Patent Application
20120111580
The technical field of the invention is downhole tools and methods for employing downhole tools in oil and gas wells.
Oil and gas wells are drilled at greater depths than in the past. Extended reach wells may be drilled several miles into the earth, with a large portion of the wellbore oriented in a direction that deviates substantially from the vertical direction. The operation of drill strings and other tubular devices with attached downhole tools at great distances within a deviated wellbore provides significant challenges in the drilling industry.
Sand control screens are employed in wells such as extended reach wells to inhibit entry of sand and other solid particles into the wellbore while at the same time facilitating entry of oil and gas. Screens of this type comprise a considerably heavy mass. Screens may be employed in very long sections that extend as much as one mile in length. The total weight of a screen thousands of feet in length is substantial. The frictional forces generated between the screen and the wellbore during placement of such screens into extended reach horizontal wells poses a significant technical and mechanical challenge. In the placement of such screens, it is necessary to apply a force to the screen that overcomes the frictional forces resisting screen placement. When a wellbore deviates substantially from the vertical direction, it becomes a challenge to generate sufficient forces downhole to move the screen into the desired position within the well.
This invention is directed to apparatus and methods useful for placing components of any type into a well. And, in one particular aspect of the invention, the invention is directed to apparatus and methods for placing sand control screens into wellbores.
In one aspect of the invention, an apparatus is adapted for insertion of a component into a well having a cased hole section. The apparatus comprises a tool member adapted for receiving a wellbore fluid and an engagement mechanism mounted upon the tool member. The engagement mechanism may be configured for selective frictional engagement to the cased hole section of the well. A piston is provided having a first end and a second end connected to the tool member. The piston is configured for axial extension relative to the tool member. A first choke may be attached to the piston, the first choke being configured for receiving pressurized fluid and transmitting fluid force to the piston to extend the piston axially relative to the tool member.
In another aspect of the invention, the apparatus includes an engagement mechanism with a slip. The slip is configured for movement between an inboard disengaged position and an outboard engaged position, wherein the outboard engaged position affords frictional contact between the engagement mechanism and the cased hole section to secure the tool member relative to the cased hole section. The apparatus may include an attachment mechanism upon the second end of the piston. The attachment mechanism may be configured for releasably securing the component to the piston of the tool member. A first choke may be removably secured to the tool member. The tool member may be configured for receiving additional chokes with different fluid flow characteristics. In one embodiment of the invention, a force cone may be employed for receiving pressurized wellbore fluid and transferring force to the slip to actuate the slip to the outboard engaged position.
The invention may be directed to a method for inserting a component into a well using a drill string with a tool member secured to the drill string. In the method, the well may have at least one cased hole section. A drill string is provided with an attached tool member and piston and a component secured to the distal end of the piston. The drill string is lowered into a cased hole section of a well. Then, a fluid is pumped through the drill string to the tool member. Fluid pressure is applied to the tool member that forces, with fluid pressure, an engagement mechanism of the tool member into frictional contact with the cased hole section. The tool member is secured relative to the cased hole section of the well. Fluid is forced through a choke attached to the piston to generate force upon the piston. Then, the piston is extended axially relative to the tool member, thereby inserting the component into the well. Once the component and piston are extended, the fluid pressure may be reduced, which releases the engagement mechanism from frictional engagement with the cased hole section. Subsequently, the drill string is lowered further into the well. This assists in returning the piston to a retracted position within the tool member. This procedure of raising pressure, followed by reducing pressure and lowering the drill string, may be repeated as many times as needed until the component (i.e. screen, perforating gun, or other device) is positioned correctly in the well. In the case of a screen, it is possible to release the screen from the piston in the proper position for well production through the screen.
In one aspect of the method of the invention, fluid pressure may be applied to the cone, the cone being configured for receiving pressurized fluid and transmitting force to the slips. The slips are engaged against the cased hole section of the well. In some applications of the method, a spring is applied to the cone and the spring is compressed during the application of pressure to the cone. The spring is relaxed upon reduction of fluid pressure to the cone.
In the specific embodiment of the invention that involves the placement of a screen, the screen may be released by rotating the drill string, thereby disengaging the screen. This may be accomplished, for example, by employing left-handed threads at threaded connection 58, as further discussed herein. In other applications, it may be possible to release a component, such as a screen, by applying elevated fluid pressure to break a pressure activated rupture disk, thereby releasing the component from the tool member. Other methods known in the art for releasing a component from a drill string could be used as well.
Essentially any commonly used oilfield fluid can be employed for the application of fluid pressure in the invention, including for example, brine, hydrocarbon, water based mud, oil based mud or pseudo-oil based mud. In some applications of the invention wherein excessive fluid loss into the formation is experienced, it may be useful to employ a fluid loss additive that is pumped with the fluid into the wellbore, through the choke, and into the formation. The fluid loss additive may be selected from essentially known and effective additive, including hydroxyethylcellulose (HEC) polymers, xantham gums derived from a strain of Xanthomonus campestris (XC), polymers having sized solids, and also degradable solid polymers. Such a fluid loss additive may include as well calcium carbonate or a calcium carbonate-containing additive. Thus, the invention may be particularly useful to resolve fluid loss problems by the use of fluid loss additives, which may be transported through the choke and into the subterrenean formation. The ability to pump fluid loss additives during the deployment of the component into the wellbore is a significant advantage in the use of the invention.
In one embodiment of the invention, an apparatus and method is disclosed for insertion of a component into a well. The component may be a gravel pack screen, perforating gun, or other mechanical device. Further, the invention may be applied to insertion of such a component into shallow reservoirs with relatively long well sections that deviate from vertical.
In some applications of the invention, a swiveling tool (not shown) may be applied between the drill pipe and the tool member. Such a swiveling tool could function to facilitate the rotation of the deployment string without rotating the tool member and screen. One example of such a swiveling tool is the Caledus SwivelMASTER™, manufactured by Caledus UK Ltd of Aberdeen, Scotland, which is a drill pipe deployed tool to aid sand control screens or liners to be run at high angles or in tortuous wells to achieve the required depth.
In the practice of the invention, it is possible to provide a pressure activated tool member that will anchor to the inner surface of the casing and then provide a downward stroke of a piston into the well, thereby driving a screen or other component into the well. A number of pressure cycles may be deployed until the component is located at the appropriate depth in the well.
Referring now to
When the screen 32 has reached the appropriate place in the wellbore 24, the fluid in fluid cavity 48 has entered inlet 64 (as shown in
As the circulating pressure of the fluid cavity 48 is further increased, force is applied upon choke 46 and upon the piston 50. Fluid pressure causes piston 50 to move in the axial direction 60 into the wellbore 24, which carries the screen 32 into the wellbore.
The step sequence of (1) elevating fluid pressure, (2) engaging the casing 22, (3) hydraulically pushing the piston 50 and screen 32 into the wellbore 24, (4) lowering fluid pressure and then (5) moving the drill pipe 26 into the wellbore 24 to reset the piston 50 is repeated as many times as is required to place the screen 32 into the desired position in the wellbore 24.
Once the screen 32 (or other component) is positioned in the wellbore 24, a packer 30 may be set against the casing (see
In the application wherein the component is a perforating gun (not shown), the perforating gun would not be released, but would be retracted from the well with the drill pipe 26 once perforation operations are completed.
In the specific application of placement of a screen, the screen may be released by rotating the drill string, thereby disengaging the screen, as shown in
If a fluid loss additive is deployed, the fluid loss additive may be added to the fluid and provided through the choke 46 for deployment into the formation. This may assist in blocking fluid loss into the formation. It is one advantageous feature of the invention that a fluid loss additive may be provided through the apparatus and into the formation during the deployment of the apparatus into the wellbore. The additive may be selected from essentially known and effective additive for oilfield use. Such additives may include hydroxyethylcellulose (HEC) polymers, xantham gums derived from a strain of Xanthomonus campestris (XC), polymers having sized solids, and also degradable solid polymers. Such sized solids may include calcium carbonate or salts. HEC is a known polymer that is used in gravel pack fluid systems. XC polymers are known for having good gel strength.
All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
