Abstract:
A valve assembly for reversibly governing fluid flow through coiled tubing equipment. Valves of the assembly may be directed by a telemetric line running from an oilfield surface. In this manner, valve adjustment and/or reversibility need not require removal of the assembly from the well in order to attain manual accessibility. Similarly, operation of the valves is not reliant on any particular flow rate or other application limiting means. As such, multiple fluid treatments at a variety of different downhole locations may take place with a reduced number of trips into the well and without compromise to flow rate parameters of the treatments.

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
       [0001]    The present application is a continuation-in-part claiming priority under 35 U.S.C. §120 to U.S. app. Ser. No. 12/575,024, entitled System and Methods Using Fiber Optics in Coiled Tubing, filed Oct. 7, 2009, and which is a Continuation of 11/135,314 of the same title, filed on May 23, 2005, both of which are incorporated herein by reference in their entireties along with the Provisional Parent of the same title under 35 U.S.C. §119(e), App. Ser. No. 60/575,327, filed on May 28, 2004. 
     
    
     FIELD 
       [0002]    Embodiments described relate to tools and techniques for delivering treatment fluids to downhole well locations. In particular, embodiments of tools and techniques are described for delivering treatment fluids to downhole locations of low pressure bottom hole wells. The tools and techniques are directed at achieving a degree of precision with respect to treatment fluid delivery to such downhole locations. 
       BACKGROUND 
       [0003]    Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming, and ultimately very expensive endeavors. As a result, over the years, a tremendous amount of added emphasis has been placed on monitoring and maintaining wells throughout their productive lives. Well monitoring and maintenance may be directed at maximizing production as well as extending well life. In the case of well monitoring, logging and other applications may be utilized which provide temperature, pressure and other production related information. In the case of well maintenance, a host of interventional applications may come into play. For example, perforations may be induced in the wall of the well, regions of the well closed off, debris or tools and equipment removed that have become stuck downhole, etc. Additionally, in some cases, locations in the well may be enhanced, repaired or otherwise treated by the introduction of downhole treatment fluids such as those containing acid jetting constituents, flowback control fibers and others. 
         [0004]    With respect to the delivery of downhole treatment fluid, several thousand feet of coiled tubing may be advanced through the well until a treatment location is reached. In man cases a variety of treatment locations may be present in the well, for example, where the well is of multilateral architecture. Regardless, the advancement of the coiled tubing to any of the treatment locations is achieved by appropriate positioning of a coiled tubing reel near the well, for example with a coiled tubing truck and delivery equipment. The coiled tubing may then be driven to the treatment location. 
         [0005]    Once positioned for treatment, a valve assembly at the end of the coiled tubing may be opened and the appropriate treatment fluid delivered. For example, the coiled tubing may be employed to locate and advance to within a given lateral leg of the well for treatment therein. As such, a ball, dart, or other projectile may be dropped within the coiled tubing for ballistic actuation and opening of the valve at the end of the coiled tubing. Thus, the treatment fluid may be delivered to the desired location as indicated. So, by way of example, an acid jetting clean-out application may take place within the targeted location of the lateral leg. 
         [0006]    Unfortunately, once a treatment application through a valve assembly is actuated as noted above, the entire coiled tubing has to be removed from the well to perform a subsequent treatment through the assembly. That is, as a practical matter, in order to re-close the valve until the next treatment location is reached for a subsequent application, the valve should be manually accessible. In other words, such treatments are generally ‘single-shot’ in nature. For example, once a ball is dropped to force open a sleeve or other port actuating feature, the port will remain open until the ball is manually removed and the sleeve re-closed. 
         [0007]    As a result of having to manually access the valve assembly between downhole coiled tubing treatments, a tremendous amount of delay and expense are added to operations wherever multiple coiled tubing treatments are sought. This may be particularly the case where treatments within multilaterals are sought. For example, an acid jetting treatment directed at 3-4 different legs of a multilateral well may involve 6-8 different trips into and out of the well in order to service each leg. That is, a trip in, a valve actuation and clean-out, and a trip out for manual resetting of the valve for each treatment. Given the depths involved, this may add days of delay and tens if not hundreds of thousands of dollars in lost time before complete acid treatment and clean-out to each leg is achieved. 
         [0008]    A variety of efforts have been undertaken to address the costly well trip redundancy involved in coiled tubing fluid treatments as noted above. For example, balls or other projectiles utilized for valve actuation may be constructed of degradable materials. Thus, in theory, the ball may serve to temporarily provide valve actuation, thereby obviating the need to remove the coiled tubing in order to reset or re-close the valve. Unfortunately, this involves reliance on a largely unpredictable and uncontrollable rate of degradation. As such, tight controls over the delivery of the treatment fluids or precisely when the coiled tubing might be moved to the next treatment location are foregone. 
         [0009]    As an alternative to ball-drop type of actuations, a valve assembly may be utilized which is actuated at given pre-determined flow rates. So, for example, when more than 1 barrel per minute (BPM) is driven through the coiled tubing, the valve may be opened. Of course, this narrows the range of flow rate which may be utilized for the given treatment application and reduces the number of flow rates left available for other applications. In a more specific example, this limits the range of flow available for acid jetting at the treatment location and also reduces flow options available for utilizing flow driven coiled tubing tools, as may be the case for milling, mud motors, or locating tools. Thus, as a practical matter, operators are generally left with the more viable but costly manual retrieval between each treatment. 
       SUMMARY 
       [0010]    A reversible valve assembly is disclosed for coiled tubing deployment into a well from an oilfield surface. The assembly includes a valve disposed within a channel of the assembly for reversibly regulating flow therethrough. A communication mechanism, such as a fiber optic line may be included for governing the regulating of the flow. The valve itself may be of a sleeve, ball and/or adjustable orifice configuration. Further, the valve may be the first of multiple valves governing different passages. Once more, in one embodiment first and second valves may be configured to alternatingly open their respective passages based on input from the communication mechanism. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a front view of downhole coiled tubing equipment employing an embodiment of a surface controlled reversible coiled tubing valve assembly. 
           [0012]      FIG. 2  is art enlarged cross-sectional view of the reversible coiled tubing valve assembly taken from  2 - 2  of  FIG. 1 . 
           [0013]      FIG. 3  is an overview depiction of an oilfield with a multilateral well accommodating the coiled tubing equipment and valve assembly of  FIGS. 1 and 2 . 
           [0014]      FIG. 4A  is an enlarged view of a locator extension of the coiled tubing equipment signaling access of a leg of the multilateral well of  FIG. 3 . 
           [0015]      FIG. 4B  is an enlarged view of a jetting tool of the coiled tubing equipment reaching a target location in the leg of  FIG. 4A  for cleanout. 
           [0016]      FIG. 4C  is an enlarged sectional view of the valve assembly of the coded tubing equipment adjusted for a fiber deliver application following the cleanout application of  FIG. 4B . 
           [0017]      FIG. 5  is a flow-chart summarizing an embodiment of employing a surface controlled reversible coiled tubing valve assembly in a well. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Embodiments are described with reference to certain downhole applications. For example, in the embodiments depicted herein, downhole cleanout and fiber delivery applications are depicted in detail via coiled tubing delivery. However, a variety of other application types may employ embodiments of a reversible coiled tubing valve assembly for a variety of different types of treatment fluids as described herein. Regardless, the valve assembly embodiments include the unique capacity to regulate fluid pressure and/or delivery for a given downhole application while also being adjustable or reversible for a subsequent application without the need for surface retrieval and manipulation. 
         [0019]    Referring now to  FIG. 1 , with added reference to  FIG. 3 , a front view of downhole coiled tubing equipment  101  is depicted. The equipment  101  includes a reversible valve assembly  100  which, in conjunction with other downhole tools, may be deployed by coiled tubing  110  at an oilfield  301 . Indeed, the assembly  100  and other tools of the equipment  101  may communicate with, or be controlled by, equipment located at the oilfield  301  as detailed further below. The valve assembly  100  in particular may be utilized in a reversible and/or adjustable manner. That is, it may be fully or partially opened or dosed via telemetric communication with surface equipment. 
         [0020]    A ‘universal’ valve assembly  100 , so to speak, with reversibility, may be employed to reduce trips into and out of a well  380  for fluid based treatments as indicated above. This capacity also lends to easier reverse circulation, that is, flowing fluids into and out of the well  380 . Further, this capacity also allows for utilizing the valve assembly  100  as a backpressure or check valve as needed. Once more, given that the valve assembly  100  operates independent of fluid flow, flow rates through the equipment  101  may be driven as high or as low as needed without being limited by the presence of the assembly  100 . 
         [0021]    Telemetry for such communications and/or control as noted above may be supplied through fiber optic components as detailed in either of application Ser. No. 12/575,024 or 11/135,314, both entitled System and Methods Using Fiber Optics in Coiled Tubing and incorporated herein by reference in their entireties. However, other forms of low profile coiled tubing compatible telemetry may also be employed. For example, encapsulated electrically conductive line of less than about 0.2 inches in outer diameter may be utilized to provide communications between the valve assembly  100  and surface equipment. 
         [0022]    Regardless, the particular mode of telemetry, the power supply for valve assembly  100  maneuvers may be provided through a dedicated downhole source, which addresses any concerns over the inability to transport adequate power over a low profile electrically conductive line and/or fiber optic components. More specifically, in the embodiment shown, an electronics and power housing  120  is shown coupled to the coiled tubing  110 . This housing  120  may accommodate a lithium ion battery or other suitable power source for the valve assembly  100  and any other lower power downhole tools. Electronics for certain downhole computations may also be found in the housing  120 , along with any communicative interfacing between telemetry and downhole tools, as detailed further below. 
         [0023]    The coiled tubing  110  of  FIG. 1  is likely to be no more than about 2 inches in outer diameter. Yet, at the same time, hard wired telemetry may be disposed therethrough as indicated above. Thus, the fiber optic or low profile electrically conductive line options for telemetry are many. By the same token, the limited inner diameter of the coiled tubing  110  also places physical limitations on fluid flow options therethrough. That is to say, employing flow rate to actuate downhole tools as detailed further below will be limited, as a practical matter, to flow rates of between about ½ to 2 BPM. Therefore, utilizing structural low profile telemetry for communications with the valve assembly  100 , as opposed to flow control techniques, frees up the limited range of available flow rates for use in operating other tools as detailed further below. 
         [0024]    Continuing with reference to  FIG. 1 , the coiled tubing equipment  101  may be outfitted with a locator extension  140 , arm  150  and regulator  130  for use in directing the equipment  101  to a lateral leg  391  of a well  380  as detailed below. As alluded to above, these tools  140 ,  150 ,  130  may be operate via flow control. More specifically, these tools  140 ,  150 ,  130  may cooperatively operate together as a pressure pulse locating/communication tool. Similarly, the equipment  101  is also outfitted with a flow operated jetting tool  160  for use in a cleanout application as also detailed below. 
         [0025]    Referring now to  FIG. 2 , an enlarged cross-sectional view of the valve assembly  100  taken from  2 - 2  of  FIG. 1  is depicted. The assembly  100  includes a central channel  200 . The channel  200  is defined in part by sleeve  225  and ball  250  valves. In the embodiment shown, these valves  225 ,  250  are oriented to allow and guide fluid flow through the assembly  100 . More specifically, for the depicted embodiment, any fluid entering the channel  200  from a tool uphole of the assembly  100  (e.g. the noted regulator  130 ) is directly passed through to the tool downhole of the assembly  100  (e.g. the noted locator extension  140 ). With added reference to  FIG. 3 , a clean flow of fluid through the assembly  100  in this manner may take place as a matter of providing hydraulic support to the coiled tubing  110  as it is advanced through a well  380  in advance of any interventional applications. 
         [0026]    However, depending on the application stage undertaken via the assembly, these valves  225 ,  250  may be in different positions. For example, as depicted in  FIG. 4C , the sleeve valve  225  may be shifted open to expose side ports  210  for radial circulation. Similarly, the ball valve  250  may be oriented to a closed position, perhaps further encouraging such circulation, as also shown  FIG. 4C . 
         [0027]    Continuing with reference to  FIG. 2 , with added reference to  FIG. 3 , the particular positioning of the valves  225 ,  250  may be determined by a conventional powered communication line  275 . That is, with added reference to  FIG. 1 , the line  275  may run from the electronics and power housing  120 . Thus, adequate power for actuating or manipulating the valve  225  or  250  through as solenoid, pump, motor, a piezo-electric stack, a magnetostrictive material, a shape memory material, or other suitable actuating element may be provided. 
         [0028]    At the housing  120 , the line  275  may also be provided with interfaced coupling to the above noted telemetry (of a fiber optic or low profile electrical line). Indeed, in this manner, real-time valve manipulations or adjustment may be directed from an oilfield surface  301 , such as by a control unit  315 . As a result, the entire coiled tubing equipment  101  may be left downhole during and between different fluid flow applications without the need for assembly  100  removal in order to manipulate or adjust valve positions. 
         [0029]    In one embodiment, the assembly  100  may be equipped to provide valve operational feedback to surface over the noted telemetry. For example, the assembly  100  may be outfitted with a solenoid such as that noted above, which is also linked to the communication line  275  to provide pressure monitoring capacity, thereby indicative of valve function. 
         [0030]    It is worth noting that each valve  225 ,  250  may be independently operated. So, for example, in contrast to  FIG. 2  (or  FIG. 4C ) both valves  225 ,  250  may also be opened or closed at the same time. Further, a host of additional and/or different types of valves may be incorporated into the assembly  100 . In one embodiment, for example, the ball valve  250  may be modified with a side outlet emerging from its central passage  201  and located at the position of the sleeve valve  225  of  FIG. 2 . Thus, the outlet may be aligned with one of the side ports  210  to allow simultaneous flow therethrough in addition to the central channel  200 . Of course, with such a configuration, orientation of the central passage  201  with each port  210 , and the outlet with the channel  200 , may be utilized to restrict flow to the ports  210  alone. 
         [0031]    With specific reference to  FIG. 3 , an overview of the noted oilfield  301  is depicted. In this view, the oilfield  301  is shown accommodating a multilateral well  380  which traverses various formation layers  390 ,  395 . A different lateral leg  391 ,  396 , each with its own production region  392 ,  397  is shown running through each layer  390 ,  395 . These regions  392 ,  397  may include debris  375  for cleanout with a jetting tool  160  or otherwise necessitate fluid based intervention by the coiled tubing equipment  201 . Nevertheless, due to the configuration of the valve assembly  100 , such applications may take place sequentially as detailed herein without the requirement of removing the equipment  201  between applications. 
         [0032]    Continuing with reference to  FIG. 3 , the coiled tubing equipment  101  may be deployed with the aid of a host of surface equipment  300  disposed at the oilfield  301 . As shown, the coiled tubing  110  itself may be unwound from a reel  325  and forcibly advanced into the well  380  through a conventional gooseneck injector  345 . The reel  325  itself may be positioned at the oilfield  301  atop a conventional skid  305  or perhaps by more mobile means such as a coiled tubing truck. Additionally, a control unit  315  may be provided to direct coiled tubing operations ranging from the noted deployment to valve assembly  100  adjustments and other downhole application maneuvers. 
         [0033]    In the embodiment shown, the surface equipment  300  also includes a valve and pressure regulating assembly, often referred to as a ‘Christmas Tree’  355 , through which the coiled tubing  110  may controllably be run. A rig  335  for supportably aligning the injector  345  over the Christmas Tree  355  and well head  365  is also provided. Indeed, the rig  335  may accommodate a host of other tools depending on the nature of operations. 
         [0034]    Referring now to  FIGS. 4A-4C , enlarged views of the coiled tubing equipment  101  as it reaches and performs treatments in a lateral leg  391  are shown. More specifically,  FIG. 4A  depicts a locator extension  140  and arm  150  acquiring access to the leg  391 . Subsequently,  FIGS. 48 and 4C  respectively reveal fluid cleanout and fiber delivery applications at the production region  392  of the lateral leg  391 . 
         [0035]    With specific reference to  FIG. 4A , the locator extension  149  and arm  150  may be employed to gain access to the lateral leg  391  and to signal that such access has been obtained. For example, in an embodiment similar to those detailed in application Ser. No. 12/135,682, Backpressure Valve for Wireless Communication (Xu et al.), the extension  140  and atm  150  may be drawn toward one another about a joint at an angle θ. In advance of reaching the leg  391 , the size of this angle θ may be maintained at a minimum as determined by the diameter of the main bore of the well  380 . However, once the jetting tool  160  and arm  150  gain access to the lateral leg  391 , a reduction in the size of the angle θ may be allowed. As such, a conventional pressure pulse signal  400  may be generated for transmission through a regulator  130  and to surface as detailed in the &#39;682 application and elsewhere. 
         [0036]    With knowledge of gained access to the lateral leg  391  provided to the operator, subsequent applications may be undertaken therein as detailed below. Additionally, it is worth noting that fluid flow through the coiled tubing  110 , the regulator  130 , the extension  140  and the arm  150  is unimpeded by the intervening presence of the valve assembly  100 . That is, to the extent that such flow is needed to avoid collapse of the coiled tubing  110 , to allow for adequate propagation of the pressure pulse signal  400 , or for any other reason, the assembly  100  may be rendered inconsequential. As detailed above, this is due to the fact that any valves  225 ,  250  of the assembly  100  are operable independent of the flow through the equipment  101 . 
         [0037]    Continuing now with reference to  FIG. 4B , an enlarged view of the noted jetting tool  160  of the coiled tubing equipment  101  is shown. More specifically, this tool  160  is depicted reaching a target location at the production region  392  of the leg  391  for cleanout. Indeed, as shown, debris  375  such as sand, scale or other buildup is depicted obstructing recovery from perforations  393  of the region  392 . 
         [0038]    With added reference to  FIGS. 1 and 2 , the ball valve  250  of the assembly  100  may be in an open position for a jetting application directed at the debris  375 . More specifically, 1-2 BPM of an acid based cleanout fluid may be pumped through the coiled tubing  110  and central channel  200  to achieve cleanout via the jetting tool  160 . Again, however, the ball valve  250  being in the open position for the cleanout application is achieved and/or maintained in a manner independent of the fluid flow employed for the cleanout. Rather, low profile telemetry, fiber optic or otherwise, renders operational control of the valve assembly  100  and the valve  250  of negligible consequence or impact on the fluid flow. 
         [0039]    Referring now to  FIG. 4C , with added reference to  FIG. 2 , an enlarged sectional view of the valve assembly  100  is shown. By way of contrast to the assembly  100  of  FIG. 2 , however, the valves  225 ,  250  are now adjusted for radial delivery of a fiber  450  following cleanout through the jetting tool  160  of  FIG. 4B . Delivery of the fibers  450  through the comparatively larger radial ports  210  in this manner may help avoid clogging elsewhere (e.g. at the jetting tool  160 ). The fibers  450  themselves may be of glass, ceramic, metal or other conventional flowback discouraging material for disposal at the production region  392  to help promote later hydrocarbon recovery. 
         [0040]    Regardless, in order to switch from the cleanout application of  FIG. 4B  to the fiber delivery of  FIG. 4C , the acid flow may be terminated and the ball valve  250  rotated to close off the channel  200 . As noted above, this is achieved without the need to remove the assembly  100  for manual manipulation at the oilfield surface  301  (see  FIG. 3 ). A streamlined opening of the sleeve valve  225  to expose radial ports  210  may thus take place in conjunction with providing a fluid flow of a fiber mixture for the radial delivery of the fiber  450  as depicted. Once more, while the fluid flow is affected by the change in orientation of the valves  225 ,  250 , the actual manner of changing of the orientation itself is of no particular consequence to the flow. That is, due to the telemetry provided, no particular flow modifications are needed in order to achieve the noted changes in valve orientation. 
         [0041]    Referring now to  FIG. 5 , a flow-chart is depicted which summarizes an embodiment of employing a surface controlled reversible coiled tubing valve assembly in a well. Namely, coiled tubing equipment may be deployed into a well and located at a treatment location for performing a treatment application (see  515 ,  530 ,  545 ). Of particular note, as indicated at  560 , a valve assembly of the equipment may be adjusted at an point along the way with the equipment remaining in the well. Once more, the equipment may (or may not) be moved to yet another treatment location as indicated at  575  before another fluid treatment application is performed as noted at  590 . That is, this subsequent treatment follows adjustment of the valve assembly with the equipment in the well, irrespective of any intervening repositioning of the equipment. 
         [0042]    Embodiments described hereinabove include assemblies and techniques that avoid the need for removal of coiled tubing equipment from a well in order to adjust treatment valve settings. Further, valves of the equipment may be employed or adjusted downhole without reliance on the use of any particular flow rates through the coiled tubing. As a result, trips in the well, as well as overall operation expenses may be substantially reduced where various fluid treatment applications are involved. 
         [0043]    The preceding description has been presented with reference to the disclosed embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. For example, embodiments depicted herein focus on particular cleanout applications and fiber delivery. However, embodiments of tools and techniques as detailed herein may be employed for alternative applications such as cement placement. Additionally, alternative types of circulation may be employed or additional tools such as isolation packers, multicycle circulation valves. Regardless, the foregoing description should not be read as pertaining to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.