Patent Application
20050269075
The present invention relates generally to wellbore production enhancement operations and, more particularly, to a high-velocity discharge equalizing system and method.
Various procedures have been utilized to increase the flow of hydrocarbons from subterranean formations penetrated by wellbores. For example, a commonly used production enhancement technique involves creating and extending fractures in the subterranean formation to provide flow channels therein through which hydrocarbons flow from the formation to the wellbore. The fractures are created by introducing a fracturing fluid into the formation at a high flow rate and high pressure in order to exert a sufficient force on the formation to create and extend fractures therein. Solid fracture proppant materials, such as sand, are commonly suspended in the fracturing fluid so that upon introducing the fracturing fluid into the formation and creating and extending fractures therein, the proppant material is carried into the fractures and deposited therein, whereby the fractures are prevented from closing due to subterranean forces when the introduction of the frac fluid ceases.
In the line that transports the fracturing fluid from the pumps to the wellhead, there is typically a pipe tee that facilitates the use of a return line that transports fluid to a pit or other fluid containment when so desired. A valve that controls flow through this additional line may be inadvertently opened during high-flow and high-pressure situations, such as hydraulic fracturing. This may cause the energized fluid flowing through the line to surge out through the end, which may create undesirable reaction forces that cause the line to move uncontrollably. Anchors are sometimes used to minimize movement of the line.
According to one embodiment of the invention, a high-velocity fluid discharge device includes tubing having one or more orifices formed therein, a shroud coupled to the tubing such that, when a fluid flowing through the tubing exits the orifices, the fluid impinges on an inside surface of the shroud, and openings at both ends of the shroud. The openings have substantially the same areas.
Some embodiments of the invention provide numerous technical advantages. Some embodiments may benefit from some, none, or all of these advantages. For example, according to certain embodiments, high-flow discharge of fluid due to an inadvertent opening of a valve on the line running to a pit or fluid containment during hydraulic fracturing or other high pressure operations may be equalized so as to avoid excessive movement of the end of the line, which leads to a safer environment. In some embodiments, a shield may be utilized with such an equalizing system to prevent exiting fluids from throwing projectiles on location as well as provide additional anchorage into the ground.
The features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of the exemplary embodiments that follows.
System 100 includes one or more pumps 102 that deliver a fracturing fluid or other suitable fluid to a wellhead 104 via delivery line 106 having an associated valve 107. Because of the nature of hydraulic fracturing, the fluid is typically a high-flow, high-pressure fluid. In one embodiment, the fluid is flowing at a pressure of at least 100 psi and may be a gas, homogeneous foam, a liquid, or co-mingled fluid and gas. System 100 also includes a discharge line 108 having an associated valve 109 that is utilized to deliver fluid to a pit 110, which may be any suitable fluid containment, when so desired.
According to the teachings of one embodiment of the invention, system 100 includes discharge equalizing device 200 that creates a pressure-balanced exit condition for the fluid flowing out of the open end of discharge line 108 into pit 110. Details of discharge equalizing device 200 are described in further detail below in conjunction with
Discharge equalizing device 200 may also include a shield 208 to shield any exiting fluids flowing out of discharge equalizing device 200 and also to serve as a restraint system by anchoring discharge equalizing device 200 into the ground. Although not illustrated, additional anchorage systems may be associated with discharge line 108 for anchoring discharge line 108 into the ground.
Tubing 202 may be any suitable conduit operable to transport a fluid therethrough. Tubing 202 may be any suitable size and shape and may be formed from any suitable material. In one embodiment, tubing 202 has a diameter between approximately two and three inches. The fluid flowing through tubing 202 flows in the direction of arrow 210 and escapes from tubing 202 through orifices 203, as indicated by arrows 211. Orifices 203 may be any suitable size and there may be any suitable number of orifices 203. In one embodiment, there are multiple sets of orifices 203 longitudinally spaced along tubing 202, with each set of orifices 203 including a plurality of orifices equally spaced around a circumference of tubing 202. For example, orifices 203 may be spaced around the circumference of tubing 202 at an angular spacing of 30°, 60°, 90°, or 180° depending on the number of orifices in each set. Orifices 203 may also be offset from one another. The present invention contemplates any suitable arrangement of orifices 203 formed in tubing 202.
In a particular embodiment of the invention, tubing 202 may have a buffer zone 212 associated with its downstream end in which there are no orifices. Buffer zone 212 thus facilitates the reduction of the fluid shock exiting orifices 203 by smoothing the transition from zero pressure to high pressure. In other words, as fluid starts exiting orifices 203 buffer zone 212 begins to fill up with fluid so that the full pressure of the fluid does not immediately exit orifices 203, but instead builds up progressively.
Shroud 204 couples to tubing 202 in any suitable manner. Shroud 204 may be any suitable size and may be formed from any suitable material. In one embodiment, shroud 204 is formed from ten inch casing; however, other suitable diameters may be utilized. In addition, shroud 204 may have any suitable length. In the illustrated embodiment, shroud 204 couples to tubing 202 with an end cap 214 at the downstream end of tubing 202 and an entrance cap 216 at the upstream end. In order for the fluid existing in shroud 204 to exit shroud 204, end cap 214 includes a downstream opening 215 and entrance cap 216 includes an upstream opening 217. Although both downstream opening 215 and upstream opening 217 may have any suitable open areas, downstream opening 215 and upstream opening 217 have substantially the same open areas. This facilitates the pressure-balanced exit condition. In some embodiments, shroud 204 may not be uniform, but may have openings along its length.
Because the fluid flowing through tubing 202 is flowing at high velocity, and because orifices 203 have a relatively small diameter, a great force may be exerted on an inside wall 218 of shroud 204. This may cause deterioration of the wall of shroud 204 depending on many factors, such as the thickness of shroud 204, the type of material shroud 204 is formed from, the type of fluid flowing through tubing 202, the velocity of fluid, and the size of orifices 203. Therefore, reinforcing pad 206 may be coupled to an outside surface 220 of shroud 204 in a location corresponding to where the fluid impinges on inside surface 218. Reinforcing pad 206 may also couple to inside wall 218 of shroud 204 as a sacrificial insert. Reinforcing pad 206 may be any suitable size and shape, may be formed from any suitable material, and may couple to shroud 204 in any suitable manner. In lieu of reinforcing pad 206, the wall thickness of shroud 204 may be increased or the type of material that shroud 204 is formed from may be changed.
Shield 208 functions to act as a shield for any fluid exiting upstream opening 217 of shroud 204, and may also act as an anchorage system for discharge equalizing device 200 by imbedding a portion of shield 208 into the ground. Shield 208 may be any suitable size and shape and may be formed from any suitable material.
In operation of one embodiment of the invention, a high flow fluid flows through tubing 202 in the direction of arrow 210. The fluid starts exiting orifices 203 and quickly fills up buffer zone 212 before the full pressure of the fluid exiting orifices 203 starts impinging upon inside wall 218 of shroud 204 that counteracts the reaction force generated by the exiting of the fluid through orifices 203. Fluid then exits out downstream opening 215 and upstream opening 217 before being deposited into pit 110 (
In another embodiment of the invention, illustrated in
In another embodiment of the invention, which is not illustrated in the figures, tubing 202 does not have orifices 203 formed therein and no shroud 204 exists. In this embodiment, a tee is coupled to the end of tubing 202 so that when the fluid flowing through tubing 202 exits the end orifice of tubing 202, it exerts a force on the inside of the tee and then flows out both ends of the main branch of the tee. If these ends of the tee have equal open areas, then the forces caused by the fluid flowing out of the ends offset each other, thereby facilitating a pressure-balanced exit condition.
The description of tubing 302, orifices 303, and shroud 304 is substantially similar to the discussion of tubing 202, orifices 203, and shroud 204 as found in
Shields 306a, 306b, are also similar to shield 208 of
The ends of tubing 302 may be coupled to collection tank 308 in any suitable manner. Collection tank 308, along with lifting eye 307, facilitates the portability of discharge equalizing device 300. As such, discharge equalizing device 300 may be mounted on a truck, trailer, a skid, or other suitable vehicle for easy transportation.
Although collection tank 308 may have any suitable size and shape, in one embodiment, collection tank 308 includes a top 314 disposed underneath tubing 302 and shroud 304 to collect the fluids exiting shroud 304. In a particular embodiment, top 314 has a concave surface to assure that forces on collection tank 308 are downward. In any event, top 314 includes a plurality of drain holes 316 that direct the fluid down into collection tank 308. Collecting fluid in collection tank 308 also facilitates added weight to discharge equalizing device 300, which aids in anchoring the device. A drain 318 may be coupled near a bottom of collection tank 308 to facilitate the draining of the fluid contained therein.
As illustrated in
In operation of one embodiment of the invention illustrated in
Although some embodiments of the present invention are described in detail, various changes and modifications may be suggested to one skilled in the art. The present invention intends to encompass such changes and modifications as falling within the scope of the appended claims.
