Patent Publication Number: US-8122961-B2

Title: Apparatus and method for discharging multiple fluids downhole

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application takes priority from U.S. Provisional Application Ser. No. 61/047,633, filed on Apr. 24, 2008, which application is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND INFORMATION 
     1. Field of the Disclosure 
     The disclosure herein relates to apparatus and methods for discharging multiple fluids downhole. 
     2. Description of the Related Art 
     Oil wells (also referred to as wellbores or boreholes) are drilled into subsurface formations to produce hydrocarbons (oil and gas). Various operations are performed in the wellbore to make it ready for production of hydrocarbons therethrough. These operations include logging the formations surrounding the wellbore utilizing a variety of sensors, withdrawing fluid samples from the formations at different depths and analyzing such samples to estimate the properties of the reservoir and the fluid, perforating the formation, completing the wellbore with production equipment, etc. 
     Often, it is desired to discharge different fluids, such as chemicals, at one or more depths in the wellbore. Such fluids are typically discharged at the desired depths utilizing an apparatus that can carry one fluid. Use of such apparatus can result in requiring multiple trips into the wellbore for discharging multiple fluids at one or more locations in the wellbore. Therefore, it is desirable to have apparatus and methods for discharging multiple fluids downhole. 
     SUMMARY OF THE DISCLOSURE 
     The disclosure herein provides an apparatus and methods for discharging multiple fluids into a wellbore. In one aspect, a method may include: conveying a carrier in the wellbore, the carrier including at least a first chamber and a second chamber separated by a moving barrier therebetween; draining a first fluid from the first chamber to cause the barrier to move toward the first chamber; draining a second fluid from the second chamber by opening a flow passage associated with the moving barrier by a member associated with the first chamber. 
     In another aspect, an apparatus made according to the disclosure may include: a first chamber having a first flow control device to drain a first fluid from the first chamber; a second chamber having a second flow control device associated therewith, wherein a member associated with the first chamber actuates the second flow control device when the second fluid control device moves toward the first flow control device to drain a second fluid from the second chamber. 
     Examples of the more important features of the disclosure have been summarized rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the disclosure that will be described hereinafter and which will form the subject of the claims appended hereto. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For detailed understanding of the disclosure, references should be made to the following detailed description of the drawings, taken in conjunction with the accompanying drawings, in which like elements in general have been given like numerals, wherein: 
         FIG. 1  is a schematic illustration showing a tool made according to one embodiment of the disclosure conveyed into a wellbore for discharging multiple fluids in the wellbore; 
         FIG. 2  is a schematic illustration of the tool shown in  FIG. 1  showing multiple fluid chambers for holding fluids to be discharged in the wellbore; and 
         FIG. 3  is a schematic diagram showing the tool of  FIG. 2  during operation of the tool to discharge the fluids in the wellbore or into another tool. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic showing a system  100  for discharging multiple fluids at one or more locations in a wellbore  111  formed in an earth formation  110 . The system, in one aspect, shows a tool  200  made according to one embodiment of the disclosure herein conveyed in the wellbore  111 . The tool  200  may be conveyed alone or as part of a tool string  120  by a suitable conveying member  112 , such as a wireline or tubing. The tool  200  is conveyed from a surface rig  114  using a winch  116  placed on a truck  115  and a pulley  113  placed on the rig  114 . A tubing-conveyed system generally includes an injector for conveying the tubing and the tool  200  in the wellbore  111 . Offshore systems include a wireline unit or an injector stationed on the offshore rig. Power to the tool  200  and data communication between the tool  200  and the surface unit  115  is provided via suitable conductors in the conveying member  112 . The surface unit  115  includes a control unit or controller  40 , which may be a computer-based system, for controlling the operations of the tool  200 . Controller  115  further includes: data storage devices, such as magnetic tapes, solid state memory, etc.; data input devices; display devices; and other circuitry for controlling and processing data received from the tool  200 . To discharge the multiple fluids in the wellbore, the tool  200  is conveyed to a selected location, where one or more fluids, as desired, are discharged at such location. The tool may then be moved to other locations to discharge the remaining fluids at such locations. In this manner the tool  200  may be utilized to discharge multiple fluids in the wellbore or another tool for deployment during a single trip in the wellbore as more fully described in reference to  FIGS. 2 and 3 . 
       FIG. 2  shows an embodiment of the downhole tool  200  configured to discharge multiple fluids downhole. The tool  200  includes a carrier or tool body  201  that contains a number of fluid chambers, such as chambers  210   a ,  210   b ,  210   c  and  210   n , wherein each chamber is adapted to respectively hold therein fluids  212   a ,  212   b ,  212   c  and  212   n . The fluids in these chambers may be the same or different. The size and number of chambers carried by a carrier are chosen based on suitable design criteria. The tool  200  may further include a pressure equalizer sub  214  (also referred to herein as the “pressure chamber” or “top section”) to equalize pressure, as explained in more detail below. The top section  214  may be attached to the top of the carrier  201  by any suitable mechanism, including but not limited to threads  219 . A floating barrier, such as piston  222   a  (also referred to herein as the “top barrier” or “top piston”) separates the fluid chamber  210   a  from the top section  214 . The top piston  222   a , in one aspect, may be a solid piston that does not permit fluid to pass from the top section  214  into chamber  210   a . A suitable stopping mechanism, such as a mechanical stop  230 , may be provided in the carrier  201  to prevent the piston  222   a  from moving beyond the mechanical stop  230 . 
     A flow-through sub  220  may be provided at the bottom of the carrier  201  to form the last chamber  210   n  in the carrier. The flow-through sub  220  may be affixed at or proximate the bottom end  201   a  of the carrier  201 . The flow-through sub  220  may further include a flow device  218  that enables the fluid  212   n  to drain out from the chamber  210   n . The flow device  218  may be any suitable device, including but not limited to a pop-up valve, flow-through opening, an electrically-operated valve, or a pump. The flow-through sub  220  may further include an actuating member  217 , such as a nipple or pin configured to open a valve  223   n  in the piston  222   n  associated with chamber  210   c , i.e., the chamber above the last chamber  210   n , as explained in more detail below. 
     Still referring to  FIG. 2 , any number of intermediate chambers, such as chambers  210   b  and  210   c  may be formed between the top chamber  210   a  and the bottom chamber  210   n , each such chamber being separated from the adjoining chamber by a separate floating barrier, such as a floating piston. For example, fluid chambers  210   a  and  210   b  may be separated by a floating piston  222   b , fluid chambers  210   b  and  210   c  by a floating piston  222   c , etc. Also, the pistons  222   b  and  222   c  respectively may include flow-through devices  223   b  and  223   c  that further may include actuating members  221   b  and  221   c  respectively. The actuating member may be any suitable device, including but not limited to a protruding member, such as a nail or nipple. Therefore, in the configuration shown in  FIG. 2 , any number of fluid chambers may be linearly formed in the carrier  201 . Additional carriers may be attached to the carrier  201  to extend the tool  200  length to carry additional fluid chambers. Also, carriers of different sizes may be attached to each other using any suitable mechanism. 
     Still referring to  FIG. 2 , the tool  200  may further include a device  232  that is configured to selectively apply pressure on top of the floating piston  222   a . The device  232  may be a pump that is configured to pump a suitable fluid  234  under pressure into the upper section  214 . The fluid  234  may be the wellbore fluid or another fluid, such as oil, stored in a storage tank  235 . A valve  236  may be provided between the top section  214  and the pump  232  to control the flow of the fluid  234  into the top section  214 . By controlling the pump  232 , the pressure applied on the piston  222   a  may be controlled. In another aspect, a flow device  237 , such as a valve, may be provided to expose the top section  214  to the wellbore fluid so as to apply the hydrostatic pressure on the top piston  222   a . Yet, in another aspect, a gas (such as nitrogen or another inert gas) stored under pressure (not shown) may be discharged into the top section  214  to apply pressure on the top piston  222   a . In this manner the pressure at the top piston  222   a  may be equalized or create a positive differential during the operation of the tool downhole. 
     The tool  200  may further include a bottom section  216  below the last chamber  210   n  to drain the fluid  212   n  from chamber  210   n  and/or discharge the fluid received from chamber  210   n  into the wellbore, another location in the wellbore or the tool in the wellbore. In one aspect, the bottom section  216  may include a chamber  224  for receiving fluid from the bottom chamber  210   n . A pump  240  associated with the bottom section  216  may be utilized to pump fluid from the chamber  224  into the wellbore or to another device or location in the wellbore. Alternatively, the flow-through sub  220  may include a flow device  241  configured to be activated to drain fluid from chamber  210   n . The flow device  241  may be an electronically-operated valve, a mechanical valve (such as a pressure valve) that may be operated by applying sufficient pressure on the fluid  212   n  from the chamber  241 , or any other suitable flow device. Each piston  222   b - 222   c  and the flow-through sub  220  may include a suitable actuating member or an actuating device, such as a nipple  221   b - 221   n  to initiate the discharge or draining of the fluid from the fluid chamber above it, as explained in more detail in reference to  FIG. 3 . 
       FIG. 3  shows an exploded view  300  of a floating piston and the manner in which fluids from chambers  210   a - 210   n  are drained during a typical operation of the tool  200 .  FIG. 3  shows an exemplary floating piston  310  having a piston body  312 . One or more sealing elements  314  are placed on an outer surface of the piston body  312  to provide a seal between the piston and the inside of the carrier body  201 . When the piston  310  is placed inside the carrier, the piston can move in both directions and the sealing elements  314  seal the chambers above and below the piston  310 . The piston  310  may include a valve, such as a pop-up valve  320 , in the piston body. The valve  320  has a seat  250  (see  FIG. 2 ) inside the piston body and an extension  252  (see  FIG. 2 ) that may be pushed to open the valve  320 . A nipple member  321  is configured to be inserted in an opening  260  (see  FIG. 2 ) in the piston to open the valve  320 . The piston  310  may include one or more protruding elements  316  (also referred to herein as “shoulders”) that extend from the piston body upper surface  317  to stop a piston above it from moving further toward the piston  310 . A loading valve  318  may be provided through which a chamber below the piston  310  may be loaded with the desired fluid. The loading valve  318  also may act as an air bypass. The piston  310  also may include one or more fluid flow passages  330  that allow the fluid from one chamber to flow into the chamber below it when the pop-up valve  320  associated therewith is opened. 
     Referring to  FIGS. 2 and 3 , in operation, individual fluid chambers such as  210   a - 210   n  are filled with selected fluids at the surface. In one aspect, each valves  221   a - 221   n  may include a suitable mechanism, including, but not limited to, a ball detent, to temporarily hold its corresponding valve in a closed position until it is activated by an actuating member. The tool  200  is then conveyed alone or as a part of a tool string to a selected depth in the wellbore. The fluid  212   n  from the bottom chamber  210   n  is drained at a selected rate. When a valve, such as valve  218 , is provided, the flow rate may be controlled by controlling the valve. When a pump  240  or another device is provided, the flow rate may be controlled by the pump or such other device as shown by arrows  322 . The fluid  212   n  may be discharged into the wellbore, another suitable location or a downhole tool by using the pump  240 . As the fluid  212   n  drains out from the chamber  210   n , the piston  222   n  associated with the fluid chamber  210   c  starts to slide down toward the valve  218 . The pin member  217  of the valve  218  pushes the valve  223   n  upward, thereby opening the valve  223   n  to allow the fluid  212   c  to drain out from the chamber  210   c  and into the chamber  210   n  via the passages  330  in the piston  223   n , as shown by arrows  332 . The fluid  212   c  then drains out of the tool  200  via the chamber  210   n  as shown by arrows  322 . The loading valve  318   n  aids air to bypass the valve  223   n  during flow of the fluid. The piston  222   n  will continue to move downward until it rests on the shoulders  316 . The movement of the piston  222   n  may be stopped at any time by closing the valve  218  or stopping the pump  240 . As the fluid drains from the chambers  210   n  and  210   c , the piston  222   c  moves toward the piston  222   n . The pin member  221   n  of piston  222   n  will then open the valve  223   c  to drain the fluid  212   b  from chamber  210   b  out of the tool via the fluid passages  334 ,  332  and  322 . The above process continues until the fluid from all the chambers is drained. The tool  200 , therefore, may carry multiple fluids, wherein a first fluid may be discharged at a first downhole location, a second fluid may be discharged at the first location or a second location, and a third fluid may be discharged at any of the first and second locations or at a third location, etc. 
     Therefore, the apparatus shown in  FIGS. 1-3 , in general, may include a hollow carrier body that may include attachment mechanisms on each end, such as threads—male threads on one end and female threads on the other end. Carriers may be joined or attached together to increase the overall length of the apparatus and thus the total fluid-carrying capacity. Pistons may be placed to separate the fluids in successive fluid chambers. Each piston may include a pop-up valve with an actuating or initiating member (such as a nipple). As the fluid from the bottom chamber is drained, the initiating nipple associated with the bottom chamber will push open the pop-up valve of the piston associated with the fluid chamber above it. This piston will continue to move until it comes to rest on a shoulder mount associated with the bottom valve. Thus, the fluid from the second fluid chamber will drain until the piston comes to a rest. The nipple associated with the second chamber will then start opening the pop-up valve of the third chamber and so on. 
     Thus, in view of the disclosure herein, an apparatus for discharging multiple fluids downhole made according to one embodiment of the disclosure herein may include: a first chamber configured to contain a first fluid; a second chamber configured to contain a second fluid; a movable barrier separating the first chamber and the second chamber; and an actuating member configured to drain the second fluid from the second chamber when the first fluid is drained from the first chamber. The apparatus may further include a device or unit to equalize pressure on the barrier. The apparatus may further include a device that drains the fluid from the first chamber. In another aspect, a device may be provided that discharges the fluid drained from the first chamber into a suitable location downhole, including the wellbore and a tool downhole. 
     In another aspect, an apparatus made according to another embodiment of this disclosure may include: a first chamber; a first flow device for draining a first fluid out from the first chamber; a second chamber; a second flow device between the first chamber and the second chamber; and an actuating member that is configured to actuate the second flow control device to drain a second fluid out from the second chamber when the first fluid is drained from the first chamber. The actuating member may be a nipple. A carrier or housing may be used to carry the first and second chambers. In one aspect, the first flow device may be fixed at the bottom end of the carrier while the second flow device may be placed inside the carrier so that the second flow device moves within the chamber toward the first flow device when the first fluid is drained out from the first chamber. The actuating member may be configured to actuate a valve of the second flow device to drain the second fluid out from the second chamber and into the first chamber. In another aspect, the apparatus may further include a loading device suitable for loading fluids into the first and second chambers. The loading device may be one-way loading valve integral to the second flow device for loading a fluid into the first chamber. Additional chambers may be provided uphole of the second chamber, each such chamber separated by a flow device that may further include a loading valve for loading the chamber below or downhole of the valve. 
     In another aspect, the apparatus also may include a pressure equalizer configured to apply pressure on the top barrier in the apparatus. Yet, in another aspect, the apparatus may further include a device to apply pressure on the top barrier that is selected from one of: (i) a pump to pump a fluid under pressure in a pressure chamber; (ii) an opening in the pressure chamber that exposes the pressure chamber to a hydrostatic pressure when the apparatus is in the wellbore; and (iii) a gas unit that injects a gas under pressure into the pressure chamber. In another aspect, the apparatus may further include a device that opens and closes the first flow device to allow the fluid from the first chamber to drain out from the first chamber. In another aspect, the apparatus may further include at least one additional chamber above the second chamber that is separated from the second chamber by a third flow device having a valve that is configured to be opened by an actuating member of the second flow device. 
     In another aspect, a method for discharging a plurality of fluids downhole according to one aspect disclosed herein may include: conveying a fluid carrier in a wellbore, the fluid carrier including a first chamber and a second chamber, each chamber having an associated flow device; draining a first fluid from the first chamber to cause the second chamber to move within the carrier so that an actuating device associated with the first chamber actuates the flow device of the second chamber to drain a second fluid from the second chamber. The method may further include equalizing pressure on the second chamber before or after conveying the carrier in the wellbore. Draining the fluid from the first carrier may include actuating the flow device associated with the first chamber by one of: (i) an electric motor; and (ii) a pump. In another aspect, the carrier may include additional chambers, wherein the chambers are separated from each other by a movable barrier therebetween. The method may further include providing a loading valve that allows air to bypass the valve associated with second chamber. 
     The foregoing disclosure is directed to certain embodiments of the disclosure. Various modifications will be apparent to those skilled in the art. It is intended that all variations of the disclosed embodiments and modification thereto that fall within the scope of any claims of this application be embraced by the foregoing disclosure.