Patent Application
20080236843
1. Field of the Invention
Embodiments of the present invention generally relate to the control of fluid flow in a wellbore. More particularly, the invention relates to a flow control apparatus that actuates upon contact with an actuating agent in the wellbore.
2. Description of the Related Art
In hydrocarbon wells, horizontal wellbores are formed at a predetermined depth to effectively reach formations bearing oil or other hydrocarbons in the earth. Typically, a vertical wellbore is formed from the surface of a well and thereafter, using some means of directional drilling like a diverter, the wellbore is extended along a horizontal path. Because the hydrocarbon bearing formations can be hundreds of feet across, these horizontal wellbores are sometimes equipped with long sections of screened tubing. Generally, the screened tubing consists of tubing having apertures therethough and covered with screened walls, leaving the interior of the tubing open to the inflow of filtered oil.
Horizontal wellbores are often formed to intersect narrow oil bearing formations that might have water and gas bearing formations nearby. Even with exact drilling techniques, the migration of gas and water towards the oil formation and the wellbore is inevitable due to pressure drops caused by the collection and travel of fluid in the wellbore. Typically, operators do not want to collect gas or water along with oil from the same horizontal wellbore. The gas and water must be separated at the surface and once the flow of gas begins it typically increases to a point where further production of oil is not cost effective. Devices have been developed that control the flow of fluid in a horizontal wellbore. Generally, these devices are configured to allow oil to flow through the device but upon indication of water, the device actuates to block the flow of water through the device. One such device is a flow control system that includes a tubular having a plurality of production nozzles. The flow control system further includes a plurality of balls which float in water to seal off the plurality of production nozzles when water is present in the formation fluid. Even though the flow control system is capable of controlling the flow of fluid in the horizontal wellbore, the flow control system may not effectively operate when the formation fluid comprises a mixture of fluid. Additionally, the flow control system can be expensive to manufacture.
There is a need therefore for a cost effective flow control device that effectively operates to limit the inflow of gas or water into the production tubing from the surrounding wellbore formations.
The present invention generally relates to the control of fluid flow in a wellbore. In one aspect, a flow control device for use in a wellbore is provided. The flow control device includes an inner member having at least one aperture formed therein. The flow control device also includes an outer member disposed around the inner member such that a flow path is defined between the inner member and the outer member. Additionally, the flow control device includes an elastomer member disposed within the outer member adjacent a portion of the flow path, wherein the elastomer member is capable of swelling upon contact with an actuating agent.
In another aspect, a method of controlling fluid flow in a wellbore is provided. The method includes the step of inserting a flow control device into the wellbore. The flow control device includes a flow path therethrough and an elastomer member disposed adjacent a portion of the flow path. The method also includes the step of allowing fluid from a formation in the wellbore to flow through the flow path in the flow control device. Further, the method includes the step of exposing the elastomer member to an actuating agent, thereby causing the elatomeric material to swell. Additionally, the method includes sealing off the flow path as a result of the swelling.
In yet a further aspect, an apparatus for controlling the flow of fluid in a wellbore is provided. The apparatus includes a tubular member with at least one aperture formed therein. The apparatus further includes an outer housing disposed on the tubular member. The apparatus also includes a flow path through the apparatus, wherein the flow path includes the aperture in the tubular member. Additionally, the apparatus includes a seal member disposed between the tubular member and the outer housing, wherein the seal member is configured to swell upon contact with an actuating agent and block the flow path through the apparatus.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
The present invention generally relates to an apparatus and method of controlling fluid flow in a wellbore. More specifically, an apparatus is provided that activates upon contact with an actuating agent. As will be described herein, the apparatus relates to a flow control device. It is to be noted, however, that aspects of the present invention are not limited to a flow control device, but are equally applicable to other types of wellbore tools. Additionally, the present invention will be described as it relates to a wellbore having a single flow control device. However, it should be understood that multiple flow control devices may be employed in the wellbore without departing from the principles of the present invention. To better understand the novelty of the apparatus of the present invention and the methods of use thereof, reference is hereafter made to the accompanying drawings.
Referring back to
The expansion and/or swelling of the elastomer member 125 can take place either by absorption of the actuating agent into the porous structure of the elastomer member 125, or through chemical attack resulting in a breakdown of cross-linked bonds. In the interest of brevity, use of the terms “swell” and “swelling” or the like will be understood also to relate to the possibility that the elastomer member 125 may additionally or alternatively expand.
The elastomer member 125 is typically a rubber material, such as NITRILE™, VITON™, AFLAS™, Ethylene-propylene rubbers (EPM or EPDM), and KALREZ™. The actuating agent is typically a fluid, such as water. In another embodiment, the actuating agent is gas. The actuating agent used to actuate the swelling of the elastomer member 125 can either be naturally occurring in the wellbore 10 or with other specific fluids. The type of actuating agent that causes the elastomer member 125 to swell generally depends upon the properties of the material and, in particular, the hardening matter, material, or chemicals used in the elastomer member 125.
The amount of swelling of the elastomer member 125 depends on the type of actuating agent used to actuate the swelling, the amount of actuating agent, and the amount of elastomer member 125 exposed to the actuating agent. The amount of swelling of the elastomer member 125 can be controlled by controlling the amount of actuating agent that is allowed to contact the elastomer member 125 and the length of time the actuating agent contacts the elastomer member 125. For instance, the material may only be exposed to a restricted amount of fluid where the material can only absorb this restricted amount. Thus, swelling of the elastomer member 125 will stop once all the fluid has been absorbed by the material.
The elastomer member 125 can typically swell by around 5% (or less) to around 200% (or more) depending upon the type of elastomeric material and actuating agent used. If the particular properties of the material and the amount of fluid that the material is exposed to are known, then it is possible to predict the amount of expansion or swelling. It is also possible to predict how much material and fluid will be required to fill a known volume.
The structure of the elastomer member 125 can be a combination of swelling or expanding and non-swelling or non-expanding elastomers. Furthermore, the outer surfaces of the elastomer member 125 may be profiled to enable maximum material exposure to the swelling or expanding medium. In the interest of brevity, non-swelling and non-expanding elastomeric material will be referred to commonly by “non-swelling”, but it should be appreciated that this may include non-expanding elastomeric materials also.
The non-swelling elastomeric material can be an elastomer that swells in a particular fluid that is not added or injected into the wellbore 10 or is not naturally occurring in the wellbore 10. Alternatively, the non-swelling elastomeric material can be an elastomer that swells to a lesser extent upon contact with an actuating agent. As a further alternative, a non-swelling polymer (e.g. a plastic) may be used in place of the non-swelling elastomeric material. For example, TEFLON™, RYTON™, or PEEK™, may be used. It should be appreciated that the term “non-swelling elastomeric material” is intended to encompass all of these options.
In some situations, the elastomer member 125 in the apparatus 100 may begin to swell as soon as the apparatus 100 is located in the wellbore 10 as the fluid that actuates the swelling may be naturally occurring in the borehole. In this case, there is generally no requirement to inject chemicals or other fluids to actuate the swelling of the elastomer member 125. Additionally, it is possible to delay the swelling of the elastomer member 125. This can be done by using chemical additives in the base formulation that causes a delay in swelling. The type of additives that may be added will typically vary and may be different for each elastomer member 125 depending on the base polymer used in the material. Typical pigments that can be added that are known to delay or have a slowing influence on the rate of swelling includes carbon black, glue, magnesium carbonate, zinc oxide, litharge, and sulfur.
In another embodiment, the elastomer member 125 can be at least partially or totally encased in a water-soluble or alkali-soluble polymeric covering. The covering can be at least partially dissolved by the water or the alkalinity of the water so that the actuating agent can contact the elastomer member 125. This can be used to delay the swelling by selecting a specific soluble covering. The delay in swelling can allow the apparatus 100 to be located in the wellbore 10 before the swelling or a substantial part thereof takes place. The delay in swelling can be any length of time.
The mechanical properties of the elastomer member 125 can be adjusted or tuned to specific requirements. For instance, chemical additives such as reinforcing agents, carbon black, plasticizers, accelerators, activators, anti-oxidants, and pigments may be added to the base polymer to have an effect on the final material properties, including the amount of swell. These chemical additives can vary or change the tensile strength, modulus of elasticity, hardness, and other factors of the elastomer member 125.
As shown in
Generally, the production fluid flows through the screen 50 and into the apparatus 100 via a pathway 155 as indicated by a fluid pathway arrow 205. The production fluid then flows through the annular area 120 into a flow port 135 formed in the tubular body 105 and subsequently into a bore 190 of the tubular body 110 via a plurality of apertures 140. Thereafter, the production fluid flows through the production tubing and out of the wellbore.
The flow port 135 is formed in the tubular body 105 such that production fluid entering the screen 50 can flow into the bore 190 of the tubular body 110. A gap 160 between the outer tubular body 105 and the inner tubular body 110 is sized such that the total area 170 of the flow port 135 is smaller than the gap 160. This arrangement allows the creation of a pressure drop in the area of the flow port 135 which may increase the flow pressure of the production fluid as the production fluid enters into the production tubing via the plurality of apertures 140.
The outer tubular body 105 may optionally include a plurality of cutouts 180 (or ridges) proximate the pathway 155, as shown in
Upon swelling, the elastomer member 125 retains sufficient mechanical properties (e.g. hardness, tensile strength, modulus of elasticity, elongation at break, etc.) to withstand differential pressure between the inner tubular body 110 and the outer tubular body 105. The mechanical properties can be maintained over a significant time period so that the seal created by the swelling of the elastomer member 125 does not deteriorate over time.
Although the apparatus 100 has been described in relation to a flow control device, the aspects of the present invention are equally applicable to other types of wellbore tools, such as sliding sleeves, slotted liners, and well screens, that require shutoff of water production in an oil or gas well.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
