Abstract:
Disclosed is an apparatus and method for providing an activation pressure for a down hole too comprising a tool string having a pressure activated tool located at a distal end thereof, an opening passing through the tool string from an interior to an exterior thereof and a blocking body locatable in said opening operable to block a portion of said opening while leaving a reduced opening therethrough selected to produce a pressure within the tool string sufficient to activate the tool at a first fluid flow rate, wherein the blocking body is formed of a material operable to be dissolved by a solvent. The method comprises pumping a fluid down the tool string at a first fluid flow rate to activate the tool, pumping a solvent down the tool string operable to dissolve the blocking body, pumping the fluid down the tool string at a second fluid flow rate above the first flow rate and transporting a replacement blocking body down the tool string to the opening.

Description:
BACKGROUND 
       [0001]    1 Field 
         [0002]    The present disclosure relates generally to down hole tool activation and in particular to a selectably removable and reloadable orifice for providing an activation pressure for a downhole tool. 
         [0003]    2 Description of Related Art 
         [0004]    In the field of hydrocarbon development and production a variety of tools are frequently located down an oil well to perform a function. In many cases, the operation of the tool is not required or desired until located at a specific location within the oil well. Accordingly, such tools will require to be activated at such work location. 
         [0005]    Currently some downhole tools use an orifice to create differential pressures within the tool string to activate tools. However, the presence of these orifices limits the rate that can be pumped down the coil (or drill pipe if used) due to the limited flow rate that is possible through such an orifice. Additionally, it will be appreciated that the higher pressures produced within the tool string will also result in greater wear on the tool string which may be formed of coil tubing or the like. 
         [0006]    Conventionally, therefore where an orifice is utilized, an operator must therefore remove the tool string to therefore also remove the orifice therefrom for operations not requiring such higher pressures. Such removal operation is time consuming. 
       SUMMARY 
       [0007]    According to embodiments there is disclosed an apparatus for providing an activation pressure for a down hole too comprising a tool string having a pressure activated tool located at a distal end thereof, the tool string being operable to have a fluid pumped down therethrough to the tool. The apparatus further comprises an opening passing through the tool string from an interior to an exterior thereof and a blocking body locatable in said opening operable to block a portion of said opening while leaving a reduced opening therethrough selected to produce a pressure within the tool string at the tool sufficient to activate the tool at a first fluid flow rate through the tool string, wherein the blocking body is formed of a material operable to be dissolved by a solvent. 
         [0008]    The opening may be located at a distal end of the tool string with the tool being upstream therefrom. The opening may have a diameter selected to produce a pressure within the tool string below a pressure required to activate the tool at the first fluid flow rate. The opening may have a diameter selected to produce a pressure within the tool string below a pressure required to activate the tool at a second fluid flow rate. The second fluid flow rate may be higher than the first fluid flow rate. The blocking body may be formed of a material selected from the group consisting of biodegradable plastics, metals susceptible to dissolution, inorganic non-metals and pressed salts. 
         [0009]    The reduced opening may comprise an orifice through the blocking body. The orifice may comprise a plurality of perforations through the blocking body. The reduced opening may comprise a passage around the blocking body. The passage around the reduced opening may extend annularly around said blocking body. The tool string may include a central support adapted to support the blocking body centrally therein with the passage located annularly between the blocking body and the tool string. 
         [0010]    According to further embodiments there is disclosed a method for providing an activation pressure for a down hole too comprising providing a tool string locatable down a well operable to have a fluid pumped down through an interior thereof and locating a pressure activated tool at a distal end of the tool string in fluidic communication with the interior of the tool string. The method further comprises providing an opening passing through the tool string from an interior to an exterior thereof and locating a blocking body in the opening operable to block a portion of the opening while leaving a reduced opening therethrough selected to produce a pressure within the tool string at the tool sufficient to activate the tool at a first fluid flow rate through the tool string, wherein the blocking body is formed of a material operable to be dissolved by a solvent. 
         [0011]    According yet to further embodiments there is disclosed a method for providing an activation pressure for a down hole too comprising pumping a fluid down a tool string having a pressure activated tool located at a distal end thereof at a first fluid flow rate to activate the tool and pumping a solvent down the tool string operable to dissolve a blocking body located within an opening through a distal end of the tool string to remove the blocking body, the blocking body being operable to block a portion of the opening while leaving a reduced opening therethrough. The method further comprises pumping the fluid down the tool string at a second fluid flow rate above the first flow rate such that the flow through the opening produces a pressure lower than the pressure required to activate the tool and transporting a replacement blocking body down the tool string to the opening. 
         [0012]    Other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the disclosure in conjunction with the accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying drawings illustrate only the various implementations described herein and are not meant to limit the scope of various technologies described herein. The drawings show and describe various embodiments of the current disclosure. 
           [0014]      FIG. 1  is a cross-sectional view of a wellbore having tool string located therein. 
           [0015]      FIG. 2  is a cross sectional view of the tool string of  FIG. 1  at an initial or run in configuration. 
           [0016]      FIG. 3  is a cross sectional view of the tool string of  FIG. 1  at a second or high flow configuration with the orifice dissolved. 
           [0017]      FIG. 4  is a cross sectional view of the tool string of  FIG. 1  at a third or orifice replacement configuration. 
           [0018]      FIG. 5A  is a cross sectional view of a reloading body for use with the wellbore of  FIG. 1  according to a further embodiment. 
           [0019]      FIG. 5B  is a cross sectional view of a reloading body for use with the wellbore of  FIG. 1  according to a further embodiment. 
           [0020]      FIG. 6  is a cross sectional view of a tool string having a replaceable orifice according to a further embodiment. 
           [0021]      FIG. 7  is a cross sectional view of a tool string having a replaceable orifice according to a further embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    At the outset, it should be noted that in the development of any such actual embodiment, numerous implementation—specific decisions must be made to achieve the developer&#39;s specific goals, such as compliance with system related and business related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. In addition, the composition used/disclosed herein can also comprise some components other than those cited. In the summary and this detailed description, each numerical value should be read once as modified by the term “about” (unless already expressly so modified), and then read again as not so modified unless otherwise indicated in context. Also, in the summary and this detailed description, it should be understood that a concentration range listed or described as being useful, suitable, or the like, is intended that any and every concentration within the range, including the end points, is to be considered as having been stated. For example, “a range of from 1 to 10” is to be read as indicating each and every possible number along the continuum between about 1 and about 10. Thus, even if specific data points within the range, or even no data points within the range, are explicitly identified or refer to only a few specific, it is to be understood that inventors appreciate and understand that any and all data points within the range are to be considered to have been specified, and that inventors possessed knowledge of the entire range and all points within the range. 
         [0023]    The statements made herein merely provide information related to the present disclosure and may not constitute prior art, and may describe some embodiments illustrating the disclosure. 
         [0024]    In the specification and appended claims: the terms “connect”, “connection”, “connected”, “in connection with”, and “connecting” are used to mean “in direct connection with” or “in connection with via one or more elements”; and the term “set” is used to mean “one element” or “more than one element”. Further, the terms “couple”, “coupling”, “coupled”, “coupled together”, and “coupled with” are used to mean “directly coupled together” or “coupled together via one or more elements”. As used herein, the terms “up” and “down”, “upper” and “lower”, “upwardly” and downwardly”, “upstream” and “downstream”; “above” and “below”; and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments of the disclosure. 
         [0025]    Referring to  FIG. 1 , a wellbore  10  is drilled into the ground  8  to a production zone  6  by known methods. The production zone  6  may contain a horizontally extending hydrocarbon bearing rock formation or may span a plurality of hydrocarbon bearing rock formations such that the wellbore  10  has a path designed to cross or intersect each formation. After the wellbore  10  is drilled the tool string  20  located therein which may have one or more tools  22  located proximate to a distal end  24  thereof. 
         [0026]    Turning now to  FIG. 2 , a partial cross sectional view of the tool string is illustrated. For the purposes of the current disclosure, only the tool string is illustrated in cross sectional whereas an exterior view of the tool  22  is illustrated. It will be appreciated that any tool may be utilized herein wherein the tool is activated by the internal pressure within the tool string. The tool string  20  may be formed of a coil tubing  26  or the like having a tubing wall  28  defining a central passage  30  therethrough. It will be appreciated that the tool  22  may have a passage therethrough corresponding in size to the central passage  30  so as to enable a replacement blocking body as will be described further below to pass therethrough. 
         [0027]    The distal end  24  of the tool string  20  includes an opening  32  therethrough having a blocking body  40  located therein. The blocking body  40  includes an orifice  42  therethrough. The orifice  42  is sized to produce a first pressure within the tool string  20  at a first fluid flow rate therethrough according to known principles. The blocking body  40  may be formed of any material that is dissolvable by a solvent but stable in the presence of other fluids encountered within the well bore, such as, by way of non-limiting example, biodegradable plastics, polylactic acid (PLA), polyglycolic acid (PGA), polyvinyl alcohol (PVOH) or polyethylene terephthalate (PET), metals susceptible to dissolution such as aluminum as well as inorganic non-metals, such as calcium carbonate, or pressed salts. Optionally, the blocking body  40  may be formed of a primary material as set out above, such as a water or acid soluble material with a coating of a different dissolvable material such that such a coating may be dissolved by a solvent for that coating and thereafter water or an acid may dissolve, extrude or break apart and remove the remainder of the blocking body. It will also be appreciated that the blocking body may also be formed of a frangible or brittle material such that it may be broken apart by increasing the pressure upon the blocking body above a predetermined pressure to permit the remnant to be passed through the opening  32 . By way of non-limited example, the pressure differential across the orifice may be kept between 2000 and 3000 psi by pumping at a rate sufficient to maintain such pressure. If the blocking body is needed to be removed, the operator may pump at a higher pressure, such as above 3500 psi until the blocking body ruptures, breaks, cracks extrudes or is otherwise passed through the opening  32 . In other embodiments, the blocking body may be formed of a deformable material such that such higher pressures may be operable to extrude or press the blocking body through the opening  32 . 
         [0028]    In operation, the orifice  42  is sized such that the first pressure is adequate to actuate the tool  22 . Accordingly, when a user wishes to activate the tool  22 , they may pump the fluid down the tool string at or above the first fluid flow rate. It will be appreciated that such fluid flow rates will be desired to be relatively low for efficiency purposes. Thereafter, when the user wishes to no longer have the tool activated and also to pump a larger volume of fluid through the tool string, a solvent such as, by way of non-limiting example, bases such as NaOH, acids, solvent mixes and hot solvents such as xylene and toluene may be pumped down the well to dissolve the blocking body  40 . As illustrated in  FIG. 3 , once the blocking body  40  has been removed, the fluid may pass through the opening  32  which is larger than the orifice  42  and therefore produces a lower pressure within the tool string  20  under the first fluid flow rate. It will be appreciated that such lower pressure reduces the wear on the tool string and associated components. Additionally, the opening  32  also permits the use of a second fluid flow rate which may be higher than the first fluid flow rate which may also not produce a high enough pressure to activate the tool. It will be appreciated that such higher flow rates permit more rapid operations such as clean outs and the like while avoiding activating the tool which may be undesirable. 
         [0029]    Then the tool  22  is again required, a user may pump down a replacement blocking body  40  through the central passage  38  of the tool string  20  so as to re-seat the blocking body  40  within the opening  32  as illustrated in  FIG. 4 . As illustrated in  FIG. 3 , the opening  32  may be profiled to guide and receive the blocking body  40  therein, such as, by way of non-limiting example, tapered as illustrated. The opening  32  may also have other profiles adapted to receive the blocking body  32  such as rounded or other profiles as are known. 
         [0030]    As illustrated in  FIGS. 5 a  and 5 b   , the replacement blocking body  40  have tapered sides adapted to be received within the opening  32  or may also optionally include a protrusion  52  extending downwardly therefrom to be passed through the opening  32  wild retaining the tapered sides within the opening. It will also be appreciated that other darts and balls as are known may also be utilized. 
         [0031]    Turning now to  FIG. 6 , a portion of the tool string  20  is illustrated having a selectably removable orifice. The central passage  38  includes a tubular body  60  axially located therein forming an annulus  62  between the tubing wall  28  and the tubular body  60 . The tubular body  60  includes a passage  64  therethrough and a shoulder  66  at a top end thereof adapted to receive a ball  68  or other body thereon. In operation, the ball  68  may be seated upon the shoulder  66  to restrict the flow therepast through the annulus  62  thereby increasing pressure above the ball. When greater flow is required to reduce the pressure above the ball, the ball may be dissolved or otherwise broken apart as set out above to permit fluid to flow through the passage  64  and the annulus  62 . 
         [0032]    With reference to  FIG. 7 , a further embodiment is illustrated for reducing the flow rate through the tool string with a selectably removable orifice. The central passage  38  includes a narrowed portion  70  with a shoulder  72  at a top end thereof adapted to receive a perforated ball  74  thereon. The ball  74  includes a plurality of passages or openings  76  therethrough to permit a reduced flow of fluid to move therepast. In operation, the perforated ball  74  may be seated upon the shoulder  72  to restrict the flow of fluid to flow therepast to what is permitted to flow through the openings  76  thereby increasing pressure above the ball. When greater flow is required to reduce the pressure above the perforated ball  74 , the perforated ball may be dissolved or otherwise broken apart as set out above to permit fluid to flow through the entire narrowed portion  70 . 
         [0033]    While the present disclosure has been disclosed with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations there from. It is intended that the appended claims cover such modifications and variations as fall within the true spirit and scope of the disclosure.