High productivity core drilling systems include a drill string, an inner core barrel assembly, an outer core barrel assembly, and a retrieval tool that connects the inner core barrel assembly to a wireline cable and hoist. The drill string comprises multiple variable geometry drill rods. The inner core barrel assembly comprises a non-dragging latching mechanism, such as a fluid-driven latching mechanism that contains a detect mechanism that retains the latches in either an engaged or a retracted position. The inner core barrel assembly also comprised high efficiency fluid porting.

CROSS REFERENCE TO RELATED APPLICATIONS 
     This patent application is a continuation application of U.S. patent application Ser. No. 12/528,949, filed Aug. 27, 2009, which was filed as a 35 U.S.C. §371 national phase application of International Application No. PCT/US2008/055656, filed Mar. 3, 2008, which claims benefit of U.S. Provisional Patent Application No. 60/892,848, filed Mar. 3, 2007. The contents of each of the above-referenced applications are hereby incorporated by reference in their entirety. 
    
    
     FIELD OF INVENTION 
     This application generally relates to the field of drilling. In particular, this application discusses a drilling system for drilling core samples that can increase drilling productivity by reducing the amount of time needed to place and retrieve a core sample tube (or sample tube) in a drill string. 
     BACKGROUND 
     Drilling core samples (or core sampling) allows observation of subterranean formations within the earth at various depths for many different purposes. For example, by drilling a core sample and testing the retrieved core, scientists can determine what materials, such as petroleum, precious metals, and other desirable materials, are present or are likely to be present at a desired depth. In some cases, core sampling can be used to give a geological timeline of materials and events. As such, core sampling may be used to determine the desirability of further exploration in a particular area. 
     In order to properly explore an area or even a single site, many core samples may be needed at varying depths. In some cases, core samples may be retrieved from thousands of feet below ground level. In such cases, retrieving a core sample may require the time consuming and costly process of removing the entire drill string (or tripping the drill string out) from the borehole. In other cases, a faster wireline core drilling system may include a core retrieval assembly that travels (or trips in and out of) the drill string by using a wireline cable and hoist. 
     While wireline systems may be more efficient than retracting and extending the entire drill string, the time to trip the core sample tube in and out of the drill string still often remains a time-consuming portion of the drilling process. The slow rate of the core retrieval assembly of some conventional wireline tripping systems may be cause by several factors. For example, the core retrieval assembly of some wireline systems may include a spring-loaded latching mechanism. Often the latches of such a mechanism may drag against the interior surface of the drill string and, thereby, slow the tripping of the core sample tube in the drill string. Additionally, because drilling fluid and/or ground fluid may be present inside the drill string, the movement of many conventional core retrieval assemblies within the drill string may create a hydraulic pressure that limits the rate at which the core sample tube may be tripped in and out of the borehole. 
     SUMMARY 
     This application describes a high productivity core drilling system. The system includes a drill string, an inner core barrel assembly, an outer core barrel assembly, and a retrieval tool that connects the inner core barrel assembly to a wireline cable and hoist. The drill string comprises multiple variable geometry drill rods. The inner core barrel assembly comprises a latching mechanism that can be configured to not drag against the interior surface of the drill string during tripping. In some instances, the latching mechanism may be fluid-driven and contain a detent mechanism that retains the latches in either an engaged or a retracted position. The inner core barrel assembly also comprises high efficiency fluid porting. Accordingly, the drilling system significantly increases productivity and efficiency in core drilling operations by reducing the time required for the inner core barrel assembly to travel through the drill string. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       To further clarify the advantages and features of the drilling systems described herein, a particular description of the systems will be rendered by reference to specific embodiments illustrated in the drawings. These drawings depict only some illustrative embodiments of the drilling systems and are, therefore, not to be considered as limiting in scope. The same reference numerals in different drawings represent the same element, and thus their descriptions will be omitted. The systems will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1  is a depiction of some embodiments of a core sample drilling system; 
         FIGS. 2A and 2B  contain different views of some embodiments of an inner core barrel assembly; 
         FIGS. 3A and 3B  depict cross-sectional views of some embodiments of one portion of a core sample drilling system; 
         FIG. 4  is a cross-sectional view of some embodiments of a portion of a core sample drilling system; 
         FIGS. 5A-5C  are cross-sectional views of some embodiments of a portion of a core sample drilling system in different modes of performance; and 
         FIGS. 6A-6C  are cross-sectional views of some embodiments of a portion of a core sample drilling system in different modes of performance. 
     
    
    
     DETAILED DESCRIPTION 
     The following description supplies specific details in order to provide a thorough understanding. Nevertheless, the skilled artisan would understand that the drilling systems and drilling systems and associated methods can be implemented and used without employing these specific details. Indeed, the systems and associated methods can be placed into practice by modifying the systems and associated components and methods and can be used in conjunction with any existing apparatus, system, component, and/or technique conventionally used in the industry. For instance, while the drilling systems are described as being used in a downhole drilling operation, they can be modified to be used in an uphole drilling operation. Additionally, while the description below focuses on a drilling system used to trip a core barrel assembly into and out of a drill string, portions of the described system can be used with any suitable downhole or uphole tool, such as a core sample orientation measuring device, a hole direction measuring device, a drill hole deviation device, or any other suitable downhole or uphole object. 
       FIG. 1  illustrates some embodiments of a drilling system. Although the system may comprise any suitable component,  FIG. 1  shows the drilling system  100  may comprise a drill string  110 , an inner core barrel assembly comprising an inner core barrel  200 , an outer core barrel assembly comprising an outer core barrel  205 , and a retrieval tool  300  that is connected to a cable  310 . 
     The drill string may include several sections of tubular drill rod that are connected together to create an elongated, tubular drill string. The drill string may have any suitable characteristic known in the art. For example,  FIG. 1  shows a section of drill rod  120  where the drill rod  120  may be of any suitable length, depending on the drilling application. 
     The drill rod sections may also have any suitable cross-sectional wall thickness. In some embodiments, at least one section of the drill rod in the drill string may have a varying cross-sectional wall thickness. For example,  FIG. 1  shows a drill string  110  in which the inner diameter of the drill rod sections  120  varies along the length of the drill rod, while the outer diameter of the sections remains constant.  FIG. 1  also shows that the wall thickness at the first end  122  of a section of the drill rod  120  can be thicker than the wall thickness near the middle  124  of that section of the drill rod  120 . 
     The cross-sectional wall thickness of the drill rod may vary any suitable amount. For instance, the cross-sectional wall thickness of the drill rod may be varied to the extent that the drill rod maintains sufficient structural integrity and remains compatible with standard drill rods, wirelines, and/or drilling tools. By way of example, a drill rod with an outer diameter (OD) of about 2.75 inches may have a cross-sectional wall thickness that varies about 15% from its thickest to its thinnest section. In another example, a drill rod with an OD of about 3.5 inches may have a cross-sectional wall thickness that varies about 22% from its thickest to its thinnest section. In yet another example, a drill rod with an OD of about 4.5 inches may have a cross-sectional wall thickness that varies about 30% from its thickest to its thinnest section. Nevertheless, the cross-sectional wall thickness of the drill rods may vary to a greater or lesser extent than in these examples. 
     The varying cross-sectional wall thickness of the drill rod may serve many purposes. One purpose is that the varying wall thickness may allow the inner core barrel to move through the drill string with less resistance. Often, the drilling fluid and/or ground fluid within the drill string may cause fluid drag and hydraulic resistance to the movement of the inner core barrel. However, the varying inner diameter of drill string  110  may allow drilling fluid or other materials (e.g., drilling gases, drilling muds, debris, air, etc.) contained in the drill string  110  to flow past the inner core barrel in greater volume, and therefore to flow more quickly. For example, fluid may flow past the inner core barrel  200  as the inner barrel passes through the wider sections (e.g., near the middle  124  of a section  120 ) of the drill string  110  during tripping. 
     In some embodiments, the drilling system comprises a mechanism for retaining the inner core barrel at a desired distance from the drilling end of the outer core barrel. Although any mechanism suitable for achieving the intended purpose may be used,  FIG. 1  shows some embodiments where the retaining mechanism comprises a landing shoulder  140  and a landing ring  219 . Specifically,  FIG. 1  shows that the landing shoulder  140  comprises an enlarged shoulder portion on the inner core barrel  200 . Further,  FIG. 1  shows the outer core barrel  205  can comprise a landing ring  219  that mates with the landing shoulder  140 . 
     The landing ring and landing shoulder may have any feature that allows the inner core barrel to “seat” at a desired distance from the drilling end of drill string  110 . For example, the landing shoulder may be slightly larger than the outer diameter of the inner core barrel and the core sample tube. In another example, the landing ring may have a smaller inner diameter than the smallest inner diameter of any section of drill rod. Thus, the reduced diameter of the landing ring may be wide enough to allow passage of the sample tube, while being narrow enough to stop and seat the landing shoulder of the inner core barrel in a desired drilling position. 
     The annular space between the outer perimeter of the landing shoulder and the interior surface of the drill string may be any suitable width. In some instances, the annular space may be thin because a thin annular space may allow the sample tube to have a larger diameter. In other instances, though, because a thin annular space may prevent substantial passage of fluid as the inner core barrel trips through the drill string, the landing shoulder may comprise any suitable feature that allows for increased fluid flow past the landing shoulder. In these other instances,  FIG. 28  shows that the landing shoulder  140  may have a plurality of flat surfaces or flats  145  incorporated into its outer perimeter, giving the outer perimeter of the landing shoulder  140  a polygonal appearance. Such flats can increase the average width of the annular space so as to reduce fluid resistance and thereby increase fluid flow-in both tripping directions. 
     The drill string  110  may be oriented at any angle, including between about 30 and about 90 degrees from a horizontal surface, whether for an up-hole or a down-hole drilling process. Indeed, when the system  100  used with a drilling fluid in a downhole drilling process, a downward angle may help retain some of the drilling fluid at the bottom of a borehole. Additionally, the downward angle may allow the use of a retrieval tool and cable to trip the inner core barrel from the drill string. 
     The inner core barrel may have any characteristic or component that allows it to connect a downhole object (e.g., a sample tube) with retrieval tool so that the downhole object can be tripped in or out of the drill string. For example,  FIG. 2A  shows the inner core barrel  200  may include a retrieval point  280 , an upper core barrel assembly comprising an upper core barrel  210  (or in other words a core barrel head assembly), and a lower core barrel assembly comprising a lower core barrel  240 . 
     The retrieval point  280  of the inner core barrel  200  may have any characteristic that allows it to be selectively attached to any retrieval tool, such as an overshot assembly and a wireline hoist. For example,  FIG. 2A  shows the retrieval point  280  may be shaped like a spear point so as to aid the retrieval tool to correctly align and couple with the retrieval tool. In another example, the retrieval point  280  may be pivotally attached to the upper core barrel so as to pivot in one plane with a plurality of detent positions. By way of illustration,  FIG. 2B  shows the retrieval point  280  may be pivotally attached to a spearhead base  285  of a retrieval tool via a pin  290  so a spring-loaded detent plunger  292  can interact with a corresponding part on the spearhead base  285 . 
     The upper core barrel  210  may have any suitable component or characteristic that allows the core sample tube to be positioned for core sample collection and to be tripped out of the drill string. For example,  FIGS. 3A and 3B  show the upper core barrel  210  may include an inner sub-assembly  230  (or in other words an inner member), an outer sub-assembly  270  (or in other words an outer sleeve), a fluid control valve  212 , a latching mechanism  220 , and a connection member  213  for connecting to the lower core barrel. 
     The inner sub-assembly  230  and the outer sub-assembly  270  may have any component or characteristic suitable for use in an inner core barrel. For instance,  FIG. 2B  shows some embodiments where the inner and the outer sub-assembly may be configured to allow the inner sub-assembly  230  to be coupled to and move axially (or move back and/or forth in the drilling direction) with respect to the outer sub-assembly  270 .  FIG. 2B  also shows that the inner sub-assembly  230  can be connected to the outer sub-assembly  270  via a pin  227  that passes through a slot  232  in the inner sub-assembly  230  in a manner that allows the inner sub-assembly  230  to move axially with respect to the outer sub-assembly  270  for a distance corresponding to the length of the slot  232 . 
     In some embodiments, the upper core barrel comprises a fluid control valve. Such a valve may serve many functions, including providing control over the amount of drilling fluid that passes through the inner core barrel during tripping and/or drilling. Another function can include partially controlling the latching mechanism, as described herein. 
     The fluid control valve may have any characteristic or component consistent with these functions. For example,  FIGS. 2B and 3A  show that the fluid control valve  212  can comprise a fluid control valve member  215  and a valve ring  211 . The valve member  215  may be coupled to the outer sub-assembly  270  by any known connector, such as pin  216 . The pin  216  may travel in a slot  214  of the valve member  215  so that the valve member  215  can move axially with respect to both the inner sub-assembly  230  and the outer sub-assembly  270 . The movement of the valve member  215  relative to the inner sub-assembly  230  allows the fluid control valve  212  to be selectively opened or closed by interacting with the valve ring  211 . For example,  FIG. 3A  shows the fluid control valve  212  in an open position where the valve member  215  has traveled past the valve ring  211 , to one extent of the slot  214 . Conversely,  FIG. 3B  shows the fluid control valve  212  in an open position where the valve member  215  is retracted to another extent of the slot  214 . The fluid control valve in  FIG. 3B  is in a position ready to be inserted into the drill string where it can allow fluid to flow from the lower core barrel to the upper core barrel. 
     In some embodiments, the upper core barrel  210  can contain an inner channel  242  that allows a portion of the drilling fluid to pass through the upper core barrel  210 . While fluid ports may be provided along the length of the inner core barrel  200  as desired,  FIGS. 2A and 3B  show fluid ports  217  and  217 B that provides fluid communication between the inner channel  242  and the exterior of inner core barrel  200 . The fluid ports  217  and  217 B may be designed to be efficient and to allow fluid to flow through and past portions of inner core barrel  200  where fluid flow may be limited by geometry or by features and aspects of inner core barrel  200 . Similarly, any additional fluid flow features may be incorporated as desired, i.e., flats machined into portions of inner core barrel. 
       FIG. 3A  shows some embodiments where the fluid control valve  212  is located within the inner channel  242 . In such embodiments, a drilling fluid supply pump (not shown) may be engaged to deliver fluid flow and pressure to generate fluid drag across the valve member  215  so as to push the valve member  215  to engage and/or move past the valve ring  211 . 
     In some embodiments, the upper core barrel also comprises a latching mechanism that can retain the core sample tube in a desired position with respect to the outer core barrel while the core sample tube is filled. In order to not hinder the movement of the inner core barrel within the drill string, the latching mechanism can be configured so that the latches do not drag against the drill string's interior surface. Accordingly, this non-dragging latching mechanism can be any latching mechanism that allows it to perform this retaining function without dragging against the interior surface of the drill string during tripping. For instance, the latching mechanism can comprise a fluid-driven latching mechanism, a gravity-actuated latching mechanism, a pressure-activated latching mechanism, a contact-actuated mechanism, or a magnetic-actuated latching mechanism. Consequently, in some embodiments, the latching mechanism can be actuated by electronic or magnetic sub-systems, by valve works driven by hydraulic differences above and/or below the latching mechanism, or by another suitable actuating mechanism. 
     The latching mechanism may also comprise any component or characteristic that allows it to perform its intended purposes. For example, the latching mechanism may comprise any number of latch arms, latch rollers, latch balls, multi-component linkages, or any mechanism configured to move the latching mechanism into the engaged position when the landing shoulder of the inner core barrel is seated against the landing ring. 
     By way of non-limiting example,  FIGS. 2B and 3A  show some embodiments of the latching mechanism  220  comprising at least one pivot member  225  that is pivotally coupled to the outer sub-assembly  270  by a connector, such as pin  227 .  FIGS. 2B and 3A  also show the latching mechanism  220  can include at least one latch arm  226  that is coupled to the inner sub-assembly  230  by a connector (such as pin  228 ) so that the latch arm or arms  226  may be retracted or extended from the outer sub-assembly  270 .  FIG. 2B  shows the latch arm  226  can comprise an engagement flange  229 , or a surface configured to frictionally engage the interior surface of the drill string when the latching mechanism is in an engaged position. For example,  FIG. 3A  shows that when in an engaged position, the latch arms  226  may extend out of and/or away from the outer sub-assembly  270 . Conversely, when in a retracted position (as shown in  FIG. 5C ), the latch arms  226  may not extend outside the outer diameter of the outer sub-assembly  270 . 
     In some embodiments, the latching mechanism may also comprise a detent mechanism that helps maintain the latching mechanism in an engaged or retracted position. The detent mechanism may help hold the latch arms in contact with the interior surface of the drill string during drilling. The detent mechanism may also help the latch arms to stay retracted so as to not contact and drag against the interior surface of the drill string during any tripping action. 
     The detent mechanism may contain any feature that allows the mechanism to have a plurality of detent positions.  FIG. 3B  shows some embodiments where the detent mechanism  234  comprises a spring  237  with a ball  238  at each end. The detent mechanism  234  is located in the inner sub-assembly  230  and cooperates with detent positions  235  and  236  in the outer sub-assembly  270  to hold the latching mechanism in either an engaged position, as when the detent mechanism  234  is in an engaged detent position  235 , or a retracted position, as when the detent mechanism  234  is in a retracted detent position  236 . 
     In some preferred embodiments, the latching mechanism may cooperate with the fluid control valve so as to be a fluid-driven latching mechanism. Accordingly, the fluid control valve  212  can operate in conjunction with the latching mechanism  220  so as to allow the inner core barrel  200  to be quickly and efficiently tripped in and out of the drill string  110 . The latching mechanism and the fluid control valve may be operatively connected in any suitable manner that allows the fluid control valve to move the latching mechanism to the engaged position as shown in  FIGS. 5A-6C , as described in detail below. 
       FIG. 4  illustrates some embodiments of the lower core barrel  240 . The lower core barrel  240  may include any component or characteristic suitable for use with an inner core barrel. In some embodiments, as shown in  FIG. 4 , the lower core barrel may comprise at least one inner channel  242 , check valve  256 , core breaking apparatus  252 , bearing assembly  255 , compression washer  254 , and core sample tube connection  258 . 
       FIG. 4  shows that the inner channel  242  can extend from the upper core barrel through the lower core barrel  240 . Among other things, the inner channel can increase productivity by allowing fluid to flow directly through the lower core barrel. The inner channel may have any feature that allows fluid to flow through it. For example,  FIG. 2B  shows the inner channel  242  may comprise a hollow spindle  251  that runs from the upper core barrel  210  to the lower core barrel  240 . 
     According to some embodiments, the lower core barrel comprises a check valve  256  that allows fluid to flow from the core sample tube to the inner channel, but does not allow fluid to flow from the inner channel to the core sample tube. Accordingly, the check valve may allow fluid to pass into the inner channel and then through the inner core barrel when the inner core barrel is being tripped into the drill string and when core sample tube is empty. In this manner, fluid resistance can be lessened so the inner core barrel can be tripped into the drill string faster and more easily. On the other hand, when the inner core barrel is tripped out of the drill string, the check valve can prevent fluid from pressing down on a core sample contained in core sample tube. Accordingly, the check valve may prevent the sample from being dislodged or lost. And when the check valve prevents fluid from passing through the lower core barrel and into the core sample tube, the fluid may be forced to flow around the outside of the core sample tube and the lower core barrel. Although any unidirectional valve may serve as the check valve,  FIG. 4  shows some embodiments where the check valve  256  comprises a ball valve  259 . 
     In some embodiments, the lower core barrel  240  may comprise a bearing assembly that allows the core sample tube to remain stationary while the upper core barrel and drill string rotate. The lower core barrel may comprise any bearing assembly that operates in this manner. In the embodiments shown in  FIG. 4 , the bearing assembly  255  comprises ball bearings that allow an outer portion  257  of the lower core barrel  240  to rotate with the drill string during drilling operations, while maintaining the core sample tube in a fixed rotational position with respect to the core sample. 
     The lower core barrel may be connected to the core sample tube in any suitable manner.  FIG. 4  shows some embodiments where the lower core barrel  240  is configured to be threadingly connected to the inner tube cap  275  (shown in  FIG. 2B ) and/or the core sample tube by a core sample tube connection  258 , which is coupled to the bearing assembly  255 . 
       FIG. 4  also shows some embodiments where the lower core barrel  240  contains a core breaking apparatus. The core breaking apparatus may be used to apply a moment to the core sample and, thereby, cause the core sample to break at or near the drill head (not shown) so the core sample can be retrieved in the core sample tube. While the lower core barrel  240  may comprise any core breaking apparatus,  FIG. 4  shows some embodiments where the core breaking apparatus  252  comprises a spring  261  and a bushing  263  that can allow relative movement of the core sample tube and the lower core barrel  240 . 
     In some embodiments, the lower core barrel may also comprise one or more compression washers that restrict the flow of drilling fluid once the core sample tube is full, or once a core sample is jammed in the core sample tube. The compression washers ( 254  shown in  FIG. 4 ) can be axially compressed when the drill string and the upper core barrel press in the drilling direction, but the core sample tube does not move axially because the sample tube is full or otherwise prevented from moving downwardly with the drill string. This axial compression causes the washers to increase in diameter so as to reduce, and eventually eliminate, any space between the interior surface of the drill string and the outer perimeter of the washers. As the washers reduce this space, they can cause an increase in drilling fluid pressure. This increase in drilling fluid pressure may function to notify an operator of the need to retrieve the core sample and/or the inner core barrel. 
       FIGS. 5A-6C  illustrate some examples of the function of the inner core barrel  200  during tripping and drilling and the function of some embodiments of both the detent mechanism  234  and the fluid-driven latching mechanism  220 .  FIG. 5A  depicts the detent mechanism  234  in an intermediary position, as may be the case when the latching mechanism  220  is manually placed in a retracted position in preparation for insertion into the drill string.  FIG. 5B  shows that when the latch arms  226  are in an engaged position, the pivot member  225  is extended to force the latch arms  226  to remain outward (as also shown in  FIG. 3A ). On the contrary, when the latch arms  226  are in a retracted position, as shown in  FIG. 5C , the pivot member  225  can be rotated such that the latch arms  226  may be retracted into the upper core barrel  210 . 
     As described above, the inner sub-assembly  230  can move axially with respect to the outer sub-assembly  270 . In some embodiments, this movement can cause the latching mechanism to move between the retracted and the engaged positions as illustrated in  FIGS. 5A-5C , where the movement of the inner sub-assembly  230  with respect to the outer sub-assembly  270  may change the position of the latch arms  226 . The pin  228  holding the latch arms  226  can be connected only to the inner sub-assembly  230  and the pin  227  holding the pivot member  225  can be connected to the outer sub-assembly  270 . Thus, when the outer sub-assembly  270  moves axially with respect to the inner sub-assembly  230  so as to cover less of the of the inner sub-assembly  230 , the distance between the two pins (pin  228  and pin  227 ) can increase and the pivot member  225  can rotate. As a result, the latch arms  226  may partially or completely move into the outer sub-assembly  270  and the detent mechanism  234  can move from the engaged detent position  235  to the retracted detent position  236  (as shown in  FIG. 5C ). On the contrary, when the outer sub-assembly  270  moves axially so as to cover more of the inner sub-assembly  230 , the distance between the two pins (pins  228  and  227 ) can decrease and the latch arms  226  may be forced out of the outer sub-assembly  270  into an engaged position (as shown in  FIG. 5B ). 
       FIGS. 6A-6C  shows some examples of how the fluid control valve  212  can function.  FIG. 6A  shows the fluid control valve  212  in an open position so that fluid can flow from the lower core barrel  240 , through the inner channel  242 , past the fluid ring  211 , past the fluid control valve  212 , and through the fluid ports  217 B to the exterior of the inner core barrel  200 . With the fluid control valve  212  in an open position, the latching mechanism  220  can be in a retracted position and ready for insertion into the drill string. In this open position shown in  FIG. 6A , the fluid can flow from the lower core barrel  240  to the upper core barrel  210 , but fluid pressure forces the valve member  215  towards the fluid ring  211  and causes the fluid control valve to press against the fluid ring  211  and prevent fluid flow. 
     When the landing shoulder of the inner core barrel reaches the landing ring in the drill string, the inner core barrel can be prevented from moving closer to the drilling end of the outer core barrel. Because the landing shoulder can be in close tolerance with the interior surface of the drill string, drilling fluid may be substantially prevented from flowing around the landing shoulder  140 . Instead, the drilling fluid can travel through the inner core barrel  200  (e.g., via fluid ports  217 B and the inner channel  242 ). Thus, the fluid can flow and press against the valve member  215 . The slot  214  may then allow the valve member  215  to move axially so as to press into and past the fluid ring  211  until the slot  214  engages pin  216 .  FIGS. 6B and 3A  show that at this point, the fluid control valve  212  may again be in an open position below the fluid ring  211 . Where the detent mechanism  234  is in an intermediary position (as shown in  FIG. 5A ), the inner sub-assembly  230  may be moved when the valve member  215  pulls on the pin  216  that is attached to the inner sub-assembly  230 . Thus, fluid pressure can cause the valve member  215  to move past the fluid ring  211  and, thereby, move the inner sub-assembly  230  and the detent mechanism  234  so that the latching mechanism  220  moves into and is retained in the engaged position. 
       FIGS. 5B and 6B  illustrate some embodiments of the inner core barrel  200  with the latching mechanism  220  in the engaged position (i.e., ready for drilling). As shown in  FIG. 5B , the detent mechanism  234  can be held in the engaged detent position  235 . And as shown in  FIG. 6B , during drilling the fluid control valve  212  can be held in an open position with the valve member  215  pushed below the fluid ring  211  by the fluid pressure. 
     Once the core sample tube is filled as desired, the drilling process may be stopped and the core sample can be tripped out of the drill string. To retrieve the core sample, the retrieval point  280  is pulled towards earth's surface by a retrieval tool  300  connected to a wireline cable  310  and hoist (not shown). The pulling force on the retrieval point  280  (and hence the pulling force on the outer sub-assembly  270 ) may be resisted by the engaged latching mechanism (e.g., mechanism  220 ) and the weight of the core sample in the core sample tube. These resisting forces may cause the inner sub-assembly  230  to move with respect to the outer sub-assembly  270  so that the detent mechanism  234  moves from the engaged detent position  235  (as shown in  FIG. 5B ) to the retracted detent position  236  (as shown in  FIG. 5C ). The movement of the inner sub-assembly  230  forces the pin  216  to move away from the fluid ring  211 . As the slot  214  in the valve member  215  is caught by the pin  216 , the fluid control valve  212  moves into a closed position where the valve member  215  is seated in the fluid ring  211  (as shown in  FIG. 6C ). And as the inner core barrel stripped out of the drill string, downward fluid pressure may prevent the fluid control valve  212  from opening upwardly. 
     As mentioned above, the movement of the inner sub-assembly  230  may force the latching mechanism  220  into a retracted position, as shown in  FIG. 6C . In the retracted position, the latching mechanism  220  does not drag or otherwise resist extraction of the inner core barrel  200  from the drill string. Thus, the fluid driven latching mechanism greatly reduces the time required to retrieve a core sample. Once the inner core barrel  200  is tripped out of the drill string and the core sample is removed, the inner core barrel can be reset, as illustrated by  FIGS. 5A and 6A , to be placed into drill string to retrieve another core sample. 
     In some variations of the described system, one or more of the various components of the inner core barrel may be incorporated with a variety of other downhole or uphole tools and/or objects. For instance, some form of the non-dragging latching mechanism, such as the fluid-driven latching mechanism with the detent mechanism, may be incorporated with a ground or hole measuring instrument or a hole conditioning mechanism. By way of example, any in-hole measuring instrument assembly may comprise a fluid-driven latching mechanism, such as that previously described. In this example, the assembly may be tripped into the drill string and stopped at a desired position (e.g., at the landing ring). Then, as fluid applies pressure to the fluid control valve in the assembly, the latching mechanism can be moved to the engaged position in a manner similar to that described above. 
     The embodiments described in connection with this disclosure are intended to be illustrative only and non-limiting. The skilled artisan will recognize many diverse and varied embodiments and implementations consistent with this disclosure. Accordingly, the appended claims are not to be limited by particular details set forth in the above description, as many apparent variations thereof are possible without departing from the spirit or scope thereof.