Patent Publication Number: US-8978757-B2

Title: Remote actuation testing tool for high pressure differential downhole environments

Description:
PRIORITY CLAIM/CROSS REFERENCE TO RELATED APPLICATION(S) 
     This patent Document claims priority under 35 U.S.C. §119 to U.S. Provisional App. Ser. No. 61/427,402, filed on Dec. 27, 2010, and entitled, “High Pressure High Temperature (HPHT) Well Tool Control System and Method”, and also to U.S. Provisional App. Ser. No. 61/428,754, filed on Dec. 30, 2010, and entitled “IRDV Tool for HPHT Environments”, both of which incorporated herein by reference in their entireties. This Patent Document is also a continuation-in-part claiming priority under 35 U.S.C. §120 to U.S. application Ser. No. 12/505,340, entitled “Downhole Piezoelectric Devices”, filed Jul. 17, 2009, and which claims priority to Provisional App. Ser. No. 61/081,465, filed on Jul. 17, 2009, and entitled “Piezoelectric Actuator and Pump in Oilfield Application”, both of which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     Exploring, drilling, completing, and operating hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. In recognition of these expenses, added emphasis has been placed on well access, monitoring and management throughout the productive life of the well. That is to say, from a cost standpoint, an increased focus on ready access to well information and/or more efficient interventions have played key roles in maximizing overall returns from the completed well. 
     By the same token, added emphasis on completions efficiencies may also play a critical role in maximizing returns. That is, enhancing efficiencies over the course of well testing, hardware installation and other standard up front tasks may also ultimately improve overall returns on the significant investments placed in well completions. For example, a host of well testing applications may be run upon completion of initial drilling operations but in advance of casing and other hardware installations. Such tests may be carried out by a testing tool outfitted with a ball valve, a circulation valve, and other features directed at acquiring flow, pressure, and other downhole data. 
     The described ‘dual valve’ testing tool may be utilized in conjunction with temporary packer-based drill stem isolation. Thus, the tool may be delivered to a known downhole location, acquire relevant sampling information, and be moved to another location for repeating of the data acquisition process. 
     Given ever increasing well depths and other factors, the dual valve testing tool may be configured to operate as described without the use of heavy cabling. For example, valve actuation may be triggered by way of pressure pulse signaling from surface. Thus, the dual valve tool is often referred to as an ‘intelligent remote’ dual valve tool or “IRDV tool” with different pressure pulse signatures from surface signaling different valve opening and closing actuations. 
     Once more, power requirements for valve shifting and other actuations may be met by taking advantage of the natural differential pressure that exists between the downhole environment and the atmospheric pressure provided to the tool from the oilfield surface. In fact, even powering requirements for solenoid triggering of such actuations may be met by use of small scale piezo-material. As such, the overall IRDV tool footprint and testing deployment weight may be kept to a minimum. 
     Unfortunately, given the ever increasing well depths and the incomplete, largely uncontrolled, nature of the well at this stage of completions, the testing environment may be particularly challenging in terms of the high temperatures and differential pressures involved. For example, the hydraulic nature of the tool may result in hydrostatic pressure hydraulics (i.e. in communication with the downhole environment) that may be in excess of 30,000 PSI above the atmospheric pressure hydraulics (i.e. determined at the oilfield surface). 
     While the described differential certainly provides more than enough potential power for driving the noted actuations, the differential may be more than the hydraulics of the tool are able to maintain throughout testing operations. For example, the architectural layout of tool components may lead to thinner walled or less structurally sound regions of atmospheric pressure hydraulics. These locations may be susceptible to failure when faced with holding back such dramatically high pressures. Further, the failure rate may be exacerbated where similarly dramatic high temperatures are found downhole. 
     Ultimately, due to tool failure rates of IRDV tools in such high pressure incomplete wells, operators may elect to employ alternate, more cumbersome, modes of power and actuation. However, as a practical matter, IRDV tools as described are generally employed with failure resulting in significant cost and time delays associated with re-outfitting, positioning, and testing of various well locations. 
     SUMMARY 
     A downhole tool is provided which is configured for remote actuation in a well from an oilfield surface. The tool includes one chamber for exposure to downhole well pressure and another which is at about an atmospheric pressure found at the oilfield surface. An intermediate volumetric mechanism is provided which is in fluid communication with the chambers and configured to retain fluid pressure at a level that is between the different pressures of the chambers. This mechanism may be of a discrete intermediate pressure chamber or take the form of a hydraulic line system of the tool. Additionally, fluid pressure into the mechanism from the one chamber may be governed by a regulator thereof whereas fluid pressure release into the other chamber from the mechanism may be governed by a relief valve thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of an embodiment of a remote actuation testing tool of enhanced high pressure differential capacity. 
         FIG. 2  is a schematic representation of an embodiment of a hydraulic layout for the tool of  FIG. 1 . 
         FIG. 3A  is a schematic representation of alternate embodiment of a hydraulic layout for the tool of  FIG. 1  upon male solenoid valve firing. 
         FIG. 3B  is a schematic representation of the alternate embodiment of  FIG. 3A  upon female solenoid firing. 
         FIG. 4A  is a schematic representation of the testing tool of  FIG. 1  revealing an embodiment of internal gun-drill hydraulics between different tool segments. 
         FIG. 4B  is a schematic representation of prior art internal gun drill hydraulics in contrast to that of  FIG. 4A . 
         FIG. 5  is an overview of an oilfield accommodating a well and the testing tool of  FIG. 1  disposed therein. 
         FIG. 6  is a schematic representation of an alternate embodiment of a pilot valve for use with the hydraulic layout of  FIGS. 3A and 3B . 
         FIG. 7  is a flow-chart summarizing an embodiment of utilizing a remote actuation testing tool of enhanced high pressure differential capacity in a well. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments are described with reference to certain tool enhancements for a remote actuation testing tool (i.e. IRDV tool). More specifically, enhancements are directed at improving durability of tool segments upon exposure to harsh high pressure downhole environments. Along these lines, tool embodiments are provided with unique pressure accommodating hydraulics, reduced gun-drill hydraulics, an improved pilot valve and other durability enhancing features. Regardless, embodiments of testing tools detailed herein may include an intermediate volumetric mechanism configured to retain an intermediate pressure in a manner so as to reduce the degree of differential pressure at the interface of atmospheric and hydrostatic chambers of the tool. 
     Referring now to  FIG. 1 , a front view of an embodiment of a remote actuation testing tool  100  is depicted. The tool  100  is of enhanced durability, particularly in terms of high pressure differential capacity. So, for example, the tool  100  is outfitted with circulating  130  and testing  145  valve segments. These segments  130 ,  145  are actuated via power drawn from an inherent differential that exists between atmospheric  175  and hydrostatic  115  chambers of the tool  100 . 
     However, with added reference to  FIG. 2 , an intermediate volumetric mechanism  200  may be provided so as to accommodate a certain degree of pressure and reduce the overall differential imparted on weak hydraulic tool components. As a result, hydraulic failure due to extreme differential at this location may be reduced. So for example, in one embodiment, downhole pressure might dictate an overall differential of about 35,000 PSI relative the tool  100 . Nevertheless, the amount of differential actually directed at associated components, relative the volumetric mechanism  200 , may be held to between about 10,000 PSI and 25,000 PSI (depending on regulator  225  and relief valve  275  settings as detailed further herein). 
     Continuing with reference to  FIG. 1 , the testing tool  100  is also equipped with a hydraulic sub  160  as well as an electronics housing  190 . The sub  160  may be a conventional hydraulic sub  160  for downhole use. However, in an embodiment where the testing valve  145  is located adjacent the sub  160  such may also be configured to accommodate solenoid wiring and other features of the valve  145  as needed. Similarly, the housing  190  may be a conventional electronics housing and may even provide an added degree of processing and/or battery capacity to the tool  100 . Indeed, apart from circulating or testing applications of the tool  100 , other downhole applications and tools may be provided for added downhole operations which may benefit from the added processing and/or power availability. For example, note the packer  575  and perforating gun  560  of  FIG. 5 . 
     Referring more specifically now to  FIG. 2 , a schematic representation of an embodiment of a hydraulic layout is depicted for the tool  100  of  FIG. 1 . The schematic represents a simplified version of the hydraulic relationship between the hydrostatic chamber  115  and the atmospheric chamber  175  in one embodiment. More specifically, as alluded to above and detailed below, a volumetric mechanism  200  is disposed between these chambers  115 ,  175  which serves to minimize the amount of pressure that structurally weaker hydraulic components are exposed to between actuations. Thus, the differential pressure rating of the overall tool  100  of  FIG. 1  may be significantly increased. 
     Continuing with reference to  FIG. 2 , with added reference to  FIGS. 1 and 5 , the noted actuations of the circulating  130  or testing  145  valve segments are driven by the available pressure differential that is inherently present between the chambers  115 ,  175 . More specifically, the hydrostatic chamber  115  is openly exposed to an annular space  210  and downhole pressures of a well  580  in which the tool  100  is located. By contrast, however, the atmospheric chamber  175  is of a surface-based pressure (e.g. atmospheric pressure of below about 200 PSI) that is set in an isolated fashion at the oilfield surface  500  before deployment of the tool  100  into the well  580 . Thus, depending on the depth of the well  580  and other characteristics, a pressure differential in the tens of thousands PSI may be available between the chambers  115 ,  175 . 
     With added reference to  FIGS. 1 and 3 , the noted differential may be employed in conjunction with triggers such as solenoids (e.g.  330 ,  340 ) to controllably allow pressure breaches between the chambers  115 ,  175 . Such controlled breaches may then be used to hydraulically drive a power piston  325  which in turn drives actuations of the circulating  130  and testing  145  valve segments. Thus, an available pressure differential, as opposed to more cumbersome power delivery, may be utilized in driving the primary valve functions of the testing tool  100 . 
     However, unlike a conventional testing tool, the embodiment of  FIGS. 2  (and  3 A,  3 B), are outfitted with a volumetric mechanism  200  so as to ensure pressure breaches of the atmospheric chamber  175  are limited to those actually controllably triggered as noted above. More specifically, the volumetric mechanism  200  is provided so as to retain an intermediate pressure in fluid communication with the atmospheric chamber  175 . Thus, between actuations, associated tool components need not hold back the full pressure differential in order to prevent fluid leakage and hydraulic failure of the tool  100 . In a practical sense, this means that and structurally weaker hydraulic components linked to the mechanism  200 , may be required to effectively hold back substantially less than the overall differential. Depending on the overall tool layout, this may be particularly beneficial where more likely, other hydraulic components linked to the mechanism  200  are constructed of minimal wall thicknesses or face other pressure related design challenges. 
     Continuing with reference to  FIG. 2 , the volumetric mechanism  200  is made up of a discrete intermediate pressure chamber  201  for holding an intermediate pressure as governed by a regulator  225  and a relief valve  275 . More specifically, the regulator  225  is in fluid communication with the hydrostatic chamber  225  and hydraulic lines  250  running to the intermediate pressure chamber  201  so as to govern fluid pressure into the mechanism  200 . In an embodiment where the mechanism  200  is initially at atmospheric pressure, the regulator  225  may face the full differential pressure from the well annulus  210 . Regardless, the relief valve  275 , which is in fluid communication with the atmospheric chamber  175  via the lines  250 , need not hold back the full differential pressure, but rather only the intermediate pressure of the volumetric mechanism. Perhaps more importantly, as noted above, structurally weaker hydraulic tool components may be linked to the lines  250  and need not be exposed to the full differential. 
     In one embodiment, the regulator  225  and relief valve  275  settings result in an intermediate pressure in the mechanism  200  that is kept at a range of 10,000-25,000 PSI, even where the full differential may be in excess of 35,000 PSI. Thus, weaker hydraulic components are exposed to substantially less than the full differential. In other embodiments, alternative pressure ranges may be utilized which are below the full differential (and above atmospheric pressure). Indeed, the regulator  225  may be an adjustable mechanical regulator. Similarly, in alternative embodiments, mechanisms that utilize a hydraulic line system  300  as opposed to a discrete chamber  201  may serve to contain the intermediate pressure (see  FIGS. 3A and 3B ). 
     Referring now to  FIGS. 3A and 3B , schematic representations of an alternate hydraulic layout for the tool of  FIG. 1  are depicted. As noted above, in this embodiment, the discrete chamber  201  version of the volumetric mechanism  200  of  FIG. 2  is replaced with one that is provided in the form of a hydraulic line system  300 . Nevertheless, the hydrostatic chamber  115  is included and remains hydraulically linked to the atmospheric chamber  175  with governing regulator  225  and relief valve  275  disposed therebetween. Only, in the embodiment here, a hydraulic line system  300  accommodates the above noted intermediate pressure in the absence of any discrete chamber  201 . 
     With specific reference to  FIG. 3A , a male solenoid  330  is triggered via a signal  375  to hydraulically shift a power piston  325  which ultimately drives the valve actuations of the circulating  130  or testing  145  valve segments as described above. The solenoid  330  itself may be of piezoelectric or other low power capacity for effective response to such signaling without the requirement of any significant dedicated power source from surface or elsewhere (see U.S. application Ser. No. 12/505,340, incorporated by reference herein as noted above). Additionally, the solenoid  330  may be coupled to a sensor configured to detect pressure pulse or other suitable wireless signaling, for example as directed by a control unit  524  positioned at the oilfield  500  (see  FIG. 5 ). 
     Continuing with reference to  FIG. 3A , the hydraulic shift of the power piston  325  is managed through a pilot valve  350  as detailed further below. Regardless, the intermediate pressure line (i.e. the hydraulic line system  300 ) retains an intermediate pressure throughout this drive of the piston  325 . As noted, the intermediate pressure into the system  300  is initially governed by a regulator  225 . However, where appropriate, a rupture disk  380  of suitable high pressure setting may be provided so as to overcome the regulator  225  in certain circumstances. Whatever the case, other potentially weak hydraulic components coupled to the system  300  remain protected from exposure to the full pressure differential emanating from the hydrostatic chamber  115 . 
     The appreciated benefit of protection from exposure to the full pressure differential by certain hydraulics may be even more apparent with reference to  FIG. 3B .  FIG. 3B  is a schematic representation of the same hydraulic layout of  FIG. 3A . However, in  FIG. 3B , the depiction is of the female solenoid  340  firing. That is, again a signal  375  is employed to direct a solenoid  340  to ultimately drive the piston  325 , this time in the opposite direction. Thereby, another actuation of the circulating  130  and/or testing  145  valve may be achieved. The driving of the piston  325  in this manner is again managed through the pilot valve  350  while retaining an intermediate pressure through the hydraulic line system  300 . 
     In the view of  FIG. 3B , the more direct relationship between the female solenoid  340  and the atmospheric chamber  175 , both at the same hydraulic side of the regulator  225  clearly illustrates the benefit of the intermediate pressure in the system  300 . Such pressure may overcome the relief valve  275  into the atmospheric chamber  175  as necessary. This intermediate pressure may even be utilized in return lines  360  to the male regulator  330  or back through the pilot valve  350  and over to driving of the piston  325  in the opposite direction as described. However, throughout such hydraulic routing an intermediate pressure, substantially below the full differential, is provided. As such, weaker hydraulic components or regions of the tool  100  may be hydraulically coupled for functionality without concern over failure due to inability to hold excessive pressure. 
     Referring now to  FIGS. 4A and 4B  another manner of enhancing hydraulic capacity of the tool  100  is depicted. With focus on  FIG. 4A , a schematic representation of an embodiment of the testing tool  100  is shown employing a particular arrangement of tool segments  115 ,  130 ,  145 ,  160 ,  175 ,  190 . More specifically, this arrangement is of a configuration that reduces overall gun-drill hydraulics  415 ,  430 ,  445 ,  475 ,  490  by way of contrast to a more conventional prior art arrangement as depicted in  FIG. 4B . 
     Continuing with reference to  FIG. 4A , the hydraulic sub  160  is central to the arrangement given that, just as with a conventional embodiment of  FIG. 4B , each of the other segments  115 ,  130 ,  145 ,  175 ,  190  is configured for hydraulic linkage to the sub  160 . Therefore, given that any increase in gun-drill hydraulics  415 ,  430 ,  445 ,  475 ,  490  is accompanied by an increase in costly machining and potential seal failure,  FIG. 4A  reveals an embodiment whereby segment rearrangement may be employed to reduce overall gun-drill hydraulics  415 ,  430 ,  445 ,  475 ,  490 . More specifically, excluding the electronic housing  190 , by positioning the hydrostatic chamber  115  and the atmospheric chamber  175  to the far ends of the tool  100 , the overall footprint of the gun-drill hydraulics  415 ,  430 ,  445 ,  475 ,  490  may be kept to a minimum. This is due to the fact that these chambers  115 ,  175  require no direct hydraulic interface with one another. 
     Further, the circulating  130  and testing  145  valve segments may be disposed between the sub  160  and the hydrostatic chamber  115  which ultimately drives their actuation as described above. Thus, the gun-drill line  401  between these segments  130 ,  145  as shown in  FIG. 4B  may be eliminated. That is, due to the outermost positioning of the hydrostatic chamber  115  as shown in  FIG. 4A , the hydraulic coupling between the valve segments  130 ,  145  may be leverage off of the same gun-drill line  415  which links the hydrostatic chamber  115  over to the sub  160 . 
     All in all, given that each tool segment  115 ,  130 ,  145 ,  160 ,  175 ,  190  may be of between about 4 and 6 feet long, the amount of gun-drill line reduction may be quite significant. That is, when contrasting the prior art arrangement of  FIG. 4B , note that most gun-drill lines  415 ,  430 ,  445  are reduced by at least one segment length and that another  401  is eliminated altogether in the arrangement of  FIG. 4A . Thus, in terms of hydraulics, construction costs, service time, and failure risks are all substantially reduced whereas the overall reliability of the tool  100  is enhanced. 
     Referring now to  FIG. 5 , an overview of an oilfield  500  is depicted which accommodates a well  580  having an embodiment of the remote actuation testing tool  100  of  FIG. 1  disposed therein. More specifically, the tool  100  is shown deployed across various formation layers  590 ,  595  of the well  580  via pipe  550 . Once more, a conventional packer  575  and perforation gun  560  are coupled to the tool  100  as part of a larger overall bottom hole assembly. So for example, the packer  575  may be deployed for isolation at a casing  585  defining the well  580  followed by a perforation application with the gun  560  for forming perforations  597 . 
     Of course, the testing tool  100  may be employed in absence of a packer  575  or with a variety of interventional or sampling tools other than a perforating gun  560 . Indeed, due to the nature of the testing tool  100  may be utilized in advance of any casing installation or in conjunction with less interventional tools such as a conventional tail pipe and sensor assembly for positioning below the packer  575 . Further, conveyance may be by alternate form of tubular or well access line. 
     Continuing with reference to  FIG. 5 , the testing tool  110  operates as detailed above. That is, a signal may be sent downhole through the annular space  210  via pressure pulse signature from a control unit  524  positioned at the oilfield  500 . Thus, circulating  130  or testing  145  valve segments of the tool  100  may be actuated. Additionally, as noted above, the actuation itself may be powered by the pressure differential presented by the hydrostatic chamber  115  and its exposure to the annular space  210  at the depicted location (see  FIG. 1 ). However, unlike a conventional testing tool, certain weaker hydraulic features of the tool  100  are spared exposure to the full measure of the differential pressure due to the incorporation of an intermediate pressure containing volumetric mechanism  200  (see  FIG. 2 ). 
       FIG. 5  depicts a host of surface equipment  520  located at the oilfield  500  including a conventional rig  522 , well head  526  and recovery line  528 . However, it is the noted control unit  524  which may be employed to direct the actuations of the testing tool  100  as described herein. Indeed, communications from the control unit  524  may be utilized to direct other applications such as perforating or sampling, perhaps even with added support from the electronic housing  190  of the tool  100 . 
     Referring now to  FIG. 6 , yet another manner of enhancing hydraulic capacity of the remote actuation testing tool  100  of  FIG. 1  is depicted. More specifically, an alternate embodiment of the pilot valve  350  of  FIGS. 3A and 3B  is shown. Namely, the more unitary pilot valve  350  of  FIGS. 3A and 3B  is replaced with one that is segmented into a normally open valve  650  and a normally closed valve  651  with a flow restrictor  660  and check valves  675  disposed therebetween at a hydraulic control circuit. As a result, the separate valve segments  650 ,  651  and circuit portions may be separately installed relative the tool  100  of  FIG. 1 . Thus, added flexibility may be afforded in terms of pilot valve design packages that may be outfitted on the tool. 
     In the embodiment of  FIG. 6 , the pilot valve segments  650 ,  651  utilize metal to metal sealing by way of conventional O-rings  680  so as to provide more robust hydraulics for a high pressure differential and temperature environment. That is, elastomer seals subject to wear and failure in such environments have been replaced with the O-rings  680 . 
     During operation of the pilot valve  350 , the valve segments  650 ,  651  function in a manner so as to prevent excessive fluid losses from the high pressure line  625  to the low pressure line  630 . Thus, the total number of actuation cycles available to the tool  100  may be increased (see  FIG. 1 ). This is achieved through use of the hydraulic control circuit with its check valves  675  and flow restrictor  660 . More specifically, these features ensure a sequential operation of the valve segments  650 ,  651  which assures avoidance of excessive fluid loss as noted above. 
     As with the embodiment of  FIGS. 3A and 3B , the overall pilot valve  350  of  FIG. 6  functions to amplify high pressure flow input (i.e. from the high pressure line  625 ). when the input pressure is higher (with a reduction in flow), the output of the valve  350  may be commensurately raised to provide a larger amount of flow. 
     Continuing with reference to  FIG. 6 , achieving the proper sequential operation of the valve segments  650 ,  651  so as to avoid excess fluid loss is detailed further. Namely, the segments are shown in their normally open  650  and normally closed  651  positions. At this time, the output pressure line  645  is of a comparatively low pressure. However, as the pressure increases at the  640 , fluid will flow through the check valve  675  adjacent the normally open valve  650  but be unable to traverse the other check valve  675  adjacent the normally closed valve  651 . As a result, the fluid will shift the normally open valve  650  (to the left in the depiction of  FIG. 6 ) and allow fluid flow through the flow restrictor  660 , eventually shifting open the normally closed valve  651 . As a result, fluid loss directly from the high pressure lines  625  to the low pressure line  630  is avoided. Further, the opening of the normally closed valve  651  allows a large amount of high pressure fluid through to the output pressure line  645 . 
     Lastly, as the pressure at the input line  640  is reduced fluid will initially flow through the check valve  675  adjacent the normally closed valve  651 , but remain unable to go through the other check valve  675  adjacent the normally open valve  650 . As a result, the normally closed valve  651  will be returned to its closed position (as depicted in  FIG. 6 ). The fluid then proceeds through the flow restrictor  660  and returns the normally open valve  650  to its open position (again, as depicted in  FIG. 6 ). As a result of such sequential operation fluid losses from the high pressure lines  625  are minimized as indicated. 
     Referring now to  FIG. 7 , a flow-chart summarizing an embodiment of utilizing a remote actuation testing tool of enhanced high pressure differential capacity is shown. The tool may be positioned at an oilfield where the atmospheric chamber is provided with a surface-based pressure (see  705 ,  720 ). That is, an atmospheric pressure of between about 0-200 PSI may be supplied. Although, in one embodiment, the chamber may actually be pressurized above 200 PSI, for example, with inert nitrogen. Nevertheless, the pressure in the atmospheric chamber would be considered ‘surface-based’ and below pressures of the well as described below. 
     As indicated at  735  and  750 , the tool may then be deployed into the well with a hydrostatic chamber exposed to the noted well pressure. Further, once reaching the target location, an actuation signal may be transmitted from surface as noted at  765 . This signal may be trigger valve actuation of the testing tool as indicated at  795 . However, such takes place in conjunction with the establishing of an intermediate pressure within a volumetric mechanism of the tool (see  780 ). Thus, weaker hydraulic features of the tool may be exposed to an intermediate pressure of the mechanism as opposed to a potentially much larger pressure differential. 
     Embodiments detailed herein provide a testing tool that is able to utilize a downhole pressure differential for powering of valve actuations. However, in contrast to a conventional testing tool, tools of embodiments described herein are also equipped with the capacity to handle pressure differentials in excess of 35,000 PSI. Thus, valve failure may be substantially avoided in today&#39;s more common deeper, higher pressure and/or higher temperature well environments. As a result, time related costs associated with pressure related tool failure may be largely avoided along with the need for more cumbersome surface deployed power supply to the tool. 
     The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. This may include a variety of additional measures to enhance overall tool durability in light of excessively high pressure differential and/or temperatures of the downhole environment. For example, in one embodiment, the ball valve seat of the testing valve segment of the tool may be of a high strength polyether ether ketone (PEEK) as opposed to a more conventional polytetrafluoroethylene. Thus, the reliability of the valve in holding off excessive differential pressure at the ball-seat interface may be enhanced. Similarly, the atmospheric chamber or volumetric mechanism may be pre-charged with pressures above an atmospheric level so as to reduce the overall differential downhole (e.g. nitrogen may be utilized for such purposes). Along such lines, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.