Patent Application
20060124320
1. Field of the Invention
Embodiments of this invention are generally related to safety valves. More particularly, embodiments of this invention pertain to a non-elastomeric cement through tubing retrievable safety valve configured to control fluid flow through a production tubing string.
2. Description of the Related Art
Surface-controlled, subsurface safety valves (SCSSVs) are commonly used to shut-in oil and gas wells. Such SCSSVs are typically fitted into a production tubing in a hydrocarbon producing well and operate to selectively block the flow of formation fluids upwardly through the production tubing should a failure or hazardous condition occur at the well surface.
SCSSVs are typically configured to be rigidly connected to the production tubing (tubing retrievable) or may be installed and retrieved by wireline without disturbing the production tubing (wireline retrievable). During normal production, the subsurface safety valve is maintained in an open position by the application of hydraulic fluid pressure transmitted to an actuating mechanism. The actuating mechanism in one embodiment is charged by application of hydraulic pressure. The hydraulic pressure is commonly a clean oil supplied from a surface fluid reservoir through a control line. A pump at the surface delivers regulated hydraulic fluid under pressure from the surface to the actuating mechanism through the control line. The control line resides within the annular region between the production tubing and the surrounding well casing.
Where a failure or hazardous condition occurs at the well surface, fluid communication between the surface reservoir and the control line is broke. This, in turn, breaks the application of hydraulic pressure against the actuating mechanism. The actuating mechanism recedes within the valve, allowing the flapper to close against an annular seat quickly and with great force.
Most surface controlled subsurface safety valves are “normally closed” valves, i.e. The valve is in its closed position when the hydraulic pressure is not present. The hydraulic pressure typically works against a spring and/or gas charge acting through a piston. In many commercially available valve systems, the spring is overcome by hydraulic pressure acting against the piston, thus producing longitudinal movement of the piston. The piston, in turn, acts against an elongated “flow tube.” In this manner, the actuating mechanism is a hydraulically actuated and longitudinally movable piston that acts against the flow tube to move it downward within the tubing and across the flapper.
During well production, the flapper is maintained in the open position by the force of the piston acting against the flow tube downhole. Hydraulic fluid is pumped into a variable volume pressure chamber (or cylinder) and acts against a seal area on the piston. The piston, in turn, acts against the flow tube to selectively open the flapper member in the valve. Any loss of hydraulic pressure in the control line causes the piston and actuated flow tube to retract. This, in turn, causes the flapper to rotate about a hinge pin to its valve-closed position. In this manner, the SCSSV is able to provide a shutoff of production flow within the tubing as the hydraulic pressure in the control line is released.
During well completions, certain cement operations can create a dilemma for the operator. In this respect, the pumping of cement down the production tubing and through the SCSSV presents the risk of damaging the valve. Operative parts of the valve, such as the flow tube or flapper, could become cemented into place and inoperative. At the least, particulates from the cementing fluid could invade chamber areas in the valve and cause the valve to become inoperable.
In an attempt to overcome this possibility, the voids within the valve have been liberally filled with grease or other heavy viscous material. The viscous material limits displacement of cement into the operating parts of the valve. In addition to grease packing, an isolation sleeve may be used to temporarily straddle the inner diameter of the valve and seal off the polished bore portion along the safety valve. However, this procedure requires additional trips to install the sleeve before cementing and then later remove the sleeve at completion.
Additionally, SCSSVs are typically constructed with wiper seals and/or restrictive communication members disposed around the flow tube to minimize the potential of cement from entering into the valve's operative parts. However, the valve's operative parts are not completely isolated from the bore of the SCSSV and therefore cement may enter the valve's operative parts and cause damage therein.
Therefore, a need exists for an apparatus and a method for an SCSSV that includes an improved sealing system to seal off the flow tube or other operative parts of the safety valve during a cement-through operation. There is a further need for an apparatus and a method for protecting the SCSSV from cement infiltrating the inner mechanisms of the valve during a cementing operation. Still further, there is a need for an improved SCSSV that isolates certain parts of the valve from cement infiltration during a cement-through operation, without unduly restricting the inner diameter of the safety valve for later operations.
The present invention generally relates to a non-elastomeric cement through tubing retrievable safety valve configured to control fluid flow through a production tubing string. In one aspect, a valve for use in a wellbore is provided. The valve includes a tubular body. The valve further includes a flow tube having a bore therethrough, wherein the flow tube is disposed in the tubular body to form an annular area therebetween. The valve further includes a flapper movable between an open position and a closed position in response to movement of the flow tube. Additionally, the valve includes a sealing system constructed and arranged to substantially isolate the annular area from the bore, thereby substantially eliminating the potential of contaminants in the bore from entering into the annular area.
In another aspect, a downhole valve for use in a wellbore is provided. The downhole valve includes a tubular body and a movable flow tube having a bore therethrough. The flow tube is disposed in the tubular body to form a first annular area and a second annular area therebetween. The downhole valve further includes a flapper movable between an open position and a closed position, whereby in the closed position the flapper is substantially within the second annular area. The downhole valve also includes a first sealing system for substantially isolating the first annular area from contaminates in the bore. Additionally, the downhole valve includes a second sealing system for substantially isolating the second annular area from contaminates in the bore.
In yet another aspect, a method of controlling fluid in a wellbore is provided. The method includes positioning in the wellbore a string of production tubing and a valve. The method further includes opening a flapper in response to the movement of the flow tube and then pumping cement through a bore of the production tubing and the bore of the flow tube. Additionally, the method includes substantially isolating the annular area from the cement pumped through the valve.
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 is generally directed to a tubing-retrievable subsurface safety valve for controlling fluid flow in a wellbore. Various terms as used herein are defined below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term, as reflected in printed publications and issued patents. In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals. The drawings may be, but are not necessarily, to scale and the proportions of certain parts have been exaggerated to better illustrate details and features described below. One of normal skill in the art of subsurface safety valves will appreciate that the various embodiments of the invention can and may be used in all types of subsurface safety valves, including but not limited to tubing retrievable, wireline retrievable, injection valves, or subsurface controlled valves.
For ease of explanation, the invention will be described generally in relation to a cased vertical wellbore. It is to be understood, however, that the invention may be employed in an open wellbore, a horizontal wellbore, or a lateral wellbore without departing from principles of the present invention. Furthermore, a land well is shown for the purpose of illustration; however, it is understood that the invention may also be employed in offshore wells or extended reach wells that are drilled on land but completed below an ocean or lake shelf.
During the completion operation, the wellbore 100 is lined with a string of casing 105. Thereafter, the production tubing 120, with the safety valve 200 disposed in series, is deployed in the wellbore 100 to a predetermined depth. In connection with the completion operation, the production tubing 120 is cemented in situ. To accomplish this, a column of cement is pumped downward through the bore of the production tubing 120. Cement is urged under pressure through the open safety valve 200, through the bore of the tubing 120, and then into an annulus 125 formed between the tubing 120 and the surrounding casing 105. Preferably, the cement 160 will fill the annulus 125 to a predetermined height, which is proximate to or higher than a desired zone of interest in an adjacent formation 115.
After the cement 160 is cured, the formation 115 is opened to the bore of the production tubing 120 at the zone of interest. Typically, perforation guns (not shown) are lowered through the production tubing 120 and the valve 200 to a desired location proximate the formation 115. Thereafter, the perforation guns are activated to form a plurality of perforations 110, thereby establishing fluid communication between the formation 115 and the production tubing 120. The perforation guns can be removed or dropped off into the bottom of the wellbore below the perforations. Hydrocarbons (illustrated by arrows) may subsequently flow into the production tubing 120, through the open safety valve 200, through a valve 135 at the surface, and out into a production flow line 130.
During this operation, the valve 200 preferably remains in the open position. However, the flow of hydrocarbons may be stopped at any time during the production operation by switching the valve 200 from the open position to the closed position. This may be accomplished either intentionally by having the operator remove the hydraulic pressure applied through the control line 145 or through a catastrophic event at the surface such as an act of terrorism. The valve 200 is demonstrated in its open and closed positions in connection with
The valve 200 includes a top sub 270 and a bottom sub 275. The top 270 and bottom 275 subs are threadedly connected in series with the production tubing (shown in
In the arrangement of
As illustrated in
Disposed below the spring spacer 265 is a flapper 220. The flapper 220 is rotationally attached by a pin 230 to a flapper mount 290. The flapper 220 pivots between an open position and a closed position in response to movement of a flow tube 225. A shoulder 226 is provided for a connection between the piston 205 and the flow tube 225. In the open position, a fluid pathway is created through the bore 260, thereby allowing the flow of fluid through the valve 200. Conversely, in the closed position, the flapper 220 blocks the fluid pathway through the bore 260, thereby preventing the flow of fluid through the valve 200.
Further illustrated in
Each of
As illustrated in
In one embodiment, the seal member 305 is placed in a groove (not shown) in an upper end of the flow tube 225. In this respect, the movement of the piston 205 in response to the hydraulic pressure in the line 145 would also cause the seal member 305 and the flow tube 225 to move. In so moving, the seal member 305 would traverse upon the outer diameter of the isolation sleeve 215. Alternatively, the seal member 305 is fixed along the outer diameter of the sleeve 215 and therefore would remain stationary relative to the movable flow tube 225. The seal member 305 is typically made from a non-elastomeric material such as PTFE or another type of polymer. Where the seal member 305 is provided, the isolation sleeve 215 fluidly seals an inside of the chamber housing 255. In an alternative embodiment, the sleeve 215 could be machined integral to the housing 255.
The valve 200 includes a second sealing system 325. The primary reason for the second sealing system 325 is to substantially eliminate the potential of contaminants in the bore 260, such as cement, from entering into an annular area 310 adjacent the flapper 220 while the valve 200 is in the open position (seen in
Typically, the flow tube 225 remains in the open position throughout the completion operation and later production. However, if the flapper 220 is closed during the production operation, it may be reopened by moving the flow tube 225 back to the open position. Generally, the flow tube 225 moves to the open position as the piston 205 moves to the lower position and compresses the biasing member 210 against the spring spacer 265. Typically, fluid from the line (not shown) enters the chamber 245, thereby creating a hydraulic pressure on the piston 205. As more fluid enters the chamber 245, the hydraulic pressure continues to increase until the hydraulic pressure on the upper end of the piston 205 becomes greater than the biasing member 210 on the lower end of the piston 205. At that point, the hydraulic pressure in the chamber 245 causes the piston 205 to move to the lower position. Since the flow tube 225 is operatively attached to the piston 205, the movement of the piston 205 causes longitudinal movement of the flow tube 225 and the seal member 305.
During closure, fluid in the chamber 245 exits into the line 145, thereby decreasing the hydraulic pressure on the piston 205. As more fluid exits the chamber 245, the hydraulic pressure continues to decrease until the hydraulic pressure on the upper end of the piston 205 becomes less than the opposite force on the lower end of the piston 205. At that point, the force created by the biasing member 210 causes the piston 205 to move to the upper position. Since the flow tube 225 is operatively attached to the piston 205, the movement of the piston 205 causes the movement of flow tube 225 and the seal member 305 into the annular area 240 until the flow tube 225 is substantially disposed within the annular area 240. In this manner, the flow tube 225 is moved to the closed position.
Although the invention has been described in part by making detailed reference to specific embodiments, such detail is intended to be and will be understood to be instructional rather than restrictive. It should be noted that while embodiments of the invention disclosed herein are described in connection with a subsurface safety valve, the embodiments described herein may be used with any well completion equipment, such as a packer, a sliding sleeve, a landing nipple, and the like.
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.
This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/853,568, filed May 25, 2004, which claims benefit of U.S. provisional patent application Ser. No. 60/505,515 filed Sep. 24, 2003. Each of the aforementioned related patent applications is herein incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60505515 | Sep 2003 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10853568 | May 2004 | US |
| Child | 11255349 | Oct 2005 | US |
