Patent Publication Number: US-10323507-B2

Title: Apparatus, system and method for multi zone monitoring in boreholes

Description:
RELATED APPLICATIONS 
     This application is a divisional application which claims priority from U.S. utility application Ser. No. 14/476,867, filed Sep. 4, 2014, which is itself a nonprovisional application that claims the benefit of and priority to Provisional Application entitled Apparatus, System and Method for Multi Zone Monitoring in Boreholes filed Sep. 10, 2013, assigned application Ser. No. 61/876,190 and which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The invention relates to an apparatus, system and method for deploying, suspending, retrieving and monitoring multiple downhole logging tools, positioned between zonal isolation packers, from a surface deployment unit. In particular, the invention relates, but is not limited, to isolating multiple separate geological formations penetrated by a single borehole and monitoring the pressure and temperature of the fluid-filled pores in each formation. 
     BACKGROUND TO THE DISCLOSURE 
     Reference to background art herein is not to be construed as an admission that such art constitutes common general knowledge. 
     Borehole monitoring, particularly across multiple zones (e.g. two to 10+), is a relatively complicated, time consuming, and expensive operation. Heavy tubing deployed systems, typically connected to a surface control and measurement system using electric and hydraulic control lines strapped to the tubing, along with an expensive drilling or workover rig, have been known to be used for such borehole monitoring operations. An expensive drilling or workover rig typically includes a frame that provides support for various components such as a drill head support structure, which would usually include a drill string capable of drilling a borehole. 
     One aspect of borehole monitoring that is identified as being particularly onerous is the requirement of a drilling rig and heavy duty tubing to deploy and retrieve any monitoring system. Typically the borehole pressure and temperature is monitored by drilling a borehole and installing some form of tubing in the hole. At the required depths of the tubing, special tools such as isolating packers and pressure/temperature sensors are attached as required. Typically an electrical cable is installed with the tubing to provide telemetry to the sensors and a hydraulic cable is also installed to provide inflation control to the isolation packers. 
     Once the monitoring system has gathered all the required data, however, the monitoring system, isolating system and tubing must then be retrieved. Typically, system retrieval involves the use of a drilling rig. The time and cost associated with recovering the monitoring systems in this manner renders multi-zone borehole monitoring impractical for non-permanent applications. 
     Some efforts have been made to reduce the problems, such as by using battery powered sensors that record data to a local memory device and which are deployed on solid wire spooled off wireline units and surface winches without the requirement for a drilling rig. Pressure readings can then be obtained at any depth of the borehole without having to install or retrieve a tubing string. However this technique does not provide for real time data, or the ability to isolate various zones or sections of the borehole, and so is not suited for applications requiring continuous monitoring of borehole or geological properties in a multi-zone setting. 
     A further problem with isolating and monitoring these zones is associated with legislation requirements for abandoning old boreholes. Typically the isolating packers used are expensive tubing mounted devices that are not capable of being retrieved due to their mechanical setting design and that often require use of drilling rigs with expensive specialist equipment to remove these devices from the borehole and satisfy legislation requirements. 
     Having a borehole isolating and monitoring system which can be deployed, suspended and retrieved from a portable surface winch is therefore an attractive yet unavailable system. It is desirable to be able to deploy a plurality of sensors at different depths in order to isolate the borehole sections above and below each sensor. The sensors could be powered from an autonomous surface cabinet that could also display and record real-time data. The provision of surface electrical power would eliminate the need for battery powered downhole sensors, which otherwise would need to be retrieved periodically to recharge or replace the batteries. 
     OBJECT OF THE DISCLOSURE 
     It is an aim of this invention to provide an apparatus, system and method for deploying, suspending and retrieving a multi-zone borehole monitoring system from a portable surface winch which enables economical, regulatory-compliant downhole monitoring, real time data collection, and eventual retrieval. 
     Other preferred objects of the present invention are apparent from the following description. 
     SUMMARY OF DISCLOSURE 
     According to a first aspect of the disclosure, there is provided a retrievable, multi-zone downhole monitoring system for use in multi-zone borehole operations, the downhole monitoring system comprising: 
     At least one downhole measuring instrument comprising electronic components including sensors transmitting real time data to surface; and 
     At least one pressure isolation packer that can be actuated from surface to provide a borehole seal; 
     a control and suspension umbilical comprising power and telemetry electrical cables for the sensors, a hydraulic inflation line for the packers and means of conveyance into the borehole; 
     pressure-testable sealed connectors to attach the control and suspension umbilical to the pressure isolation packer; and 
     a suspension hang off apparatus comprising umbilical slips to suspend the system and umbilical exiting ports; 
     wherein the measuring instruments include at least a pressure sensor or a temperature sensor, and the isolation packer is actuated from a surface to provide zonal isolation across each sensor. 
     Hereinafter, such a downhole measuring instrument and companion pressure isolation packer will be referred to as a zonal isolation module. 
     The isolation packers can include pressure rated connections to allow all hydraulic and electrical lines to bypass through each packer. It will be appreciated that the environment of a borehole may contain significant pressure, particularly due to hydrostatic pressure of borehole fluid at a significant depth in the well. This can cause infiltration of fluids into the electrical wires and hydraulic fluid lines. The connectors are preferably located above and below each packer. Even more preferably the connectors are capable of being pressure tested prior to deployment to ensure pressure integrity. Even more preferably the connectors may provide a tertiary weak point to allow for emergency disconnect capabilities by means ensuring the connectors break from an applied tensile load less than the maximum tensile strength of the umbilical and other components. 
     Preferably the system is connected to a multi-core downhole umbilical on a portable winch at the surface. The multi-core downhole umbilical can be spooled into the borehole to deploy the system to the required depth. The multi-core or wire downhole umbilical allows more than one instrument or sensor to be connected to the umbilical cord. The portable winch provides a depth counter and slip ring to capture sensor measurements and attribute them to precise depths while running (raising and lowering) in the hole. 
     Preferably the downhole umbilical components include a data transfer system in communication with the measuring instruments and a hydraulic system for inflating and deflating the isolation packers. The downhole umbilical also provides sufficient tensile strength to accommodate the total number of packers and sensors required. 
     The downhole monitoring system may further comprise measuring instruments to diagnose well integrity such as vibration or chemical composition of the fluids between each isolation packer. 
     Preferably the downhole measuring instruments comprise a mating portion that secures to a corresponding mating portion of the downhole umbilical. Preferably the downhole tool contains the sensors, the data transfer system, and the power system. The downhole tool could be actuated from a surface control unit to retrieve real time data. 
     The surface control unit may comprise data storage for storing data received from the sensors. The data transfer system may store the data for transmission at a requested time. The control unit also provides power to the downhole tool and hydraulic pressure for the isolation packers. 
     The portable surface winch is used to lower the downhole monitoring system through the borehole, preferably to total depth, and suspend the monitoring system by a portion of the downhole umbilical, preferably at a well head. Preferably at least a portion of the downhole umbilical protrudes from the wellhead to allow a portable surface winch to recover the system from the borehole at the end of the monitoring period. 
     Further features and advantages of the present invention will become apparent from the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the disclosure. These drawings, together with the general description of the disclosure given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the disclosure. By way of example only, preferred embodiments of the disclosure will be described more fully hereinafter with reference to the accompanying figures. 
         FIG. 1  is a diagrammatic view of a multi-zone monitoring system suspended in a borehole; 
         FIG. 2 a    is a diagrammatic view of a portable surface winch lowering a monitoring system into a borehole on the downhole umbilical; 
         FIG. 2 b    is a diagrammatic view of a multi-zone monitoring system being lowered to total depth into a borehole; 
         FIG. 3  is a diagrammatic view of an integral zonal isolation module comprising an isolation packer and downhole monitoring instrument; 
         FIG. 4  is a cross-sectional view of a downhole umbilical 
         FIG. 5  is a diagrammatic view of the wellhead suspension apparatus 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
       FIG. 1  illustrates a diagrammatic view of a multi-zone downhole monitoring system  10  located in a borehole  11  below surface  12 . The multi-zone downhole monitoring system  10  may be located at various depths below surface  12 , but typically the borehole  11  will be greater than 50 m below surface  12  and, in many cases, approximately 1000 m below surface  12 . 
     The multi-zone downhole monitoring system  10  has a wellhead  13  located at the top of the borehole  11  for equipment suspension and well control. The umbilical  14  provides the monitoring system  10  with power, control, and telemetry. Typically the monitoring system  10  is powered and operated at surface  12 , via surface cable  17 , and umbilical  14 , from the surface control unit  16 . Although the surface control unit  16  is illustrated as being located on the surface adjacent to the borehole  11 , it will be appreciated that the surface control unit could also be located elsewhere, such as a control office. 
     The multi-zone downhole monitoring system  10  has a wellhead outlet  18  connected to the wellhead  13  at the surface of the borehole. The wellhead outlet provides a sealable barrier between the borehole  11  and surface  12  allowing hydraulic and electrical connections to be connected between the downhole umbilical  14  and surface cable  17 . During suspension, the wellhead  13  uses a wellhead suspension apparatus “slips”  19 , known in the industry, to lock the umbilical in place and hold the weight of the monitoring system  10 . At pre-specified intervals, i.e., length separation, multiple isolation packers  20  are attached to the umbilical  14  to provide barriers between different geological formations  23  intersected by the borehole. Typically there may be any number of formations  23  between one to ten. Between each isolated formation  23 , downhole measuring instruments  21  are attached to the umbilical to provide real time data (typically pressure and temperature) from each isolated zone  23 . Other measurements may be taken, e.g. gas partial pressure in fluid. During monitoring operations, the isolation packers  20  are inflated to create sealing barriers between each formation while the measuring instruments monitor various formation fluid and well parameters. The monitoring information can be conveyed through the wires of the umbilical to the surface. 
       FIG. 2 a    illustrates a diagrammatic view of the multi-zone monitoring system  10  being deployed at surface  12  into the borehole  11 . An isolation packer  20  and measuring instruments  21  are connected to the umbilical  14  at surface  12 . This array comprises an integral zonal isolation and monitoring module  15 . The integral zonal isolation and monitoring module  15  is then lowered through the wellhead  13 , and possibly a well control valve  31  into the opening of the borehole  11  using the portable winch  30  at surface. The umbilical is configured from the portable winch  30  over a pulley  32  above the wellhead  13  to allow smooth deployment into the borehole  11 . The portable winch  30  is used to lower the integral zonal isolation and monitoring module  15  into the borehole  11  to a depth equal to that between the deepest two zones requiring isolation  32 . The hydraulic line contained within the umbilical is also in communication with a hydraulic pump for the inflation and deflation of the inflatable isolation packers that forms part of the surface control unit  16 . Once the first integral zonal isolation module is at a depth equal to that between the deepest two zones requiring isolation  32 , the umbilical  14  is suspended in the slips  19  and cut to allow the installation of another integral zonal isolation and monitoring module  15  on the umbilical  14 . The subsequent integral zonal isolation module  15  is connected to the cut umbilical  14  using compression fittings  40  and a pressure testable sealed connector  41  (see  FIG. 3 ) before removing the slips  19  and continuing with the deployment of the multi-zone system. 
       FIG. 2 b    illustrates a diagrammatic view of the multi-zone downhole monitoring system  10  having been deployed to total depth into the borehole  11 . The steps as detailed in the description of  FIG. 2 a    are repeated as required to position a sequence of integral zonal isolation and monitoring modules  15  between the target formations  23  of the borehole  11 . Each integral zonal isolation and monitoring module  15  is connected to the umbilical  14  at surface with the distance between each system matching the distance between each target formation  32 . Once the entire multi-zone downhole monitoring system  10  is installed in the borehole at the appropriate total depth, the umbilical  14  is severed at surface  12 . The umbilical  14  is suspended in the slips  19  at the wellhead  13  allowing for the weight of the multi-zone system to be suspended at the point of the slips without dropping into the hole.  FIG. 1  shows that the top of the hydraulic line  50  and electrical cable  51  (see  FIG. 3 ) in the severed umbilical  14  are connected at the wellhead outlet  18  to establish communication from the surface control unit  16  to the monitoring system, via surface cable  17 . It will be appreciated that the monitoring equipment of the system can be positioned on the umbilical proximate to a geologic formation intersected by the wellbore. 
       FIG. 3  illustrates a preferred integral zonal isolation and monitoring module  15 . The integral zonal isolation and monitoring module  15  has an isolation packer  20  in the form of an inflatable, pressure sealing elastomic bladder inflated and shaped to seal or “pack-off” the internal diameter of the borehole  11  in  FIG. 1 . The integral zonal isolation and monitoring module  15  has an inner mandrel  46  to provide a cylindrical shaft and bore through the center of the isolation packer to provide for a base for the isolation packer  20 , a hydraulic chamber  58  and inflate port  45  for inflation of the isolation packer  20  and contains one or more cable bypass feed throughs for the umbilical&#39;s  14  electric cable  51 . The inner mandrel  46  may also provide the ability for a “shear-release” functionality as a secondary method of deflation. The shear-release function would allow for the inner mandrel to shear under a determined applied load and therefore release the stored pressure in the packer allowing it to deflate. Located at the top and bottom of the inner mandrel  46  are compression fittings  40  and pressure testable sealed connectors  41  to provide sealed connections between the umbilical&#39;s  14  hydraulic line  50  and the inner mandrel  46 . The sealed connections  41  provide a pressure barrier to ensure pressure can be applied directly to the isolation packer&#39;s inflate port  45  and monitored at surface to ensure there is no pressure leak, this also provides the ability for the isolation packer to maintain its required inflate pressure for the life of the system without pressure leaks, further, the ability to pressure test these connections at surface provides confidence to the systems integrity prior to deployment down a borehole. The isolation packers are inflated by use of a common hydraulic line  50  in the umbilical  14 . When hydraulic pressure is applied from the surface control unit  16  (see  FIG. 1 ) to the line  50 , all isolation packers are inflated to create a barrier seal against the bore hole walls. 
     The umbilical  14  also houses electrical cable  51  for the monitoring sensors, i.e., instruments. Typically, a multi zone system shall require between one to ten separate electrical cable  51  to power and transmit data from the measuring instruments  21 . The electric cable  51  are routed through the inner mandrel  46  using cable feed through bypass  47  and the bypasses are sealed using compression fittings  40  above and below. 
       FIG. 4  illustrates a cross-sectional view of preferred downhole umbilical  14 . The umbilical  14  has capacity to house all the required control lines for the monitoring system  15 . The electrical cable  51  is used to supply electrical power and real time data transmission from the monitoring sensors  21  (See  FIG. 2 b   ). The electrical cable  51  has a core conductor  53 , a core insulation  54 , a filler  57  and is constructed within a single metal tube  52 . The hydraulic line  50  is used to supply a common hydraulic pressure to each of the isolation packers  20 . The hydraulic line  50  is a single metal tube which provides a polished surface for a compression fitting. The umbilical  14  shall also comprise some form of protection  55  such as a rubber or thermoplastic to protect against downhole environments. 
       FIG. 5  illustrates a diagrammatic view of the wellhead suspension system  70  to provide well control and umbilical suspension cap. The multi-zone downhole monitoring system exits the wellbore through a well head or flange system  13 , and a Blow Out Preventer (BOP)  60  or similar well control device is used to provide a barrier between the wellbore surface. The BOP seals around the downhole umbilical  14  and allows the umbilical to be suspended in the well by means of an umbilical clamp or hang-off plate  61  situated in a hang-off sub  62 . Preferably the hang-off plate  61  is bolted or clamped around the outer diameter of the umbilical  14  and prevents any slippage of the umbilical  14  and attached monitoring system. The wellhead suspension system also has an end cap sub  63  to allow the umbilical to be terminated to an electrical wellhead outlet  18  and provide the necessary barriers to ensure all possible leak paths from the well are sealed. A surface cable  17  is terminated to the umbilical  14  in the wellhead outlet  18 . The surface cable  17  is then tied into the surface control unit  16  for data capture and further telemetry if required. 
     This specification is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the manner of carrying out the disclosure. It is to be understood that the forms of the disclosure herein shown and described are to be taken as the presently preferred embodiments. As already stated, various changes may be made in the shape, size and arrangement of components or adjustments made in the steps of the method without departing from the scope of this disclosure. For example, equivalent elements may be substituted for those illustrated and described herein and certain features of the invention maybe utilized independently of the use of other features, all as would be apparent to one skilled in the art after having the benefit of this description of the disclosure. 
     While specific embodiments have been illustrated and described, numerous modifications are possible without departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying claims.