Patent Publication Number: US-11035231-B2

Title: Apparatus and methods for tools for collecting high quality reservoir samples

Description:
BACKGROUND OF THE DISCLOSURE 
     Field of the Invention 
     Embodiments of the disclosure generally relate to tools and techniques for performing formation testing and, more particularly, to a novel formation sampling apparatus and method. 
     Description of the Related Art 
     Wireline formation testing tools are well known in the prior art in providing permeability, mobility, sampling and other information that can be inferenced therefrom about the reservoir. 
     In oil and gas exploration, a primary goal of a wireline testing tool is to obtain fluid samples from earth formations representative of the reservoir. These samples are examined in special laboratories for purposes, such as to discover their physical composition. 
     Obtaining samples is commonly achieved by the use of special tools that are run into boreholes. A tool is sealed to the formation at a predetermined station of interest, and has an internal conduit hydraulically coupled to a pump. The tool can comprise a probe having a packer that seals against the wellbore wall and surrounds a snorkel through which fluids flow. The tool can also comprise a straddle packer type tool having a pair of inflatable packers positioned a distance apart from each other that seal off a portion of the borehole and the fluids are drawn in through the tool between the straddle packers. The pump is used to lower the pressure in the conduit until fluid is induced to flow from the formation wherein such pressure is referred to as the draw down pressure. The fluid is drawn into the tool and typically initially discharged to the well bore. Monitoring devices are used to ascertain the quality of the fluid that is being pumped, until at some point the fluid is transferred to a sampling receptacle, sometimes referred to as a “bottle”. The bottle is sealed, then recovered to surface. At surface it may be transported directly to a laboratory or transferred to another bottle better suited to transportation. A small amount of fluid may first be withdrawn for immediate, but preliminary, assessment. 
     The nature of well bore management is that it is filled with special fluids, commonly called ‘mud’. This fluid is a mixture of chemicals, solids and oil or water. The mud is designed to maintain a pressure gradient such that at any depth in the borehole, the mud fluid pressure exceeds that of the reservoir. This prevents collapse of the well bore, and prevents uncontrolled production of reservoir fluids to surface. The fluid has additional properties such as preventing chemical destabilization of the formation material. 
     The excess pressure of the well bore fluid over the reservoir fluid causes permeation of the former into the formation immediately surrounding the well bore. This permeation of the well bore fluids into the formation is known as invasion, and the fluid that enters the formation is known as invasion filtrate. Solid particles in the well bore fluid are unable to permeate into the formation and are left behind on the well bore surface. Over time these particles build up a thickness which itself becomes sensibly impermeable to fluid, and the invasion process ceases. The layer of particles is referred to as filter cake or mud cake. 
     During the pumping of formation fluids, it is readily apparent to those skilled in the art that when pumping of the fluid first commences the fluid will be invasion filtrate, followed by an increasing proportion of representative reservoir fluid. The fluid within the reservoir generally flows in streamlines. Removed from the sampling point, the flow pattern progressively changes shape, for example from omnidirectional radially converging flow (“spherical”) to flow perpendicular to the borehole but radially converging (“cylindrical”). Eventually there is a direct stream of reservoir fluid entering the sampling conduit, and the fluid boundary between invasion filtrate and reservoir fluid may, for example, be conical around the sampling point. The particular flow pattern is not significant here other than that it exists. 
     When pumping, the pressure at the probe will be less than the reservoir pressure by an amount known as the reservoir drawdown pressure. Many times, prior art sampling tools fail to maintain a steady drawdown pressure and as a result “shock” the formation by transmitting pressure gradients into the formation. When the formation is shocked during the sampling process, as in the case where there is an interruption to the flow, then the flow pattern rapidly changes. When flow resumes, it takes time for the pattern to return to its condition prior to the interruption. This results in a period of renewed contamination, and also a change in reservoir state, such as the deposition of particles or fluid constituents within the pore space that may affect the representativeness of subsequently pumped fluids. 
     Asphaltenes are an example of a constituent present in almost all crude oils. These carbon solids have a propensity to aggregate (flocculate) and deposit from the fluid, causing irreversible changes in fluid characteristics, mobility through the formation, and, in subsequent production operations, can block pipelines and hinder refining. It is important to sample carefully without shocks to the fluid in the formation in order to obtain a representative sample, and to maintain the acquired sample above the critical pressure at which aggregation starts. 
     It is also important to note that in the nature of complex formation exploration tools, that failures occur when the tools are in the borehole. Therefore, the cost of providing exploration services and the value of the formation samples are both high. A typical operational strategy might be to take a first sample as soon as contamination has been reduced significantly, to reduce exposure to failure. It is desirable to be able to take additional samples as soon as possible, but these should be high quality as the number of samples that can be taken in a single run of the formation tool in the hole is limited. 
     Even when representative reservoir fluid enters the sampling conduit of the formation tool, the sample can be altered or damaged by the tool itself. For example, the sour gas (such as H 2 S) content of the fluid is immensely important to assessing a reservoir since it determines, among other things, the price of the crude and whether very large capital expenditures will be needed in production plant to accommodate and remove this poisonous and corroding gas. However, many commonly used materials in downhole tools readily absorb this gas. Examples of these materials includes elastomers, lubricating and hydraulic oils, and certain metals. During sampling it is desirable to minimize exposure to these materials both in surface contact area and in residence time. 
     Another consideration in the use of formation testing tools is that almost all oil reservoirs include a significant amount of dissolved gas. This gas may have many components. When the fluid pressure is reduced below the bubble-point pressure of any of the gas components, such as while being pumped into a formation testing tool or sample container, the gas will come out of solution. It is known to be very difficult, if not impossible, to make this gas go back into solution to restore the initial composition. Therefore, an important requirement of reservoir fluid sampling tools is to be configured to sample at pressures above the bubble point pressure, and to maintain the sampled fluid above the bubble point pressure throughout its journey from the reservoir to the laboratory. This means that pressure drops within the tool sampling conduit and within the pump as well as within the sample container must be minimized. Once extracted from the formation the sample cools, and therefore shrinks in volume, during its return to surface and can cool further during transportation depending on season and geographical transit. If the sampling receptacle has a fixed volume, shrinkage will be accompanied by a reduction in pressure, and almost always results in some gas components coming out of solution. To avoid this reduction in pressure, methods of maintaining pressure have been developed in the prior art. The methods in current practice generally entail using pressurized nitrogen bearing on the fluid sample via some sort of freely moving barrier within the sample container. The design premise behind these methods is that the nitrogen expands to fill the space left by sample fluid shrinkage, but that as a gas, its pressure does not drop dramatically with temperature, and its pressure remains above the sample bubble point pressure. In this way the nitrogen acts as a spring and urges the freely moving barrier against the sample to maintain pressure above the bubble point. 
     Another consideration in the use of formation tools is the consequence of prolonged residence time within the tool between the time the reservoir fluid enters the sampling conduit and the time when the reservoir fluid enters the sampling receptacle. If the time is too long, the components of the sample can separate. The residence time can be prolonged by the nature of the tool design or by the reservoir characteristics. In the latter case, a low permeability formation may only permit a low sampling flow rate, as a higher rate would drop the sampling pressure to below the fluid bubble point. A low sampling rate necessarily results in a longer residence time. It is desirable therefore to minimize the physical volume of the conduit and, in most prior art formation tools, the pump displacement, to reduce the separation of the sample components. Filling a receptacle with a fluid of stratified components will result in a mixture that is unrepresentative of the formation. Moreover, the component fractions may differ from the original fluid due to different transit times and traps within the tool. 
     A further consequence of a complex fluid path between the formation and the receptacle is that contamination can occur from residues of samples taken earlier in the process, including from a previous station. 
     There are several patents in the prior art directed at sample receptacles that attempt to maintain samples at reservoir conditions. One such patent is U.S. Pat. No. 6,688,390 which comprises a cylinder having two pistons separating the bottle into three chambers. Samples are run through the main pump and injected into one end of the bottle. A middle chamber is filled with a buffer fluid and the other end of the bottle contains a gas. The pressure of the gas is regulated to exert pressure onto the buffer fluid and in turn onto the sample. Other such patents include U.S. Pat. Nos. 7,246,664 and 7,191,672 both of which disclose a bottle which comprises a cylinder having two pistons separating the bottle into three chambers. In a similar manner to the U.S. Pat. No. 6,688,390, sample fluids are run through the main pump and injected into one end of the bottle. The middle chamber is filled with a gas fluid and the other end of the bottle is filled with wellbore fluid. Both of these latter patents disclose a method of filling the bottle through the middle chamber through a valve located in one of the pistons. 
     It is therefore an object of the present invention to have a method and apparatus for obtaining formation fluid samples that will minimize operation time, reduce the complexity and volume of the those parts of the tool in contact with the fluid prior to the sample container, not disturb the formation throughout the sample taking at a given station and will maintain the fluid above its bubble and asphaltene points throughout its journey from reservoir to laboratory. It is a further objective to maximize reliability and minimize cost by implementing a novel sample container. 
     SUMMARY OF THE DISCLOSURE 
     A system of one or more computers can be configured to perform particular operations or actions by virtue of having software, firmware, hardware, or a combination of them installed on the system that in operation causes or cause the system to perform the actions. One or more computer programs can be configured to perform particular operations or actions by virtue of including instructions that, when executed by data processing apparatus, cause the apparatus to perform the actions. One general aspect includes a tool configured to sample a formation fluid from a reservoir that includes a reservoir flowline configured to be in fluid communication with a portion of the reservoir, a main pump in fluid communication with the reservoir flowline, a sample container in fluid communication with the reservoir flowline, a sampling pump hydraulically coupled to the sample container and configured to transfer a buffer fluid in and out of the sample container, and a power and processing unit configured to control the main pump and the sampling pump to maintain the reservoir approximately at a drawdown pressure. 
     Implementations may include one or more of the following features. The tool where the sample container includes a housing having at least two pistons slidably disposed therein and dividing the housing into at least three chambers, each of the at least three chambers having a variable volume, including an intermediate chamber, a first end chamber and a second end chamber, the intermediate chamber defined by the pistons and where the pistons are free of valves, a first conduit configured to pressurize the intermediate chamber with a gas, a second conduit coupled to the first end chamber and the reservoir flowline, and a third conduit coupled to the second end chamber and the sampling pump. The tool further including a packer, the packer includes of one of a donut packer and a straddle packer. The tool further including a probe assembly, the probe assembly including: a snorkel coupled to the reservoir flowline and configured to penetrate at least partially into the portion of the reservoir. The tool further including a buffer fluid tank coupled to the sampling pump. 
     One general aspect includes a method of sampling a formation fluid from a reservoir including positioning a reservoir flowline in fluid communication with a portion of the reservoir located below a surface, coupling a main pump to the reservoir flowline, coupling a sample container to the reservoir flowline and to a sampling pump, the sample container having a buffer chamber and a sample chamber, pumping the formation fluid continuously with the main pump until the formation fluid is substantially free of filtrate, splitting the formation fluid into a first portion and a second portion, pumping the first portion with the main pump, pumping a buffer fluid out of the buffer chamber with the sample pump, and drawing the second portion of the formation fluid into the sample chamber. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods. 
     Implementations may include one or more of the following features. The method further including continuously controlling the main pump and the sample pump to maintain the reservoir approximately at a reservoir drawdown pressure. The method where the sample container further includes a pressure chamber positioned between the buffer chamber and the sample chamber, the method further including pressurizing the pressure chamber to a predetermined initial pressure. The method further including: continuously pumping the formation fluid with the main pump, uncoupling the sample container from the reservoir flowline and the sampling pump, and coupling a subsequent sample container to the reservoir flowline and to the sampling pump. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium. 
     A system of one or more computers can be configured to perform particular operations or actions by virtue of having software, firmware, hardware, or a combination of them installed on the system that in operation causes or cause the system to perform the actions. One or more computer programs can be configured to perform particular operations or actions by virtue of including instructions that, when executed by data processing apparatus, cause the apparatus to perform the actions. One general aspect includes a method of sampling a formation fluid from a reservoir including providing a first sample container and a second sample container each including. The method also includes dividing a housing into at least three chambers, each of the at least three chambers having a variable volume, including an intermediate chamber, a first end chamber and a second end chamber. The method also includes pressurizing the intermediate chamber with a gas. The method also includes pumping the formation fluid continuously with a main pump until the formation fluid is substantially free of filtrate. The method also includes coupling the second end chamber of the first sample container to a sampling pump. The method also includes simultaneously pumping a first portion of the formation fluid with the main pump and transferring a buffer fluid out of the second end chamber of the first sample container using the sampling pump. The method also includes drawing a second portion of the formation fluid into the first end chamber of the first sample container until the first end chamber of the first sample container is full of formation fluid. The method also includes sealing the first end chamber of the first sample container and the second end chamber of the first sample container. The method also includes pumping the formation fluid continuously with the main pump. The method also includes uncoupling the first sample container. The method also includes coupling the second end chamber of the second sample container to a sampling pump. The method also includes simultaneously pumping a third portion of the formation fluid with the main pump and transferring a buffer fluid out of the second end chamber of the second sample container using the sampling pump. The method also includes drawing a fourth portion of the formation fluid into the first end chamber of the second sample container until the first end chamber of the second sample container is full of formation fluid. The method also includes sealing the first end chamber of the second sample container and the second end chamber of the second sample container. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods. 
     Implementations may include one or more of the following features. The method further including continuously maintaining the reservoir at a reservoir drawdown pressure. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  illustrates a high level schematic representation of the use of a formation tester, including a sample collection module in accordance with certain aspects of the present disclosure. 
         FIG. 2  illustrates a formation tester, including a sample collection module of a sample collection system in accordance with certain aspects of the present disclosure. 
         FIG. 3  is a schematic representation of an exemplary sample receptacle for obtaining samples of downhole formation fluids in accordance with certain aspects of the present disclosure. 
         FIG. 4  is a schematic representation of an exemplary sample receptacle for obtaining samples of downhole formation fluids in accordance with certain aspects of the present disclosure. 
         FIG. 5  is a schematic representation of an exemplary sample receptacle for obtaining samples of downhole formation fluids in accordance with certain aspects of the present disclosure. 
         FIG. 6  is a schematic representation of an exemplary sample receptacle for obtaining samples of downhole formation fluids in accordance with certain aspects of the present disclosure. 
         FIG. 7  is a schematic representation of an exemplary sample receptacle for obtaining samples of downhole formation fluids in accordance with certain aspects of the present disclosure. 
         FIG. 8  is a hydraulic diagram of a system for obtaining samples of downhole formation fluids in accordance with certain aspects of the present disclosure. 
         FIG. 9  is a hydraulic diagram of a system for obtaining samples of downhole formation fluids in accordance with certain aspects of the present disclosure. 
         FIG. 10  is a hydraulic diagram of a system for obtaining samples of downhole formation fluids in accordance with certain aspects of the present disclosure. 
         FIG. 11  is a section view of an exemplary sample receptacle for obtaining samples of downhole formation fluids in accordance with certain aspects of the present disclosure. 
         FIG. 12 a    is a section view of an embodiment of a testing fluid vessel and pressurizing tool in accordance with certain aspects of the present disclosure. 
         FIG. 12 b    is a section view of an embodiment of a testing fluid vessel and pressurizing tool in accordance with certain aspects of the present disclosure. 
         FIG. 13  is a section view of an embodiment of a testing fluid vessel and pressurizing tool in accordance with certain aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is directed at a formation dynamic testing (FDT) tool which includes a probe and sample collection system for collecting high quality reservoir samples. The collection sample system includes sample receptacles positioned in close proximity to the probe. Embodiments of the present disclosure may comprise a wireline deployed formation tester or a logging while drilling (LWD) or measurement while drilling (MWD) tool having the ability to dynamically flow fluids from the reservoir while producing information about the reservoir fluids and their production. 
     Examples of Tools for Collecting High Quality Reservoir Samples 
     With reference to  FIG. 1  there is shown an embodiment of a wireline formation tester  20  deployed within a well  12  drilled into formation  13 . In operation, the wireline formation tester  20  is deployed into well  12  via wireline cable  22  over pulley  16 . As is well known in the art, wireline cable  22  includes electrical conductors for powering the tool, data communications conductors as well as tensile members for supporting the weight of the testing tool. The borehole typically contains various mixtures of fluids and gasses wherein the mixture varies by depth, age of the well and various other factors. The well is shown as an open hole however, the present disclosure is not limited to open hole wells and could, for instance, be used within a cased hole well. 
       FIG. 1  illustrates an embodiment of the formation testing tool  20  wherein the tool is shown deployed in borehole  14  and includes various modules as will be described in more detail herein below. The multi-conductor cable  22  carries electrical power and data to and from processing unit  24  located at the surface. The power and processing unit  24  is configured to control the various modules, pumps, valves and other components included in the formation testing tool  20 . In addition, power and processing module  24  includes a processor  40 , in the form of a computer and the like, for processing the electrical signals from the formation testing tool into information concerning the analysis and characterization of the downhole fluids, and usually includes a storage medium  42 . In this particular embodiment, the formation tester  20  includes a clamping mechanism comprised of pistons  15 ,  16  that is urged against the borehole wall by the pistons to stabilize the formation tester within the wellbore  14 . The formation tester includes a probe assembly  28  having a mechanism to urge the probe pad  164  against borehole wall with sufficient force to releasably fix the formation tester in place. The probe pad further seals the formation  13  from the wellbore  14  in the area of contact. The probe assembly  28  can, at least partially, penetrate the borehole wall and any mud cake that may exist adjacent thereto and enters into fluid communication with the formation area  13 . As will be described in greater detail herein below, the probe  28  is in hydraulic communication with a pump mounted within the formation tester housing  26 . The probe assembly may also include a guard ring (not shown) and which may comprise a loop that encircles the ring and is hydraulically coupled to a pump mounted within the formation tester housing  26 . An exemplary embodiment of a focused guard probe is disclosed in U.S. Pat. No. 6,301,959 (959) to Hrametz, the disclosure of which is included herein in its entirety. 
     With reference to  FIG. 2  there is shown an embodiment of a wireline formation tester  102  deployed within a well  105  drilled into formation  106  having a porosity  1  and a permeability k. The well is shown as an open hole however, the present disclosure is not limited to open hole wells and could, for instance, be used within a cased hole well with proper additions made thereto to penetrate the casing. In this particular embodiment, the formation tester  102  includes a clamping mechanism  161  that is urged against the borehole wall  135  by pistons  162  with shoes to stabilize the formation tester within the wellbore  105 . The formation tester includes a probe assembly  160  having a pair of pistons  163  to urge the probe pad (or donut packer)  164  against borehole wall  135  with sufficient force to releasably fix the formation tester in place. The probe and the pistons with shoes are three points that can determine a plane so that the formation tool does not rotate or wobble in the preselected downhole position. The probe pad  164  further seals the formation  106  from the wellbore  105  in the area of contact. The probe  165  penetrate at least a portion of the borehole wall  135  and any mudcake that may exist adjacent thereto and enters into fluid communication with the formation area  106 . The probe  165  is in hydraulic communication with main pump  180  mounted within the formation tester housing  102 . The probe assembly may also include a guard ring (not shown) as which may comprise a loop that encircles the ring and is hydraulically coupled to main pump  180  mounted within the formation tester housing  102 . Although the present disclosure is described with reference to an embodiment having a donut packer and probe, it is within the scope of the present disclosure that embodiments can include any type of sampling tool including straddle packer tools. Still referring to  FIG. 2 , there is illustrated the presence of directional streamlines of formation fluid  140  that are established as pumping occurs through probe  165  occurs first for clean-up and afterwards for sampling as will be described in more detail herein after. Although streamlines  140  are shown as being horizontal in nature, it should be appreciated by those skilled in the art that, in certain embodiments of the present disclosure, the streamlines may form a cone shape within testing volume  187  and the cone can persist for long periods of time using the non-stop, no shock methods described herein. Such non-stop, no shock methods can inventively be practiced using tools disclosed herein wherein main pump  180  is run continuously during the clean-up and sampling processes and the operation of sample pump  403  is controlled cooperatively with the main pump during the sample process to keep the reservoir pressure at or near the drawn pressure. 
     It is known in the art to provide a wellbore fluid (not shown to avoid confusion), sometimes referred to as a mud, within the wellbore to produce a mud pressure P M  greater than the reservoir pressure P R  to create an overbalanced condition and prevent formation fluid  140  from entering the wellbore. As described herein above, because P M  is greater than P R , some of the mud enters the formation creating both a mud cake (solids from the mud) on the borehole wall  135  and a zone of formation fluid that is contaminated with the filtrate (fluid from the mud), also known as invaded fluid, in the formation  106  adjacent to the borehole wall. 
     In operation, the formation testing tool  102  is lowered by wireline ( 22  in  FIG. 1 ) to a nominal predetermined depth  130 . As is known in the art, the clamping mechanism  162  and probe assembly  160  are urged against the borehole wall  135 , and the probe  165  penetrate at least partially into the formation  106 . A small piston pump driven pretest module  182  draws a sample to confirm the seal is made and determine the initial reservoir pressure P F  and permeability using well-known techniques. With probe valve  312 , sample valve  405  and circulation valve  303  appropriately positioned, main pump  180  draws fluid through the snorkel  165 , into reservoir flowline  181 , and circulates at least some of the fluid back into the wellbore  105  via flow line  185 . During this cleaning process fluid is pumped through probe  165  for a sufficient period of time to remove most, if not all, of the invaded fluid in the testing volume  187  near the probe  165  to obtain formation fluid  140 . Using well-known techniques, testing module  183  provides real time data to operators to assist in determining when the formation tester is producing filtrate free formation fluid  140 . Such testing modules may include, pressure sensors, optical analyzers, density analyzers, NMR, Sigma Neutron as disclosed in co-pending application WO2017015340, the disclosure of which is incorporated herein in its entirety, and other such known testing modules. In prior art sampling devices, the sample receptacles are placed downstream of main pump  180 , and due to the effects on the fluid of passing through the pump, an additional testing module (not shown) is typically required to verify the sample quality after exiting the pump and prior to entering the sample receptacle. The second testing module adds expense and complexity to the prior art tools. In the embodiment shown, once the formation fluids  140  are being produced in a single phase and free of invaded fluid from the testing volume  187  of the formation  106  they are ready to be sampled. 
     Still referring to  FIG. 2 , the present disclosure includes a sampling module  400  which includes sample line  401 , sample fluid receptacle (or bottle)  402 , sampling pump  403 , sampling valve  405  and buffer fluid tank  404 . In accordance with the present invention, it is advantageously possible to position the sampling module  400  in close proximity to the probe  165 . With the sample module  400  and the sample receptacle  402  positioned close to the probe  165 , many of the prior art problems are eliminated including minimizing the time that the sample is in line  181  and elsewhere, including sample line  401 , to reduce stratification and reaction of the formation fluid  140  with the flow lines and minimizing pressure drops caused by long flow lines. In certain embodiments, buffer fluid tank  404  may be exposed to P M  to facilitate the operation of sample receptacle  402  as will be more fully described herein after. 
     Referring to  FIGS. 3-7 , an embodiment of the present disclosure sample receptacle  402  having three variable volume chambers will be described in greater detail. In one such embodiment sample receptacle  402  may comprise the type of pump disclosed in co-pending Patent Cooperation Treaty application number PCT/US2018/030068, the disclosure of which is included herein in its entirety. The nomenclature and relationships in the following Table 1 is useful in interpreting the operational steps and methods associated with the present invention as will be more fully disclosed herein after. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Volumes 
                 Pressures 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Step 
                 Buffer 
                 Nitrogen 
                 Sample 
                 Buffer 
                 Nitrogen 
                 Sample 
               
               
                   
               
               
                 0 
                 V B0 , 
                 V N0   
                 0 
                 0 
                 P N0   
                 0 
               
               
                 Prep- 
                 bal. 
               
               
                 aration 
               
            
           
           
               
               
               
               
               
            
               
                 1 Prefill 
                 V B1 , 
                 V N1   
                 0 
                 P 1  = P R  − P drawdown   
               
               
                   
                 bal. 
               
               
                 2 Filled 
                 0 
                 V N1   
                 V S2 , 
                 P 1   
               
               
                   
                   
                   
                 bal. 
               
               
                 3 
                 V B3 , 
                 V N3   
                 V S3   
                 P 3  = P 1  + ΔP 
               
               
                 Pressurize 
                 bal. 
               
               
                 4 Surface 
                 V B4 , 
                 V N4   
                 V S4   
                 P 4   
               
               
                   
                 bal. 
               
               
                   
               
            
           
         
       
     
     In Table 1, because the total volume of the bottle is fixed, the notation “bal.” is that volume remaining in the receptacle after subtracting the volume of the other two fluid components. It will be readily understood by one practiced in the art that piston seal friction requires a small pressure difference to overcome the friction, but it may be ignored herein without departing from the scope of the invention. Similarly, zero pressure is an approximation to atmospheric pressure. Now, with reference to Table 1 and to  FIG. 3 , there is shown an embodiment of receptacle  402  after initially being prepared at the surface at Step 0. Receptacle  402  includes a hollow housing  410 , which in certain embodiments is cylindrical in shape, and includes a wall  411  and end caps  412 ,  413 . Positioned within housing  410  are a pair of pistons  414 ,  415  arranged to seal against the inner surface of wall  411  and are further permitted to slide in the axial direction of housing  410 . Pistons  414 ,  415  include holes  417 ,  418 , respectably, which accommodate limit bar  416  disposed in a slidable sealing arrangement therein, and in this particular embodiment, further include shoulder slots  419 ,  420  which cooperate with shoulders  421 ,  422  of the limit bar to limit the axial travel of the pistons to the length of the limit bar as will be more fully described herein below. With pistons  414 ,  415  positioned as shown, an intermediate chamber, namely pressure chamber  423  having an initial volume of V N0  is formed therebetween. Pressure chamber  423  is filled at the surface with nitrogen, or other suitable compressible composition including other noble gases such as argon, as will be more fully described herein below, to a predetermined pressure P N0  and pistons  414 ,  415  are urged apart by the pressure and against shoulders  419 ,  420 . The nitrogen in chamber  423  provides a compressible cushion against which the pressures of the sample and buffer fluid are maintained as will be fully described herein below. An end chamber, namely buffer chamber  424  is then filled with a suitable buffer fluid, chosen from a group of nearly incompressible fluids such as mineral oil, and piston  415  is urged against end wall  413  as shown in the figure. Buffer chamber  424  is thus formed between piston  414  and end wall  412  and has a starting volume of V B0  and, because the pressure at the surface is atmospheric, the starting pressure is P B0 =0. In the embodiment shown, P N0  may be less than the pressure of the buffer fluid P B  and with piston  415  against end wall  413  there exists minimal “dead space” in the sample receptacle. It is important to note that the receptacle  402 , as well as all of its components, must be comprised of materials and design sufficient to withstand the downhole temperatures, pressures and chemicals encountered in such an operation, and the corresponding conditions at all stages of its subsequent handling and transport when filled. Although the embodiment is shown as a rigid structure, the present invention includes any embodiment having a constant volume and multiple chambers therein divided by moveable barriers such as membranes. 
     Now referring to  FIG. 4 , there is shown the receptacle  402  of  FIG. 3  at Step 1, of Table 1, when the receptacle is positioned within sampling module ( 400  of  FIG. 2 ) while the formation tool  102  is lowered to a predetermined depth  130  in the borehole by wireline ( 22  in  FIG. 1 ). As described herein before, the borehole is filled with wellbore fluid or mud, to produce a mud pressure P M  greater than the reservoir pressure P R , wherein P R  is normally determined by the aforementioned drawdown pressure test, and wherein it is well known that P M  increases with depth. In some embodiments, orifice  425  may be open to the borehole wherein P B  is equal to P M . In other embodiments, sample pump  403  of  FIG. 2  is controlled to provide buffer fluid from buffer chamber  404  to chamber  424  through buffer orifice  425  at a pressure P B1  approximately equal to, or greater than, P M . It is important to note that when tank  404  is exposed to P M  sample pump  403  may be bypassed with a hydraulic valve (not shown) or the pump only has to provide an additional pressure slightly greater than P M  to position the piston-limit bar assembly  428  (comprised of pistons  414 ,  415  and limit bar  416 ) as shown in  FIG. 4 . Because of the increase in P B , the nitrogen pressure is similarly increased to P N1  and piston  414  is urged off shoulder  419  and traverses axially along limit bar  416 . Piston  415  maintains contact with end wall  413  and the volume V N1  of pressure chamber  423  is proportionally reduced in accordance with well-known principles. 
     With specific reference to  FIG. 5 , and general reference to  FIG. 2 , at Step 2 of Table 1, receptacle  402  is shown after an end chamber, namely sample chamber  426  has been filled with a sample of formation fluid  140 . As should be understood by those skilled in the art, port  427  in end wall  413  may be fitted with a valve (not shown), which valve may comprise a self-actuating check valve, a motorized or hydraulically actuated valve or the like, opened to probe  165 , to allow the entry of formation fluid  140 . In order for formation fluid  140  to enter receptacle  402 , probe valve  312 , sample valve  405  main pump  180  and sample pump  403  are selectively cooperatively controlled in such a manner that the flow through probe  165  maintains a constant pressure at the probe near P 1  so as not to shock the formation. Embodiments of the present disclosure include those that pump formation fluids  140  from formation  106  without stopping and without interruption from the time main pump  180  begins the clean-up process through the filling process of sampling container  402 , which is selectively coupled to reservoir flowline  181  by sample valve  405 , by maintaining the flow rates of main pump  180  and sample pump  403  to maintain the formation at pressure P 1 . During the filling of sample container  402 , as well as subsequent sample containers, and as pumping continues, the streamlines of formation fluid  140  become longer reaching farther and farther into the formation  106  and the direction of flow does not change, i.e. it is constantly flowing toward probe  165 . This directional flow at a constant rate is similar to that during the production phase of a producing well and thereby produces samples that more closely resemble that of the formation  106 . Using embodiments of the present disclosure, as one or more sample containers  402  are filled, these embodiments provide for continuous and constant flow of formation fluid  140 . It should be appreciated by one skilled in the art that since the flow of formation fluid  140  is continuous and constant, there is no shock to the formation  106 , and there is no phase change during the time that these streamlines of formation fluid maintain direction. In so controlling the pumps, sample pump  403  withdraws buffer fluid from chamber  424  through buffer orifice  425  reducing the pressure in pressure chamber  423  below P N1 , and as the nitrogen pressure approaches P 1 , piston  415  moves off of wall  413 . Because the overall internal volume of receptacle  402  is constant, as piston  415  moves away from wall  413  the volume V B  of buffer chamber  424  decreases and the volume V S  of sample chamber  426  increases. Reservoir fluid  140  is drawn into sample chamber  426  though sample port  427  and exerts a pressure nearly equal to P 1  against piston  415 . As sample pump  403  continues to draw buffer fluid out of buffer chamber  424 , the syringe-like action produces a negative displace condition and causes piston-limit bar assembly  428  to move axially inside of housing  410  until piston  414  is urged against end wall  412  wherein the volume of buffer chamber  424  becomes 0, pressure chamber  423  is at V N1 , P 1  and sample chamber  426  is at V S2 , P 1 . In the case where limit bar  416  touches end wall  412  first, the pistons  414 ,  415  will continue to slide on the limit bar until piston  414  is urged against end wall  412 . It should be appreciated by those skilled in the art that the volume of buffer fluid in chamber  424  is displaced by the sample fluid  140  ( FIG. 2 ) that is drawn into sample volume  426 . Once sample chamber  426  is filled, port  427  is closed off by any known method, including the aforementioned valve, and sample pump  403  is gradually stopped while main pump  180  is increased to maintain a constant pressure at the probe  165  and a constant flow rate of formation fluid  140 . With this unchanged flow rate at the probe, the formation intake pressure and reservoir fluid equilibrium is undisturbed. In addition, the negative, or non-positive, displacement, with respect to sample chamber  426 , caused by the sucking action of the buffer fluid by sample pump  403  allows the sample fluid  140  to be drawn into the sample chamber without having to go through a pump as in the prior art. This is an important aspect of the present invention in that the sample fluid arrives within the sample chamber  426  with minimal changes from the condition it was in within the reservoir, i.e. it is more representative of the reservoir fluid than samples provided by sampling tools of the prior art. 
     As described herein before, it is an important aspect of the present disclosure to constantly maintain P S  above the predicted bubble point of the reservoir fluid where the sample was taken. Referring to  FIG. 6 , and in accordance with the present disclosure, an over pressure procedure, Step 3 of Table 1, is undertaken whereby buffer fluid is added through port  425  by sample pump  403  into buffer chamber  424  in a sufficient quantity and pressure to reduce the volume of pressure chamber  423  to V N3  and increase the pressure thereby to P 3 . Because the sample fluid  140  in sample chamber  423  may be compressible due to dissolved gas in the fluid, the volume of the sample chamber after over pressure V S3  may be somewhat smaller than when the sample was at P 1 . Also, since the buffer fluid is also chosen from a group of nearly incompressible fluids, piston  414  is urged off shoulder  421  during the over pressure procedure creating volume V B3  in buffer chamber  424 . As the pressure increases to P 3 , piston  415  will pressurize the sample and may also travel a little in the direction of the sample until pressures in buffer chamber  424 , pressure chamber  423  and sample chamber  423  are in balance. The volume of the pressure chamber  423  reduces as the pressure increases. The final pressure P 3  of sample, nitrogen and buffer fluid (ignoring seal frictions as herein above mentioned) exceeds P 1  and is chosen to provide sufficient pressure P S  within sample chamber  423  when the sample is brought to the surface to maintain P S  above the bubble point. Where possible, the embodiment design and pressures are such that P S  will always be above P 1 . P 1  is known to be above bubble point since it is the sampling pressure, and the fluid at this pressure is carefully monitored for gas-breakout during pumping as herein before described. 
     Upon completion of the sample filling of Step 2 and over pressure procedures of Step 3 described directly herein above, formation tool  102  may be raised back to the surface by a wireline ( 22  in  FIG. 1 ). As will be understood by those skilled in the art, when the sample receptacle(s)  402  are raised to the surface, the ambient temperature and pressure conditions outside of the receptacle are lower than existed at the testing depth  130 . The temperature difference between the surface elevation and the testing elevation can exceed several hundred degrees Fahrenheit. As formation tool  102  is retrieved, the sample chamber  426  temperature drops, causing the sample volume, and to a lesser extent the buffer fluid volume, to reduce by well known principles and so causing P S  to drop. If allowed to go unchecked, as in many sample containers of the prior art, this substantial pressure drop in the sample chamber can result in P S  dropping below the bubble point, resulting in a multi-phase sample. In accordance with the present disclosure, the ambient pressure at the surface has no effect on the chambers  423 ,  424 ,  426  because the housing is sealed from the atmosphere. Because the temperature at the surface is lower, and the volume of buffer chamber  424  and sample chamber  426  are reduce to V B4  and V S4  respectively, the volume of pressure chamber  423  will increased proportionally to V N4  and its pressure P 4  will be less than P 3 . It should be appreciated by those skilled in the art that the combination of the preselected P N0  and over pressure condition P 3  ensure that P 4  is maintained in sample chamber  426 , and the sample fluid  140  therein, above the bubble point pressure at all times during the sampling, retrieval and transporting processes. 
     After sample container(s)  402  is filled and over pressurized as described directly herein above, and the drawdown is complete, the flow of formation fluid  140  is interrupted and a transient pressure buildup occurs in the formation. For analysis, and since times are recorded during the pumping, a volumetric flow rate can be determined by computing the total volume of the flow lines  181 ,  401 , snorkel  165 , and sample volume V S2  in the one or more sample containers  402  that are filled and dividing that total volume by the time that the drawdown commenced and was ended. It should be appreciated by those skilled in the art that this is an important piece of information in determining the producibility of the formation  106  at the stated depth of the well  130 . The producibility of the formation  106  can now accurately be determined using the calculated volumetric flow rate together with other data obtained from the aforementioned sensors along the flow lines  180  and probe  165  in the tool. 
     It is a further aspect of the present invention that a pressure gauge (not shown) may be added to port  425  to directly monitor the pressure of the buffer fluid or port  427  to monitor the pressure of the sample directly thereby as will be more fully explained herein below. It should be recognized by one skilled in the art that such an arrangement is advantageous in logging the pressure of the sample during transportation and maintaining the chain of custody of the sample. Such a pressure gauge may be any suitable type such as a MEMS pressure gauge. 
     It should also be appreciated by those skilled in the art that although embodiments of the present disclosure are show with a limit bar as a tension member between the piston pair, any suitable tension member such as a chain, cable, carbon fiber and the like may be substituted without departing from the scope of the present invention. 
     It should further be appreciated by those skilled in the art that sample receptacle  402  of the present invention delivers a more representative sample of the formation fluid than that of the prior art and includes many advantages over the prior art such as the sample fluid does not pass through a pump. The fact that the formation fluid does not pass through a pump, as in the prior art, prior to entering the sample receptacle  402  means that there is no scavenging of H 2 S, no pressure disturbances caused by valves in which gas can break out, no residence time in pump cylinders that permits segregation (leading to the taking of samples unrepresentative of the formation), no contamination with residual fluids taken at other stations, and that only one set of monitoring equipment is required. The fact that the sample chamber may be filled using a negative displacement method leads to the sample being taken at sensibly constant sampling pressure further ensuring the consistency of sample quality and its representativeness of the fluid in the reservoir. 
     Many tools of the prior art use a main pump  180  of positive displacement piston pump type. In an embodiment of the present disclosure main pump  180  may comprise the type of pump disclosed in co-pending United States application number U.S. Ser. No. 16/426,677, the disclosure of which is included herein in its entirety. The pistons reciprocate and at their change of direction causing short periods of flow interruption to occur. Embodiments of the present disclosure may improve upon this by using the sampling pump  403  to maintain constant flow during sampling as described herein above. Where this arrangement may be insufficient, it is also possible to select the displacement volume of the main pump  180  to be greater than the sample volume V S2  and coordinate the timing of the piston strokes so that the sample is taken within one stroke. Alternatively, main pump  180  may be of a progressive cavity type, which is valveless and non-reciprocating, resulting in a continuous smooth flow rate of formation fluid  140 . Progressive cavity pumps have a low pressure head rating relative to their length, so their use is practically limited to lower reservoir drawdown pressure applications, of which sampling from a straddle packer is one. A further alternative pump type may be a multi-piston swash-plate pump type, which maintains a more continuous flow considering the overlapping action of the pistons eliminates interruptions in the flow. This is practically limited to smaller pumps and is the preferred type for sample pump  403   
     Referring now to  FIG. 8 , there is shown a hydraulic circuit  900  associated with an embodiment of the present disclosure.  FIG. 8  illustrates receptacle  402  during the initial preparation stage, at Step 0 of Table 1, and corresponding  FIG. 3 , where like numerals indicate like components. Hydraulic circuit  900  includes buffer fluid control circuit  901  which comprises buffer oil tank  404 , isolation valve  902 , pressure gauge  903 , filter  904 , sample pump  403 , relief valve  905 , electronically controlled valve  906 , check valve  907  and a second pressure gauge  908 . Hydraulic control circuit further includes means for actuating piloted check valve  910 , shown as closed in this figure, to control fluid communication between buffer fluid chamber  424  and buffer buffer fluid tank  404  as will explained more fully herein below. Also shown in the figure is sample check valve  911 , shown in the closed position, disposed between sample orifice  427  and probe assembly  165  to control reservoir fluid communication there between. In this embodiment, isolation valve  902  is closed, as well as check valves  910  and  911 , which maintains the closed volume of receptacle  402  at a balanced condition from the initial preparation stage at the surface as it is lowered into the well to a predetermined depth  130  to prefill Step 1, just prior to filling the sample chamber. 
       FIG. 9  shows hydraulic circuit  900  during the filling of the sample chamber  426 . During sample filling operations, actuator  912  of buffer fluid control circuit  901  positions servo valve  902  as shown to establish fluid communication between flow line  913  and flow line  916  and to further establish fluid communication between flow line  914  and flow line  915 . Isolation valve  917  is energized and sample pump  403  pumps buffer fluid through flow line  918  to open piloted check valve  910  and piloted check valve  920  as shown. Orifice  425  is connected to check valve  919  which check valve is shown in the figure as open. As described herein above, sample pump  403  is controlled in conjunction with main pump  180  to maintain the reservoir at P 1  so as to not shock the reservoir. As buffer fluid is pumped from buffer fluid chamber  424  it travels into flow line  913  and makes its way through hydraulic circuit  900  and into buffer buffer fluid tank  404  as shown by the directional arrows in the figure. As described herein above with reference to  FIG. 5 , as the buffer fluid is withdrawn from buffer fluid chamber  424  there is a negative displacement created within receptacle  402 , creating sample chamber  426 , which draws reservoir fluid into the sample chamber through sample flow line  401 , check valve  911  and orifice  427 . The remainder of the reservoir fluid in reservoir fluid line  181 , that which is not drawn into sample container  411 , passes through main pump  180  and circulates back into the wellbore  106  via flow line  185 . 
       FIG. 10  shows hydraulic circuit  900  during the overcharging, or pressurization, stage of Step 3. During overcharging operations, actuator  912  of buffer fluid control circuit  901  positions servo valve  902  as shown to establish buffer fluid communication between flow line  914  and flow line  913  and to further establish fluid communication between flow line  915  and flow line  916 . Isolation valve  917  is energized and sample pump  403  pumps buffer fluid through flow line  918  to open piloted check valves  910 ,  920  as shown. Check valve  919  is also closed during the overcharge operation. Check valve  911  is closed and no reservoir fluid flows into, or out of, sample flow line  401  and the reservoir fluid in reservoir fluid line  181  passes through main pump  180  and circulates the fluid back into the wellbore  106  via flow line  185 . Sample pump  403  draws buffer fluid from buffer fluid tank  404  via flow lines  915 ,  916  and pumps the fluid into chamber  424  via flow lines  914 ,  913  through piloted valve  910  and check valve  919  as shown by the directional arrows in the figure. As described herein above with reference to  FIG. 6 , buffer fluid is added to chamber  424  in a sufficient quantity and pressure to maintain sample chamber  404  at a pressure above the bubble point pressure of the sample. Once the desired overcharge pressure P 3  is achieved, the components of the hydraulic circuit are returned to the states and positions shown in  FIG. 8 . Another receptacle  402  may be placed between piloted check valve  910  and sample flow line  401  and another sample may be taken at the same predetermined depth  130  or at another location within the borehole in the same manner described herein above. 
     An embodiment of a sample receptacle  402  in accordance with the present invention is best shown with reference to  FIG. 11 . Sample inlet orifice  427  is disposed within sample inlet housing  429  which threaded into housing  410  and further includes seals  430  which may comprise o-rings to isolate the pressure within chamber  426  described herein above. Spring loaded check valve  911  is disposed within sample inlet orifice  427  and works to block sample inlet  431  from fluid communication with sample flow line  401  ( FIG. 2 ) except during the sample filling operation described herein before with reference to  FIG. 9 . Also included in sample inlet housing  427  is sample check valve opening jack  432  screwed therein. It should be appreciated that sample check valve opening jack  432  allows for the manual opening of check valve  911  to access the sample fluid within sample chamber  426 . Sample inlet housing  427  further includes screw threads  433  at its proximal end to engage with other devices such as a pressure gage (not shown) to interact with sample check valve opening jack  432  to enable a user at the surface to determine the pressure within sample chamber  426 . 
     Still referring to  FIG. 11  buffer inlet housing  435  is threadably engaged within housing  410  on an end opposite of sample inlet housing  427  and it further includes seals  436  which may comprise o-rings to isolate the pressure within buffer fluid chamber  424  described herein above. Buffer inlet housing  435  further includes buffer orifice  425  which is in fluid communication with buffer oil inlet valve  919  and also includes screw threads  438  to engage with piloted check valve  910  ( FIGS. 8-10 ). Also included in this particular embodiment of the present invention is buffer oil axial force shutoff valve  439  which is used for locking buffer oil inlet valve  919  while at the surface. 
     Still referring to  FIG. 11  piston limit bar assembly  428  is shown disposed within housing  410  and includes limit bar  416  having shoulders  421 ,  422  disposed on either end wherein shoulder  422  is integral with nitrogen fill adapter  441  which will be more fully described herein below. Pistons  414 ,  415  are also positioned within housing  410  on limit bar  416  between shoulders  421 ,  422  forming pressure chamber  423  therebetween. Pistons  421 ,  422  further include a set of outer seals  439  and inner seals  440  to both allow the pistons to slide within the housing and along the limit bar and to isolate the pressure within pressure chamber  428  as described herein above. Nitrogen fill adapter  441  includes nitrogen fill check valve  442  for filling pressure chamber  423  at the surface as will be explained more fully herein below. 
     It is an important aspect of the present disclosure that pressure chamber  423  is filled with a sufficient amount of nitrogen at the surface to maintain the sample above its bubble point pressure at all times. In the embodiment of the present disclosure shown in  FIG. 11 , the predetermined initial pressure of the nitrogen P N0  may be several thousand psi. The piston limit bar assembly  428  must be disposed within housing  410  before chamber  423  can be filled with nitrogen. With piston limit bar assembly  428  disposed within housing  410  as shown, and buffer inlet housing  435  removed, a nitrogen source (not shown) is readily attached to screw threads  443  of nitrogen fill adapter  441 . The nitrogen is introduced through nitrogen check valve  442  and through piston  414  into pressure chamber  423  until P N0  is reached forcing pistons  414 ,  415  onto their respective shoulders  422 ,  421 . The nitrogen source is then unscrewed and buffer inlet housing  435  is screwed into housing  410 . With piston limit bar assembly  428  positioned with shoulder  422  against buffer inlet housing  435 , and eliminating any volume there between, a buffer fluid source (not shown) is then threaded onto screw threads  438 . With sample check valve  911  open, buffer fluid is introduced through buffer inlet housing  435  to fill buffer fluid chamber  424  to a pressure P B0  at or slightly below P N0  as depicted in the initial condition of Step 0 shown in  FIG. 3 . Buffer oil axial force shutoff valve  439  is then closed to maintain buffer oil chamber  424  at P B0 . 
     Another embodiment of a sample receptacle  502  in accordance with the present invention is best shown with reference to  FIGS. 12 a  and 12 b   . In this particular embodiment there is no limit bar connecting pistons  515  and  516  and further there are no openings, holes, valves or otherwise, in either of the pistons. This important aspect of the present invention greatly simplifies the pistons and eliminates complicated valve arrangements either in the limit bar as described herein above or in the pistons themselves as disclosed in the &#39;664 and &#39;672 patents of the prior art discussed herein above. In the embodiment shown in  FIG. 12 a   , sample inlet orifice  527  is disposed within sample inlet housing  529  which is disposed in housing  510 . The sample inlet housing  529 , pistons  515 ,  516  and buffer bulkhead  535  include seals  530  which may comprise o-rings to isolate the pressure within the chambers described herein above with reference to  FIG. 11 . In the embodiment shown in  FIG. 12 a   , the buffer piston  516  is inserted into housing  510  and is positioned against sample inlet housing  529 . Sample piston  515  is partially disposed within housing  510  and sample inlet bulkhead  535  is partially inserted into housing  510  and axially secured preferably by the engagement of threads (not shown). Pressure chamber  523  is then filled with a suitable pressurization medium, such as N 2 , through pressurization port  542  disposed in the wall of housing  510 . Pressure chamber  523  is filled to a predetermined pressure and pressurization port  542  is sealed off using a plug  543  ( FIG. 12 b   ). For instance, if the total volume between pistons  515 ,  516  is 900 cc the initial fill pressure of the N 2  may be 2000 psi. At P 1 =6000 psi, the volume of N 2  will be approximately 300 cc leaving 600 cc for the sample. Once pressure chamber  523  is filled, bulkhead  535  is fully installed within housing  510  as shown in  FIG. 12 b   . Buffer port  542  is filled with a fluid, such as a buffer fluid or wellbore fluid, and controls the flow of sample fluid through sample orifice  527  in a similar manner to the embodiments described herein above. 
     Referring now to  FIG. 13 , there is shown an alternative embodiment of the present disclosure for pressuring the pressure chamber  623  of sample receptacle  602 . The sample inlet end of this particular embodiment may be the same as that shown in  FIGS. 12 a , 12 b    and is not shown in  FIG. 13  for the sake of clarity and brevity. Sample receptacle  602  includes a pressurizing fixture  603  removable fixed to the buffer fluid end of housing  610  behind retaining ring  604 . Buffer piston  615  is fixed to bulkhead  635  by screw  625  and the bulkhead is fixed to the fixture by a screw (not shown). With pressurizing fixture  603  positioned on sample receptacle  602  as shown pressurization chamber  623  is filled with a suitable pressurization medium, such as N 2 , through pressurization port  642  disposed in the wall of pressurizing fixture  603  to a predetermined pressure. Once the desired predetermined level of pressure is receive pressurizing fixture  603  is translated axially along housing  610  by any known means (not shown) until the treads of bulkhead  635  and housing  610  start to engage. Bulkhead  635  is then screwed into housing  610  by rotating the fixture until o-rings  630  are suitably installed within the housing. Fixture  603  may then be removed from the bulkhead and screw  625  may then be removed from buffer piston  615  leaving a port in the bulkhead. The buffer port may then be filled with a fluid, such as a buffer fluid or wellbore fluid, and controls the flow of sample fluid through the sample orifice in a similar manner to the embodiments described herein above. 
     While the foregoing is directed to only certain embodiments of the present disclosure certain observations of the breadth of the present disclosure should be made. Wireline, as referred to herein, may be electric wireline including telemetry and power. Wireline may also include wired slickline and wired coil tubing. Embodiments of the present disclosure include pumped-down-the-drill-pipe formation testing where the tools described herein exit through the drill bit. Otherwise heretofore conventional LWD that include the present disclosure allow for formation testing and sampling where the drill pipe may be wired for power and telemetry or some other telemetry such as mud pulse or electromagnetic through the earth. Embodiments of the present disclosure further include probe mounted sampling tools as well as straddle packer types and their use in open hole and cased hole wells. Further, commands and data can be stored using battery power, and power can come from a turbine during circulation. Other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.