Abstract:
An apparatus comprising a fluid communication device configured to extend from a drill string and establish fluid communication with a subterranean formation penetrated by a wellbore in which the drill string is positioned, wherein the drill string comprises a passage configured to conduct drilling mud and an opening extending through an outer surface thereof and into a cavity. A sample chamber is coupled within the cavity and is in selectable fluid communication with the formation via the fluid communication device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of and claims priority to U.S. Pat. No. 7,367,394 (“the &#39;394 patent”), entitled “FORMATION EVALUATION WHILE DRILLING,” filed Dec. 19, 2005, and issued May 6, 2008, the entire disclosure of which is hereby incorporated herein by reference. 
         [0002]    This application is also related to U.S. patent application Ser. No. 11/942,796 (“the &#39;796 application”), entitled “FORMATION EVALUATION WHILE DRILLING,” filed Nov. 20, 2007, which is a continuation-in-part of the &#39;394 patent. 
         [0003]    This application is also related to U.S. patent application Ser. No. 12/355,956, entitled “FORMATION EVALUATION WHILE DRILLING,” filed Jan. 19, 2009, which is a continuation of the 796 application. 
         [0004]    This application is also related to U.S. patent application Ser. No. ______ (Attorney Docket No. 24.0952C2), entitled “Formation Evaluation While Drilling,” and filed concurrently herewith. 
         [0005]    This application is also related to U.S. patent application Ser. No. ______ (Attorney Docket No. 24.0952C3), entitled “Formation Evaluation While Drilling,” and filed concurrently herewith. 
     
    
     BACKGROUND OF THE DISCLOSURE 
       [0006]    Wellbores are drilled to locate and produce hydrocarbons. A downhole drilling tool with a bit at and end thereof is advanced into the ground to form a wellbore. As the drilling tool is advanced, a drilling mud is pumped from a surface mud pit, through the drilling tool and out the drill bit to cool the drilling tool and carry away cuttings. The fluid exits the drill bit and flows back up to the surface for recirculation through the tool. The drilling mud is also used to form a mudcake to line the wellbore. 
         [0007]    During the drilling operation, it is desirable to perform various evaluations of the formations penetrated by the wellbore. In some cases, the drilling tool may be provided with devices to test and/or sample the surrounding formation. In some cases, the drilling tool may be removed and a wireline tool may be deployed into the wellbore to test and/or sample the formation. See, for example, U.S. Pat. Nos. 4,860,581 and 4,936,139. In other cases, the drilling tool may be used to perform the testing and/or sampling. See, for example, U.S. Pat. Nos. 5,233,866; 6,230,557; 7,114,562 and 6,986,282. These samples and/or tests may be used, for example, to locate valuable hydrocarbons. 
         [0008]    Formation evaluation often requires that fluid from the formation be drawn into the downhole tool for testing and/or sampling. Various fluid communication devices, such as probes, are typically extended from the downhole tool and placed in contact with the wellbore wall to establish fluid communication with the formation surrounding the wellbore and to draw fluid into the downhole tool. A typical probe is a circular element extended from the downhole tool and positioned against the sidewall of the wellbore. A rubber packer at the end of the probe is used to create a seal with the wellbore sidewall. 
         [0009]    Another device used to form a seal with the wellbore sidewall is referred to as a dual packer. With a dual packer, two elastomeric rings expand radially about the tool to isolate a portion of the wellbore therebetween. The rings form a seal with the wellbore wall and permit fluid to be drawn into the isolated portion of the wellbore and into an inlet in the downhole tool. 
         [0010]    The mudcake lining the wellbore is often useful in assisting the probe and/or dual packers in making the seal with the wellbore wall. Once the seal is made, fluid from the formation is drawn into the downhole tool through an inlet by lowering the pressure in the downhole tool. Examples of probes and/or packers used in downhole tools are described in U.S. Pat. Nos. 6,301,959; 4,860,581; 4,936,139; 6,585,045; 6,609,568; 6,719,049; and 6,964,301. 
         [0011]    In cases where a sample of fluid drawn into the tool is desired, a sample may be collected in one or more sample chambers or bottles positioned in the downhole tool. Examples of such sample chambers and sampling techniques used in wireline tools are described in U.S. Pat. Nos. 6,688,390; 6,659,177; and 5,303,775. Examples of such sample chambers and sampling techniques used in drilling tools are described in U.S. Pat. Nos. 5,233,866 and 7,124,819. Typically, the sample chambers are removable from the downhole tool as shown, for example, in U.S. Pat. Nos. 6,837,314; 4,856,585; and 6,688,390. 
         [0012]    Despite these advancements in sampling technology, there remains a need to provide sample chamber and/or sampling techniques capable of providing more efficient sampling in harsh drilling environments. It is desirable that such techniques are usable in the limited space of a downhole drilling tool and provide easy access to the sample. Such techniques preferably provide one or more of the following, among others: selective access to and/or removal of the sample chambers; locking mechanisms to secure the sample chamber; isolation from shocks, vibrations, cyclic deformations and/or other downhole stresses; protection of sample chamber sealing mechanisms; controlling thermal stresses related to sample chambers without inducing concentrated stresses or compromising utility; redundant sample chamber retainers and/or protectors; and modularity of the sample chambers. Such techniques are also preferably achieved without requiring the use of high cost materials to achieve the desired operability. 
       SUMMARY OF THE DISCLOSURE 
       [0013]    In at least one aspect, the present disclosure relates to a sample module for a sampling while drilling tool positionable in a wellbore penetrating a subterranean formation is provided. The tool includes a drill collar, at least one sample chamber, at least one flowline and at least one cover. The drill collar is operatively connectable to a drill string of the sampling while drilling tool. The drill collar has at least one opening extending through an outer surface thereof and into a cavity. The drill collar has a passage therein for conducting mud therethrough. The sample chamber is positionable in the cavity of the drill collar. The flowline in the drill collar, the at least one flowline operatively connectable to the sample chamber for passing a downhole fluid thereto. The cover is positionable about the at least one opening of the drill collar whereby the sample chamber is removably secured therein. 
         [0014]    In another aspect, the disclosure relates to a downhole sampling while drilling tool positionable in a wellbore penetrating a subterranean formation. The sampling tool includes a fluid communication device, a drill collar, at least one sample chamber, at least one flowline and at least one cover. The fluid communication device is operatively connectable to a drill string of the sampling while drilling tool and extendable therefrom for establishing fluid communication with the formation. The fluid communication device has an inlet for receiving formation fluid. The drill collar is operatively connectable to a drill string, the drill collar having at least one opening extending through an outer surface thereof and into a cavity. The drill collar has a passage therein for conducting mud therethrough. The sample chamber is positionable in the cavity of the drill collar. The flowline is in the drill collar. The flowline is fluidly connectable to inlet and the sample chamber for passing a downhole fluid therebetween. The cover is positionable about the at least one opening of the drill collar whereby the sample chamber is removably secured therein. 
         [0015]    Finally, in another aspect, the disclosure relates to a method of sampling while drilling via a downhole sampling while drilling tool positionable in a wellbore penetrating a subterranean formation. The method involves positioning a sample chamber through an opening in an outer surface of a drill collar of the sampling while drilling tool and into a cavity therein, positioning a cover over the opening of the drill collar, deploying the downhole sampling while drilling tool into the wellbore, establishing fluid communication between the sampling while drilling tool and the formation, drawing a formation fluid into the sampling while drilling tool via an inlet in the sampling while drilling tool and passing the formation fluid from the inlet to the sample chamber. 
         [0016]    Other aspects of the disclosure may be discerned from the description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
           [0018]      FIG. 1  is an schematic representation of a wellsite having a downhole tool positioned in a wellbore penetrating a subterranean formation, the downhole tool having a sampling while drilling (“SWD”) system. 
           [0019]      FIG. 2A  is a longitudinal cross-sectional representation of a portion of the downhole tool of  FIG. 1  depicting a sample module of the SWD system in greater detail, the sample module having a fluid flow system and a plurality of sample chambers therein. 
           [0020]      FIG. 2B  is a horizontal cross-sectional representation of the sample module of  FIG. 2A , taken along section line  2 B- 2 B. 
           [0021]      FIG. 3  is a schematic representation of the fluid flow system of  FIGS. 2A and 2B . 
           [0022]      FIG. 4A  is a partial sectional representation of the sample module of  FIG. 2A  having a removable sample chamber retained therein by a two piece cover. 
           [0023]      FIG. 4B  is a partial sectional representation of an alternate sample module having a removable sample chamber retained therein by a multi-piece cover. 
           [0024]      FIG. 5A  is a detailed sectional representation of a portion of the sample module of  FIG. 4A  depicting an interface thereof in greater detail. 
           [0025]      FIG. 5B  is an isometric representation, partially in section, of an alternate sample module and interface. 
           [0026]      FIGS. 6A-6D  are detailed sectional representations of a portion of the sample module of  FIG. 4A  depicting the shock absorber in greater detail. 
           [0027]      FIG. 7  is an isometric representation of an alternative shock absorber having a retainer usable with the sample module of  FIG. 4A . 
           [0028]      FIG. 8A  is an alternate view of the shock absorber of  FIG. 7  positioned in a drill collar. 
           [0029]      FIG. 8B  is an exploded view of an alternate shock absorber and drill collar. 
           [0030]      FIG. 8C  is an isometric representation, partially in section, of an alternate shock absorber and drill collar. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Certain terms are defined throughout this description as they are first used, while certain other terms used in this description are defined below: 
         [0032]    “Electrical” and “electrically” refer to connection(s) and/or line(s) for transmitting electronic signals. 
         [0033]    “Electronic signals” mean signals that are capable of transmitting electrical power and/or data (e.g., binary data). 
         [0034]    “Module” means a section of a downhole tool, particularly a multi-functional or integrated downhole tool having two or more interconnected modules, for performing a separate or discrete function. 
         [0035]    “Modular” means adapted for (inter)connecting modules and/or tools, and possibly constructed with standardized units or dimensions for flexibility and variety in use. 
         [0036]    “Single phase” refers to a fluid sample stored in a sample chamber, and means that the pressure of the chamber is maintained or controlled to such an extent that sample constituents which are maintained in a solution through pressure only, such as gasses and asphaltenes, should not separate out of solution as the sample cools upon retrieval of the chamber from a wellbore. 
         [0037]      FIG. 1  depicts a wellsite  1  including a rig  10  with a downhole tool  100  suspended therefrom and into a wellbore  11  via a drill string  12 . The downhole tool  10  has a drill bit  15  at its lower end thereof that is used to advance the downhole tool into the formation and form the wellbore. 
         [0038]    The drillstring  12  is rotated by a rotary table  16 , energized by means not shown, which engages a kelly  17  at the upper end of the drillstring. The drillstring  12  is suspended from a hook  18 , attached to a traveling block (also not shown), through the kelly  17  and a rotary swivel  19  which permits rotation of the drillstring relative to the hook. 
         [0039]    The rig is depicted as a land-based platform and derrick assembly  10  used to form the wellbore  11  by rotary drilling in a manner that is well known. Those of ordinary skill in the art given the benefit of this disclosure will appreciate, however, that the present invention also finds application in other downhole applications, such as rotary drilling, and is not limited to land-based rigs. 
         [0040]    Drilling fluid or mud  26  is stored in a pit  27  formed at the well site. A pump  29  delivers drilling fluid  26  to the interior of the drillstring  12  via a port in the swivel  19 , inducing the drilling fluid to flow downwardly through the drillstring  12  as indicated by a directional arrow  9 . The drilling fluid exits the drillstring  12  via ports in the drill bit  15 , and then circulates upwardly through the region between the outside of the drillstring and the wall of the wellbore, called the annulus, as indicated by direction arrows  32 . In this manner, the drilling fluid lubricates the drill bit  15  and carries formation cuttings up to the surface as it is returned to the pit  27  for recirculation. 
         [0041]    The downhole tool  100 , sometimes referred to as a bottom hole assembly (“BHA”), is preferably positioned near the drill bit  15  (in other words, within several drill collar lengths from the drill bit). The bottom hole assembly includes various components with capabilities, such as measuring, processing, and storing information, as well as communicating with the surface. A telemetry device (not shown) is also preferably provided for communicating with a surface unit (not shown). 
         [0042]    The BHA  100  further includes a sampling while drilling (“SWD”) system  230  including a fluid communication module  210  and a sample module  220 . The modules are preferably housed in a drill collar for performing various formation evaluation functions (described in detail below). As shown in  FIG. 1 , the fluid communication module  210  is preferably positioned adjacent the sample module  220 . The fluid communication module is depicted as having a probe with an inlet for receiving formation fluid. Additional devices, such as pumps, gauges, sensor, monitors or other devices usable in downhole sampling and/or testing may also be provided. While  FIG. 1  is depicted as having a modular construction with specific components in certain modules, the tool may be unitary or select portions thereof may be modular. The modules and/or the components therein may be positioned in a variety of configurations throughout the downhole tool. 
         [0043]    The fluid communication module  210  has a fluid communication device  214 , such as a probe, preferably positioned in a stabilizer blade or rib  212 . An exemplary fluid communication device that can be used is depicted in US patent Application No. 20050109538, the entire contents of which are hereby incorporated by reference. The fluid communication device is provided with an inlet for receiving downhole fluids and a flowline (not shown) extending into the downhole tool for passing fluids therethrough. The fluid communication device is preferably movable between extended and retracted positions for selectively engaging a wall of the wellbore  11  and acquiring a plurality of fluid samples from the formation F. As shown, a back up piston  250  may be provided to assist in positioning the fluid communication device against the wellbore wall. 
         [0044]    Examples of fluid communication devices, such as probes or packers, that can be used, are described in greater detail in U.S. Patent/Application Nos. US 2005/0109538 and 5,803,186. A variety of fluid communication devices alone or in combination with protuberant devices, such as stabilizer blades or ribs, may be used. 
         [0045]      FIGS. 2A and 2B  depict a portion of the downhole tool  100  with the sample module  220  of  FIG. 1  shown in greater detail.  FIG. 2A  is a longitudinal cross-section of a portion of the probe module  210  and the sample module  220 .  FIG. 2B  is a horizontal cross-sectional of the sample module  220  taken along section line  2 B- 2 B of  FIG. 2A . 
         [0046]    The sample module  220  is preferably housed in a drill collar  302  that is threadably connectable to adjacent drill collars of the BHA, such as the probe module  210  of  FIG. 1 . The drill collar has a mandrel  326  supported therein. A passage  323  extends between the mandrel and the drill collar to permit the passage of mud therethrough as indicated by the arrows. 
         [0047]    The sample chamber, drill collar and associated components may be made of high strength materials, such as stainless steel alloy, titanium or inconel. However, the materials may be selected to achieve the desired thermal expansion matching between components. In particular, it may be desirable to use a combination of low cost, high strength and limited thermal expansion materials, such as peek or kevlar. 
         [0048]    Interface  322  is provided at an end thereof to provide hydraulic and/or electrical connections with an adjacent drill collar. An additional interface  324  may be provided at another end to operatively connect to adjacent drill collars if desired. In this manner, fluid and/or signals may be passed between the sample module and other modules as described, for example, in U.S. patent application Ser. No. 11/160,240. In this case, such an interface is preferably provided to establish fluid communication between the fluid communication module and the sample module to pass formation fluid received by the fluid communication module to the sample module. 
         [0049]    Interface  322  is depicted as being at an uphole end of the sample module  220  for operative connection with adjacent fluid communication module  210 . However, it will be appreciated that one or more fluid communication and/or probe modules may be positioned in the downhole tool with one or more interfaces at either or both ends thereof for operative connection with adjacent modules. In some cases one or more intervening modules may be positioned between the fluid communication and probe modules. 
         [0050]    The sample module has fluid flow system  301  for passing fluid through the drill collar  302 . The fluid flow system includes a primary flow line  310  that extends from the interface and into the downhole tool. The flowline is preferably in fluid communication with the flowline of the fluid communication module via the interface for receiving fluids received thereby. As shown, the flowline is positioned in mandrel  326  and conducts fluid, received from the fluid communication module through the sample module. 
         [0051]    As shown, the fluid flow system  301  also has a secondary flowline  311  and a dump flowline  260 . The secondary flowline diverts fluid from the primary flowline  310  to one or more sample chambers  314  for collection therein. Additional flowlines, such as dump flowline  260  may also be provided to divert flow to the wellbore or other locations in the downhole tool. As shown, a flow diverter  332  is provided to selectively divert fluid to various locations. One or more such diverters may be provided to divert fluid to desired locations. 
         [0052]    The sample chambers may be provided with various devices, such as valves, pistons, pressure chambers or other devices to assist in manipulating the capture of fluid and/or maintaining the quality of such fluid. The sample chambers  314  are each adapted for receiving a sample of formation fluid, acquired through the probe  214  (see  FIG. 1 ), via the primary flow line  310  and respective secondary flow lines  311 . 
         [0053]    As shown, the sample chambers are preferably removably positioned in an aperture  303  in drill collar  302 . A cover  342  is positioned about the sample chambers and drill collar  302  to retain the sample chambers therein. 
         [0054]    As seen in the horizontal cross-section taken along line  2 B- 2 B of  FIG. 2A  and shown in  FIG. 2B , the sample module is provided with three sample chambers  314 . The sample chambers  314  are preferably evenly spaced apart within the body at 120° intervals. However, it will be appreciated that one or more sample chambers in a variety of configurations may be positioned about the drill collar. Additional sample chambers may also be positioned in additional vertical locations about the module and/or downhole tool. 
         [0055]    The chambers are preferably positioned about the periphery of the drill collar  302 . As shown the chambers are removably positioned in apertures  303  in the drill collar  302 . The apertures are configured to receive the sample chambers. Preferably, the sample chambers fit in the apertures in a manner that prevents damage when exposed to the harsh wellbore conditions. 
         [0056]    Passage  318  extends through the downhole tool. The passage preferably defines a plurality of radially-projecting lobes  320 . The number of lobes  320  is preferably equal to the number of sample chambers  314 , i.e., three in  FIG. 2B . As shown, the lobes  320  project between the sample chambers  314  at a spacing interval of about 60° therefrom. Preferably, the lobes expand the dimension of the passage about the sample chambers to permit drilling fluid to pass therethrough. 
         [0057]    The lobed bore  318  is preferably configured to provide adequate flow area for the drilling fluid to be conducted through the drillstring past the sample chambers  314 . It is further preferred that the chambers and/or containers be positioned in a balanced configuration that reduces drilling rotation induced wobbling tendencies, reduces erosion of the downhole tool and simplifies manufacturing. It is desirable that such a configuration be provided to optimize the mechanical strength of the sample module, while facilitating fluid flow therethrough. The configuration is desirably adjusted to enhance the operability of the downhole tool and the sampling while drilling system. 
         [0058]      FIG. 3  is a schematic representation of the fluid flow system  301  of the sample module  220  of  FIGS. 2A-2B . As described above, the fluid flow system  301  includes a flow diverter  332  for selectively diverting flow through the sample module and a plurality of sample chambers  314 . The flow diverter selectively diverts fluid from primary flowline  310  to secondary flowlines  311  leading to sample chambers  314  and/or a dump flowline  260  leading to the wellbore. 
         [0059]    One or more flowlines valves may be provided to selectively divert fluid to desired locations throughout the downhole tool. In some cases, fluid is diverted to the sample chamber(s) for collection. In other cases, fluid may be diverted to the wellbore, the passage  318  or other locations as desired. 
         [0060]    The secondary flowlines  311  branch off from primary flowline  310  and extend to sample chambers  314 . The sample chambers may be any type of sample chamber known in the art to capture downhole fluid samples. As shown, the sample chambers preferably include a slidable piston  360  defining a variable volume sample cavity  307  and a variable volume buffer cavity  309 . The sample cavity is adapted to receive and house the fluid sample. The buffer cavity typically contains a buffer fluid that applies a pressure to the piston to maintain a pressure differential between the cavities sufficient to maintain the pressure of the sample as it flows into the sample cavity. Additional features, such as pressure compensators, pressure chambers, sensors and other components may be used with the sample chambers as desired. 
         [0061]    The sample chamber is also preferably provided with an agitator  362  positioned in the sample chamber. The agitator may be a rotating blade or other mixing device capable of moving the fluid in the sample chamber to retain the quality thereof. 
         [0062]    Each sample chamber  314  is shown to have container valves  330   a ,  330   b . Container valves  330   a  are preferably provided to selectively fluidly connect the sample cavity of the sample chambers to flowline  311 . The chamber valves  330   b  selectively fluidly connect the buffer cavity of the sample chambers to a pressure source, such as the wellbore, a nitrogen charging chamber or other pressure source. 
         [0063]    Each sample chamber  314  is also associated with a set of flowline valves  328   a ,  328   b  inside a flow diverter/router  332 , for controlling the flow of fluid into the sample chamber. One or more of the flowline valves may be selectively activated to permit fluid from flowline  310  to enter the sample cavity of one or more of the sample chambers. A check valve may be employed in one or more flow lines to restrict flow therethrough. 
         [0064]    Additional valves may be provided in various locations about the flowline to permit selective fluid communication between locations. For example, a valve  334 , such as a relief or check valve, is preferably provided in a dump flowline  260  to allow selective fluid communication with the wellbore. This permits formation fluid to selectively eject fluid from the flowline  260 . This fluid is typically dumped out dump flowline  260  and out the tool body&#39;s sidewall  329 . Valve  334  may also be is preferably open to the wellbore at a given differential pressure setting. Valve  334  may be a relief or seal valve that is controlled passively, actively or by a preset relief pressure. The relief valve  334  may be used to flush the flowline  310  before sampling and/or to prevent over-pressuring of fluid samples pumped into the respective sample chambers  314 . The relief valve may also be used as a safety to prevent trapping high pressure at the surface. 
         [0065]    Additional flowlines and valves may also be provided as desired to manipulate the flow of fluid through the tool. For example, a wellbore flowline  315  is preferably provided to establish fluid communication between buffer cavities  309  and the wellbore. Valves  330   b  permit selective fluid communication with the buffer chambers. 
         [0066]    In instances where multiple sample modules  220  are run in a tool string, the respective relief valves  334  may be operated in a selective fashion, e.g., so as to be active when the sample chambers of each respective module  220  are being filled. Thus, while fluid samples are routed to a first sample module  220 , its corresponding relief valve  334  may be operable. Once all the sample chambers  314  of the first sample module  220  are filled, its relief valve is disabled. The relief valve of an additional sample module may then be enabled to permit flushing of the flow line in the additional sample module prior to sample acquisition (and/or over-pressure protection). The position and activation of such valves may be actuated manually or automatically to achieve the desired operation. 
         [0067]    Valves  328   a ,  328   b  are preferably provided in flowlines  311  to permit selective fluid communication between the primary flowline  310  and the sample cavity  307 . These valves may be selectively actuated to open and close the secondary flow lines  311  sequentially or independently. 
         [0068]    The valves  328   a, b  are preferably electric valves adapted to selectively permit fluid communication. These valves are also preferably selectively actuated. Such valves may be provided with a spring-loaded stem (not shown) that biases the valves to either an open or closed position. In some cases, the valves may be commercially available exo or seal valves. 
         [0069]    To operate the valves, an electric current is applied across the exo washers, causing the washers to fail, which in turn releases the springs to push their respective stems to its other, normal position. Fluid sample storage may therefore be achieved by actuating the (first) valves  328   a  from the displaced closed positions to the normal open positions, which allows fluid samples to enter and fill the sample chambers  314 . The collected samples may be sealed by actuating the (second) valves  328   b  from the displaced open positions to the normal closed positions. 
         [0070]    The valves are preferably selectively operated to facilitate the flow of fluid through the flowlines. The valves may also be used to seal fluid in the sample chambers. Once the sample chambers are sealed, they may be removed for testing, evaluation and/or transport. The valves  330   a  (valve  330   b  may remain open to expose the backside of the container piston  360  to wellbore fluid pressure) are preferably actuated after the sample module  220  is retrieved from the wellbore to provide physical access by an operator at the surface. Accordingly, a protective cover (described below) may be equipped with a window for quickly accessing the manually-operable valves—even when the cover is moved to a position closing the sample chamber apertures  313  ( FIG. 4 ). 
         [0071]    One or more of the valves may be remotely controlled from the surface, for example, by using standard mud-pulse telemetry, or other suitable telemetry means (e.g., wired drill pipe). The sample module  220  may be equipped with its own modem and electronics (not shown) for deciphering and executing the telemetry signals. Alternatively, one or more of the valves may be manually activated. Downhole processors may also be provided for such actuation. 
         [0072]    Those skilled in the art will appreciate that a variety of valves can be employed. Those skilled in the art will appreciate that alternative sample chamber designs can be used. Those skilled in the art will appreciate that alternative fluid flow system designs can be used. 
         [0073]      FIGS. 4A and 4B  depict techniques for removably positioning sample chambers in the downhole tool.  FIG. 4A  depicts a sample chamber retained with the downhole tool by a cover, such as a ring or sleeve, slidably positionable about the outer surface of the drill collar to cover one or more openings therein.  FIG. 4B  depicts a cover, such as a plate or lid, positionable over an opening in the drill collar. 
         [0074]      FIG. 4A  is a partial sectional representation of the sample module  220 , showing a sample chamber  314  retained therein. The sample chamber is positioned in aperture  303  in drill collar  302 . The drill collar has a passage  318  for the passage of mud therethrough. 
         [0075]    Cover  342  is positioned about the drill collar to retain the sample chamber in the downhole tool. The sample chambers  314  are positioned in the apertures  303  in drill collar  302 . Cover  342  is preferably a ring slidably positionable about drill collar  302  to provide access to the sample chambers  314 . Such access permits insertion and withdrawal of sample chamber  314  from the drill collar  302 . 
         [0076]    The cover  342  acts as a gate in the form of a protective cylindrical cover that preferably fits closely about a portion of the drill collar  302 . The cover  342  is movable between positions closing (see  FIG. 4A ) and opening (not shown) the one or more apertures  303  in the drill collar. The cover thereby provides selective access to the sample chambers  314 . The cover also preferably prevents the entry of large particles, such as cuttings, from the wellbore into the aperture when in the closed position. 
         [0077]    The cover  342  may comprise one or more components that are slidable along drill collar  302 . The cover preferably has an outer surface adapted to provide mechanical protection from the drilling environment. The cover is also preferably fitted about the sample chamber to seal the opening(s) and/or secure the sample chamber in position and prevent damage due to harsh conditions, such as shock, external abrasive forces and vibration. 
         [0078]    The cover  342  is operatively connected to the drill collar  302  to provide selective access to the sample chambers. As shown, the cover has a first cover section  342   a  and a second cover section  342   b . The first cover section  342   a  is held in place about drill collar  302  by connection means, such as engaging threads  344 , for operatively connecting an inner surface of the first cover section  342   a  and an outer surface of the drill collar  302 . 
         [0079]    The cover may be formed as a single piece, or it may include two or more complementing sections. For example,  FIG. 4A  illustrates a two-piece cover  342  with first and second cover sections  342   a ,  342   b . Both the first cover section  342   a  and second cover section  342   b  are preferably slidably positioned about an opening  305  the tool body  302 . The first cover section  342   b  may be slid about the drill collar until it rests upon an downwardly-facing shoulder  347  of the body. A shim  345 , or a bellows, spring-washer stack or other device capable of axial loading of the bottle to secure it in place, may be positioned between the shoulder  347  and the first cover section  342   b . The second cover section  342   a  may also be slidably positioned about the drill collar  302 . The cover sections have complementing stops (referenced as  348 ) adapted for operative connection therebetween. The second cover section may be operatively connected to the first cover section before or after positioning the covers sections about the drill collar. The first cover section is also threaded onto the drill collar at threaded connection  344 . 
         [0080]    The cover sections may then be rotated relative to the drill collar  302  to tighten the threaded connection  344  and secure the cover sections in place. Preferably, the covers are securably positioned to preload the cover sections and reduce (or eliminate) relative motion between the cover sections and the tool body  302  during drilling. 
         [0081]    The cover  342  may be removed from drill collar  302  to access the sample chambers. For example, the cover  342  may be rotated to un-mate the threaded connection  344  to allow access to the sample chamber. The cover  342  may be provided with one or more windows  346 . Window  346  of the cover  342  may be used to access the sample chamber  314 . The window may be used to access valves  330   a ,  330   b  on the sample chamber  314 . Window  346  permits the manual valve  330   a  to be accessed at the surface without the need for removing the cover  342 . Also, it will be appreciated by those skilled in that art that a windowed cover may be bolted or otherwise operatively connected to the tool body  302  instead of being threadably engaged thereto. One or more such windows and/or covers may be provided about the drill collar to selectively provide access and/or to secure the sample chamber in the drill collar. 
         [0082]    The sample chamber is preferably removably supported in the drill collar. The sample chamber is supported at an end thereof by a shock absorber  552 . An interface  550  is provided at an opposite end adjacent flowline  311  to operatively connect the sample chamber thereto. The interface  550  is also preferably adapted to releasably secure the sample chamber in the drill collar. The interface and shock absorbers may be used to assist in securing the sample chamber in the tool body. These devices may be used to provide redundant retainer mechanisms for the sample chambers in addition to the cover  342 . 
         [0083]      FIG. 4B  depicts an alternate sample module  220 ′. The sample module  220 ′ is the same as the sample module  220  of  FIG. 4A , except that the sample chamber  314 ′ is retained in drill collar  302  by cover  342 ′, an interface  550 ′ and a shock absorber  552 . The cover  342 ′ includes a plurality of cover portions  342   c  and  342   d.    
         [0084]    Cover  342   d  is slidably positionable in opening  305  of the drill collar  302 . Cover  342 ′ is preferably a rectangular plate having an overhang  385  along an edge thereof. The cover may be inserted into the drill collar such that the overhang  385  engages an inner surface  400  of the drill collar. The overhang allows the cover to slidingly engage the inner surface of the drill collar and be retained therein. One or more covers  342   d  are typically configured such that they may be dropped into the opening  305  and slid over the sample chamber  314  (not shown) to the desired position along the chamber cavity opening. The covers may be provided with countersink holes  374  to aid in the removal of the cover  342   d . The cover  342   d  may be configured with one or more windows, such as the window  346  of  FIG. 4A . 
         [0085]    Cover  342   c  is preferably a rectangular plate connectable to drill collar  302  about opening  305 . The cover is preferably removably connected to the drill collar by bolts, screws or other fasteners. The cover may be slidably positionable along the drill collar and secured into place. The cover may be provided with receptacles  381  extending from its sides and having holes therethrough for attaching fasteners therethrough. 
         [0086]    The covers as provided herein are preferably configured with the appropriate width to fit snuggly within the opening  305  of the drill collar. One or more such covers or similar or different configurations may be used. The covers may be provided with devices to prevent damage thereto, such as the strain relief cuts  390  in cover  342  of  FIG. 4B . In this manner, the covers may act as shields. 
         [0087]      FIG. 5A  is a detailed representation of a portion of the sample module of  FIG. 4A  depicting the interface  550  in greater detail. The interface includes a hydraulic stabber  340  fluidly connecting the sample chamber  314  disposed therein to one of the secondary flow lines  311 . The sample chamber  314  has a conical neck  315  having an inlet for passing fluids therethrough. The upper portion of the hydraulic stabber  340  is in fluid-sealing engagement with the conical neck  315  of the sample chamber  314 , and the lower portion of the hydraulic stabber in fluid-sealing engagement with the secondary flow line  311  of the drill collar  302 . 
         [0088]    Such retainer mechanisms are preferably positioned at each of the ends of the sample chambers to releasably retain the sample chamber. A first end of the sample chamber  314  may be laterally fixed, e.g., by sample chamber neck  315 . An opposite end typically may also be provided with a retainer mechanism. Alternatively, the opposite end may be held in place by shock absorber  552  ( FIG. 4A ). These retainer mechanisms may be reversed or various combinations of retainer mechanisms may be used. 
         [0089]    The conical neck  315  of the sample chamber  314  is supported in a complementing conical aperture  317  in the tool body  302 . This engagement of conical surfaces constitutes a portion of a retainer for the sample chamber. The conical neck may be used to provide lateral support for the sample chamber  314 . The conical neck may be used in combination with other mechanisms, such as an axial loading device (described below), to support the sample chamber in place. Preferably, little if any forces are acting on the hydraulic stabber  340  and its O-ring seals  341  to prevent wear of the stabber/seal materials and erosion thereof over time. The absence of forces at the hydraulic seals  341  preferably equates to minimal, if any, relative motion at the seals  341 , thereby reducing the likelihood of leakage past the seals. 
         [0090]      FIG. 5B  is a detailed view of a portion of the sample module  220 ′ of  FIG. 4B  with an alternate interface to that of  FIG. 4A . The sample chamber  314 ′ of  FIG. 5B  is equipped with double-wedge or pyramidal neck  315 ′ that engages a complementing pyramidal aperture  317 ′ in the tool body  302 . Hydraulic stabber  340 ′ is positioned in an inlet in pyramidal neck  315 ′ for insertion into pyramidal aperture  317 ′ for fluidly coupling the sample chamber to flowline  311 . Hydraulic seals  341 ′ are preferably provided to fluidly seal the sample chamber to the drill collar. 
         [0091]    This pyramidal engagement provides torsional support for the sample chamber, and prevents it from rotating about its axis within the sample chamber. This functionality may be desirable to ensure a proper alignment of manually operated valves  330   a ′ and  330   b ′ within the opening  313  of the sample chambers  314 . 
         [0092]      FIGS. 6A-D  illustrate a portion of the sample module  220  of  FIG. 4A  in greater detail. In these figures, the sample module  220  is provided with alternative configurations of retainers  552   a - d  usable as the shock absorbers  552  and/or  552 ′ of  FIGS. 4A-4B . These retainers assist in supporting sample chamber  314  within aperture  303  of drill collar  302 . Cover  342  also assists in retaining sample chamber  314  in position. The retainer and/or cover also preferably provide shock absorption and otherwise assist in preventing damage to the sample chamber. 
         [0093]    As shown in  FIG. 6A , the retainer  552   a  includes an axial-loading device  1050  and a washer  852 . An adjustable setscrew  851  is also provided between the drill collar  302  and the retainer  552   a  to adjustably position the sample chamber  314  within the drill collar. The washer may be a belleville stack washer or other spring mechanism to counteract drilling shock, internal pressure in the sample chamber and/or assist in shock absorption. 
         [0094]    The sample chamber preferably has a tip  815  extending from an end thereof. The tip  815  is preferably provided to support washer  852  and axial loading device  1050  at an end of the sample chamber. 
         [0095]      FIG. 6B  shows an alternate shock absorber  552   b . The retainer  552   b  is essentially the same as the retainer  552   a , but does not have a setscrew  851 . In this configuration, support is provided by cover  342 ′. Cover  342 ′ operates the same as covers  342 , but is provided with a stepped inner surface  343 . The stepped inner surface defines a cover shoulder  343  adapted to support sample chamber  314  within drill collar  302 . 
         [0096]    Referring now to  FIG. 6C , the shock absorber  552   c  is the same as the shock absorber  552   a  of  FIG. 6A , but is further provided with a hydraulic jack  1051 . The hydraulic jack includes a hydraulic cylinder  1152 , a hydraulic piston  1154 , and a hydraulic ram  1156  that are operable to axially load the axial loading spacer  1050 . 
         [0097]    When the cover  342  is open (not shown), the hydraulic jack may be extended under pressurized hydraulic fluid (e.g., using a surface source) to fully compress the spring member  852 . An axial lock (not shown) is then inserted and the pressure in the hydraulic cylinder  1152  may be released. The length of the axial lock is preferably dimensioned so that the counteracting spring force of the spring member is sufficient in the full temperature and/or pressure range of operation of the sample module, even if the sample module expands more than the sample chamber. 
         [0098]    When the cover  342  is retracted (not shown), the hydraulic jack may be extended under pressurized hydraulic fluid (e.g., using a surface source) to fully compress the washer  852 . An axial lock  1158  may then be inserted and the pressure in the hydraulic cylinder  1152  released. The length of the axial lock  1158  is preferably dimensioned so that the counteracting spring force of spring member is sufficient to operate in a variety of wellbore temperatures and pressures. 
         [0099]      FIG. 6D  depicts an alternate shock absorber  552   d  with an alternate jack  1051 ′. The shock absorber is the same as the shock absorber  552   c  of  FIG. 6C , except that an alternate jack is used. In this configuration, the jack includes opposing lead screws  1060   a  and  1060   b , rotational lock  1172  and a jackscrew  1062 . 
         [0100]    The jackscrew  1062  is engaged in opposing lead screws  1060   a  and  1060   b . Opposing lead screws  1060   a  and  1060   b  are provided with threaded connections  1061   a  and  1061   b  for mating connection with threads on jackscrew  1062 . When the cover  342  is open (not shown), the distance between opposing lead screws  1060   a  and  1060   b  may be increased under torque applied to a central, hexagonal link  1171  until a desirable compression of the spring member  852  is achieved. Then a rotation lock  1172  may be inserted around the central, hexagonal link  1171  to prevent further rotation. 
         [0101]      FIG. 7  illustrates an alternative retainer  552   e  usable as the shock absorber for a sample chamber, such as the one depicted in  FIG. 4A . The retainer  552   e  includes an axial-loading spacer  1050 ′ and a head component  715 . Preferably, the axial load spacer has a flat sidewall  751  for engaging a complementing flat sidewall  752  of an end  815 ′ of the sample chamber  314  and preventing relative rotation therebetween. The head component  715  is insertable into the axial loading spacer  1050 ′ and the sample chamber to provide an operative connection therebetween. A spring member (not shown) may be provided about on a head component  815  of sample chamber  314  between the axial-loading spacer and the sample chamber. 
         [0102]      FIGS. 8A-8C  show alternative retainers usable with the sample chamber  314  of  FIG. 7 .  FIG. 8A  depicts the retainer  552   e  of  FIG. 7  positioned in a drill collar  302   a .  FIG. 8B  depicts an alternate retainer  552   f  having an axial-loading spacer  1050 ″ having a key  808  insertable into a drill collar  302   b ′.  FIG. 8C  depicts an alternate retainer  552   g  having a radial retainer  860  operatively connected to a drill collar  302   c ′. The drill collars of these figures may be the same drill collar  302  as depicted in previous figures, except that they are adapted to receive the respective retainers. Preferably, these retainers and drill collars are adapted to prevent rotation and lateral movement therebetween, and provide torsional support. 
         [0103]    As shown in  FIG. 8A , the axial-loading spacers  1050 ′ of retainer  552   e  has rounded and flat edge portions  804  and  805 , respectively. Drill collar  302  has a rounded cavity  806  adapted to receive the axial loading spacer  1050 ′. 
         [0104]    In  FIG. 8B , the retainer  552   e  includes an axial-loading spacer  1050 ′ having a rectangular periphery  810  and a key  808  extending therefrom. The key  808  is preferably configured such that it is removably insertable into a cavity  812  in drill collar  302   b ′. As shown, the key has an extension  811  with a tip  814  at an end thereof. The tip  814  is insertable into cavity  812 , but resists removal therefrom. The dimension of cavity  812  is preferably smaller than the tip  814  and provides an inner surface (not shown) that grippingly engages the tip to resist removal. In some cases, it may be necessary to break the tip  814  to enable removal of the sample chamber when desired. Optionally, the tip may be fabricated such that a predetermined force is required to permit removal. In this manner, it is desirable to retain the sample chamber  314  in position in the drill collar during operation, but enable removal when desired. 
         [0105]      FIG. 8C  the alternative retainer  552   g  includes an arm  950  operatively connected to drill collar  302   c ′. The arm  950  is preferably connected to drill collar  302   c ′ via one or more screws  951 . Preferably, the arm  950  is radially movable in a hinge like fashion. The arm  950  has a concave inner surface  955  adapted to engage and retain sample chamber  314  in place in drill collar  302   c′.    
         [0106]    Preferably, the retainers provided herein permit selective removal of the sample chambers. One or more such retainers may be used to removably secure the sample chamber in the drill collar. Preferably, such retainers assist in securing the sample chamber in place and prevent shock, vibration or other damaging forces from affecting the sample chamber. 
         [0107]    In operation, the sample module is threadedly connected to adjacent drill collars to form the BHA and drill string. Referring to  FIG. 1 , the sample module may be pre-assembled by loading the sample chamber  314  into the aperture  303  of the drill collar  302 . The interface  550  is created by positioning and end of the sample chamber  314  adjacent the flowline  311 . 
         [0108]    The interface  550  (also known as a pre-loading mechanism) may be adjusted at the surface such that a minimum acceptable axial or other desirable load is applied to achieve the required container isolation in the expected operating temperature range of the sample module  220 , thereby compensating for greater thermal expansion. 
         [0109]    Retainer  552  may also be operatively connected to an opposite end of the sample chamber to secure the sample chamber in place. The cover  342  may then be slidably positioned about the sample chamber to secure it in place. 
         [0110]    The interface  550  at the (lower) end with the hydraulic connection may be laterally fixed, e.g., by conical engagement surfaces  315 ,  317  (see, e.g.  FIG. 5A ) as described above. The retainer  552  at the opposite (upper) end typically constrains axial movement of the sample chamber  314  (see, e.g.,  FIGS. 6A-8C ). The two work together to hold the sample chamber within the drill collar  302 . The cover  342  is then disposed about the sample chamber to seal the opening  305  of the sample chamber as shown, for example in  FIG. 4A . 
         [0111]    One or more covers, shock absorbers, retainers, sample chambers, drill collars, wet stabbers and other devices may be used alone and/or in combination to provide mechanisms to protect the sample chamber and its contents. Preferably redundant mechanisms are provided to achieve the desired configuration to protect the sample chamber. As shown in  FIG. 4 , the sample chamber may be inserted into the drill collar  302  and secured in place by interface  550 , retainer  552  and cover  342 . Various configurations of such components may be used to achieve the desired protection. Additionally, such a configuration may facilitate removal of the sample chamber from the drill collar. 
         [0112]    Once the sample module is assembled, the downhole tool is deployed into the wellbore on a drillstring  12  (see  FIG. 1 ). A sampling operation may then be performed by drawing fluid into the downhole tool via the probe module  210  ( FIG. 1 ). Fluid passes from the probe module to the sample module via flowline  310  ( FIG. 2A ). Fluid may then be diverted to one or more sample chambers via flow diverter  332  ( FIG. 3 ). 
         [0113]    Valve  330   b  and/or  330   a  may remain open. In particular, valve  330   b  may remain open to expose the backside of the chamber piston  360  to wellbore fluid pressure. A typical sampling sequence would start with a formation fluid pressure measurement, followed by a pump-out operation combined with in situ fluid analysis (e.g., using an optical fluid analyzer). Once a certain amount of mud filtrate has been pumped out, genuine formation fluid may also be observed as it starts to be produced along with the filtrate. As soon as the ratio of formation fluid versus mud filtrate has reached an acceptable threshold, a decision to collect a sample can be made. Up to this point the liquid pumped from the formation is typically pumped through the probe tool  210  into the wellbore via dump flowline  260 . Typically, valves  328  and  335  are closed and valve  334  is open to direct fluid flow out dump flowline  260  and to the wellbore. 
         [0114]    After this flushing is achieved, the electrical valves  328   a  may selectively be opened so as to direct fluid samples into the respective sample cavities  307  of sample chambers  314 . Typically, valves  334  and  335  are closed and valves  328   a ,  328   b  are opened to direct fluid flow into the sample chamber. 
         [0115]    Once a sample chamber  314  is filled as desired the electrical valves  328   b  may be moved to the closed position to fluidly isolate the sample chambers  314  and capture the sample for retrieval to surface. The electrical valves  328   a ,  328   b  may be remotely controlled manually or automatically. The valves may be actuated from the surface using standard mud-pulse telemetry, or other suitable telemetry means (e.g., wired drill pipe), or may be controlled by a processor (not shown) in the BHA  100 . 
         [0116]    The downhole tool may then be retrieved from the wellbore  11 . Upon retrieval of the sample module  220 , the manually-operable valves  330   a, b  of sample chamber  314  may be closed by opening the cover  342  to (redundantly) isolate the fluid samples therein for safeguarded transport and storage. The closed sample cavities  312  are then opened, and the sample chambers  314  may be removed therefrom for transporting the chambers to a suitable lab so that testing and evaluation of the samples may be conducted. Upon retrieval, the sample chambers and/or module may be replaced with one or more sample modules and/or chambers and deployed into the wellbore to obtain more samples. 
         [0117]    It will be understood from the foregoing description that various modifications and changes may be made in the preferred and alternative embodiments of the present invention without departing from its true spirit. 
         [0118]    This description is intended for purposes of illustration only and should not be construed in a limiting sense. The scope of this invention should be determined only by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open set or group. Similarly, the terms “containing,” having,” and “including” are all intended to mean an open set or group of elements. “A,” “an” and other singular terms are intended to include the plural forms thereof unless specifically excluded. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words “means for” together with an associated function. 
         [0119]    &lt;next-to-last paragraphs—one paragraph for each independent claim, each paraphrasing the claim; additional paragraphs or sentences for dependent claims, if desired&gt; 
         [0120]    The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure. 
         [0121]    The Abstract at the end of this disclosure is provided to comply with 37 C.F.R. §1.72(b) to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.