Patent Publication Number: US-2022235655-A1

Title: Apparatus and method for observing performance of a treatment fluid in a core sample

Description:
BACKGROUND 
     In the field of oil and gas production, the delivery of treatment fluids, such as reactive fluids, and such as acidic fluids especially, to not only a remote location, but also, within a formation downhole provides a myriad of logistical and technical problems and solutions. Treatment fluid systems are used for a variety of reasons, including to create improved flow paths for oil or gas recovery. Using acid systems can permit the formation of wormholes via dissolution of formation matrix near the wellbore, for example, in a well that is damaged due to the drilling process. Treatment fluids may be used in large quantities, the volume of which is dependent on the nature of the operation. For example, a matrix acidizing treatment or acid fracturing treatment of a single stage of a multistage vertical or horizontal well may require significant volumes of treatment fluid. Testing that may provide any insight into the handling, use or even alternatives to hazardous, toxic, reactive, or expensive/rare chemicals is valuable information to those in the field. 
     SUMMARY 
     The foregoing general description and the following detailed description are exemplary and are intended to provide an overview or framework for understanding the nature of what is claimed. 
     Embodiment testing apparatuses may include a top housing that is coupled to a front side of a base housing. In so coupling, a surface-surface contact forms between the top housing and the base housing. The testing apparatus has a sample viewing window that is paneless. The testing apparatus has a sample recess, which is defined by the front side of the base housing, that is configured to receive a core sample assembly. The sample recess is configured such that the position of the core sample assembly within the testing apparatus is directly observable through the sample viewing window. The testing apparatus has a primary distribution hole that permits direct fluid access to a core sample, which is part of the core sample assembly, within the sample recess. The core sample assembly is secured and immobile when the top housing is coupled to the bottom housing. A surface-surface contact is formed between the lower surface of the core sample assembly and the front side of the base housing. Optionally, a light connector is coupled to a back side of the case housing. In such instances, a surface-surface contact forms between the base housing and the light connector. 
     Embodiment methods of testing a core sample using the previously described testing apparatus may include providing the previously described testing apparatus with a core sample assembly secured and immobile within the testing apparatus. The core sample assembly is viewable through the sample viewing window. The methods include introducing a treatment fluid into the testing apparatus. The treatment fluid is introduced such that that it passes through the primary fluid distribution hole and interacts with the core sample. The methods include detecting the interaction within the testing apparatus between the treatment fluid and the core sample. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The following is a description of the figures in the accompanying drawings. The accompanying drawings are included to provide further understanding and are incorporated in and constitute a part of the specification. The drawings illustrate various embodiments and together with the description explain principles and operations of an apparatus and system useful for evaluating fluids both reactive and non-reactive through a sample of formation material. 
         FIGS. 1A-B  show an assembled embodiment testing apparatus in perspective and side view according to one or more embodiments. 
         FIGS. 2A-C  show the top housing in perspective, front, and side views according to one or more embodiments of the testing apparatus  100 . 
         FIGS. 3A-D  show the base housing in perspective, front, side and back view according to one or more embodiments of the testing apparatus  100 . 
         FIGS. 4A-C  show the light connector in side, front and back view according to one or more embodiments of the testing apparatus  100 . 
         FIG. 5  shows an exploded perspective view of the embodiment testing apparatus  100 . 
         FIG. 6A  shows an exploded perspective view of an example of a core sample assembly. 
         FIGS. 6B-1-3  shows a side view of a second example core sample assembly, and the upper surface and the lower surface of said core sample assembly. 
         FIGS. 6C-1-3  shows a side view of a second example core sample assembly, and the upper surface and the lower surface of said core sample assembly. 
         FIGS. 7A-C  show an assembled testing apparatus in front, side, and back views according to one or more embodiments. 
         FIGS. 8A-C  show the yolk in front, side, and back view according to one or more embodiments of the testing apparatus  700 . 
         FIGS. 9A-C  show the base housing in front, side, and back view according to one or more embodiments of the testing apparatus  700 . 
         FIGS. 10A-C  show the top housing in front, side, and back views according to one or more embodiments of the testing apparatus  700 . 
         FIG. 11  shows an exploded perspective view of a portion of the embodiment testing apparatus  700 . 
         FIGS. 12A-C  show an assembled testing apparatus in front, side, and back views according to one or more embodiments. 
         FIGS. 13A-C  show the top housing in front, side, and back views according to one or more embodiments of the testing apparatus  1200 . 
         FIGS. 14A-C  show the base housing in front, side, and back according to one or more embodiments of the testing apparatus  1200 . 
         FIG. 15  shows an exploded perspective view of a portion of the embodiment testing apparatus  1200 . 
         FIG. 16  shows a flowchart of an embodiment method for use with an embodiment testing apparatus, such as the apparatuses described previously and pictured in part or in total in  FIGS. 1A-15 , and parts thereof. 
     
    
    
     For the sake of continuity, and in the interest of conciseness, the same or similar reference characters may be used for same or similar objects in multiple figures. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and positioned to improve drawing legibility. Further, the shapes of the elements as drawn are not necessarily intended to convey any information regarding the actual shape of the elements and have been selected for ease of recognition in the drawing. 
     DETAILED DESCRIPTION 
     In the following detailed description, certain specific details are set forth in order to provide a thorough understanding of various disclosed implementations and embodiments. However, one skilled in the relevant art will recognize that implementations and embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, and so forth. 
     Evaluating the relative performance of a fluid used in the field, such as a treatment fluid, such as a reactive fluid system, such as an acidic fluid, in laboratory scale testing still has traditionally had similar handling issues. Using full-sized core samples is not effective means to perform screening tests on new materials. Laboratory tests commonly rely on the use of core flow measurements to evaluate the acidizing performance of a reactive fluid. Data such as pore volume to breakthrough and visual representations of wormhole characteristics are needed. To visualize wormholes, though, usually a computer-tomography (CT) image is needed. This is an off-line test—it cannot be obtained during the application of the acid medium. As well, it is nearly impossible to observe the results of the acidification visually in “real time”. Other problems in using whole core samples include physically handling the cores themselves. Core samples are heavy, awkward to handle, and contain a lot of material that is difficult to obtain and is in high demand of many scientists, engineers, geologists, and researchers. Regarding the difficulty to obtain the core sample material, the issue of scarcity is especially true if the laboratory is supporting a site where active drilling or production is occurring thousands of miles away. Finally, the hazards of handling and using quantities of materials that are in proportion to the core sample may lead to the use and exposure of lab personnel to the same safety concerns that are in the field for applying reactive, acidic, toxic, or expensive chemical packages to the core samples. 
     A useful testing apparatus and its method of use would provide a way to permit the reduction of the sample size of the core material to preserve scarce resources. Such an apparatus and method of use would also result in reducing the amount of treatment fluid applied to such core material samples, which would not only reduce waste from excessive chemical use but also reduce the hazards of using such chemicals by reducing their overall quantities handled by a researcher. Reducing sample size would also avoid any issues with handling whole cores, including injury, logistics, and downtime. A useful testing apparatus and its method of use would permit direct observation of the interaction of the treatment fluid with the core sample so that a real-time assessment could be made for the viability of using the treatment fluid with the formation material. A useful testing apparatus would be made of only several parts. A useful testing apparatus would be relatively easy to assemble, use, disassemble, and clean so that a number of samples or treatment fluids may be rapidly tested in succession to determine potential solutions for issues confronting the field. A useful testing apparatus may be of a hand-held size and possibly light enough that the device may be held in hand while a test is performed. Embodiment testing apparatuses and methods of their use provide such advantages and more. 
     In some implementations, an embodiment testing apparatus may allow for observation and memorialization of the behavior and reactivity of treatment fluids, such as a reactive fluid, such as an acidic fluid, propagating into and through a core sample in real-time. “Real-time” means as it relates to an observer, whether it is a person, a computer, or an object acting as a means for detecting a change, such as a sensor, some or all, that the observer is capable using the embodiment device to monitor the initiation of treatment and witness a change in configuration to the core sample, if any, from before the introduction of the treatment fluid, during the introduction of the treatment fluid, and through the conclusion of the introduction of the treatment fluid or the cessation of observation, whichever occurs first, as the events occur and without delay. For example, using an embodiment testing apparatus, an observer may witness through the sample viewing window the introduction of a treatment fluid that is an acidic fluid into the core sample and the resultant impact on the core sample matrix, such as etching, reactivity, or dissolution of matrix material. There is no effective delay for the observer between performing the introduction action and the ability to obtain visual or optical information on the result of that action due to the configuration of the embodiment testing apparatus. With such near-instantaneous results, laboratory personnel can make quick decisions regarding scaling up testing, modifying testing programs, or report initial trial results to the field for their information and possible action. 
     Embodiment testing apparatuses and the methods of use effectively promote the use of a “reservoir on a chip” type of testing. Small amounts of synthetic or real formation material, such as samples of recovered core materials or slices of core plugs may be used to run experiments with the intention of application to the field. Attempts using a testing apparatus may be made to simulate on a microscale-sized core sample (that is, several millimeters to several inches in width or diameter) the fluid behavior and interaction that occurs within a vast formation or reservoir comprised of the same material. Testing both simulated and actual formation materials aids in the development of treatment fluids, especially reactive fluids, such as acidic fluids, for use in in the field on similar or the same formation compositions. 
     Embodiment testing apparatuses and the methods of use facilitate the safe handling and effective use of scarce resources, like core materials. Embodiment testing apparatuses, such as those of a hand-held size, only use several cubic centimeters of formation material per test. This preserves hard-to-obtain samples material for additional research or preservation, benefiting other researchers as well as reducing requests to the field to recover such materials, which may be bothersome to production operations. 
     In using reduced sample sizes, the amount of chemicals, including potentially toxic or life-threatening materials, is reduced significantly versus the amounts required to test whole core samples. Being able to perform screening tests using small portions of chemicals reduces risks for researchers that may be using unfamiliar materials, such as a new composition. Smaller portions also result in smaller amounts of waste of which to dispose. 
     Embodiment testing apparatuses are only made of a few components, the two largest being a bottom housing and a top housing that couple together. This simple design results in a testing apparatus that is easy to assemble, use, disassemble, and clean. In combination with the small samples and the quantity of chemicals, the use and maintenance of the apparatus may be relatively easier and lead to an increased turnover rate of experiments using the same apparatus. 
     Unlike other testing apparatuses, embodiment testing apparatuses provide the ability to directly observe interaction between a treatment fluid and the core sample. Based upon the configuration of the core sample assembly in relation to the top housing, a sample viewing window in the top housing affords easy visual and physical access to the core sample assembly while positioned within the testing apparatus. There is no requirement for the sample viewing window to have viewing surface pane, such as one made of glass or plastic, between the observer and the core sample apparatus. Rather, viewing at least a portion of the core sample assembly is unrestricted. This is possible because of the surface-surface contact between the upper surface and the core sample in the core sample assembly that not only prevent fluid bypass of the core sample, but also, shields the observer from exposure to the treatment fluid. This unobstructed view of the core sample, such as by a person or a device using recording media, to study or optionally memorialize the performance of the treatment fluid interacting with the core sample, permits direct and immediate observation of the treatment fluid with the core sample. 
     First Embodiment Testing Apparatus 
       FIGS. 1A and 1B  show an assembled embodiment testing apparatus in perspective and side view according to one or more embodiments. Testing apparatus  100  has an apparatus front surface  102 , an apparatus side edge  104 , and an apparatus back surface  106 . Embodiments of the testing apparatus  100  include several exterior-observable components that are coupled, including top housing  200 , base housing  300 , and optional light connector  400 . 
     Observable from perspective view  FIG. 1A  are several features of embodiment testing apparatus  100 . Fasteners  126  may couple the top housing  200  to the base housing  300 . There are also associated top housing alignment mark  224  and first base housing alignment mark  324  that appears generally aligned. Sample viewing window  220  is defined by top housing  200 , permitting observation of a core sample  603  (in relief) positioned within testing apparatus  100 . These and others attributes of the embodiment testing apparatus  100  will be described in more detail. 
       FIG. 1B  shows optional light connector  400  coupled to base housing  300  along the apparatus back surface  106  using a second coupling means, which will be described. Coupled to light connector  400  via light connector fluid connector  486  is primary fluid conduit  116  (in relief). Coupled to light connector  400  via light connector power connector  494  is power conduit  118  (in relief). Optionally, a secondary fluid conduit  122  (shown in relief) is coupled to the testing apparatus  100  along the apparatus back surface  106  at some space from light connector  400 . 
     In  FIG. 1A , the embodiment testing apparatus  100  appears as if resting in the palm of a human hand shown in relief. Although embodiment apparatus  100  may take any general form and size, testing apparatus  100  may have an apparatus diameter  108  and an apparatus thickness  110  in some embodiments that are appropriate for a hand-held sized testing apparatus. 
       FIGS. 2A-C  show the top housing in perspective, front, and side views according to one or more embodiments of the testing apparatus  100 . Top housing  200  has a top housing front surface  202 , a top housing side edge  204 , and a top housing back surface  206 . Top housing front surface  202  comprises part of apparatus front surface  102 . 
     Top housing  200  is also shown to have a top housing thickness  210  and a top housing diameter  208 . For testing apparatus  100 , top housing thickness  210  is less than apparatus thickens  110 , and top housing diameter  208  is less than apparatus diameter  108 . 
       FIGS. 2A-B  also shows top housing alignment mark  224  on top housing front surface  202  and sample viewing window  220 , as previously described. Embodiment testing apparatus have a “paneless” sample-viewing window. That is, the sample-viewing window  220  does not have a pane; that is, there is no transparent surface, such as glass or plastic, traversing that is traversing the void of the sample viewing window. Sample viewing window  220  traverses through a top housing thickness  210  and provides an unobstructed view of the interior of testing apparatus, such as into sample recess  360 . The configuration of sample viewing window  220  is shown in  FIG. 2A  is being approximately square; however, instances of the sample-viewing window  220  are not so limited. 
     In some other embodiments, the space defined by sample viewing window is occupied by a transparent material, such as glass or plastic. 
     In some embodiment, the top housing alignment mark  224  may be formed of a material subject to magnetism or a magnetic material, that is, a material that is operable to induce a magnetic effect, such as attraction or repulsion, in a material subject to magnetism. 
     In addition,  FIGS. 2A-C  show one or more fastener holes  226  formed in top housing  200 . Fastener holes  226  are disposed in a radial pattern around a center of the top housing  200 , although one of ordinary skill in the art may select another appropriate pattern for applying equilateral sealing pressure. Fastener holes  226  are configured for embodiment testing apparatus  100  to permit a portion of fasteners  126  to pass through the top housing  200 . 
       FIGS. 3A-D  show the base housing in perspective, front, side, and back views according to one or more embodiments of the testing apparatus  100 . Base housing  300  has a base housing side edge  304  and a base housing back surface  306 . Base housing side edge  304  comprises apparatus side edge  104 . Base housing back surface  306  comprises apparatus back surface  106 . Base housing  300  has several front-facing surfaces. The front edge  352  of base lip  350 , top housing recess front surface  348 , and sample recess front surface  361  all combine to provide the front-facing surfaces of base housing  300 , as seen in  FIG. 3B . 
     Base housing  300  along its exterior surface has a base housing thickness  310  and a base housing diameter  308 . For embodiment testing apparatus  100 , base housing thickness  310  is the apparatus thickens  110 , and base housing diameter  308  is the apparatus diameter  108 . 
     Base housing  300  of embodiment testing apparatus  100  includes several recesses, such as top housing recess  340 . Top housing recess  340  is configured such that top housing  200  may be introduced into top housing recess  340 . Top housing recess  340  is defined in base housing  300  by top housing recess diameter  342  and top housing recess depth  344 . In some embodiments, the top housing recess diameter  342  is approximately the same as the top housing diameter  208 . In some embodiments, the top housing recess depth  344  is approximately the same as top housing thickness  210 . Top housing recess  340  is bound by the top housing recess edge  346  of base lip  350  and top housing recess front surface  348 . 
     The testing apparatus is configured with a sample recess  360  in base housing  300 . Sample recess  360  is configured to accept and retain a core sample assembly for testing in testing apparatus  100 . Sample recess  360  is positioned relative to top housing recess  340  such that when top housing  200  is in position within top housing recess  340 , sample recess  360  forms a defined, fixed volume within base housing  300  for a core sample assembly  301  to occupy. Although the volume of sample recess may take any variation, in the embodiment testing apparatus  100 , sample recess  360  is defined in base housing  300  to have sample recess width  362 , sample recess depth  364 , and sample recess length  366 . Sample recess  360  is bound by the sample recess edge  363  and sample recess front surface  361 . 
     Base housing  300  of embodiment testing apparatus may include several holes or conduits that traverse the base housing  300  from base housing back surface  306  to top housing recess front surface  348 . In an embodiment of the testing apparatus  100 , base housing  300  may define one or more release holes  332 . The release hole  332  may be distributed in the portion of base housing  300  among top housing recess front surface  348 . During coupling of the top housing with the base housing, the release hole  332  may permit trapped air to escape the embodiment apparatus  100 . The release holes  332  may also be a means to part the coupled top housing  200  from the base housing  300  after the two housings  200 ,  300  have been mated. 
     Another set of holes defined in the portion of base housing  300  among top housing recess front surface  348  is one or more fastener holes  326 . As seen in  FIGS. 3A-D , fastener holes  326  are disposed in a radial pattern around a center of the bottom housing  300 , although one of ordinary skill in the art may select another appropriate pattern for applying equilateral sealing pressure. Fastener holes  326  are configured for embodiment testing apparatus  100  to permit a least a portion of fasteners  126  to pass through the base housing  300 . In embodiments, the number and position of fastener holes  326  in base housing correspond with the number and position of fastener holes  226  in top housing  200 . 
     In alternative embodiments, the fastener holes  326  do not fully pass through base housing  300  and out base housing back surface  306 . Rather, in such embodiments, fastener holes  326  are instead fastener stops. A fastener stop is understood to have a defined depth that is less than the thickness  310  of the base housing  300  minus the top housing recess depth  344 , which in the portion of base housing  300  in the area having top housing recess front surface  348  is the thickness of base housing  300 . In such instances, fastener stops may have counter-threads to any threads fasteners  126  possess to engage fasteners  126  and halts the progress of the fasteners  126 . The depth of the fastener stop may be related to preventing the over-torqueing of fasteners  126  and mitigation of potential damage to the core sample assembly position when testing apparatus  100  is fully assembled. As well, the lack of holes in base housing may also provide additional insurance of fluid containment within testing apparatus  100 . 
     Base housing  300  of embodiment testing apparatus may include several holes or conduit that traverse the base housing  300  from base housing back surface  306  to sample recess  360 . In an embodiment of the testing apparatus, base housing  300  may define one or more light distribution holes  372 . As shown in  FIGS. 3A-D , light distribution holes  372  are positioned as a cluster in the center of base housing  300  and traverses into sample recess  360 ; however, this configuration is not required. Light distribution holes  372  permit the transmission of artificial light or other electromagnetic energy (EM) from optional light connector  400 , through base housing  300 , and into sample recess  360 . In some embodiments of the testing apparatus  100 , the position of the light distribution holes  372  in base housing  300  is configured such that light distribution holes  372  are associated with the position of sample viewing window  220  when top housing  200  coupled with base housing  300 , although it is understood that this is not necessarily required. 
     Testing apparatus is configured with a primary fluid distribution hole, defined in the portion of base housing  300  among sample recess  360 . As shown in  FIGS. 3A-D , primary fluid distribution hole  370  is positioned in the center of base housing  300 ; however, this is not required. In  FIGS. 3A  and D, light distribution holes  372  are configured to surround primary fluid distribution hole  370 . Again, this is not required for embodiments of the testing apparatus. Primary fluid distribution hole  370  permits the conveyance of a treatment fluid, such as reactive fluid, such as an acidic fluid, from optional light connector  400  (or a non-pictured optional removable fluid connector), through base housing  300 , and into sample recess  360 . In some embodiments of the testing apparatus  100 , the position of primary fluid distribution hole  370  in base housing  300  is configured such that primary fluid distribution hole  370  is associated with the position of sample viewing window  220  when top housing  200  is coupled with base housing  300 , although it is understood that this is not required. 
     Optionally, one or more additional holes may be defined in the portion of base housing  300  among sample recess  360 . As shown in  FIGS. 3A-B  and D, there is a secondary fluid distribution hole  374  configured in the base housing  300 . The secondary fluid distribution hone  374  is a fluid conduit that may convey both fluid and solids from the sample recess  360 , through base housing  300 , and out of the testing apparatus  100 , such as by optional secondary fluid conduit  122  (such as shown in relief in  FIG. 1B ). An opening for secondary fluid distribution hole  374  in sample recess  360  is along sample recess edge  363  proximate to the cluster of light distribution holes  372 . In other embodiments, there may be more than one secondary fluid distribution holes. In such embodiments, treatment fluid may flow from the primary fluid distribution hole  370  to the more than one secondary fluid distribution holes  374  and show interaction of treatment fluid, such as reactive fluid, such as acidic fluid, along multiple fluid flow paths to multiple exit points. Other combinations, configuration patterns, numbers, and uses of the primary fluid distribution hole  370  and the one or more secondary fluid distribution hole  374  in coordination with each other to produce fluid flow patterns within sample recess  360  are envisioned. In some embodiments of the testing apparatus  100 , the position of secondary fluid distribution hole  374  in base housing  300  is configured such that secondary fluid distribution hole  374  is associated with the position of sample viewing window  220  when top housing  200  coupled with base housing  300 , although it is understood that this is not required. 
     Optionally, and in association with the one or more secondary fluid distribution holes, embodiments of the testing apparatus may include a means for coupling one or more secondary fluid conduits  122  to base housing  300  via base housing back surface  306 . In some embodiments of the testing apparatus  100 , the coupling means is an extension of base housing, similar to such as light connector fluid connector  486  ( FIG. 1B ), or other known mechanical connections (for example, ¼ turn connector, clamp, twist tie). In some embodiments of the testing apparatus, a removable fluid connector may couple the secondary fluid conduits  122  to the base housing  300 . 
     The removable fluid connector may be configured, for example, to frictionally couple with at least a portion of the interior of the secondary fluid distribution hole  374 . Such a removable fluid connector may be made of a material that is resistant to the treatment fluid while retaining flexibility, such as a silicone. One of ordinary skill in the art may appreciate that fastening one or more secondary fluid conduits  122  to base housing  300  may take the form of any common connector for securing a fluid conduit, including such connectors as may be required for conveying a treatment fluid or its resultant fluid or slurry after interaction with the core sample at a pressure greater than atmospheric pressure, such as at wellbore pressure. In some embodiments, the coupling means may be done by a magnetic connection, such as where base connector  300  includes a material subject to magnetism or a magnetic material and the secondary fluid conduit  122  has an appropriately reciprocal coupling means. Other common coupling means for distributing treatment fluids, such as reactive fluids, such as acidic fluids, or receiving the effluent fluid or slurry of said fluids after interaction with a core sample, are understood within the art and envisioned. 
       FIGS. 3A-B  also shows first base housing alignment mark  324  on front edge  352  of base lip  350 . The first base housing alignment mark  324  is associated with the top housing alignment mark  224 . The association of first base housing alignment mark  324  with top housing alignment mark  224  is such that the configuration of certain other elements of both top housing  200  and base housing  300  are aligned when top housing  200  in top housing recess  340  of base housing  300  and base housing are aligned. For example, top housing alignment mark  224  and first base housing alignment mark  324  may be configured such that when the two alignment marks  224 ,  324  are aligned, the fastener holes  226 ,  326  are aligned. In another example, the when the two alignment marks  224 ,  324  are aligned, the sample viewing window  220  may be aligned with light distribution holes  372  in sample recess  360 . 
     In some embodiment, the first base housing alignment mark  324  may be formed of a material subject to magnetism or a magnetic material, as previously described. In such an embodiment, the use of a magnetic material is configured in testing apparatus  100  such that there is an attractive force that confirms alignment of top housing  200  with base housing  300 . For example, top housing alignment mark  224  may comprise a magnetic material whereas first base housing alignment mark  324  may comprise a material subject to magnetism. In such an instance, when of top housing  200  is positioned within top housing recess  340  of base housing  300  and top housing alignment mark  224  is proximate to first base housing alignment mark  324 , a magnetic force between the two alignment marks  224 ,  324  is induced that can be detected. Other variations between magnetic material and material subject to magnetism for guiding the positioning of top housing  200  within base housing  300  are envisioned. 
       FIG. 3D  shows optional second base housing alignment mark  378  on base housing back surface  306 . Second base housing alignment mark  378  is associated with optional light connector  400 , as will be described. In some embodiment, the second base housing alignment mark  378  may be formed of a material subject to magnetism or a magnetic material, as previously described. 
       FIG. 3D  also shows optional base housing magnetic coupling  380  on base housing back surface  306 . Base housing magnetic coupling  380  is associated with optional light connector  400 , as will be described. Base housing magnetic coupling  380  is formed of materials subject to magnetism, a magnetic material, or combinations thereof, as previously described. 
     As shown in  FIG. 3D  for embodiment of the testing apparatus  100 , optional base housing magnetic coupling  380  may be configured in an asymmetric pattern, such as an asymmetric box-like pattern around a center of the base housing  300 ; however, other asymmetric and symmetric geometric patterns are envisioned. As well, the base housing magnetic coupling  380  may be configured in a regular or irregular distribution of its member elements along base housing back surface  306 .  FIG. 3D  shows an example of this. Elements of base housing magnetic coupling  380  are distributed 5 elements stage right and left and 7 stage top and bottom around the cluster of light distribution holes  372 . Other symmetrical or asymmetrical patterns are envisioned. 
     In some embodiments of the testing apparatus, such as testing apparatus  100 , an optional, removable fluid connector may couple the primary fluid conduit  116  to the base housing  300 . Such a connector may permit treatment fluid, such as a reactive fluid, such as an acidic fluid, to be conveyed to the core sample assembly in the sample recess  360  from the primary fluid conduit  116  without use of light connector  400 . The removable fluid connector may be configured, for example, to frictionally couple with at least a portion of the interior of the primary fluid distribution hole  370 . Such a removable fluid connector may be made of a material that is resistant to the treatment fluid while retaining flexibility, such as a silicone. 
       FIGS. 4A-C  show optional the light connector (LC) in side, front, and back views according to one or more embodiments of the testing apparatus  100 . LC  400  as shown has flat LC front surface  489  and a LC back surface  491 . The LC housing  488  between the LC front surface  489  and LC back surface  491  has a generally cylindrical shape except for a portion that is a flat edge  498  on one side that makes the shape asymmetrical. Other configurations of LC housing  488 , including symmetrical versions, are envisioned. 
     As shown in  FIG. 4A , LC fluid front connector  482  is positioned on LC front surface  489 . LC front fluid connector  482  acts as an extension of the LC fluid conduit  484  and assists in conveying treatment fluid from the light connector  400  into the base housing  300 . One of ordinary skill in the art may appreciate that LC front fluid connector  482  may take the form of any common connector for securing a fluid conduit to LC  400 , including such connectors as may be required for conveying a treatment fluid at a pressure greater than atmospheric pressure. As well, LC fluid front connector  482  may be configured to frictionally couple with at least a portion of the interior of the primary fluid distribution hole  370 . 
     As shown in  FIGS. 4A  and C and as previously described, both LC fluid back connector  486  and LC power connector  494  are shown optionally positioned on LC back surface  491 . LC fluid back connector  486  in  FIG. 4A  is shown coupled to primary fluid conduit  116  (in relief). LC fluid back connector  486  may provide not only an external connection to a conduit providing a source of treatment fluid, such as a reactive fluid, such as an acidic fluid, but also, may act as an extension of LC fluid conduit  484 , which traverses LC housing  488  from LC back surface  491  to LC front surface  489 . LC fluid back connector  486  and fluid conduit  116  may both be configured such that they fasten to one another using known and common coupling techniques, such as a clamp, ¼ turn connector or wire tie, to form a fluid-tight seal between the two. A “fluid-tight seal” is such that no interior or exterior sealants, adhesives, or gaskets are required to prevent a loss of fluid containment from between a first surface and a second surface. One of ordinary skill in the art may appreciate that LC fluid back connector  486  may take the form of any common connector for securing a fluid conduit to LC  400 , including such connectors as may be required for conveying a treatment fluid at a pressure greater than atmospheric pressure. 
     Another connector optionally positioned on LC back surface  491  is LC power connector  494 . LC power connector  494  in  FIG. 4A  is shown coupled to power conduit  118  (in relief). LC power connector  494  provides not only an external connection to conduit providing a source of power, but also, connects to power wiring  492  within LC housing  488 , which is connected to LC lights  490  positioned just beneath the LC front surface  489 . In embodiments, one of ordinary skill in the art may appreciate that LC power connector  494  may take the form of any common connector for securing an electrical conduit to LC  400 . LC power connector  494  and power wiring  492  may both be configured such that they fasten to one another using known and common coupling techniques to complete an electrical connection between the two. One of ordinary skill in the art may appreciate that LC power connector  494  may take the form of any common connector for securing an electrical connection to LC  400 , including such connectors as may be required for conveying power to generate light through LC lights  490 . 
       FIGS. 4A-C  also show that LC alignment mark  478  may be positioned on both LC front surface  489  ( FIG. 4B ) and flat edge ( FIG. 4A ). The second base alignment mark  378  is associated with the LC alignment mark  478 . The association of second base alignment mark  378  with LC alignment mark  478  is such that the configuration of certain other elements of base housing  300  and light connector  400  are aligned when light connector  400  couples to base housing  300 . For example, second base alignment mark  378  and LC alignment mark  478  may be configured such that when the two alignment marks  378 ,  478  are aligned, LC fluid conduit  484  of light connector  400  is aligned with primary fluid distribution hole  370  of base housing  300  for introducing a treatment fluid into sample recess  360 . As another example, when the two alignment marks  378 ,  478  are aligned, LC lights  490  are aligned with light distribution holes  372  such that light may be transmitted into sample recess  360 . 
     In some embodiments, LC lights  490  may include fiber optics within the interior of and on the outer surface of LC housing  488 . In some other embodiments, LC lights  490  may include thin organic light emitting diode (OLED) or light emitting diode (LED) panels for optionally transmitting visible light into sample recess  360 . In some alternative embodiments, LC lights may transmit other electromagnetic (EM) frequencies into sample recess  360  through light distribution holes  372  that may assist with the imaging of the core sample in sample recess  360 , for example, infrared (IR) light or X-rays. 
     Second base alignment mark  378  and LC alignment mark  478  may be configured such that when the two alignment marks  378 ,  478  are aligned, base housing magnetic coupling  380  is aligned with LC magnetic coupling  480  such that a magnetically induced connection forms. LC magnetic coupling  480  is formed of materials subject to magnetism, a magnetic material, or combinations thereof, as previously described. As shown in  FIG. 4B  for embodiment of the testing apparatus  100 , LC magnetic coupling  480  may be configured in an asymmetric pattern, such as previously described for base housing  300 . As well, the LC magnetic coupling  480  may be configured in a regular or irregular distribution of its member elements, as previously described for base housing  300 . As shown in the embodiment, LC magnetic coupling  480  and base housing magnetic coupling  380  are configured to be asymmetrically coordinated of one another not only in pattern, but also, in coupling mechanism such that the LC magnetic coupling  480  and housing magnetic coupling  380  affirmably interact when positioned together. As seen in  FIG. 3D , for example, base housing magnetic coupling  380  may be configured such that the rows of 5 elements may be comprised of magnets and the rows of 7 elements may be comprised of material subject to magnetism. As its reciprocal, LC magnetic coupling  480  may be configured such that rows of 5 elements may be comprised of material subject to magnetism and the rows of 7 elements may be comprised of magnets. Variations in such symmetrical or asymmetrical coordinated configurations, including using configurations of magnets with the same and opposing polarities to attract and repel the LC magnetic coupling  480  to and from the base housing magnetic coupling  380 , are envisioned. 
       FIG. 5  shows an exploded perspective view of the embodiment testing apparatus  100 . According to one or more embodiments, the testing apparatus  100  may be used for observing the interaction and performance of a treatment fluid, such as a reactive fluid, such as an acidic fluid, on a core sample as part of a core sample assembly. The exploded view of the testing apparatus  100  shows the top housing  200 , the base housing  300 , and the optional light connector  400  relative to one another and how the three components couple to form testing apparatus  100 . 
     Preparing embodiment testing apparatuses like testing apparatus  100  for use encompasses a few steps. A core sample assembly, which includes a core sample to be tested, configured for use in the embodiment testing apparatus is provided. The core sample assembly is introduced into the sample recess such that a core sample is directly observable through the sample viewing window. A core sample assembly (not shown) is introduced into sample recess  360  of base housing  300 . Configurations of the core sample assembly may vary depending on the configuration of embodiment testing apparatuses, such as testing apparatus  100 , and the dimensions of the sample recess  360 ; however, it is assumed that the core sample assembly is configured to be positioned entirely within sample recess  360 . Three examples of possible core sample assembly configurations are provided in  FIGS. 6A-C , as will be described. The core sample is directly fluidly accessible through the primary fluid distribution hole. 
     Top housing is coupled to the front side of the base housing. Fasteners and other such coupling means for securing one item to another are well understood in the art. Bolts and nuts, screws, tie-wires, and magnetic couplings are examples and are included. Other common means are clearly envisioned. Sealants, adhesives, and gaskets may or may not be used. The top housing  200  is introduced into the top housing recess  340  such that the top housing alignment mark  224  and the first base housing alignment mark  324  are aligned. This ensures that the fastener holes  226 ,  326  are aligned. The fasteners  126  are introduced into the fastener holes  226 ,  326  via threads  136  and locked with fastener locks (not shown), which secures top housing  200  to base housing  300 . Core sample assembly (not shown) containing the core sample (not shown) is rendered secure and immobile in the sample recess  360  while the top housing  100  is coupled to the base housing  200 . 
     Embodiments of the testing apparatus are configured to secure the core sample assembly without crushing or breaking any part of the core sample assembly—the core sample or the surfaces—when the embodiment testing apparatus is closed. Surface-surface contact fluid-tight seals between the embodiment testing apparatus and the core sample assembly will be describe in the discussion of  FIGS. 6A-C . 
     Optionally, light connector is coupled to the backside of the base housing. To continue the assembly of embodiment testing apparatus  100 , light connector  400  may be coupled with base housing  300  such that light connector alignment mark  478  and the second base housing alignment mark  378  are aligned. This ensures that several elements of base housing  300  and LC  400  are aligned and operable. The base housing magnetic coupling  380  is aligned with LC magnetic coupling  480 , which permits a magnetic coupling to form between LC  400  and base housing  300 . Primary fluid distribution hole  370  on the apparatus back surface  106  is aligned with LC fluid conduit  484  so as to form a continuous fluid flow pathway configured to selectively convey treatment fluid, such as a reactive fluid, such as an acidic fluid, from an external source (via primary fluid conduit  116 ) into sample recess  360 . Light distribution holes  372  on the apparatus back surface  106  are aligned with LC lights  490  to form a continuous pathway configured to convey electromagnetic energy, such as visible light, into sample recess  360 . Fasteners and other such coupling means for securing one item to another are well understood in the art and have been previously described. 
     Optionally, secondary fluid conduit  122  is coupled to the testing apparatus  100  along the apparatus back surface  106 . This aligns secondary fluid conduit  122  with the secondary fluid distribution hole  374  and permits fluid accessibility from sample recess  360  for passing of effluent fluid or slurry from testing. 
     Embodiments of the testing apparatus and its components may be configured to be corrosion-resistant to resist damage from introduced treatment fluids, such as reactive fluids, such as acidic fluids. The top and base housings as well as the optional light connector exterior or body of the testing apparatus may be comprised of materials that are resistant to the treatment fluids, such as reactive fluids, such as acid fluids. Example useful materials may include fluoropolymers and metals like Inconel® 718, Hastelloy®, and Monel®. In some instances, certain parts of top and base housing, such as those surfaces exposed to the treatment fluids, may be clad with such materials resistant to the treatment fluids, whereas other parts of the embodiment testing apparatus may be made of more simple or base materials. 
     The configuration of the embodiment testing apparatus may permit testing under simulated downhole environmental conditions. In some embodiments, the testing apparatus is configured to withstand testing at conditions understood in the industry to be at high-pressure/high-temperature (HPHT) wellbore conditions. In some embodiments, the embodiment testing apparatus is operable at a temperature between about 20° C. to about 150° C. In some embodiments, the embodiment testing apparatus is operable at an internal pressure in a range of from about atmospheric to about 4000 psi (pounds per square inch). 
     Core Sample Assembly 
       FIG. 6A  shows an exploded perspective view of an example of a core sample assembly.  FIGS. 6B-1-3  shows a side view of a second example core sample assembly, and the upper surface and the lower surface of said core sample assembly.  FIGS. 6C-1-3  shows a side view of a second example core sample assembly, and the upper surface and the lower surface of said core sample assembly. Core sample assemblies  601 ,  601 ′, and  601 ″ include a core sample  603 ,  603 ′, and  603 ″, respectively. 
     Embodiment testing apparatus  100  may be used with a core sample assembly, such as  601  and  601 ′, which is configured for and introduced into the sample recess before an embodiment testing apparatus, such as the testing apparatus  100  of  FIG. 1 , is fully assembled, as seen in  FIGS. 3A-C .  FIG. 6A  shows an exploded perspective view of an example of a core sample assembly configured for use with an embodiment testing apparatus. 
     An example of a core sample—core sample  603 —as shown in  FIG. 6A  is formed as a square with a thickness (that is, a square prism) much smaller than its other dimensions. The core sample for use in a core sample assembly may be obtained by cutting a rock sample to form a core slice or coring. Core samples may comprise samples of reservoir and reservoir-like material, such as carbonates, sandstones, or shales, and other materials, and combinations thereof. “Other materials” may include special geological configurations, such as outcrops, intrusions and salt domes, and other specialty testing formats, such as synthetic core samples (that is, non-natural or mathematically designed models on polymers or metal). In some embodiments, the core sample comes from reservoir, which is a hydrocarbon-bearing formation, material. Testing may permit observation and memorialization of the core sample material with different treatment fluids, including reactive fluids, including fluids useful in acidizing operations. 
     Other configurations of the core sample  603  are envisioned. Core sample  603  may be configured in any regular geometric or non-geometric shape (2D with a thickness or 3D) that meets the bounds of an enclosed sample recess, including a circular shape, a rectangular shape, a triangular shape, or any regular polygon shape, or an irregular shape, to form various prisms. A circular shape (more likely a flat-cylinder or coin-like configuration as the sample has a determinable thickness) may be useful for testing across an entire diameter of a coring from a formation or reservoir. In some embodiments, the core sample may be a slice from a coring and, as such, takes the form of a flat, coin-like cylinder that may have a diameter that up to several inches and a thickness of only a few millimeters. The length and width (or diameter) of the core sample assembly  601  cannot exceed the dimensions of the core sample recess and therefore is limited only by such configuration of embodiment testing apparatuses. 
     The slice of core sample  603  may be of various thicknesses—from greater than a micrometer to about 15 millimeters (mm). For core sample  603 , the back and the front surfaces may be parallel to each other. Both the surfaces may be flat and smooth. A smooth surface may be achieved using specialized cutting and grinding equipment known to those of skill in the art. 
     In instances where the core sample is less than 2 mm thick, backlighting from the light connector while the core sample is positioned in the core recess may be sufficient to make the opaque sample appear semi-translucent. Under such conditions, direct observation of the treatment fluid, such as a reactive fluid, such as an acidic fluid, interacting with the core sample matrix through the sample viewing window may be feasible. 
     In  FIG. 6A , the core sample  603  is shown positioned within the core sample assembly  601  between two surfaces: upper surface  609  and lower surface  613 . In some instances, the entire upper surface  609  is optically transparent; in other instances, for example, a portion of the upper surface positioned above the core sample  603  position is optically transparent. Upper surface may be comprised of any composition where optical transparence occurs over the core sample  603  and that is resistant to compromise by the treatment fluid introduced. Optical transparency permits light transmitted from the light connector passing through light distribution holes and illuminating core sample  603  to traverse out of the testing apparatus through sample viewing window to the observer or the means for memorization. 
     In some instances, the entire lower surface  609  is optically transparent; in other instances, the portion of the lower surface positioned below the core sample  603  position is optically transparent. Lower surface may be comprised of any composition where optical transparence occurs beneath the core sample  603  and that is resistant to the treatment fluid introduced. Optical transparency permits light to traverse into the core sample  603  to permit observation from the sample-viewing window while the core sample assembly  601  is positioned in the sample recess. 
     The lower surface  609  defines a void  615 . The void  615  in lower surface  609  is used in some instances to permit treatment fluid, such as a reactive fluid, such as an acidic fluid, to be introduced into the core sample  603  from primary fluid distribution hole. Void  615  is positioned associated with the primary fluid distribution relative to the sample recess. Such coordination helps to prevent fluid bypass around core sample  603  by creating seals between the core sample apparatus lower surface  609  and the base housing. 
     For example, as eluded to in  FIG. 6A , the upper surface may be a flat, rectangular slide made of glass or polymer, and of similar size to those used in microscopes. The lower surface may be configured of a similar material (glass or polymer) and have a similar size as the upper slide, but the lower surface includes a void to permit treatment fluid to be introduced into the core sample at the designated positions within the sample recess of the embodiment treatment apparatus. 
     In some instances, the upper surface is rigid and unyielding. In some instances, the lower surface is rigid and unyielding. Glass and some polymers, like polycarbonates, may be examples of a rigid material that is also transparent, that is chemically resistant to the treatment fluid, and can withstand a pressure differential between its two sides. In some other instances, the upper surface is resilient and yielding, that is, the material yields to a force applied and then rebounds or reforms its original shape when the force is removed. In some instances, the lower surface is resilient and yielding. Silicone rubbers, some polyurethanes, and some partially cured epoxy resins, may be examples of resilient materials operable to withstand operational conditions while also providing adequate transparency. In some instances, both rigid and resilient types of materials may be used in a core sample assembly. For example, a rigid surface may be used against the surface of the core sample to provide a fluid seal to prevent fluid bypass, and a resilient surface may be used to couple with the top housing proximate to the viewing window. Both the rigid surface and the resilient surface may be bonded to one another using means known to one of skill in the art. 
     Thickness of the upper and lower surfaces may be based upon the pressure requirement for the testing of the core sample. For example, the thickness of the upper or lower surface, or both, may be up to several millimeters thick. If fluid flow is introduced into the testing apparatus at a pressure similar to the downhole environment, the upper surface may have to maintain a differential pressure between the downhole environment and external conditions during introduction and use of the treatment fluid as the viewing window is present. In such an instance, the upper surface would be much thicker than a similar surface that is merely preventing slightly greater than surface pressures from escaping. Similar adjustments may be made to the lower surface to accommodate for the introduction and passing of pressurized fluids while also permitting light to enter the sample recess. 
     The top surface of the core sample  603  may be configured such the upper surface  609  mates with the top surface of the core sample  603 . The surface of the core sample  603 , for instance, may be ground flat and polished to create a glass-like smooth surface configured to mate with a similar smooth surface of upper surface  609 . As well, the lower surface of the core sample  603  may be configured such that the bottom surface  613  mates with the bottom surface of the core sample  603  in a similar manner. With both upper and lower surfaces  609 ,  613  mated, the core sample assembly is formed. When the three elements ( 603 ,  609 ,  613 ) are assembled into core sample assembly  601 , one or more fluid-tight seals are capable of being formed. The fluid-tight seals form, it is believed, when the core sample assembly  601  is in the sample recess when the top and base housings are coupled together during the assembly of the embodiment testing apparatus due to pressure being applied to the core sample assembly. During operation of the embodiment testing apparatus, the fluid tension of the treatment fluid, even under potentially reservoir-like temperatures and pressures, is insufficient to overcome the fine gap between the surface-surface contacts, effectively creating a fluid-tight seals. As well, it is envisioned that a similar surface-surface contact fluid-tight seal forms between the lower surface  613  and the lower surface of the core sample  603  in the locations where the void  615  is not present, which assists in routing treatment fluid to a specific contact location for and into the core sample  603 . 
     In some instances, the core sample assembly  601  may use sealants, adhesives or gaskets to prevent fluid bypass between the upper surface  609  and the core sample  603 , between the core sample  603  and the lower surface  613 , and between the upper surface  609  and the lower surface  613  where the core sample  603  is not present. Such sealants, adhesives or gaskets are used within the core sample assembly and not on the embodiment testing apparatus. In such instances, the introduced sealant may be transparent, may be acid resistant, and may be chemically inert to the introduced treatment fluids. In some other embodiments, the introduced seal may be configured to withstand elevated temperatures, such as those experienced in a high-pressure/high-temperature (HPHT) environment downhole. Seals used in HPHT-type environments may need to be resistant to the introduced fluids or byproducts of reactions that may occur under such conditions. 
       FIG. 6B-1-3  shows an end, upper surface and lower surface of a second example of a core sample assembly  601 ′ that may be used with embodiment testing apparatus. An example of a core sample—a core sample  603 ′—is formed as a rectangular prism with a core sample length  666 ′ and a core sample width  662 ′, which are substantially similar to sample recess length and sample recess width of sample recess of an embodiment testing apparatus. Core sample assembly thickness  664  is at or less than the sample recess depth) because core sample assembly  601 ′ includes upper surface  609 ′ and lower surface  613 ′. 
     In the second example, it can be envisioned that both upper surface  609 ′ and lower surface  613 ′ are comprised of transparent sealant material that adheres to the core sample  603 ′ surface. The composition of the sealant may be varied depending on a variety of reasons, including type of treatment fluid, testing conditions, and transmissiveness of the surfaces  609 ′,  613 ′. 
       FIG. 6B-3  shows the lower surface lower surface  613 ′ having voids  615 . Such a configuration may be supportive of a base housing with a primary fluid distribution hole and a side secondary distribution hole. 
       FIG. 6C-1-3  shows an end, upper surface and lower surface of a third example of a core sample assembly  601 ″ that may be used with embodiment testing apparatus. An example of a core sample—a core sample  603 ″—is formed as a thick cylinder with a core sample diameter  667 ″. The thickness of the core sample may be several millimeters thick. Testing such a large core sample may require a embodiment testing apparatus that has the ability to expand to accommodate the thickness of the core sample, such as embodiment testing apparatus  1200  (to be detailed). Core sample assembly  605 ″ includes upper surface  609 ″ and lower surface  613 ″. 
     In this example, upper surface  609 ″ and lower surface  613 ″ are envisioned to be a transparent, rigid, and unyielding material, such as glass or polycarbonate. Such materials are useful when the sample size creates a core sample  603 ″ that is weighty. Rigid upper and lower surfaces  609 ″,  613 ″ provide for ease of handling the sample when the core sample assembly  601 ″ is assembled as well as for disassembly and cleaning after the test is performed, and reuse. 
       FIG. 6C-3  shows the lower surface  613 ″ having a single, centralized void  615 ″. Such a configuration may be supportive of a base housing with a primary fluid distribution hole in the center of the base housing and one or more secondary fluid distribution holes along the side of instead of through the bottom of the base housing. 
     Second Embodiment Testing Apparatus 
       FIGS. 7A-C  show an assembled testing apparatus in front, side, and back views according to one or more embodiments  700 . The embodiment testing apparatus  700  may have similar use functionality to apparatus  100  in relation to how the core sample assembly  601  (or  601 ′) may be introduced and a treatment fluid used on it with the testing apparatus. However, there are several structural differences to testing apparatus  700  that are of note and will be described in detail. 
     Testing apparatus  700  has an apparatus front surface  702 , an apparatus side edge  704  and an apparatus back surface  706 . Embodiments of the apparatus  700  include several exterior-observable components that are coupled, including yolk  800 , base housing  900 , and top housing  1000 . Optional light connector  400 ′, which is also present, has been effectively described previously as light connector  400 . 
     Testing apparatus  700  has an apparatus diameter  708  and an apparatus thickness  710  as seen in  FIG. 7B . 
     Several features are readily apparent from the view of testing apparatus  700  in  FIGS. 7A-C  that are common with testing apparatus  100  but with slight configuration variations. Given that the functionally is equivalent, the introduction of each will be brief. Sample viewing window  220 ′ in  FIG. 7A  is configured slightly different to show more of the core sample assembly. The configuration of optional light connector  400 ′ is slightly different in that the LC housing  488 ′ is fully cylindrical. As well, LC back surface  491 ′ has a LC alignment mark  478 . Everything else is as previously described. 
       FIG. 7B  shows that top housing  1000  has a ribbed edge  1005  that extends the apparatus diameter  708  to a diameter greater than base housing  900 , as can be seen from the back view of  FIG. 7C . The ribbed edge  1005  configuration provides a grip that permits the top housing  1000  to more easily rotate using a frictional grip on the external contacting surface and applying torque to top housing  1000 . 
       FIGS. 8A-C  show the yolk  800  in front, side, and back views according to one or more embodiments of the testing apparatus  700 . Yolk  800  may be described as having a “tiered cake” or “stair step” configuration. The yolk  800  has two sections: a top yolk section  813  and a bottom yolk section  814 . The yolk  800  has two yolk front-facing surfaces:  802   a  (top yolk front surface) and  802   b  (bottom yolk front surface). Yolk  800  also has two side-facing edges:  804   a  (top yolk side edge) and  804   b  (bottom yolk side edge). Yolk  800  has a yolk back surface  806 . Of the surfaces of yolk, only top yolk front surface  802   a  is visible externally as a portion of apparatus front surface  706 . 
     Configurations of yolk  800  have a paneless sample viewing window  220 ′. 
     Yolk  800  is also shown to have a top yolk section diameter  809  and a bottom yolk section diameter  808 , which is greater than top yolk section diameter  809 . Bottom yolk section diameter  808  is effectively the yolk diameter. Both diameters  808 ,  809  are less than apparatus diameter  708 . Yolk  800  also has two yolk thicknesses: a top yolk section thickness  812  and a bottom yolk section thickness  811 . Additively, the two yolk thicknesses  811 ,  812  add up to the yolk thickness  810 . Yolk thickness  810  is less than the apparatus thickness  710 . 
     The yolk  800  does not have any internal or external threads along either top yolk side edge  804   a  or bottom yolk side edge  804   b.    
       FIG. 8A  shows yolk alignment mark  824  on bottom yolk front surface  802   b . Yolk alignment mark  824  is similar in configuration and function as previously described alignment marks. 
     In some embodiments, the yolk  800  includes yolk stops  817  that extend a fixed length from the yolk back surface  802 . In some other embodiments, the yolk  800  includes yolk stop gaps  815  that extend a fixed depth into the bottom yolk section  814  of the yolk  800 . In some other instances, such as shown in  FIGS. 8B-C , both yolk stops  817  and yolk stop gaps  815  are present. 
       FIGS. 9A-C  show the base housing  900  in top, side, and back views according to one or more embodiments of the testing apparatus  700 . Base housing  900  has a base housing side edge  904  and a base housing back surface  906 . Base housing side edge  904  comprises a portion of apparatus side edge  704 . Base housing back surface  906  comprises apparatus back surface  706 . Base housing  900  has several front-facing surfaces. The front edge  352  of base lip  350 , top housing and yolk recess front surface  348 ′, and sample recess front surface  361  all combine to provide the front-facing surfaces of base housing  900 ; however, none are visible from the front view when testing apparatus  700  is fully assembled. 
     Base housing  900  along its exterior surface has a base housing thickness  910  and a base housing diameter  908 . Top housing and yolk recess  340 ′ has a top housing and yolk recess diameter  942 . Top housing and yolk recess diameter  942  is greater than bottom yolk section diameter  808 . 
     Base housing  900  has a configuration similar to base housing  300 , but with slight variations. Top and yolk housing recess  340 ′ has many similar configurational aspects as top housing recess  340 . In  FIG. 9C , base housing magnetic coupling  380 ′ is in a dual bar-like configuration; however, functionally for coupling LC  400 ′, it is similar to the prior-described base housing magnetic coupling  380 . 
     The testing apparatus is configured with a sample recess  360 ′. 
     Testing apparatus is configured with a primary fluid distribution hole  372 ′. 
       FIGS. 9A  and B show that along top housing recess edge  346  of base lip  350  there is internal threading  946 . 
     In some embodiments, the base housing  900  includes base housing stops  915  that extend a fixed length from the top housing and yolk recess front surface  348 ′. In some other embodiments, the base housing  900  includes base housing stop gaps  917  that extend a fixed depth into the top housing and yolk recess front surface  348 ′ of the base housing  900 . In some other instances, such as shown in  FIG. 9A , both base housing stops  915  and base housing stop gaps  917  are present. 
     Yolk stop gaps  815  and base housing stops  915  are configured and coordinated. For example, when yolk  800  is positioned within top housing and yolk recess  340 ′, base housing stops  915  will fit within yolk stop gaps  815  such that yolk  800  can no longer rotate against base housing  900 . Yolk stops  817  and base housing stop gaps  917  are similarly yet oppositely configured to the same purpose. The configuration of stops and stop gaps between the yolk and the base housing can allow other features, for example, the viewing window  220 , to be properly aligned for the assembly of the embodiment testing apparatus. 
     Although not shown in  FIGS. 9A-C , in some embodiments of the base housing there are secondary fluid distribution holes for withdrawing treatment fluid residual, introducing treatment fluid or components of treatment fluids, or both, similar to as having been described previously. 
       FIGS. 10A-C  show the top housing  1000  in front, side, and back views according to one or more embodiments of the testing apparatus  700 . Top housing  1000  has a top housing front surface  1002 , a top housing side edge  1004 , and several back-facing surfaces. Top housing front surface  1002  comprises part of apparatus front surface  702 . Ribbed edge  1005  comprises part of apparatus side edge  704 . Back-facing edges of top housing  1000  including top housing back edge  1006   a , top housing backfacing yolk edge  1006   b  and top housing backfacing base lip edge  1006   c.    
     Top housing  1000  is also shown to have a top housing thickness  1010  and a top housing diameter  1008 . For testing apparatus  700 , top housing thickness  1010  is less than apparatus thickens  710 . Top housing diameter  1008  is equal to the apparatus diameter  708 . 
     There are other diameters of note in describing top housing  1000 .  FIGS. 10B  and C show the top housing threading diameter  1023  associated with external threading  1046 . Top housing threading diameter  1023  corresponds to the diameter of top housing and yolk recess diameter  942  of base housing  900  such that the top housing  1000  and the base housing  900  may threadily couple when assembling testing apparatus  700 . 
     There are also other thicknesses that help describe top housing  1000 . Top housing thickness  1010  describes the total thickness of top housing  1000 ; however, this can be divided amongst several portions of meaning. The thickness of top housing  1000  associated with the ribbed edge  1005  is measurable as ribbed edge thickness  1033 . The remainder of the top thickness housing  1010  is associated with external threading  1046 , and external threading thickness  1031 . 
     A yolk recess  1040  is formed within the body of top housing  1000  configured to accept yolk  800  into top housing  1000 . Yolk  800  fits within yolk recess  1040  such that top yolk front surface  802   a  and top housing front surface  1002  sit flush with each other when testing apparatus  700  is assembled; however, it can be envisioned that other variations are feasible. As well, yolk back surface  806  and top housing back edge  1006   a  also sit flush with each other when assembled, although it can be envisioned that other variations may be feasible. 
     Several dimensions of the yolk  800  and the top housing  1000  are configured to reciprocate with one another. Top housing yolk bottom diameter  1021  corresponds to the diameter of the bottom yolk section diameter  808  of the yolk  800  such that the bottom yolk section  814  may fit within the lower portion of yolk recess  1029 . Top housing yolk top diameter  1009  corresponds to the diameter of the top yolk section diameter  809  such that the top yolk section  813  may fit within the upper portion of yolk recess  1027  and be observed as part of the exterior of testing apparatus  700  when coupled with top housing  1000 . The bottom yolk thickness  1011  is similar to the bottom yolk section thickness  811  such that in embodiment testing apparatus  700  entire bottom yolk section  814  fits within lower portion of yolk recess  1029 . The top yolk thickness  1012  is similar to the top yolk section thickness  812  such that in embodiment testing apparatus  700  the entire top yolk section  813  fits within upper portion of yolk recess  1027 . 
       FIGS. 10B  and C show that along top housing side edge  1004  there is external threading  1046 . The configuration of external threading  1046  corresponds to the internal threading  946  such that the external threading  1046  and the internal threading  946  are operable to couple together. Top housing  1000  and the base housing  900  are joined by threadily coupling the top housing  1000  into the base housing  900  until one of the following occurs first: (1.) the internal and external threads  1046 ,  946  are played out; (2.) top housing back edge  1006   a  contacts top housing and yolk recess front surface  348 ′; or (3.) a pair of stop/stop gap prevent the yolk descending further onto the top housing and yolk recess front surface. The stop/stop gap interaction will be described further. In some embodiments, the external threading thickness  1031  of external threading  1046  of top housing  1000  is equal to or greater than the top housing recess depth  344  of internal threading  946  of base housing  900 . 
       FIG. 11  shows an exploded perspective view of the embodiment testing apparatus  700 . According to one or more embodiments, the testing apparatus  700  may be used for observing the interaction and performance of a treatment fluid on a core sample as part of a core sample assembly. The exploded view of the testing apparatus  700  shows the top housing  1000 , the base housing  900 , and the yolk  800  relative to one another and how the three components couple to form testing apparatus  100 . Light connector  400 ′ is not presently shown; however, its function and coupling with the base housing  900  has been previously described and shown in similar embodiment testing apparatuses. 
     Preparing embodiment testing apparatus  700  for use encompasses a few steps. The core sample assembly is positioned within the sample recess such that a core sample is directly observable through the sample viewing window. A core sample assembly, such as the configurations previously described, is introduced into sample recess  360  of base housing  900 . The core sample assembly is configured to be positioned entirely within sample recess  360 . The core sample is directly fluidly accessible through the primary fluid distribution hole. Yolk  800  is introduced into the top and yolk housing recess  340 ′ such that yolk alignment mark  824  and first base housing alignment mark  324  are aligned; base housing stops  915  fit into yolk stop gaps  815 , if present; and yolk stops  817  fit into base housing stop gaps  917 , if present. 
     The length of stops  817 ,  915  and the depth of stop gaps  815 ,  917  may be used to prevent over-pressuring of the core sample assembly  601  in core sample recess  360  by the yolk  800 . As well as preventing over-pressurization and assisting with alignment of the yolk  800  with the base housing  900 , the stops  817 ,  915  and the stop gaps  815 ,  917  may also prevent the yolk  800  from turning or spinning when the top housing  1000  is threadily fitted to base housing  900 . 
     Continuing the assembly process, top housing couples to the front side of the base housing and is secured in place with a fastening means. The top housing  900  is introduced into the portion of the top and yolk housing recess  340 ′ not occupied by the yolk  800 . Coupling occurs by threadily engaging external threading  1046  of top housing  1000  with internal threading  946  of base housing  900  until the rotation of top housing  1000  stops. Yolk  800  occupies yolk recess  1040  of top housing  1000  when base housing  900  couples with top housing  1000 . 
     Optionally, light connector is coupled to the back side of the base housing with a second fastening means. Although not shown in  FIG. 11 , to continue the assembly of embodiment testing apparatus  700 , light connector  400 ′ is coupled with base housing  900  as previously described in other embodiments. 
     Optionally, one or more secondary fluid conduits  122  may be coupled as previously described. In such embodiments, the testing apparatus  700  has supporting attachments for such connectors. 
     Third Embodiment Testing Apparatus 
       FIGS. 12A-C  show an assembled testing apparatus  1200  in front, side, and back views according to one or more embodiments. The testing apparatus  1200  has a similar purpose as testing apparatuses  100  and  700 ; however, its configuration varies in certain ways from the two embodiment testing apparatuses previously described. The configurational differences can be attributed to the handling of a cylindrical “core slice” as the core sample. Potentially, greater operating pressures and treatment fluid volumes may also be explored. One of skill in the art will note that the vision of embodiment testing apparatus  1200 , just as with testing apparatuses  100  and  700 , include versions that may be scaled upwards or downwards in size and capacity to accommodate different amounts of treatment fluid, sample sizes, and testing conditions. 
     Testing apparatus  1200  has an apparatus front surface  1202 , an apparatus side edge  1204  and an apparatus back surface  1206 . Embodiments of the apparatus  1200  include several exterior-observable components, including top housing  1300  and base housing  1400 . 
     Testing apparatus  1200  has an apparatus diameter  1208  and an apparatus thickness  1210  as seen in  FIG. 12B . 
     Several features previously described can be seen in  FIGS. 12A-C . Upper surface  609 ″ (in relief) is visible through sample viewing window  220 ″. Sample viewing window  220 ″ provides a circular view of core sample assembly  601 ″. Core sample assembly  601 ″ is positioned within base housing  1400 . The core sample assembly  601 ″ is held in position by downward pressure along the circular outer edge of upper surface  609 ″ applied by coupled top housing  1300 . Fasteners  126  couple top housing  1300  to base housing  1400 . 
     Embodiment testing apparatus  1200  does not show optional light connector. Rather, primary fluid distribution hole  370 ″ is coupled to a primary fluid coupling connector  1286  (in relief). Primary fluid coupling connector  1286  may be coupled to a primary fluid conduit, such as primary fluid conduit  116  of  FIG. 1B , as previously described. 
     Testing apparatus  1200  does show that secondary fluid distribution hole  374 ″ is coupled to secondary fluid coupling connector  1222  (in relief). Secondary fluid coupling connector  1222  may be coupled to a secondary fluid conduit, such as secondary fluid conduit  122  of  FIG. 1B , as previously described. 
     Several testing apparatus stand legs  1207  (in relief) are coupled to the embodiment testing apparatus  1200  through the bottom side. This permits the testing apparatus  1200  to be placed on a work bench while providing appropriate clearance for connectors and tubing coupled to the bottom side. Testing apparatus stand legs  1207  couple with the testing apparatus  1200  via stand holes  1407  defined by base housing  1400 . In some instances, stand holes  1407  may be threaded to secure testing apparatus stand legs  1207  in position. 
       FIGS. 13A-C  show the top housing  1300  in front, side, and back according to one or more embodiments of the testing apparatus  1200 . Top housing  1300  has a top housing front surface  1302 , which is part of the apparatus front surface  1202 . Top housing is made of two different sections: a top section  1313  and a bottom section  1314 . Each section has its own side edge and back-facing surface. Top section  1313  has top section side edge  1304   b  and top section back surface  1306   b . Bottom section  1314  has bottom section side edge  1304   a  and bottom section back surface  1306   a.    
     Top housing  1300  has two sets of diameters—one for each section. Top section diameter  1308  is the broadest diameter for the top housing  1300  and is affiliated with top section side edge  1304   b . Bottom section diameter  1309  is narrower and is affiliated with bottom section side edge  1304   a . There is a third diameter for the paneless sample viewing window  220 ″ that is sample viewing window diameter  1320 , which is less than bottom section diameter  1309 . 
     Top housing  1300  is also shown to have a top section thickness  1312  associated with top section  1313 . Bottom section thickness  1311  is associated with bottom section  1314 . 
     Top housing  1300  also has fastener holes  1326 . Fastener holes  1326  are configured  1200  to permit a portion of fasteners  126  to pass through the top housing  1300 . 
       FIGS. 14A-C  show the base housing  1400  in front, side, and back according to one or more embodiments of the testing apparatus  1200 . Similar to the configuration of embodiment testing apparatus  100 , the base housing side edge  1404  and base housing back surface  1406  are the same as apparatus side edge  1204  and an apparatus back surface  1206  of embodiment apparatus  1200 . In  FIG. 14B , front edge  352 ′ of base lip  350 ′ extends forward and is part of the apparatus front surface  1202 . The other front-facing surfaces of embodiment testing apparatus  1200  are recess front-facing surface  1461 , which is associated with the sample recess  1460 , and top housing recess front surface  1448 . 
     Base housing  1400  has several diameters of note. Base housing diameter  1408  is the same as apparatus diameter  1208 . Base housing  1400  also has top housing recess diameter  1442  that is less than the base housing diameter  1408 . Top housing recess  1440  is configured to receive the top section  1313  of the top housing  1300 . Sample recess diameter  1462  is configured such that the bottom section  1314  of the top housing  1300  similarly may fit into the base housing  1400 . Core sample assembly  601 ″ have an appropriate diameter configuration to fit into sample recess dimeter  1462  when embodiment testing apparatus  1200  is used. 
     Base housing  1400  also has several thicknesses. Base housing has base housing thickness  1410 , which is the same as apparatus thickness  1210 . Top housing recess thickness  1444  is associated with the top section thickness  1312  of top section  1313 . In some embodiments, when top housing  1300  is introduced into base housing  1400 , the top housing recess thickness  1444  and the top section thickness  1312  are configured as such that top housing front surface  1302  sits flush with front edge  352 ′. In other embodiments, such as shown in  FIG. 12B , the surfaces are not flush. 
     The testing apparatus is configured with a sample recess. Sample recess depth  1464  as determined along sample recess edge  1463  of sample recess  1460  is configured to accommodate bottom section thickness  1311  of bottom section  1314  of top housing  1300 . In some embodiments, bottom section thickness  1311  is less than sample recess depth  1464 . In such embodiments, the difference between the bottom section thickness  1311   a  and sample recess depth  1464  is to accommodate the core sample assembly thickness  664 ″ of core sample assembly  601 . When introduced into sample recess  1460 , as seen in  FIG. 12B , core sample assembly  601 ″ resides on sample recess front surface  1461 . 
     Testing apparatus is configured with a primary fluid distribution hole. Base housing  1400  includes primary fluid distribution hole  370 ″ and light distribution holes  372 ″, both of which function in this embodiment testing apparatus  1200  as previously described. 
     In the embodiment of base housing  1400 , the light distribution holes  372 ″ are configured in a circle pattern to maximize backlighting of core sample  601 ″. The light distribution holes in this instance are configured not only to provide space for primary fluid distribution hole  370 , but also, to provide for a solid ring along the outer periphery of sample recess front surface  1461 . This space approximately mimics the footprint of where the bottom section back surface  1306   a  of top housing  1300  contacts upper surface  609  of core sample assembly  601 ″. The space provides a visual reminder to ensure that core sample assembly  601 ″ is configured and positioned appropriately for use when top housing  1300  and base housing  1400  are coupled. 
     Although not shown in  FIGS. 14A-C , one or more secondary fluid distribution holes  374 ″ for withdrawing treatment fluid residual similar to as having been described previously. 
     Base housing  1400  also has fastener holes  1426 . Fastener holes  1426  are configured for embodiment testing apparatus  1200  to permit a portion of fasteners  126  to pass through the base housing  1400 . 
     Optionally, testing apparatus  1200  has recesses  1407  for permitting apparatus stand legs  1207  to be coupled to the base housing  1400 . As previously described, this may permit testing apparatus  1200  to be positioned level and on a flat support surface for allowing the test to be performed. 
       FIG. 15  shows an exploded perspective view of the embodiment testing apparatus  1200 . According to one or more embodiments, the testing apparatus  1200  may be used for observing the interaction and performance of a treatment fluid on a core sample as part of a core sample assembly. The exploded view of the testing apparatus  1200  shows the top housing  1300  and the base housing relative to one another and how the components couple to form testing apparatus  1200 . The optional light connector is not shown from this view; however, its function with the base housing  1400  has been previously described and shown with other embodiments, and such may be applied to testing apparatus  1200 . A pair of hands (in relief) to give perspective to a useful size of embodiment testing apparatus  1200 ; however, as previously stated, embodiment testing apparatuses may be scaled to greater or reduced sizes. 
     Preparing embodiment testing apparatus  1200  only takes a few steps. The core sample assembly is positioned within the sample recess such that a core sample is directly observable through the sample viewing window. The core sample assembly, such as core sample assembly  01 ″, is introduced into sample recess  1460  of base housing  1400 . The core sample assembly is configured to be positioned entirely within sample recess. Lower surface  613 ″ (not shown) of core sample assembly  601 ″ rests on top of sample recess front surface  1461 . 
     The core sample is directly fluidly accessible through a primary fluid distribution hole in base housing. Resultant fluid or slurry from the test may be expelled from the apparatus  1200  using one or more secondary fluid distribution holes  374 ″. 
     Top housing couples to the front side of the base housing with a fastening means. Top housing  1300  is introduced at least partially into base housing  1400  such at least a portion of the bottom section  1314  is positioned within sample recess  1460 . Bottom section back surface  1306   a  rests on upper surface  609 ″ (not shown) of core sample assembly  601 ″. At the same time, the upper section  1313  is positioned either within or above top housing recess  1440 , depending on the thickness  664 ″ of the core sample assembly  601 ″. The top housing  1300  is rotated such that fastener holes  1326  are aligned with fastener holes  1426  of base housing. In this embodiment of the testing apparatus, the apparatus is symmetrical; there is no need or requirement for alignment marks, although they may be optionally included. The fasteners  126  are introduced into the fastener holes  1326 ,  1426  and are tightened down, securing top housing  1300  to base housing  1400  and fixing core sample assembly  601 ″ in sample recess  1460 . 
     With the securing of the fasteners  126 , a surface-to-surface contact is made that form surface contacts within embodiments of testing apparatus  1200 . In some embodiments of the testing apparatus, top housing  1300  couples with base housing  1400  such that a surface-surface contact is between sample recess front surface  1461  and the lower surface  613 ″ (not shown) of core sample assembly  601 ″. In regard to the seal between sample recess front surface  1461  and the lower surface (not shown) of core sample assembly  601 ″, a fluid-tight seal does not form where primary fluid distribution hole  372 ″ is positioned; however, the lack of a seal at these locations does not compromise external integrity. Other surface-surface contacts may form upon formation of the testing portion of the embodiment testing apparatus. 
     Optional light connector is coupled to the back side of the base housing with a second fastening means. Although not shown in  FIG. 15 , to continue the assembly of embodiment testing apparatus  1200 , light connector  400 ″ is coupled with base housing  1400 , as has been previously described in other embodiments. 
     Optionally, one or more secondary fluid conduits  122  may be coupled to a secondary fluid distribution hole  374 ″ as previously described. In such embodiments, the testing apparatus  1200  may have supporting connectors to secure one more secondary fluid conduits. 
     Method of Use of Testing Apparatus 
       FIG. 16  shows a flowchart of an embodiment method for use of an embodiment testing apparatus, such as the apparatuses described previously and pictured in  FIGS. 1A-15 , and parts thereof. While the various steps are represented as a series of blocks and are described sequentially, one of ordinary skill in the art will appreciate that some or all of the steps may be executed in a different order, may be combined, may be omitted, or may be executed in parallel. Furthermore, the steps may be performed actively or passively. The steps may be performed in part or in total by a human, by a machine following pre-written instructions, or both. 
     For step  1610 , a testing apparatus with a core sample assembly having a core sample is provided. For example, an embodiment testing apparatus, such as those previously described as testing apparatus  100 ,  700 , or  1200 , may be provided, along with other variants of the testing apparatus. The testing apparatus has a top housing coupled to the front side of the base housing with a fastening means, such as like by fasteners or by the internal/external threading as previously described. Optionally, the light connector is coupled to the back side of the base housing with a second fastening means, for example, the magnetic coupling as previously described, or by other means as can be envisioned by one of ordinary skill in the art. 
     The testing apparatus is configured with a sample viewing window as previously described. In some embodiments, the viewing window is paneless; in other embodiments, there is a transparent pane, such as a glass or plastic window, present and enclosing sample viewing window. 
     As previously described for the embodiment testing apparatuses  100 ,  700 , and  1200 , the testing apparatus is configured with a sample recess. A core sample assembly is positioned within the sample recess such that the core sample is directly observable through the sample viewing window. 
     In some embodiments, the core sample assembly is provided. Core sample assembly comprises a core sample to the tested positioned in between an upper surface and a lower surface. The lower surface is configured with a void in the surface to permit fluid to access the core sample thought he lower surface. The core sample has a surface finish such that it may form a fluid-tight seal with both the upper surface and the lower surface (except for where the void is present) such that fluid may not bypass the sample in between the respective surfaces and the core sample when pressure is applied to the core sample assembly. 
     The testing apparatus is also configured as previously described with a primary fluid distribution hole. With the core sample assembly in the sample recess and the primary fluid distribution hole traversing the base housing of the testing apparatus, the core sample is directly fluidly accessible from outside the embodiment testing apparatus, such as through optional light connector or another fluid conduit as previously described. In such a position, the core sample is ready to be tested and observed. 
     In some configurations of the testing apparatus, such as embodiment testing apparatus  100  and  1200 , the sample viewing window is part of the top housing, as previously described. In some other configurations of the testing apparatus, such as embodiment testing apparatus  700 , the testing apparatus further comprises a yolk that is coupled to both the top housing and the base housing and is configured with the sample viewing window. 
     In some other configurations of the testing apparatus, the testing apparatus further comprises at least one secondary fluid distribution hole. In such instances, the core sample assembly is configured such that the core sample is also directly fluidly accessible via the secondary fluid distribution hole(s). 
     In step  1620 , a treatment fluid is introduced into the testing apparatus such that the treatment fluid and the core sample interact. Treatment fluid is introduced into the core sample through the primary fluid distribution hole. As described for some embodiments, the light connector is configured to couple a treatment fluid supply line (previously described as primary fluid conduit  116 ) to primary fluid distribution hole. Light connector is coupled with base housing such that LC fluid conduit aligns with primary fluid distribution hole and a fluid flow pathway is provided for the treatment fluid to be introduced into the core sample via the void in the lower surface. In some other embodiments, the fluid conduit providing testing fluid into the primary fluid distribution hole is coupled to the base housing on the back surface using a tubing connector or some other means of coupling the fluid supply conduit to the embodiment testing apparatus. 
     As previously described, the treatment fluid may include one or more various fluids, including gases, liquids, and combinations thereof. In some instances, the treatment fluid may take the form of a slurry; however, the particles should be of an appropriate size to ensure that the core sample fluid flow pathways do not become clogged or otherwise hindered. For example, carbon dioxide may be introduced as a nanosolid in a carrier solution, a gas, a critical fluid, or a supercritical fluid. As another example, the treatment fluid may be introduced at pressures and temperatures ranging from room conditions to simulated formation conditions, including high pressure/high temperature (HPHT) wellbore conditions. In some cases, HPHT may be understood to be wellbore conditions of at least 149° C. and at least 10,000 psi (pounds per square inch), although specifics on the exact definition may vary. In another example, the treatment fluid may contain biologically hazardous components, such as hydrogen sulfide. In such cases, the embodiment testing apparatus is configured to safely handle such conditions and fluids, including by use of appropriate seals, adhesives, and gaskets, as well as materials of construction of fasteners and housings, while permitting live observation and memorialization. 
     Examples of treatment fluids may include natural and synthetic waters, such as distilled, fresh, desalinated, mineral, organic-loaded, gray, brown, black, brackish, sea, brines, formation, production, and post-industrial processing waters. Treatment fluids may include air and gas products, including, but not limited to, air, “enriched” air, nitrogen, carbon dioxide, carbon monoxide, hydrogen sulfide, noble gases, and combinations thereof. Treatment fluids may include crude oil, natural gas, liquid condensate, other naturally-occurring hydrocarbons, and synthetic and natural fractions thereof, including, but not limited to, methane, ethane, propane, butanes, light petroleum gas (LPG), natural gas lights, naphthas, mineral spirits, mineral oils, kerosenes, “Safra oil” (that is, dearomatized mineral oil and dearomatized kerosene), BTEX (benzene/toluene/ethyl benzene/xylenes), BTX, diesels, atmospheric and vacuum gas oils, vacuum residuals, maltenes, and asphaltenes, and combinations thereof. Treatment fluids may include salts, such as salts of ammonium, sodium, calcium, cesium, zinc, aluminum, magnesium, potassium, strontium, silicates, lithium, iron, and combinations thereof. Treatment fluids may include salts that disassociate to form ions of chlorides, bromides, carbonates, hydroxides, iodides, chlorates, bromates, formats, nitrates, sulfates, phosphates, oxides, fluorides, and combinations thereof. Treatment fluids may include natural and synthetic polymers. 
     Optionally, treatment fluids may include dyes, tracers, and other additives for permitting or facilitating the visual or sensor detection of the interaction of the treatment fluid with the core sample. For example, a treatment fluid, such as a reactive fluid, such as an acidic fluid, may produce bromine gas as a byproduct of the reaction. When such a reaction proceeds to generate the acid and the bromine gas, the resultant of the treatment fluid interacting with the core sample changes from colorless to orange. This vapor having a reaction product that produces a visible color permits observation and memorialization of the formation of the acid system within the core sample assembly. In some embodiments, the dye or tracer may be light or photo-sensitive such that it reacts upon exposure to light. For example, the dye or tracer may demonstrate fluorescence or phosphorescence upon exposure to electromagnetic (EM) energy, such as through visual or UV spectrum light. 
     Treatment fluids may include reactive fluids. A reactive fluid is a composition having one or more materials that upon initiating a reaction then react and form a product different than the reactant(s). Forming a product in situ of formation material, such as a core sample or core slice, is of interest. An example of a reactive fluid may include an epoxy thermosetting resin introduced with a curing agent. Introduced of this material into the core sample a reaction may occur where an epoxy thermoset polymer forms in the core sample matrix. 
     In some embodiments, the reactive fluid is configured to react with the core sample. In some embodiments, the reactive fluid is an acidic fluid. An acidic fluid may include an organic acid. Useful organic acids may include, but are not limited to, alkanesulfonic acids, arylsulfonic acids, formic acid, acetic acid, methanesulfonic acid, p-toluenesulfonic acid, alkyl carboxylic acids, aryl carboxylic acids, lactic acid, glycolic acid, malonic acid, fumaric acid, citric acid, tartaric acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, fluoroacetic acid, difluoroacetic acid, trifluoroacetic acid, glutamic acid diacetic acid, methylglycindiacetic acid, 4,5-imidazoledicarboxylic acid, and combinations thereof. 
     An acidic fluid may include an inorganic acid, also known as mineral acids. Strong acids may include, but are not limited to, hydrochloric acid, (HCl), chloric acid (HClO 3 ), hydrobromic acid (HBr), sulfuric acid (H 2 SO 4 ), nitric acid (HNO 3 ), perchloric acid (HClO 4 ), hydroiodic acid (HI), phosphoric acid (H 3 PO 4 ), and combinations thereof. Such acids may be introduced as liquid concentrates or as solids that are hydrated within the core sample, or they may be provided as their own solution. 
     In some other embodiments, the reactive fluid is configured to degrade and form a second reactive fluid in the core sample, where the second reactive fluid is reactive with the core sample. Examples of a first reactive fluid that degrades and forms a second reactive fluid, which in some instances may be an acidic fluid, include hydrolyzable compounds, such as esters or nitrile-containing compounds. 
     In some other embodiments, the reactive fluid is configured to degrade within the core sample and form a second reactive fluid within the core sample, where the second reactive fluid is reactive with a third reactive fluid that is present in the core sample or is introduced after degradation of the first reactive fluid. In such an instance, the third reactive fluid may not be reactive with the first reactive fluid. 
     In some embodiments, a first reactive fluid is configured to react with a second reactive fluid present in the core sample. An example of a first reactive fluid reacting with a second reactive fluid may include an epoxy thermosetting resin introduced with a curing agent. Introduction of this mixture into the core sample permits a reaction to occur where an epoxy thermoset polymer forms within the core sample matrix. 
     Another example of a reactive system is provided. A composition for forming an acidic fluid in situ may include introduction of a first reactive fluid—an aqueous fluid with an acid precursor—with a second reactive fluid—an oxidizing agent configured to oxidize the acid precursor. As used, “in situ acid generation” and variations thereof means that an acid used for dissolving the matrix of the core sample is generated within the core sample from introduced compositions that are acid precursors. This is in contrast to forming an acidic solution and then introducing the acidic solution into the testing apparatus, as previously described. 
     To provide an example of in situ acid generation, an acid precursor may include an ammonium salt, such as an ammonium halide. The ammonium halide may include, but is not limited to, ammonium fluoride, ammonium chloride, ammonium bromide, ammonium iodide, and combinations thereof. The ammonium salt may also include, but is not limited to, hydrogen difluoride, and a polyatomic anion. Polyatomic anions include, but are not limited to, sulfates, including hydrogen sulfate; thiosulfates; nitrites; nitrates; phosphites; phosphates, including monohydrogen phosphate and dihydrogen phosphate; carbonates; and combinations thereof. 
     In some embodiments, an ammonium salt may include one or more N-substituted ammonium salts. The N-substituted ammonium salt may be mono-substituted or di-substituted, for instance, with one or two alkyl groups. Tri-N-substituted ammonium salt is tri-substituted with, for example, three alkyl groups. Alkyl groups may include, but are not limited to, methyl, ethyl, propyl, and butyl. In some embodiments, an ammonium salt is not a tri-substituted ammonium salt. In some embodiments, an ammonium salt is not a tetra-substituted ammonium salt. 
     To continue the example, an oxidizing agent comprises an agent configured to oxidize an ammonium salt. In some embodiments, an oxidizing agent includes an inorganic oxidizer. Further, an oxidizing agent may include an agent selected from the group comprising a peroxide, a persulfate salt, a permanganate salt, a bromate salt, a perbromate salt, a chlorate salt, a perchlorate salt, an iodate salt, a periodate salt, and combinations thereof. In certain embodiments, an oxidizing agent is a bromate salt, such as an alkali bromate salt, such as sodium bromate. In some other embodiments, an oxidizing agent includes an organic oxidizer. In some such embodiments, an oxidizing agent comprises an agent selected from the group comprising peracetic acid, performic acid, and combinations thereof. 
     In some embodiments, an introduced reactive fluid includes a composition comprises an aqueous fluid having an ammonium salt configured to be oxidized to produce acid and an oxidizing agent configure to oxidize the ammonium salt. 
     In some embodiments, an ammonium salt and oxidizing agent in an aqueous fluid react to produce an acidic fluid at a temperature equal to or greater than 65° C. In such an instance, the acidic fluid may react with the core sample matrix upon formation, driving the reaction to completion. 
     In an embodiment, a first reactive fluid is introduced to the core sample through the primary fluid distribution hole. In such an embodiment, a second reactive fluid configured to react with the first reactive fluid is introduced to the core sample through the primary fluid distribution hole. In some certain embodiments, the first reactive fluid and the second reactive fluid may react to form an adduct within the core sample, effectively a third material that is different from the first and second materials. In other such embodiments, the first and the second reactive fluids may mix and dilute one another such that they act in concert on the core sample matrix. 
     In some certain embodiments, a reactive fluid is configured to disassociate and form a second fluid due to conditions in the core sample, such as pressure or temperature, or due to an interaction with a material within the core sample. Examples of possible materials within the core sample that may disassociate include salt ions and acids. 
     In some embodiments, the first reactive fluid and the second reactive fluid are both introduced simultaneously through the primary fluid distribution hole. In such instances, the two reactive materials may not react until the fluids reach the conditions of the core sample, such as temperature or pressure. 
     In some other embodiments, the first reactive fluid and the second reactive fluid are introduced in series through the primary fluid distribution hole. In such an embodiment, there may be perfect or near-perfect mixing of the two reactive materials, or there may be a residual of the first reactive material that remains that is enough to start a reaction between the first and the second reactive material within the core sample. Other variations of reactive fluid interactions within the core sample assembly are envisioned where all the reactive fluids are introduced through primary fluid distribution hole. 
     The testing apparatus may hold the core sample at various testing conditions, such as from room conditions to simulated downhole conditions, as previously described. 
     Optionally, where the embodiment testing apparatus is configured to have more than one secondary fluid distribution holes, more options for studying fluid behavior interacting with and within the core sample are feasible. The secondary fluid distribution holes may act as one or more “production wells” in studying formation behavior. In some instances, an effluent fluid or slurry as the resultant from the interaction between the core sample and the treatment fluid forms and is passed into the secondary fluid distribution hole for elimination. Fluid flow may occur between the primary fluid distribution hole and one or more secondary fluid distribution holes. The variations are potentially endless depending on the configuration and number of secondary fluid distribution holes. 
     In step  1630 , the interaction within the testing apparatus between the treatment fluid and the core sample is detected. The testing apparatus may enable detection, observation, and memorialization of the treatment fluid as it flows into and interacts with the core sample in real-time. In some instances, such as the use of a reactive fluid or an acidic fluid, the attenuation of the core sample through reaction may be observed in real-time. “Attenuation” in this use means that the core sample had an original configuration in its matrix, but after the introduction of treatment fluid a chemical or physical reaction occurs within the matrix that transforms the matrix to a new configuration. For example, the formation of wormholes, fluid flow channels, or voids fundamentally changes the configuration of the matrix from a first state to a second state, where the second state has less material comprising the matrix than the first state. 
     In some embodiments, the detection of the interaction between the treatment fluid and the core sample is through direct visual observation. Visual observation may be made by an observer, such as by a mechanical means, including a lens if the observer is synthetic, through the sample viewing window of the top housing or the yolk. The core sample assembly containing the core sample is positioned within the embodiment testing apparatus. 
     Optionally, light is transmitted through the core sample assembly and through the core sample such that it may be illuminated. In some embodiments, light is supplied by the light connector, as previously described. Light is transmitted through the one or more light distribution holes formed in the base housing of the embodiment testing apparatus. Light illuminates the core sample and any space around it where light distribution holes are present. During introduction of the treatment fluid, light is also transmitted through the treatment fluid such that it is also illuminated. 
     If the core sample of the core sample assembly has a thickness that is about or less than 2 mm, in some instances the light from the light connector is sufficient to render at least parts of the core sample semi-translucent. In such instances, it is feasible to view, detect, and memorialize the interaction of the treatment fluid within the interior of the normally opaque core sample. In other instances, external illumination through the sample viewing window may be used, as will be described. 
     In some instances, as previously described, the treatment fluid may comprise a dye or tracer that is configured to react to electromagnetic radiation (EM), such as fluorescent or phosphorescent materials, Such light-reactive dyes or tracers may assist in detecting aspects of a core sample in real-time. Another example of a useful dye or tracer-type additive may include magnetically responsive material. 
     In some embodiments, additional illumination sources external to the testing apparatus may be used to illuminate or irradiate the core sample through the sample viewing window. Such electromagnetic (EM) radiation may include, but are not limited to, visible light, infra-red (IR) light, ultra-violet (UV) light, radioactive sources (alpha, beta, gamma particle emitters), sonic emitters, and X-ray emitters. Such additional illumination may reveal other aspects of the treatment fluid interaction with the core sample in real-time. Such interactions may be memorialized using both media that can record visual as well as information that is not visual, such as IR-sensing cameras and computers with programs for detecting and recording IR-information, such that the heat flow within the core sample may be detected as the treatment fluid is introduced into the core sample. 
     Although the embodiment testing apparatus provides for the ability to visually access the core sample during testing, there are indirect testing methods that may also provide similar if not greater value. In some embodiments, the fluid or slurry flow to and from the device may be monitored to evaluate the interaction within the testing apparatus between the treatment fluid and the core sample. Such detection may include flow volume or mass detection in and out of the testing apparatus, for example, determining the rate of dissolution of a matrix acid by changes in fluid volume or slurry mass passing from a core sample. Another example is detection of the concentration of a specie in the spent treatment fluid or in both the introduced treatment fluid and the spent treatment fluid, such as looking for the appearance of a tracer from a secondary fluid distribution hole. As well, determining the change in concentration of a hydrophilic or hydrophobic component may indicate a determination of wettability ion adsorption rate into a formation sample by the relative change in concentrations between introduction and passing fluids into and out of the testing apparatus. Another example is detecting core sample weight change due to interaction with a treatment fluid, such as due to dissolution of the core sample matrix from acidification or from a liquid being pushed out of the core space by a foam, by tracking the weight of the apparatus during testing and monitoring the density of the fluids introduced. Yet another example would be taking a nuclear magnetic resonance (NMR) or a magnetic shift reading from interaction of the treatment fluid with the core sample. Detecting such treatment fluid and the core sample interactions indirectly while still operating the testing apparatus for other purposes is expected and well appreciated. 
     Optionally, the interaction within the testing apparatus between the treatment fluid and the core sample is memorialized. Detecting the interaction of the treatment fluid with the cores sample may use various apparatuses, systems, and devices for memorialization, recording and archiving the detected interaction. In some embodiments, the memorialization is optical. For example, a video or still camera may capture a single or a series of images, or collect a continuous moving image, of the interaction between the core sample and the treatment fluid as available through the sample viewing window. Such images may later be analyzed in a variety of ways known to those of skill in the art. 
     Unless defined otherwise, all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art to which these systems, apparatuses, methods, processes, and compositions belong. 
     The singular forms “a,” “an,” and “the” include plural referents, unless the context clearly dictates otherwise. 
     As used here and in the appended claims, the words “comprise,” “has,” and “include” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps. 
     “Optionally” means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur. 
     When the word “approximately” or “about” are used, this term may mean that there can be a variance in value of up to ±10%, of up to 5%, of up to 2%, of up to 1%, of up to 0.5%, of up to 0.1%, or up to 0.01%. 
     Ranges may be expressed as from about one particular value to about another particular value, inclusive. When such a range is expressed, it is to be understood that another embodiment is from the one particular value to the other particular value, along with all particular values and combinations thereof within the range. 
     While the apparatus has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate that other embodiments can be devised that do not depart from the scope as described. Accordingly, the scope should be limited only by the accompanying claims.