Wells – Conduit wall or specific conduit end structure – Downhole coupling or connector
Reexamination Certificate
1998-11-23
2001-03-13
Will, Thomas B. (Department: 3671)
Wells
Conduit wall or specific conduit end structure
Downhole coupling or connector
C166S243000, C166S212000
Reexamination Certificate
active
06199632
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates, in general, to tools used during the completion and operation of a subterranean wellbore and, in particular to, a selectively locking locator used to selectively prevent the passage of the locator through a landing nipple once the locator is locked in place within the subterranean wellbore.
BACKGROUND OF THE INVENTION
Without limiting the scope of the present invention, its background will be described with reference to perforating and fracturing a subterranean formation, as an example.
Heretofore in this field, a potentially productive geological formation beneath the earth's surface which contains a sufficient volume of valuable fluids, such as hydrocarbons, may have a very low permeability. As the valuable fluids are contained within pores in the potentially productive subterranean formation, if the pores are not interconnected, the fluids cannot move about and, thus, cannot be brought to the earth's surface without a structural modification of the production zone.
In such a formation having a very low permeability, but a sufficient quantity of valuable fluids in its pores, it becomes necessary to artificially increase the formation's permeability. This is typically accomplished by fracturing the formation, a practice that is well known in the art. Basically, fracturing is achieved by applying sufficient pressure to the formation to cause it to crack or fracture. The desired result of this process is that the cracks interconnect the formation's pores and allow the valuable fluids to be brought out of the formation and to the surface.
In conventional fracturing, the general sequence of steps needed to stimulate a production zone through which a wellbore extends is as follows. First, a plug is set in the well casing at a predetermined depth in the well, proximate the subterranean production zone requiring stimulation. Next, a perforating trip is made by lowering a perforation assembly into the wellbore on a lower end portion of a work string. The gun assembly is then detonated to create a spaced series of perforations extending outwardly through the casing, the cement and into the production zone. The discharged gun assembly is then pulled up with the work string to complete the perforating trip.
Next, the spent gun assembly may be replaced on the work string with a proppant discharge member having a spaced series of discharge openings formed therein. The proppant discharge member is then lowered into the wellbore such that the discharge openings are, at least theoretically, aligned with the gun-created perforations. Proppant slurry is then pumped down the work string so that proppant slurry is discharged through the discharge member openings and then flowed outwardly through the casing and cement perforations into the corresponding perforations in the surrounding production zone. The work string is then pulled out again to complete the stimulation trip and ready the casing for the installation therein of production tubing and its associated production packer structures.
Alternatively, attempts have been made to design a single trip apparatus and method to perforate and stimulate a hydrocarbon formation. In this case, the work string carries a drop-off type perforating gun and a locator installed thereon above the perforating gun. The gun is operatively positioned within the casing by lowering the locator through an internal profile within the nipple to a location below the nipple. The work string is then pulled upwardly to engage the key of the locator in the nipple profile. Once in place, the guns may be fired to create a spaced series of perforations extending outwardly through the work string, the casing, the cement and into the production zone. The gun is now dropped to a location below the perforations. The proppant slurry is then pumped down the work string. The proppant slurry is discharged through the openings in the work string, the casing and the cement into the corresponding perforations in the surrounding production zone.
It has been found, however, the even when the proppant slurry is pumped down the work string on the same trip as the perforation, the alignment, both axial and circumferential, of the gun-created perforations in the work string and in the casing is not maintained unless a substantial overpull tension force is exerted on the portion of the work string above the locator and maintained during the firing of the gun. The desired overpull force, however, may sheer the sheer pins in the locator causing disengagement of the locator from the nipple profile.
A need has therefore arisen for a locator device that may be used during a single trip perforating and fracturing operation. A need has also arisen for such a locating device that may be locked into a nipple profile and support substantial tensile load within the work string without sheering internal sheer pins or releasing from the nipple profile. A need has further arisen for such a locating device that is simple to disengage from the nipple profile once the perforating and fracturing operation has been completed.
SUMMARY OF THE INVENTION
The present invention disclosed herein comprises a locator device that may be used during a variety of downhole operation. The locating device of the present invention may be locked into a nipple profile and support a tensile force in the work string without sheering internal sheer pins or releasing from the nipple profile. The locating device of the present invention is also simple to disengage from the nipple profile once the wellbore operation has been completed.
The locator device of the present invention comprises a mandrel having one or more radial bores through the sidewall thereof. A housing is partially disposed exteriorily around the mandrel. A set of locator keys is disposed between the housing and the mandrel. The locator keys are radially extendable through a window in the housing. The locator keys have a first position wherein the locator keys are engageable with the landing nipple and a second position wherein the locator keys are retracted from the nipple profile. A support ring is disposed between the housing and the mandrel. The support ring prevents movement of the locator key from the first position to the second position until the support ring is axially displaced relative to the mandrel. Disposed within each of the radial bores are pistons that are selectively engagable with the support ring in response to a differential pressure between the interior and the exterior of the locator device. When the pistons are operably engaged with the support ring, axial displacement of the support ring relative to the mandrel is prevented as is retraction of the locator keys from the nipple profile. As such, upward passage of the locator device through the nipple profile is also prevented.
The locator device may include one or more sheerable members extending between the mandrel and the support ring that sheer in response to a predetermined axial force between the support ring and the mandrel. The sheerable members will not sheer, however, when the pistons are operably engaged with the support ring as the axial force from the support ring is transferred to the mandrel through the piston.
A c-ring may be disposed between the pistons and the support ring. The c-ring may include a plurality of teeth that engage a plurality of teeth on the support ring to selectively prevent axial displacement of the support ring relative to the mandrel. The c-ring radially biases the pistons to disengage the pistons from the support ring when the differential pressure between the interior and exterior of the locator device is reduced below a predetermined level. Alternatively, a differential pressure having a gradient opposite that of the prior differential pressure may be acted on the pistons to disengage the pistons from the support ring. For example, if the differential pressure used to engage the pistons requires a higher pressure on the interior of the locator device than on the exterior of the l
Halliburton Energy Service,s Inc.
Herman Paul I.
Petravick Meredith C.
Will Thomas B.
Youst Lawrence R.
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