Patent Application
20130277052
Hydrocarbon wells, horizontal wells in particular, typically have wellscreen sections having a perforated inner tube with an overlying screen portion. The purpose of the screen is to block the flow of particulate matter into the interior of the production tubing. Despite the wellscreen, some contaminants and other particulate matter still enter the production tubing. The particulate matter usually occurs naturally or is part of the drilling and production process. As the production fluids are recovered the particulate matter is also recovered at the surface. The particulate matter causes a number of problems in that the material is usually abrasive reducing the life of any associated production equipment. By controlling and reducing the amount of particulate matter that is pumped to the surface, overall production costs are reduced.
Even though the particulate matter may be too large to be produced, the particulate matter may cause problems at the downhole wellscreens. As the well fluids are produced the larger particulate matter is trapped in the filter element of the wellscreens. Over the life of the well as more and more particulate matter is trapped in the filter elements the filter elements will become clogged and restrict flow of the well fluids to the surface.
A method of reducing the inflow of particulate matter before it reaches the wellscreens is to pack gravel or sand in the annular area between the wellscreen and the wellbore. Packing gravel or sand in the annulus provides the producing formation with a stabilizing force to prevent any material around the annulus from collapsing to produce particulate matter and it also provides a pre-filter to stop the flow of particulate matter before it reaches the wellscreen.
In certain gravel packing operation a screen with a detachable member, a crossover tool, and packer are run into the wellbore together. Once the screens, crossover tool, and packer are properly located the packer is set so that it forms a seal between wellbore and the screen isolating the annular region above the packer from the annular region below the packer. The bottom of the screen is sealed so that any fluid that enters the screen should pass through the screening or filtering material.
The crossover tool has a port that directs all fluid flow from inside of the tubular to the outside of the tubular including the screens below the crossover. The crossover tool has a second port that allows fluid to flow from the interior area of the screen below the crossover tool to an annular area around the exterior of the tubular but above the packer.
Once the packer is set, a slurry, usually containing gravel, may be pumped down the well through the tubular. When the slurry reaches the crossover tool it exits the crossover tool below the crossover tool and into the annular space created on the outside of the screen.
As the slurry travels from the top of the well toward the bottom along the outside of the screen the gravel is deposited as the transport fluid that carries the gravel drains to the inside of the screen. As the fluid drains into the interior of the screen it becomes increasingly difficult to pump the slurry down the wellbore. Once a certain portion of the screen is covered the gravel will start building back from the bottom towards the top to completely pack off the screen.
After the annular area around the screen has been packed with gravel then the operator releases the packer and crossover tool from the detachable member and reverses out. After the packer and crossover tool have been released a detachable member will remain as a reconnection point. The detachable member is required to allow the operator to reconnect to the liner before the well is put into service.
Generally, some type or mechanical packer or packoff mechanism is used to seal the annulus inside the well casing and outside of the liner so that all flow is directed through the gravel pack and into the liner. This prevents flow up the annulus which could remove the gravel pack sand from around the liner. Typically the packer is run in as a separate device that attaches to the detachable member with the production tubing attached above the packer. This assembly must be run into the well, attached to the liner and then mechanically or hydraulically actuated to seal the device to the annulus. The time to run these sealing mechanisms as well as the cost of these tools can be significant.
There exists, therefore, a significant need for an improved packer assembly for use in gravel pack operations that can eliminate additional trips downhole. The present invention fulfills these needs and provides further related advantages.
In an embodiment of the invention a swelling packer element is incorporated onto the screen tubular above the screening section but below the detachable member. The swelling packer element typically has diameter that allows for freely circulating a gravel and sand slurry around the swelling packer elements exterior when run in and when initially installed in the well. Typically the swelling packer element does not swell sufficiently to form a seal between the tubular and the wellbore or casing until the gravel pack operation is complete.
A swelling packer element below the detachable member would eliminate the need to run a separate mechanical packer or packoff mechanism to seal the annulus inside the well casing and outside of the liner
As used herein the terms “swellable”” means any material that increases in size in the presence of an activation fluid such as a hydrocarbon, water, a hybrid fluid, or other activation fluid.
The description that follows includes exemplary apparatus, methods, techniques, and instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details.
Typically the swellable packer 50 is a swellable elastomer such as ethylene propylene diene monomer that swells in the presence of hydrocarbons, a blend of nitrile with super absorbing polymers (SAP) that swells in the presence of water, or a blend of ethylene propylene diene monomer with super absorbing polymers that swells in the presence of an activation fluid that could incorporate either a water or hydrocarbon base. Where the swellable elastomer is wrapped around the exterior of the blank base tubular 16.
As the wellbore assembly is run into the wellbore the bridge plug 22 in the wellbore 20 serves to locate the wellbore assembly 10 and to isolate the particular formation of interest adjacent to the perforations 24 from the lower portion of the wellbore 20. The bull plug 12 serves to guide the wellbore assembly 10 into the wellbore 20 while preventing the wellbore assembly 10 from hanging on any protrusions that might exist in the wellbore 20. The bull plug 12 also serves to seal the lower end of the screen 14 from the exterior of the screen 14 thereby forcing any fluid to flow through the screen 14 before entering the interior of the screen 14. During the initial run-in stage the packer has not yet swelled any appreciable amount.
With the desired section of the wellbore 20 isolated the gravel packing operation may begin. A gravel slurry, depicted by directional arrow 34, is pumped down the tubular string 32. As the gravel slurry moves through the interior of the wellbore assembly 10, it moves through the interior of the mechanical packer 30 arriving at the crossover tool 28. At the crossover tool 28 and as depicted by directional flow arrow 40, the gravel slurry passes though ports 36 and moves into the annular region created by the wellbore 20, the wellbore assembly 10, the bridge plug 22, and the mechanical packer 30. During the gravel packing stage the swellable packer 50 has not yet swelled any appreciable amount and has a diameter that does not significantly impede the flow of gravel slurry as the gravel slurry flows from the crossover tool 28 down the annulus 38 towards the screen 14. The gravel slurry then moves towards the perforations 24, the formation 54, and the screen 14. Once the gravel slurry reaches the screens 14 the gravel is trapped in the annular region 38 while the transport fluid, as depicted by directional arrow 42, passes through the screen 14 and back into the interior of the screen 14, leaving the gravel 56 to fill in the annular region 38 adjacent to the screens 14. The transport fluid then moves upward towards the crossover tool 28. At the crossover tool 28 the transport fluid enters a passageway that isolates the transport fluid from the gravel slurry while allowing the transport fluid to flow upward through the interior of the mechanical packer 30. Once the transport fluid is above the mechanical packer 30 the passageway allows the transport fluid, as depicted by directional arrow 46, to pass through a port 44 connecting the passageway with an annular region between the wellbore 20 and the tubular string 32.
In certain instances such as when the reservoir pressure is low or depleted a pump may be added above the swellable packer to help lift the fluid and gas to the surface. The type of pump used will depend upon the particular application, but the pump could include an electric submersible pump, a rod driven pump such as a progressive cavity pump or barrel pump, or a gas lift pump may be used.
While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible. For example, the implementations and techniques used herein may be applied to
Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter.
