Abstract:
An apparatus with a reduced dead volume associated with sampling, comprising: a sample container configured to store a fluid, a sample line configured to transport the fluid from a first sampling area to a second area in the sample container, at least one valve in the sample line, the valve configured to selectively range from a closed configuration to an open configuration, and a flow restrictor configuration placed in the sample line, the flow restrictor configured to minimize the dead volume for the sample container.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This disclosure claims priority to U.S. Provisional Application 61/635,759 filed Apr. 19, 2012, the entirety of which is incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    Aspects of the disclosure relate to containers. More specifically, aspects of the disclosure relate to containers used to store, test and transport fluids, especially in the oilfield industry. 
       BACKGROUND INFORMATION 
       [0003]    Sample containers used to store, test and transport fluids are used in a number of industries. Generally, is typically advantageous to maintain the fluid at giving conditions, such as conditions as the fluid was at the time it was positioned in the sample container. 
         [0004]    For example, in the oilfield industry, to sample and test fluids such as deposits of hydrocarbons and other desirable materials trapped in underground formations, a wellbore is drilled by connecting a drill bit to the lower end of a series of coupled sections of tubular pipe known as a drill string. A downhole sampling tool may be deployed in the wellbore drilled through the formations. The downhole sampling tool may include a fluid communication device, such as a probe or a straddle packer to establish fluid communication between the downhole sampling tool and a formation penetrated by the wellbore. 
         [0005]    Fluid samples may be extracted from the formation via a fluid communication device using a fluid pump provided with the downhole sampling tool. Various downhole sampling tools for wireline and/or while-drilling applications are known in the art such as those described in U.S. Pat. Nos. 6,964,301, 7,594,541, 7,543,659 and 7,600,420, the entireties of which are incorporated herein. 
         [0006]    Sampling tools may be provided with a plurality of sample bottles to receive and retain the fluid samples. Sample bottles include, for example, those described in U.S. Pat. Nos. 6,467,544, 7,367,394 and 7,546,885, the entireties of which are incorporated herein by reference. 
       SUMMARY 
       [0007]    An apparatus with a reduced dead volume associated with sampling, comprising a sample container configured to store a fluid, a sample line configured to transport the fluid from a first sampling area to a second area in the sample container, at least one valve in the sample line, the valve configured to selectively range from a closed configuration to an open configuration, and a flow restrictor configuration placed in the sample line, the flow restrictor configured to minimize the dead volume for the sample container. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1A  is a side view of an insert used to occupy dead volume in a modular sample bottle formation tester at low pressure. 
           [0009]      FIG. 1B  is a side view of an insert used to occupy dead volume in a modular sample bottle formation tester at high pressure. 
           [0010]      FIG. 2  is a side view of a sample bottle with an external plunger used to occupy dead volume in a modular sample bottle formation tester. 
           [0011]      FIG. 3  is a side view of a sample bottle with an internal plunger used to occupy dead volume in a modular sample bottle formation tester. 
           [0012]      FIG. 4  is a side view of a sample bottle neck disposed in a sample carrier with a fully extended position of a piston rod. 
           [0013]      FIG. 5  is a side view of an extended piston rod and accompanying extension mechanism of an alternative embodiment of the modular sample bottle formation tester. 
           [0014]      FIG. 6  is a side view of a sample chamber that is exposed to a flowline until the rod retracts and the seals trap a sample in the sample chamber. 
           [0015]      FIG. 7  is a side view of a sample chamber with associated EXO washers used for shifting rod positions for the modular sample bottle formation tester. 
           [0016]      FIG. 8  is a side view of a sample chamber with a piston rod that is flush with the flowline of a modular sample bottle formation tester. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Referring to  FIGS. 1A and 1B , one example embodiment of an arrangement for reducing the dead volume of a sample container  100  is illustrated.  FIG. 1A  depicts a first low pressure configuration for an arrangement disclosed.  FIG. 1B  depicts a second high pressure state of the arrangement disclosed in  FIG. 1A . In the illustrated embodiment, the arrangement disclosed is used in a downhole sampling apparatus used in well services for the petroleum industry. Although the arrangement described is used in a downhole sampling apparatus, the arrangement may be used in other sampling environments, such as in a laboratory setting or other industrial sampling situations where accuracy is important and the potential for contamination or dilution of the fluid stream is possible. 
         [0018]    A sample line  102  is configured to transport fluid from a source to the sample container  100 . In the example embodiment, the fluid transported is a petroleum fluid and the source of the fluid is found in geological stratum in a downhole environment. The fluid may be, for example, black oil or condensates of natural gas, as non-limiting examples. 
         [0019]    The fluid being sampled may be obtained through a probe placed in close proximity to the geological stratum where a pump module draws a vacuum, causing fluid to enter the probe and ultimately into the sample line  102 . Additionally, the fluid being sampled may be obtained through a focused sampling packer. The sample line  102  may be insulated to keep the fluid in the same state, including pressure and temperature as much as possible to the sampling conditions. 
         [0020]    The sample line  102  may connect to other sample lines throughout a string of tools, such as downhole tools or laboratory equipment so the sampled fluid may be provided to different configurations for appropriate testing. In sample containers, for example, a significant dead volume exists. This dead volume, in the form of a volume of material in sampling lines prior to the sampling container, may contain water and/or oil. When a sampled fluid enters the sample line  102  and enters the dead volume, the sampled fluid is mixed with the fluid contained in the dead volume. Contaminants may be introduced into the sampled fluid affecting overall testing results. Additionally, in the case of pure water being in the sample line, the pure water will dilute the sample fluid, again affecting overall results. Reduction of this sampled fluid mixing with dead volume fluid will increase the accuracy of results. 
         [0021]    One alternative example embodiment used to reduce dead volume fluid in the sample line  102  is to use a flow restrictor  106  in the sample line  102 . The flow restrictor  106  may be, for example, an expandable balloon. The flow restrictor, as illustrated in  FIG. 1A , is fully inflated in times of relatively low pressure. The full inflation of the flow restrictor  106  prevents fluid from occupying through the dead volume area of the sample line  102 , thereby minimizing the mixing of fluids between sampled fluids and fluids in the dead volume. Under times of higher pressure, as provided in  FIG. 1B , the flow restrictor  106  is configured to deflate, thereby allowing fluid to flow along the sample line  102 . This deflation allows sampling to occur during times of higher pressure, when a downhole tool is configured to be experiencing inflow. The deflation may be automatic after reaching a predefined pressure in the sample line  102  or may be done through actuation through an operator. In the illustrated embodiment, the deflation occurs automatically as the control equipment required for operator initiated deflation is deleted for clarity of illustration. 
         [0022]    In another example embodiment, the flow restrictor  106  may be membrane material that is spring energized such that the spring force, per Hooke&#39;s law, is constant and that higher pressure values in the sample line  102  would cause additional deflection of the flow restrictor  106 , causing a greater flow path area. In relatively low pressure environments, the spring steel strength causes the membrane to remain in contact with the walls of the sample line  102 , therefore the dead volume is occupied and contamination is minimized. The flow restrictor  106  may be constructed from a high grade spring steel, for example, where the deflection capabilities are well known. In this embodiment, the membrane may be a fluid impervious material to prevent flow of fluids, thus the flow of fluids only occurs when deflection of the spring occurs. 
         [0023]    In either embodiment, a valve  104  may be placed in the sample line  102 . The valve  104  may be any kind of valve that would prevent fluid from flowing through the sample line  102 . The valve  104  may be electronically activated to allow an operator the ability to select when fluid flow should occur through the sample line  102 . 
         [0024]    In another example embodiment, inert particles may be placed within the sample line  102  such that the inert particles occupy volume in the sample line  102 . The inert particles may be kept in place by appropriate stops placed along the sample line. The inert particles may be placed in a container or membrane that allows fluid to flow through but retains particles within the container; or particles can be used without a container or membrane to allow particles follow the flow of fluid into the sample container  100  (to avoid plugging the flowline). The inert particles may be tightly packed or loosely packed or, in an alternative configuration, the inert particles may be graded such that amount of flow path area is restricted to an even greater amount. The particles may be placed in the line for several sampling (if contained by a membrane) operations or may be a single use arrangement (if not contained). The particles may be spherical, as a non-limiting embodiment. 
         [0025]    Referring to  FIG. 2 , an arrangement  200  for sampling fluids is illustrated. The arrangement  200  has an entry port  202  that allows fluid that is desired to be sampled into the arrangement  200 . For the sake of clarity, the fluids, similar to the embodiment described in  FIG. 2 , are from a downhole environment, although the fluids may be obtained in other environments. The piston  204  in the sample bottle may be configured to move through piston seals  206  that contact the remainder of the bottle. The movement of the piston movement may allow for a vacuum to be drawn, thereby causing fluids to enter the bottle. In the illustrated embodiment, two bottle ball valves  208  are present. A plunger  210  may be used to occupy the dead space in the sample line between the entry port  202  and the bottle ball valve  208 . This plunger  210  may be inserted or withdrawn, thereby occupying space or, in the case of withdrawal, allowing space. The plunger  210  may be activated by an operator, as desired. The plunger  210  may occupy all of the space between the entry port of the bottle ball valve or, in an alternative configuration, a portion of the dead volume between the entry port  202  and the bottle ball valve arrangement  208 . The plunger  210  may be operable from a first fully inserted position to a second fully removed position. When fully inserted, the plunger  210  inside o-ring  208  blocks the fluid passage to the bottle. When the plunger is retracted, partially or all the way to restriction  209  if it occupies the full passage cross-section, fluid in the entry port  202  is allowed to come in contact with piston  204 . A pump may then push the fluid into the sample chamber  200  displacing piston  204 , or vacuum can be applied to the opposite side of piston  204 , displacing it inside the sample chamber  200  forcing the fluid to be sampled into chamber  200 . It can be appreciated that the plunger  210  takes most of the dead volume between entry port  202  and the face of the sampling bottle piston  204 . 
         [0026]    Referring to  FIG. 3 , an arrangement  300  is disclosed for sampling fluids, wherein the arrangement  300  has a minimum of dead volume, maximizing accuracy of sampling. A top end of the piston rod  302  is configured with a blank end so that fluid may not pass through the top end  302  when it is aligned with the sample line  308 . The piston rod  310  is further configured with a sample port  304  and a by-pass/flush line  306 . The piston rod  310  is movable through a series of positions. In the fully retracted position, the top end  302  of the piston rod  310  is aligned with the sample line  308  preventing materials from entering the sample bottle and eventually sample chamber  314 . The piston rod  310  is movable through a nitrogen piston  316  that is placed within a nitrogen chamber  318 . Though action of the nitrogen piston  316 , the piston rod  310  moves between the various series of positions where either the top end  302  of the piston, the sample port  304  or the by-pass/flush line  306  are aligned with the sample  308 . 
         [0027]    When the sample port  304  is aligned with the sample line  308  fluid may enter the piston rod  310  and pass down through to the sample chamber  314  for storage. Further activation of the piston rod  310  will cause the sample bottle to be closed, preventing fluid from escaping from the sample chamber  314 . An admission control valve  320  is positioned at the opposite end of the top end  302  for allowing extraction of the fluid sample in the sample chamber  314 . 
         [0028]    Referring to  FIG. 4 , an expanded view of the piston rod end is illustrated. In the expanded view  400 , the bypass-flush line  306  is aligned with the sample line  308  so that fluid passes through the piston rod  310  without entering the sample chamber  314 . 
         [0029]    Referring to  FIG. 5 , an expanded view of the piston rod end is illustrated in a sampling configuration. In this position for the embodiment, the piston rod  310  position allows fluid to enter the sample port  304  which then travels down the piston rod  310  to the sample bottle  414 . A seal  412  is provided on the sample bottle to allow the fluid to be retained in the sample bottle. 
         [0030]    Referring to  FIG. 6 , an expanded view of the piston rod end is illustrated in a sealed configuration. In this position for the embodiment, the piston rod  310  position is fully inserted into the bottle to trap fluid within the sample bottle  414 . 
         [0031]    Referring to  FIG. 7 , an arrangement  700  is presented for limiting dead volume for a sample bottle  714 . In the illustrated embodiment, a washer  704  prevents movement of the piston rod past a specific point. The washer  704  allows the sample port  712  to align with the sample line  706  so that fluid may enter the sample port  712  and be transferred down into the sample bottle  714 . Fluid is kept in the sample bottle  714  through a sample bottle seal  708 . The washer  704 , although shown as a single washer, may be a series of washers to allow for step-wise insertion of the piston. The washer  704  may be selectively eliminated by an operator, so that a step progression of the piston occurs. Elimination may be accomplished by successive burning of the washers  704 . Burning may occur through imposition of an electric charge on the washer. The control wiring to accomplish this electric charge is omitted for clarity of illustration. A flared end  702  prevents the piston from entering the bottle after elimination of the last washer  704 . A bypass/flow line  710  is present in the piston to allow for flow to bypass the sample bottle  714  as necessary. 
         [0032]    Referring to  FIG. 8 , a side view of a sample chamber with a piston rod  808  that is flush with the flowline  804  of a modular sample bottle formation tester  800 . The piston rod  808  in the illustrated configuration is movable. The flow line  804  may have a valve  802  installed to limit or increase flow as desired. A gasket  806  or sealing device may abut the piston rod  808  to prevent flow from escaping or entering the back chamber. The valve  802  closing may cause a back pressure sufficient to allow movement of the piston rod  808  and consequently flow into the bottle. The process may be reversible such that the piston rod  808  may reciprocate back once the pressure diminishes. The piston rod  808  may be kept in place through spring actuation, as a non-limiting embodiment. 
         [0033]    While the aspects has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the disclosure herein.