the mandrel. Within the locking piston is at least one plunger valve that is normally closed to a bleed port within the locking piston. The packer is set and locked by applying hydraulic pressure to a setting chamber that forces the double acting piston to slide axially and engage the slips and sealing elements. As the double acting piston slides, the locking pis
Hughes John
Lacy Rodger Dale
Newman Billy Ray
Goldstein & Healey LLP
Schlumberger Technology Corporation
Schoeppel Roger
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