Patent Publication Number: US-2011056679-A1

Title: System and method for controlling actuation of downhole tools

Description:
BACKGROUND 
     In a variety of downhole applications, actuating devices are used to control the actuation of downhole tools, such as valves or packers. In some applications, pressure pulse tools are used to recognize unique pressure pulse signatures as commands to activate a given downhole tool. In other systems, rupture discs are used to selectively permit the flow of an actuating fluid upon application of sufficient pressure in a control line, in tubing or in a casing annulus. Once the rupture disc is ruptured, fluid under pressure is directed to the downhole tool to actuate the tool. 
     SUMMARY 
     In general, the present invention provides a system and methodology for controlling the actuation of a tool in a wellbore. The technique utilizes placement of a rupture pressure membrane in a flow path of fluid used to actuate the downhole tool. An energetic material is mounted proximate the rupture disc, and this energetic material may be selectively actuated or exploded. The resultant energy is enough to weaken the rupture disc sufficiently to rupture the pressure membrane, which enables flow of actuating fluid to the downhole tool. 
     Other or alternative features will become apparent from the following description, from the drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying drawings illustrate only the various implementations described herein and are not meant to limit the scope of various described technologies. The drawings are as follows: 
         FIG. 1  is a schematic view of a well system deployed in a wellbore in which the well system utilizes a small-scale system to selectively enable actuation of a downhole tool, according to an embodiment of the present invention; 
         FIG. 2  is a front view of a portion of a system designed to enable selective actuation of the downhole tool, according to an embodiment of the present invention; 
         FIG. 3  is a view similar to that of  FIG. 2  but showing additional features of the system designed to enable selective actuation, according to an embodiment of the present invention; 
         FIG. 4  is a view similar to that of  FIG. 3  but showing additional features of the system designed to enable selective actuation, according to an embodiment of the present invention; 
         FIG. 5  is a view similar to that of  FIG. 4  but showing additional features of the system designed to enable selective actuation, according to an embodiment of the present invention; 
         FIG. 6  is a cross-sectional view of one example of a rupture disc assembly that can be used to enable selective actuation, according to an embodiment of the present invention; 
         FIG. 7  is an end view of one example of the rupture disc assembly, according to an embodiment of the present invention; and 
         FIG. 8  is a cross-sectional view of another example of a rupture disc assembly that can be used to enable selective actuation of the downhole tool, according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. In the specification and appended claims: the terms “connect”, “connection”, “connected”, “in connection with”, “connecting”, “couple”, “coupled”, “coupled with”, and “coupling” are used to mean “in direct connection with” or “in connection with via another element”; and the term “set” is used to mean “one element” or “more than one element.” 
     The present invention generally relates to a system for controlling the actuation of downhole tools that are part of a well system. In a well system having one or more downhole tools actuated via fluid, e.g. hydraulic fluid, a flow control pressure membrane may be deployed in the actuating fluid flow path. The flow control pressure membrane may be selectively activated to open the fluid flow path that allows actuation of the desired downhole tool. The flow control pressure membrane may be activated via specific operator input and/or upon detection of predetermined well parameters. 
     In one embodiment, the flow control pressure membrane is designed with very small packaging to provide a pressure membrane that can be used to replace single shot tools. In some applications, micro electromechanical system technology is employed to facilitate the very small, economical packaging. Examples of the approach are described in greater detail below and are configured to provide consistent, reliable performance as well as low production cost. 
     Referring generally to  FIG. 1 , an example of a well system  20  is illustrated as deployed in a wellbore  22 , according to one embodiment of the present invention. The well system  20  comprises downhole equipment  24  that may be in the form of a downhole completion or other equipment. As illustrated, downhole equipment  24  comprises one or more downhole tools  26  that may be actuated by fluid, e.g. hydraulic fluid, delivered along a flow path  28 , or down tubing  30 , or in the annulus between tubing  30  and the casing lining the wellbore  22 . No separate control line is needed to control the pressure membrane in this invention. The flow path  28  may be routed, at least in part, along the interior of a control line. The downhole tool  26  illustrated in  FIG. 1  may comprise, for example, a downhole control valve or a packer. However, other types of downhole tools or devices also may be actuated via actuating fluid delivered along flow path  28 . 
     The configuration of well system  20  can vary substantially depending on the specific well application for which it is designed. Accordingly, the embodiment illustrated is simply an example to facilitate explanation of the present technique for controlling actuation of downhole tools. In the example illustrated, downhole equipment  24  is deployed into wellbore  22  via a conveyance  30 , such as production tubing, coiled tubing, cable, or other suitable conveyance. The wellbore  22  extends downwardly from a wellhead  32  positioned at a surface location  34  (either terrestrial or sub-sea). Additionally, an actuating fluid supply system  36  may be used to deliver pressurized fluid along flow path  28  to downhole tool  26 . However, the pressurized actuating fluid also may be supplied from other systems or from the natural pressure within wellbore  22  at depth. Furthermore, well system  20  may be employed in wellbores  22  that are generally vertical and/or in wellbores that are deviated, e.g. horizontal. 
     The fluid that flows along flow path  28  to downhole tool  26  is selectively controlled via a control device  38  having a small, economical package size. The control device  38  may comprise a pressure membrane  40  that initially blocks the flow of actuation fluid along flow path  28 . For example, flow control pressure membrane  40  may span flow path  28  to block flow of hydraulic fluid or other actuation fluid along flow path  28  until actuation of downhole tool  26  is desired. 
     Referring generally to  FIG. 2 , one embodiment of flow control device  38  is illustrated. In this embodiment, flow control device  38  is illustrated as comprising pressure membrane  40  which, in turn, may comprise a material  42  capable of being selectively ruptured to enable flow along flow path  28  to downhole tool  26  for actuation of the tool. The material  42  may be a membrane or other suitable material formed, for example, as a disc for placement across flow path  28 . According to one embodiment, material  42  is formed as a pressure membrane made from nickel alloy metal or other material that is chemically inert to downhole fluids and temperatures. In this example, the membrane is capable of sealing between downhole pressure and an atmospheric or low-pressure chamber. The membrane is designed to be strong enough to withstand ambient differential pressure until rupture of the material is desired and initiated with a specific input. 
     In the example illustrated, flow control device  38  may further comprise a micro electromechanical system  44  that enables selective rupture initiation with respect to material  42 . In one embodiment, micro electromechanical system  44  comprises a sensor  46  for detecting differential pressure acting on pressure membrane  40 . By way of example, sensor  46  may comprise a strain gauge  48  or piezo material applied to the atmospheric/low-pressure side of pressure membrane  40 . The sensor  46  may be designed to generate a signal when the differential pressure is changing. In many applications, absolute pressure accuracy is not required if the sensor has sufficient sensitivity to recognize pressure pulse command signals that may be used to cause initiation of the rupture of pressure membrane  40 . 
     As illustrated in  FIG. 3 , the micro electromechanical system  44  may further comprise a layer or pellet of energetic material  50  that may be selectively actuated or exploded. When the energetic material  50  is ignited or detonated, the energetic material has sufficient energy to weaken the pressure membrane  40  and allow the differential pressure acting on pressure membrane  40  to rupture the pressure membrane  40 . Alternatively, energetic material  50  may be designed to have energy sufficient to cause complete rupture of pressure membrane  40  without the contribution of differential pressure. The latter option can be used in applications where functionality is desired independent of pressure. Depending on the application and the expected differential pressures, the thickness of pressure membrane  40  may be incrementally increased or decreased. For example, the thickness may be increased for wells with higher expected differential pressures in order to keep the amount of energetic material  50  to a minimum. 
     Energetic material  50  may be formed from a variety of explosive materials that explode or detonate, i.e. provide a rapid release of energy, as a result of ignition, chemical reaction, or other processes. For example, energetic material  50  may be formed from explosive materials, such as those used in perforating applications. In one embodiment, the energetic material  50  is deployed in a specific form, e.g. a shape charge, mounted on pressure membrane  40 . Furthermore, the energetic material  50  may be stationed at various locations along pressure membrane  40 . In the example illustrated, energetic material  50  is applied over sensor  46  (see  FIG. 2 ) such that sensor  46  is sandwiched between energetic material  50  and the surface of pressure membrane  40 . 
     Referring generally to  FIG. 4 , one approach for causing explosion of energetic material  50  is illustrated. In this embodiment, an initiator  52  is positioned adjacent energetic material  50  and utilized in initiating explosion of the energetic material  50 . By way of example, initiator  52  may comprise an igniter or detonator. The initiator  52  may be designed as an independent component or as an integral part of a micro electromechanical system chip. 
     Additionally, circuitry  54  may be operatively coupled between strain gauge  48  (see  FIG. 2 ) and energetic material  50  via, for example, initiator  52 , as illustrated in  FIG. 5 . The circuitry  54  may be designed to process an initiation signal, such as a pressure signal acting on pressure membrane  40 , and to initiate explosion of energetic material  50  via initiator  52  in response to the predetermined initiation signal. By way of example, circuitry  54  may be designed to process data related to measurement of differential pressure via strain gauge  48 . When the circuitry  54  determines an appropriate command signal has been given, the circuitry  54  may output a signal to initiator  52  to activate energetic material  50 . The circuitry  54  may comprise an application-specific integrated circuit (ASIC), an integrated micro electromechanical system (MEMS) chip, or another suitable circuit configured to carry out the measurement and processing functions. 
     The circuitry  54  may be powered via an electric power source  56 , which may be in the form of a battery or other suitable power source. In some applications, electric power source  56  is part of circuitry  54  or built into the overall micro electromechanical system  44 . However, in other applications the electric power source  56  may comprise an external power source, such as external batteries connected with circuitry  54 . 
     Because control device  38  is small in size, the control device  38  can be adapted for use with a variety of structures. For example, control device  38  may be incorporated into a rupture disc assembly  58 , as illustrated in  FIG. 6 . In this example, pressure membrane  40  comprises a rupture disc disposed in a surrounding rupture disc housing  60 . The rupture disc housing  60  may comprise an internal flow passage  62  to accommodate the flow of actuating fluid along flow path  28  during actuation of the downhole tool  26 . The external size and configuration of rupture disc housing  60  may be designed according to the corresponding mounting structure found in downhole tool  26  or other adjacent structures to which control device  38  is mounted along flow path  28 . 
     Initially, rupture disc  40  spans flow passage  62  and prevents flow therethrough until rupture disc  40  is ruptured via activation of energetic material  50 , as described above. By way of example, the micro electromechanical system  44  may comprise energetic material  50  in the form of a nanoenergetic material installed on the rupture disc  40 , as illustrated in  FIG. 7 . Depending on size constraints, an external power source  56  (see  FIG. 5 ) may be used to provide sufficient power to activate the initiator  52 , e.g. igniter, and cause explosion of the nanoenergetic material  50 . As described above, the energy from material  50  is used to initiate rupture of pressure membrane  40  by either directly rupturing the pressure membrane  40  or by weakening the pressure membrane  40  sufficiently to enable differential pressure to complete the rupture. 
     In another embodiment, a single micro electromechanical system chip  64  is employed, as illustrated in  FIG. 8 . In this embodiment, the single micro electromechanical system chip  64  may comprise all of the previously described system components, including strain gauge  48 , energetic material  50 , initiator  52 , circuitry  54  and power source  56  (see previous FIGS.). The single chip  64  simply is adhered or otherwise attached to the pressure membrane  40 . In some examples, the single micro electromechanical system chip  64  is constructed with an adhesive surface  66  that may be exposed for adherence to a membrane surface, for example, in the event pressure membrane  40  is formed as a membrane spanning flow path  28 . 
     The circuitry  54  is designed, e.g. programmed, to recognize specific inputs, e.g. pressure differentials, pressure inputs, combinations of downhole parameters, or other inputs, that cause the circuitry  54  to initiate explosion of the energetic material  50  (see  FIG. 3 ). The explosion, in turn, initiates rupture of pressure membrane  40  to enable flow of actuating fluid to downhole tool  26 . The circuitry  54  may be designed to recognize inputs that are specifically input by a well operator via, for example, pressure inputs, and/or the circuitry may be designed to recognize specific parameters that occur downhole. 
     System  20  can be constructed in a variety of configurations for use in many types of wells. For example, the downhole equipment  24  may comprise many types of production components, service components, and other well related components depending on the specific operations to be carried out by the well system. An individual downhole tool or a plurality of downhole tools of similar or different types may incorporate control devices  38  to control actuation. Additionally, each control device  38  may be designed to operate in response to a corresponding, unique signature or other input. In other applications, however, the plurality of control devices  38  may be designed to respond simultaneously to a single type of control input. 
     Additionally, the pressure membrane  40  may be designed from a variety of materials in a variety of shapes and thicknesses. The components mounted on pressure membrane  40  also may be designed in many shapes and configurations for mounting on either side of pressure membrane  40 . For example, micro electromechanical system chips may be used to assemble some or all of the components into a cooperating assembly. By way of further example, the amount and type of energetic material  50  may be adjusted for specific applications and environments. 
     In some embodiments, either a downhole device or a surface located device may provide an electrical signal to the micro electromechanical system to indicate initiation of the energetic material. For example, a surface device such as a simple switch, micro-processor running a modeling algorithm, or a signal generating device, could send an initiation signal to the micro electromechanical system. In other cases, a downhole device or sensor could generate an initiation signal due to downhole parameters such as water cut, flow rate, temperature, or other fluid composition. In still other cases, a signal generated by a pump down device such as an RF tag, radioactive tracer, mechanical switch, or magnetic signal could be received by the micro electromechanical system. 
     The signal may be communicated via a variety of wired and wireless methods. For example, a non-limiting list of wireless methods may include pressure pulses, electromagnetic signals, radio signals, or acoustic signals. A combination of wired and wireless communication techniques may be employed. 
     Even though the micro electromechanical system is shown in many of the figures as being mounted on the pressure membrane, other embodiments may have some or all of the components mounted proximate or near the pressure membrane. For example, the strain gauge may be on the pressure membrane but the other micro electromechanical system components may be near the pressure membrane, such as coupled to a surface of the rupture disc housing. The energetic material may be provided around the circumference of the pressure membrane or mounted just upstream of the pressure membrane in a case in which the energetic material initiates a chemical reaction when actuated. 
     Although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Accordingly, such modifications are intended to be included within the scope of this invention as defined in the claims.