Patent Application
20200386074
Embodiments disclosed herein generally relate to a valve assembly for a cementing operation.
In the drilling of oil and gas wells, a wellbore is formed using a drill bit that is urged downwardly at a lower end of a drill string. After drilling a predetermined depth, the drill string and bit are removed and the wellbore is lined with a string of casing. An annular area is thus formed between the string of casing and the wellbore. A cementing operation is then conducted to fill the annular area with cement. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons.
It is common to employ more than one string of casing in a wellbore. In this respect, the well is drilled to a first designated depth, and a first string of casing is set in the wellbore. The first string of casing is hung from the surface, and then cement is circulated into the annulus behind the casing. The well is then drilled to a second designated depth, and a second string of casing or liner is run into the well. The second string of casing or liner is also cemented. This process is typically repeated with additional casings or liners until the well has been drilled to total depth.
In a conventional cementing operation, a float collar is attached to the bottom of the casing (or liner) string as the casing string is run into the wellbore. A float collar located at the bottom of the casing string is sometimes referred to as a float shoe. The float shoe typically has a one-way valve located within the shoe. The casing is run into the wellbore to the desired depth, and the cementing operation is performed. The cementing operation commences with a first plug being dropped into the casing. The first plug typically has a through bore with a rupture disk therein. Cement is pumped into the casing behind the first plug. Following the cement, a second plug is dropped into the casing and typically does not have a through bore. After the first plug lands on the float shoe, the pressure of the cement behind the first plug will increase. When sufficient pressure is built up, the ruptured disk will fail, thereby opening the through bore. The cement flows through the bore of the first plug and past the one-way valve in the float shoe until the second plug reaches the first plug. The one-way valve allows the cement to flow out of the float shoe and into the annulus between the casing and the wellbore, while preventing the cement from re-entering the casing string.
The float shoe typically includes a tubular body, and the upper end of the tubular body couples to the casing. The interior of the tubular body includes a one-way valve, which is held in place by cured cement. The one way valve controls fluid communication through an axial bore formed in the cement. The lower end of the float shoe has a rounded nose formed of the cured cement.
During the cementing operation, the plugs will impact the float collar when they land on the float collar, thereby placing a bump pressure on the top side of the float collar. The bump pressure places stress in the cement that can weaken the float collar and may lead to its failure.
There is, therefore, a need for an improved float collar capable of withstanding the stress from the bump pressure.
Embodiments described herein relate to a valve assembly. A valve assembly for use in a wellbore includes a tubular body; a valve disposed in the tubular body and configured to control fluid communication through the tubular body; and a compound for coupling the valve to the tubular body. The upper end of the compound is configured to receive a plug, and the upper end is spaced from an inner surface of the tubular body.
In another embodiment, a downhole tool assembly includes a plug and a valve assembly. The plug may include a landing surface. The valve assembly may include a tubular body; a valve disposed in the tubular body and configured to control fluid communication through the tubular body; and a compound for coupling the valve to the tubular body; wherein an upper end of the compound is configured to receive the landing surface of the plug and wherein a ratio of an outer diameter of the upper end to an outer diameter of the landing surface is from 0.8 to 1.2.
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 tubular body 310 has a connector end 307, an internally profiled portion 318, and a lower end 309. The connector end 307 may be a box end of a threaded connection for coupling the valve assembly 300 to the casing 202. However, it is contemplated that the connector end 307 may be any suitable type of connection for use in a downhole setting, such as a pin end, a welded connection, etc. In one example, the lower end 309 forms the bottom end of the casing 202. The lower end of the tubular body 310 may include a rounded nose formed of the cured cement. However, the lower end 309 may be configured for connection to additional lengths of casing 202 or another downhole tool.
In one embodiment, the internally profiled portion 318 is formed in the internal surface of the tubular body 310. The internally profiled portion 318 is an irregular internal surface that enhances attachment of the compound 340 to the tubular body 310. The internally profiled portion 318 may extend a portion or the entire length of the interface between the compound 340 and the tubular body 310. In the example shown in
In another embodiment, the internally profiled portion 318 includes a plurality of radiused portions formed in the internal surface of the tubular body 310. The plurality of radiused portions has a series of hills and valleys. The hill is any part of the internal profiled portion 318 which culminates toward the interior of the tubular body 310. The valley is any part of the internal profiled portion 318 which culminates toward the exterior of the tubular body 310. In one embodiment, the hill has a radius that is larger than a radius of the valley. In one example, the ratio of the radius of the hill to the radius of the valley ranges from 1.5:1 to 3:1. The distance between two hills may be from 1 inch to 5 inches. In another embodiment, radius of the hill and the valley may be different from the adjacent hill and valley. In one example, the hills and valleys create an undulated surface with no abrupt changes from one radius to the next. In another embodiment, the internal profiled portion forms a sinusoidal wave. In yet another embodiment, the internal profiled portion forms a spiral pattern.
The valves 320 are held in the tubular body 310 by the compound 340.
Although two valves 320 are shown, it is contemplated the valve assembly 300 may include a single valve or three or more valves 320. The valves 320, as shown, are one-way valves having a body 323, a plunger 324, and a biasing member 326 for biasing the plunger 324 toward the closed position. The biasing member 326 is shown as a coiled spring; however, it should be appreciated that the biasing member may be any member capable of biasing the valve 320 toward the closed position, such as a resilient member, a leaf spring, a fluid bias, etc. The valves 320 are configured to selectively control fluid flow through the bore 345 of the valve assembly 300. The valves 320 open when the pressure above the valves 320 is sufficient to overcome the biasing force of the biasing members 326. The valves 320 close when the pressure is no longer sufficient to overcome the biasing force. Because the valves 320 are one-way valves, when closed, the valves 320 prevent the cement or other fluid from re-entering the casing 202
In addition to retaining the valves 320, the compound 340 forms a seat 305 at the up-hole end of the valve assembly 300. The seat 305 is configured to receive the first plug 214 during the cementing operation. The upper surface of the seat 305 includes an optional landing plate 335 for contacting the first plug 214. In one embodiment, the upper end of the compound 340 is spaced from the internal surface of the tubular body 310 such that a gap 350 is formed between the upper end and the internal surface, as shown in
In one embodiment, the gap 350 is sized such that the outer diameter of the upper end is comparable to the outer diameter of surface of the first plug 214 contacting the upper end. In one example, a ratio of the outer diameter of the upper end to the outer diameter of the contact surface ranges from 0.8 to 1.2; from 0.85 to 1.15; or from 0.95 to 1.05.
In operation, the casing string 202 is equipped with a valve assembly 300 and lowered into the wellbore 200. After reaching the desired depth, the cementing operation is commenced. The cementing operation begins by dropping a first plug 214 into the interior bore of the casing 202. Cement 216 is supplied behind the first plug 214. A second plug 218 is placed behind the cement 216. A push fluid is pumped behind the second plug 218 to push the plugs 214, 218 and the cement 216 downhole. The pushing fluid may be any fluid capable of pushing the second plug 218 through the casing 202, such as drilling mud, water, etc. The first plug 214 travels down the casing 202 until it lands on the valve assembly 300.
After the rupture disk bursts, the cement 216 flows through the first plug 214 into the bore 345 of the valve assembly 300. The pressure of the cement 216 is sufficient to push the plungers 324 down, thereby opening the valves 320. The cement 216 is allowed to flow through the valve assembly 300 and out into the annulus 203. The cement 216 continues to flow out into the annulus 203 until the second plug 218 lands on the first plug 214. When the second plug 218 lands on the first plug 214, the valves 320 close fluid communication through the bore 345, thereby preventing the cement 216 from flowing back into the tubular 202, which is also known as U-tubing.
The cement 216 is allowed to cure in the annulus 203. A milling or drilling tool then lowers into the tubular 202 to mill out the second plug 218, the first plug 214, and the valve assembly 300. If necessary, the wellbore 200 may be drilled further and any number of additional tubulars 202 placed into the wellbore 200 in the same manner as described above.
In one embodiment, a valve assembly for use in a wellbore having a tubular body; a valve disposed in the tubular body and configured to control fluid communication through the tubular body; and a compound for coupling the valve to the tubular body; wherein an upper end of the compound is configured to receive a plug and wherein the upper end is spaced from an inner surface of the tubular body.
In another embodiment, a downhole tool assembly includes a plug and a valve assembly. The plug may include a landing surface. The valve assembly may include a tubular body; a valve disposed in the tubular body and configured to control fluid communication through the tubular body; and a compound for coupling the valve to the tubular body; wherein an upper end of the compound is configured to receive the landing surface of the plug and wherein a ratio of an outer diameter of the upper end to an outer diameter of the landing surface is from 0.8 to 1.2.
In one or more of the embodiments described herein, the compound includes a tapered outer portion extending outwardly from the upper end toward the inner surface the tubular body.
In one or more of the embodiments described herein, an angle between the inner surface and the tapered outer portion is from 5° to 60°.
In one or more of the embodiments described herein, the valve assembly includes a landing plate disposed on the upper end.
In one or more of the embodiments described herein, the tubular body includes an internally profiled portion.
In one or more of the embodiments described herein, the internally profiled portion includes a first radiused portion culminating in a first minimum radius toward an exterior of the tubular body; and a second radiused portion culminating in a second minimum radius toward an interior of the tubular body.
In one or more of the embodiments described herein, the internally profiled portion includes a plurality of angled wickers.
In one or more of the embodiments described herein, the internally profiled portion is undulated.
In one or more of the embodiments described herein, the first minimum radius is larger than the second minimum radius.
In one or more of the embodiments described herein, an outer surface of the compound tapers outwardly from the upper end toward the inner surface of the tubular body.
In one or more of the embodiments described herein, the compound includes a tapered outer portion extending outwardly from the upper end toward the inner surface the tubular body.
In one or more of the embodiments described herein, the tapered outer portion intersects the internal profiled portion of the tubular body.
In one or more of the embodiments described herein, the valve is a one-way valve.
In one or more of the embodiments described herein, the upper end extends into a connection of the tubular body.
In one or more of the embodiments described herein, the valve assembly includes a landing plate disposed on the upper end for receiving the landing surface.
In one or more of the embodiments described herein, the valve assembly includes two valves.
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.
