Patent Publication Number: US-2022213766-A1

Title: Non-explosive casing perforating devices and methods

Description:
BACKGROUND 
     Technical Field 
     Embodiments of the subject matter disclosed herein generally relate to a system and method for perforating the casing of a well, and more particularly, to a system that is capable of making perforations into a casing without using an explosive material. 
     Discussion of the Background 
     In the oil and gas field, once a well is drilled to a desired depth relative to the surface, and the casing protecting the wellbore has been installed and cemented in place, it is time to connect the wellbore to the subterranean formation to extract the oil and/or gas. This process of connecting the wellbore to the subterranean formation may include a step of plugging a previously fractured stage of the well with a plug, a step of perforating a portion of the casing, which corresponds to a new stage, with a perforating gun string such that various channels are formed to connect the subterranean formation to the inside of the casing, a step of removing the perforating gun string, and a step of fracturing the various channels of the new stage. These steps are repeated until all the stages of the formation are fractured. 
     During the perforating step for a given stage, one or more perforating guns of the perforating gun string are used to create perforation clusters in the multistage well. Clusters are typically spaced along the length of a stage (a portion of the casing that is separated with plugs from the other portions of the casing), and each cluster comprises multiple perforations (or holes). Each cluster is intended to function as a point of contact between the wellbore and the formation. Each perforation is made by a corresponding shaped charge, which is located inside the housing of the perforating gun. The shaped charge includes an explosive material which when ignited, melts a lining of the shaped charge and generates a travelling melted jet. The travelling melted jet is projected outward from the shaped charge, to make a perforation into the housing of the perforating gun and then a perforation into the casing of the well, to establish the fluid communication between the oil formation outside the well and the bore of the casing. 
     After each stage is perforated, a slurry of proppant (sand) and liquid (water) is pumped into the stage at high rates and then, through the perforation holes, into the formation, with the intent of hydraulically fracturing the formation to increase the contact area between that stage and the formation. A typical design goal is for each of the clusters to take a proportional share of the slurry volume, and to generate effective fractures, or contact points, with the formation, so that the well produces a consistent amount of oil, cluster to cluster and stage to stage. 
     However, the current methods of creating the perforations (casing holes) with explosives raise issues of safety, regulatory aspects, and require high equipment costs. Mechanical means of punching a hole in the casing exist, but these approaches are slow because they require power from the surface. Thus, there is a need for a new system for making perforations into the casing without using explosives or power from the surface, but also being fast enough for the well applications. 
     BRIEF SUMMARY OF THE INVENTION 
     According to an embodiment, there is a non-explosive punch system for making perforations in a casing. The non-explosive punch system includes a housing extending along a longitudinal axis and configured to be deployed in a well, one or more punch elements configured to extend through a wall of the housing to perforate a casing of the well, an actuating device located within the housing and configured to actuate the one or more punch elements, and an energy supply device located within the housing and configured to use a pressure of a well fluid present in the casing, to actuate the actuating device. There is no explosive material within the housing. 
     According to another embodiment, there is a method for manufacturing a non-explosive punch system for making perforations in a casing. The method includes providing a housing extending along a longitudinal axis and configured to be deployed in a well, adding one or more punch elements to the housing, wherein the one or more punch elements are configured to extend through a wall of the housing to perforate a casing of the well, installing an actuating device within the housing, the actuating device being configured to actuate the one or more punch elements, and fluidly connecting an energy supply device to a well fluid present in the casing and to the actuating device, to actuate the actuating device. There is no explosive material in the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram of a non-explosive casing perforating device to be used in a well; 
         FIG. 2  illustrates a connecting mechanism between one or more punch elements and an actuating block of the non-explosive casing perforating device; 
         FIGS. 3A and 3B  illustrate various shapes of the actuating block of the non-explosive casing perforating device; 
         FIG. 4  is a schematic diagram of a controller of the non-explosive casing perforating device; 
         FIG. 5  is a flow chart of a method of perforating a casing in a well with the non-explosive casing perforating device; 
         FIG. 6  illustrates the non-explosive casing perforating device in a punching state; 
         FIG. 7  illustrates the non-explosive casing perforating device having an oil moving mechanism for removing the oil from an air chamber and returning it to the oil chamber; 
         FIG. 8  illustrates another implementation of the non-explosive casing perforating device; 
         FIG. 9  illustrates the non-explosive casing perforating device being deployed in the well; and 
         FIG. 10  is a flow chart of a method for manufacturing the non-explosive casing perforating device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to a single punch system that is used in a well for perforating the casing by not using energy from the surface. However, the embodiments to be discussed next are not limited to a single punch system, but may be applied to plural punch assemblies that are attached to each other. 
     Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments. 
     According to an embodiment, a punch system uses exclusively a hydrostatic pressure present in the well for making perforations into the casing of the well. The punch system has a housing that hosts one or more punch elements configured to perforate the casing of a well. The one or more punch elements are actuated by an actuating device. The actuating device is supplied with energy for actuation by an energy supply device. The energy supply device harness the energy associated with the pressure of the well fluid in the casing and uses this energy to actuate the actuating device. No explosive charges and no power from the surface are used to actuate the punch element or to make the perforations. 
     More specifically, as shown in  FIG. 1 , the punch system  100  is attached to a wireline  102  and lowered to a desired depth in a well  104  that is lined with a casing  106  (e.g., steel casing). The casing is surrounded by one or more formations  108  that might contain oil and gas. Perforations need to be made in the casing  106  to fluidly connect the formations  108  to the bore of the casing. The well  104  is filed with a well fluid  110 , which due to the depth of the punch system, e.g., about 1.5 km or more, creates a hydrostatic pressure in excess of about 4,000 psi, which is enough for actuating the punch system  100 . 
     To take advantage of this hydrostatic pressure P, a housing  112  of the punch system  100  hosts multiple devices that work together to generate a force that is used to puncture the casing. More specifically, the housing  112  hosts an energy supply device  118 , an actuating device  140 , and one or more punch elements  162 . The energy supply device  118  transforms the hydrostatic pressure of the well fluid into a force that is supplied to the actuating device  140 . The energy supply device  118  includes multiple chambers, for storing the well fluid  110 , oil  114 , and air  116 . More specifically, the energy supply device  118  includes a hydrostatic chamber  120  that communicates through a passage  122  with the bore of the casing  106  so that the well fluid  110  can freely enter inside the hydrostatic chamber  120 . The hydrostatic chamber  120  is separated from an oil chamber  126  by a floating piston  128 . The floating piston  128  may include seals  129  to prevent the well fluid mixing with the oil and vice-versa. Note that the hydraulic chamber  120  has no other port for communicating with the ambient, except for the passage  122 . The oil chamber  126  also has a single oil communication passage  132 , extending through a wall of the casing  112 . The oil passage  132  extends through a wall of the housing, from the oil chamber  126  to a valve assembly  134 . The valve assembly  134 , which is also part of the energy supply device  118 , may include one 4-ways valve, or two 3-ways valves or four 2-ways valves or any other combination of valves. In one embodiment, the valve assembly includes solenoid valves. The valve assembly  134  schematically shows in  FIG. 1  the two different states, that correspond to four possible paths for the various fluids in the punch system. The two states of the valve assembly  134  include a retracting state, which is characterized by fluid paths  134 - 1  and  134 - 2 , and a punching state, which is characterized by fluid paths  134 - 3  and  134 - 4 . These arrows are discussed in more detail later. 
     The energy supply device  118  further includes an air chamber  136 , which is configured to initially hold the air  116  at atmospheric pressure. However, as the punch system  100  makes perforations into the casing, oil is slowly directed into the bottom of the air chamber  136 , as schematically indicated in  FIG. 1 . When the amount of oil  114  becomes too high, the punch system needs to be recharged, as discussed later. Note that when the punch system  100  is initially lowered into the well, the air  116  in the air chamber  136  is at atmospheric pressure. The air chamber  136  has a corresponding air communication passage  138  that communicates with the valve assembly  134 . The oil passage  132  and the air passage  138  are connected on the same side of the valve assembly  134 , to corresponding first and second ports, i.e., when one passage is activated, the other passage is also activated. In other words, the two passages are simultaneously activated by the valve assembly  134 . 
     On the other side of the valve assembly  134 , there are two other communication passages that fluidly communicate corresponding third and fourth ports with the actuating device  140 . A first communication passage  139  fluidly connects the third port of the valve assembly  134  to a first chamber  144  of a double action enclosure  146  (which is part of the actuating device  140 ), and a second communication passage  142  fluidly connects the fourth port of the valve assembly  134  to a second chamber  148  of the double action enclosure  146 . The first chamber  144  is separated from the second chamber  148  by a double action piston  150 . Seals  129  are provided around the double action piston  150  for preventing a fluid to move from the first chamber to the second chamber or vice versa. After the punch system  100  is used in the well, both the first and second chambers  144  and  148  include oil  114 . The double action piston may be replaced with 2 pistons opposing each other. 
     The double action piston  150 , which is part of the actuating device  140 , is connected to an actuator block  152  (e.g., a wedge-shaped block, but other more complex shapes may be used) through a rod  154 . The rod  154  extends through the second chamber  148  and enters into an actuation chamber  160 , which is also part of the actuating device  140 , where it is connected to the actuator block  152 . Seals  129  are provided around the rod  154  for preventing the oil  114  from the second chamber to mix with the well fluid  110  that is present inside the actuation chamber  160 . The actuator block  152  may contact one or more punch elements  162  that extend through a wall  113  of the housing  112 , from the interior of the actuation chamber  160 , into the bore of the casing  106 , as illustrated in  FIG. 1 . Note that the punch elements  162  are not sealed against the wall of the housing  112  and thus, the well fluid  110  from outside the punch system  100  can freely enter inside the actuation chamber  160 . Further, the punch elements  162  have a first distal end  162 A, that is configured to make a perforation into the casing  106 , when actuated by the actuation block  152 . In one application, the distal end  162 A may be shaped as a blade, needle, cone, etc. The proximal end  162 B may be shaped to match a profile of the actuator block  152 , as schematically illustrated in the figure. In one embodiment, as illustrated in  FIG. 2 , the proximal end  162 B is mechanically and slidably attached to the actuator block  152 . 
     More specifically,  FIG. 2  shows a groove  153  formed in the body of the actuator block  152  and the groove extends along a length direction of the block. The punch element  162  has a pointy distal end  162 A while the proximal end  162 B is shaped to fit inside the groove  153  and be locked there. The groove  153  is shaped to hold the proximal end  162 B inside while the actuator block  152  moves along a length of the housing  112 , i.e., the longitudinal axis X in  FIG. 1 . Note that this arrangement allows the punch element  162  to move perpendicular to the casing  106  while also sliding along the actuator block  152 , but at the same time this arrangement forces the punch element  162  to perforate the casing  106  when the actuator block  152  is moving away from the head of the well. In this way, a downstream movement (i.e., toward the tail of the well) by the actuator block forces the punch element  162  to move toward the casing  106  to puncture it (the punching state), and an upstream movement (i.e., toward the head of the well) of the actuating block  152  retrieves the punch element  162  to its original position, i.e., mainly inside the housing  112  (the retrieved state). In one application, the groove  153  may be replaced with another connecting mechanism, for example, a spring or similar device. In one application, the punch element is fully within the housing  112  in the retrieved state. Any number of punching elements may be provided in the actuation chamber  160 . The punching elements may be angularly distributed around the actuator block  152 , with 60-, 90-, 120- or 180-degrees angle separation. The actuator block  152  may be round, as shown in  FIG. 3A , or may have multiple stages as illustrated in  FIG. 3B , for being able to actuate various layers of punch elements  162 ,  162 ′, and  162 ″. Those skilled in the art would understand that any number of punch elements may be used. 
     Returning to  FIG. 1 , the punch system  100  may have only the chambers shown, or, may have a plurality of these chambers, i.e., the structure shown in  FIG. 1  may be repeated, in series, to have a multiple-stage system, with each system being hydraulically activated independent of the other stages, and with each stage being able to puncture the casing of the well independent of the other stages. An end of the casing  112  of the punch system  100  may be closed or not. A plug setting tool  170  is schematically illustrated in the figure as being attached to the end of the punch system. The setting tool  170  may be connected to a setting plug (not shown). Although  FIG. 1  shows the punch system  100  being connected to the wireline  102 , in one embodiment, this connection may be removed so that the punch system is autonomous. In this case, a local controller  180  may include, as schematically indicated in  FIG. 4 , a processor  402 , a memory  404 , a power source  406  (for example, a battery), a pressure sensor  408  or other similar sensors, and communication means (for example, an acoustic modem)  410  for communicating with a general controller (not shown) located at the surface. The pressure sensor  408  may be used to determine a depth of the punch system, and the processor may run a software stored in the memory, to activate the valve assembly  134 , and thus, the actuator block  152  when the desired depth is reached. In one application, the processor  402  is configured to control the valve assembly  134 , so that the punching state or the retrieved state is selected. For this case, the punch system  100  moves independently towards the tail of the well, due to the gravity, or, if in a horizontal well, the well may be pumped to move the punch system to the desired depth. The punch system may be brought to the surface with a fishing tool, or with a simple cable that is attached to the housing  112 . However, this cable does not have any electrical or hydraulic capabilities. 
     A method for using the punch system  100  is now discussed with regard to  FIG. 5 . In step  500 , the punch system  100  is prepared for being lowered into the well. This step includes filling the oil chamber  126  with oil, for example, through a filing port  127  and placing the valve assembly  134  in the retrieved state. Also, the air chamber  136  is filed with air at atmospheric pressure and any oil present in this chamber is removed trough a port  137 . In one application, an external pump is connected between the two ports  127  and  137  to transfer all the oil from the air chamber back to the oil chamber. If the punch system is launched into the well with a wireline, the wireline is attached to its housing. Next, in step  502 , the punch system  100  is released into the well and allowed to move to the desired depth. The desired depth may be determined either by measuring the metered wireline or by using a sensor (e.g., pressure sensor  408 ) for calculating the depth. Once the desired depth is reached, the setting tool is instructed, through the wireline, or by the processor  402  if the punch system is autonomous, to deploy in step  504  the associated plug, to seal a stage from a previous stage. Then, in step  506 , the punch system moves to a certain distance from the plug and the processor  402  instructs the valve assembly  134  to switch from the retrieved state to the punching state, to perforate the casing. The valve assembly  134  is shown in  FIG. 1  being in the retrieved state, i.e., the oil  114  from the oil chamber  126  is directed to the second chamber  148  to push the double action piston  150  upstream, to decrease a volume of the first chamber  144  and increase a volume of the second chamber  148 . 
     When the valve assembly  134  is moved to the punching state, i.e., during the perforation step  508 , as shown in  FIG. 6 , the oil from the oil chamber  126  moves under the pressure of the well fluid  110 , exerted through the floating piston  128 , along the oil passage  132  and through the path  134 - 4  into the first chamber  144  of the double action enclosure  146 . This means that the high hydrostatic pressure P exerted by the well fluid  110  is transferred to the top of the double action piston  150 . As the piston  150  starts moving downstream, the oil present in the second chamber  148  of the double action enclosure  146  moves through the channel  142 , path  143 - 3 , and channel  138  into the air chamber  136 . Note that as the air  116  in the air chamber  136  is at atmospheric pressure and the oil  114  in the first chamber is at the high hydraulic pressure of about 4000 psi, the double action piston  150  starts moving downstream, so that the actuating block  152  starts to push away the punch elements  162 . As the pressure difference between the air in the air chamber and the well fluid is large, and this pressure is carried by the oil on top of the double action piston  150 , there is a large force exerted by the actuator block  152  onto the punch elements  162 , so that their pointy heads  162 A are able to perforate the casing  106  as shown in  FIG. 6 , and form corresponding perforations  164 . 
     Next, the double action piston  152  is retrieved in step  510 , to prepare the punch system for a next perforation. This means that in step  510  the processor  402  instructs the valve assembly  134  to return to the retrieved state shown in  FIG. 1 , so that the oil under pressure from the oil chamber  120  enters now through the path  134 - 1  and passage  142  into the second chamber  148 , and pushes the double action piston  150  in an upstream direction, to increase the volume of the second chamber  148  and to decrease the volume of the first chamber  144 . The oil from the first chamber  144  is now squeezed through the passage  139 , path  134 - 2  and the passage  138  into the air chamber  136 . This means that the punch system may be used multiple times, as long as the oil that enters into the first chamber  144  in step  506  can be discharged into the air chamber  136  during the step  510 . This also means that a large oil chamber  120 , a large air chamber  126 , and a smaller first chamber  144  would determine how many times the punch system may be used before it needs to be taken up to the surface, to remove the oil from the air chamber and refill the oil chamber. In one embodiment, as illustrated in  FIG. 7 , a conduit  710  may connect the port  127  in the oil chamber  120  to the port  137  in the air chamber  136 , and a pump  712  may be located within the housing  110 , so that the pump  712  pumps the oil from the air chamber back into the oil chamber while the punch system is deployed inside the well. In this way, there is no need to take the punch system back to the surface for recharging it and thus, the casing punching may continue for as long as necessary. The pump  712  may be feed with electrical power through the wireline  102 , or, if the punch system is autonomous, from the power source  406 . 
     After each punch is made in the casing, a volume of oil effectively moves from the oil chamber into the air chamber. The amount of oil depends on the piston  150 &#39;s area and its stroke. The volumes of the air chamber and oil chamber are selected to be large enough so that many holes (e.g., 30+) can be punched in a single run of the punch system. Since a plug is installed at the bottom of each stage, there is an optimum number of holes to be punched per stage. This system is designed to supply at least this many holes per run. As the oil enters the air chamber, the air pressure increases. The air chamber needs to have a large enough volume so that the air pressure increase is not significant. After all of the holes are punched for a given stage, the punch system may be removed, i.e., drawn uphole by the wireline. The punctured stage may be frac-ed while the punch system is being reset for another run. This consists of moving the floating piston to its initial position and moving the oil from the air chamber into the oil chamber. Also, another plug is attached to the bottom of the assembly. At the surface, an external pump can be connected to the external ports  127  and  137  to drain the oil out of the air chamber, and return it to the oil chamber. The oil moving into the oil chamber would automatically move the floating piston  128  to its initial position. The number of holes that can be punched in each run is controlled by the volume of these chambers. 
     Returning to  FIG. 5 , after the double action piston  150  has been retrieved in step  510 , the processor  402  or the operator of the system checks in step  512  whether more perforations are necessary to be performed. If the answer is yes, then the process returns to step  506 , to move the punch system to a new location and form new perforations. If the answer is no, then the process stops and the punch system is returned to the surface. 
     In a different embodiment, as illustrated in  FIG. 8 , a punch system  800  is configured to work without the oil chamber  126  and the floating piston  128 . More specifically, the air chamber  136  is located at the top of the housing  112  and communicates through the passage  138  with a first port the valve assembly  134 . A well fluid communication passage  810  fluidly communicates the well fluid  110  in the bore of the casing  106 , with a second port of the valve assembly  134 . The valve assembly  134  is identical to the one illustrated in the embodiment of  FIG. 1  and thus, its description is omitted herein. However, it is noted that in the retracted state, the well fluid moves through the passage  810 , through the valve assembly  134 , and passage  142  and enters the second chamber  148  of the double action enclosure  146 , thus biasing the floating piston  150  to not activate the punch elements  162 . However, when the valve assembly  134  changes to the punching state, the well fluid from the casing enters through the passage  810  and the passage  139  into the first chamber  144  of the double action enclosure  146 , thus acting with a force on top of the double action piston  150 . The well fluid already present in the second chamber  148  is now pushed through the passage  142  into the air chamber  136 , thus allowing the piston  150  to move in the downstream direction. The movement of the piston  150  makes the actuation block  152  to also move downstream, and thus, to extend the punch elements  162  toward the casing  106  as in the embodiment shown in  FIG. 1 . As the pressure difference between the well fluid and the air in the air chamber is very large, the force exerted by the punch elements  162  onto the casing  106  is large enough to perforate the casing, similar to the embodiment illustrated in  FIG. 1 . Note that the connections between the punch elements  162  and the actuating block  152  are similar to those discussed above with regard to  FIG. 1 . 
     To prevent debris from the casing  106  to enter together with the well fluid  110  into the passage  810 , a screen  820  may be placed at the inlet of the passage  810 . All the features discussed above with regard to  FIG. 1  are also applicable for this embodiment. The punch system  800  may be used in a similar way as the punch system  100 , and thus, a method of using this punch system follows the method illustrated in  FIG. 5 . 
       FIG. 9  generically illustrates the main parts of the punch system  100 / 800 , i.e., the housing  112  that holds the energy supply device  118 , the actuating device  140 , and the one or more punch elements  162 . Note that the energy supply device  118  has a passage  122 / 810  that allows the well fluid  110  to freely enter inside the housing and inside the energy supply device  118 . The energy of this fluid is harnessed by the energy supply device to drive the one or more punch elements  162  to perforate the casing  106 . 
     A method for manufacturing a non-explosive punch system  100  for making perforations in a casing is now discussed with regard to  FIG. 10 . The method includes a step  1000  of providing a housing extending along a longitudinal axis and configured to be deployed in a well, a step  1002  of adding one or more punch elements to the housing, wherein the one or more punch elements are configured to extend through a wall of the housing to perforate a casing of the well, a step  1004  of installing an actuating device within the housing, the actuating device being configured to actuate the one or more punch elements, a step  1006  of fluidly connecting an energy supply device to a well fluid present in the casing and to the actuating device, to actuate the actuating device, where there is no explosive material. The energy supply device includes a hydrostatic chamber, an oil chamber and an air chamber, wherein the hydrostatic chamber is open to a bore of the casing and holds the well fluid, wherein the oil chamber stores oil and is separated from the hydrostatic chamber by a floating piston, and wherein a valve assembly is fluidly connected at a first port with the oil chamber and fluidly connected at a second port with the air chamber. 
     The disclosed embodiments provide a non-explosive casing perforation system that uses an existing hydrostatic pressure to punch holes into the casing. It should be understood that this description is not intended to limit the invention. On the contrary, the embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details. 
     Although the features and elements of the present embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein. 
     This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.