Abstract:
A rotating control drilling device includes an upper sealing element and a lower sealing element positioned around a drillstring and forming a chamber therebetween and a leak detection device. The leak detection device includes a piston in communication with the chamber, a magnet disc disposed on an end of the piston, and a plurality of magnetic sensors arranged in a magnetic sensing ring around the rotating control drilling device. Upon reaching a selected critical pressure in the chamber, a spring is configured to compress as the magnet disc is positioned proximate to the plurality of magnetic sensors. Furthermore, a method to detect leaks in a rotating control device includes positioning a leak detection device in communication with a chamber located between upper and lower sealing elements and signaling with the leak detection device when a pressure of the chamber exceeds a selected critical pressure.

Description:
BACKGROUND 
   1. Field of the Disclosure 
   Embodiments disclosed herein relate generally to apparatus and methods for wellbore drilling. More particularly, the present disclosure relates to apparatus and methods for leak detection in a rotating control drilling device. 
   2. Background Art 
   Wellbores are drilled deep into the earth&#39;s crust to recover oil and gas deposits trapped in the formations below. Typically, these wellbores are drilled by an apparatus that rotates a drill bit at the end of a long string of threaded pipes known as a drillstring. Because of the energy and friction involved in drilling a wellbore in the earth&#39;s formation, drilling fluids, commonly referred to as drilling mud, are used to lubricate and cool the drill bit as it cuts the rock formations below. Furthermore, in addition to cooling and lubricating the drill bit, drilling mud also performs the secondary and tertiary functions of removing the drill cuttings from the bottom of the wellbore and applying a hydrostatic column of pressure to the drilled wellbore. 
   Typically, drilling mud is delivered to the drill bit from the surface under high pressures through a central bore of the drillstring. From there, nozzles on the drill bit direct the pressurized mud to the cutters on the drill bit where the pressurized mud cleans and cools the bit. As the fluid is delivered downhole through the central bore of the drillstring, the fluid returns to the surface in an annulus formed between the outside of the drillstring and the inner profile of the drilled wellbore. Because the ratio of the cross-sectional area of the drillstring bore to the annular area is relatively low, drilling mud returning to the surface through the annulus do so at lower pressures and velocities than they are delivered. Nonetheless, a hydrostatic column of drilling mud typically extends from the bottom of the hole up to a bell nipple of a diverter assembly on the drilling rig. Annular fluids exit the bell nipple where solids are removed, the mud is processed, and then prepared to be re-delivered to the subterranean wellbore through the drillstring. 
   As wellbores are drilled several thousand feet below the surface, the hydrostatic column of drilling mud serves to help prevent blowout of the wellbore as well. Often, hydrocarbons and other fluids trapped in subterranean formations exist under significant pressures. Absent any flow control schemes, fluids from such ruptured formations may blow out of the wellbore like a geyser and spew hydrocarbons and other undesirable fluids (e.g., H 2 S gas) into the atmosphere. As such, several thousand feet of hydraulic “head” from the column of drilling mud helps prevent the wellbore from blowing out under normal conditions. 
   However, under certain circumstances, the drill bit will encounter pockets of pressurized formations and will cause the wellbore to “kick” or experience a rapid increase in pressure. Because formation kicks are unpredictable and would otherwise result in disaster, flow control devices known as blowout preventers (“BOPs”), are mandatory on most wells drilled today. One type of BOP is an annular blowout preventer. Annular BOPs are configured to seal the annular space between the drillstring and the inside of the wellbore. Annular BOPs typically include a large flexible rubber packing unit of a substantially toroidal shape that is configured to seal around a variety of drillstring sizes when activated by a piston. Furthermore, when no drillstring is present, annular BOPs may even be capable of sealing an open bore. While annular BOPs are configured to allow a drillstring to be removed (i.e., tripped out) or inserted (i.e., tripped in) therethrough while actuated, they are no t configured to b e actuated during drilling operations (i.e., while the drillstring is rotating). Because of their configuration, rotating the drillstring through an activated annular blowout preventer would rapidly wear out the packing element. 
   As such, rotary drilling heads are frequently used in oilfield drilling operations where elevated annular pressures are present. A typical rotary drilling head includes a packing or sealing element and a bearing package, whereby the bearing package allows the sealing element to rotate along with the drillstring. Therefore, in using a rotary drilling head, there is no relative rotational movement between the sealing element and the drillstring, only the bearing package exhibits relative rotational movement. Examples of rotary drilling heads include U.S. Pat. No. 5,022,472 issued to Bailey et al. on Jun. 11, 1991 and U.S. Pat. No. 6,354,385 issued to Ford et al. on Mar. 12, 2002, both assigned to the assignee of the present application, and both hereby incorporated by reference herein in their entirety. In some instances, dual stripper rotating control devices having two sealing elements, one of which is a primary seal and the other a backup seal, may be used. As the assembly of the bearing package along with the sealing elements and the drillstring rotate, leaks may occur between the drillstring and the primary sealing element. An apparatus or method of detecting leaks between the drillstring and sealing element while drilling would be well received in the industry. 
   SUMMARY OF THE DISCLOSURE 
   In one aspect, embodiments disclosed herein relate to a method to detect leaks in a rotating control device, the method including positioning a leak detection device in communication with a chamber located between an upper sealing element and a lower sealing element of the rotating control device and signaling with the leak detection device when a pressure of the chamber exceeds a selected critical pressure. 
   In another aspect, embodiments disclosed herein relate to a rotating control drilling device including a seal assembly rotatable with respect to a housing, wherein the seal assembly comprises an upper seal element and a lower seal element and the upper and lower sealing elements are axially spaced to form a chamber therebetween, and a detection device. The detection device includes a piston assembly disposed in the seal assembly and in communication with the chamber, a magnet disc disposed on an end of the piston, and a plurality of magnetic sensors arranged in the housing axially proximate to the magnet disc of the piston assembly, wherein the plurality of magnetic sensors are configured to indicate a selected critical property in the chamber when the piston assembly is thrust toward the magnetic sensors. 
   In another aspect, embodiments disclosed herein relate to a method to detect leaks in a rotating control drilling device including operating the rotating control drilling device comprising a chamber formed between an upper sealing element and a lower sealing element, monitoring a pressure in the chamber, closing a distance between a magnet disc and a magnetic sensor to a critical distance, wherein the critical distance indicates a leak, and transmitting a warning signal to a rig floor operator to indicate the leak. 
   In another aspect, embodiments disclosed herein relate to a rotating control drilling device including an upper sealing element and a lower sealing element positioned around a drillstring and forming a chamber therebetween and a leak detection device. The leak detection device includes a piston disposed within a bore in the rotating control drilling device and in communication with the chamber, a magnet disc disposed on an end of the piston, and a plurality of magnetic sensors arranged in a magnetic sensing ring around the rotating control drilling device, wherein, upon reaching a selected critical pressure in the chamber, a spring is configured to compress as the magnet disc is positioned proximate to the plurality of magnetic sensors. 
   Other aspects and advantages of the invention will be apparent from the following description and the appended claims. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a section view of a rotating control drilling device with a leak detection device in accordance with embodiments of the present disclosure. 
       FIG. 2  is a section view of the leak detection device in accordance with embodiments of the present disclosure. 
       FIG. 3  is a schematic view of a magnetic sensing ring in accordance with embodiments of the present disclosure. 
       FIG. 4A  is a section view of the leak detection device with pressure in a chamber below a critical pressure in accordance with embodiments of the present disclosure. 
       FIG. 4B  is a section view of the leak detection device with pressure in a chamber at or above a critical pressure in accordance with embodiments of the present disclosure. 
   

   DETAILED DESCRIPTION 
   In one aspect, embodiments disclosed herein relate to apparatus and methods for wellbore drilling. More particularly, the present disclosure relates to apparatus and methods for leak detection in a dual stripper rotating control drilling device. 
   Referring to  FIG. 1 , a section view of a rotating control drilling device  10  is shown in accordance with embodiments of the present disclosure. Rotating control drilling device  10  includes a body  12  having a central axis  13  through which a drillstring  14  passes. An upper sealing element  16  and a lower sealing element  18  seal about drillstring  14  forming a chamber  20  therebetween. Chamber  20  may trap pressure between upper sealing element  16  and lower sealing element  18 . Further, rotating control device  10  includes a bearing package  15  within body  12  which allows upper sealing element  16  and lower sealing element  18  to rotate about central axis  13  along with drillstring  14  during operation. 
   Rotating control drilling device  10  further includes a leak detection device  100 . During operation of rotating control drilling device  10 , leaks may occur between drillstring  14  and lower sealing element  18  and cause pressure to build in chamber  20  between upper sealing element  16  and lower sealing element  18 . When a “critical pressure” is reached in chamber  20 , it may be advantageous to receive an indication of such a critical pressure, which may suggest that lower sealing element  18  is leaking and needs to be replaced. As used herein, critical pressure may be defined as a pressure in chamber  20  indicating a leak between lower sealing element  18  and drillstring  14 . The critical pressure may be determined and understood by a person skilled in the art. 
   Referring now to  FIG. 2 , a section view of a leak detection device  200  as installed in rotating control drilling device body  12  is shown in accordance with embodiments of the present disclosure. Leak detection device  200  includes a piston  210  disposed within a bore  215 . Bore  215  may be configured at an outer circumference of rotating control drilling device body  12  and along a central axis  216  which is perpendicular to and extends radially with respect to central axis  13  (from  FIG. 1 ) of rotating control drilling device  10  ( FIG. 1 ). An O-ring  212  and backup ring  214  may be included about piston  210  to seal with a contact area  217  between an inner surface of bore  215  and an outer surface of piston  210 . Contact area  217  may be relatively smooth to allow O-ring  212  to seal, or configured as otherwise known to those skilled in the art. 
   Still referring to  FIG. 2 , leak detection device  200  further includes a spring  220  disposed on piston  210 , and a valve cap  230  into which the subassembly of piston  210  and spring  220  may fit. An O-ring  232  is included to seal a contact area  234  between an outer surface of piston  210  and an inner surface of valve cap  230 . Valve cap  230  may be threadably secured in rotating control drilling device body  12  or by any other method known to those skilled in the art. Further, a magnet disc  240  is disposed on an outward facing end of piston  210 . Magnet disc  240  may be fastened to piston with epoxy, fasteners, or other attachment mechanisms known to those skilled in the art. 
   Leak detection device  200  further includes a magnetic sensing ring  260  attached to an aluminum ring  250  positioned inside a bore of the rotating control drilling device  10  ( FIG. 1 ). Magnetic sensing ring  260  is oriented such that a centerline of ring  260  is coincident with central axis  216  of bore  215 , thereby allowing magnetic sensing ring  260  and magnet disc  240  to be substantially even with each other. Magnetic sensing ring  260  may be sealed with an epoxy compound or other sealing compound known to those skilled in the art for protection from hazardous environments. A retaining ring  270  and a safety shroud  280  further secure aluminum ring  250  and magnetic sensing ring  260  in rotating control drilling device body  12 . 
   Referring now to  FIG. 3 , an electrical schematic of a leak detection system  202  is shown in accordance with embodiments of the present disclosure. Leak detection system  202  includes a wiring circuit  262 , multiple magnetic sensors  264  spaced around a circumference of magnetic sensing ring, and electrical components  266 ,  268  known to those skilled in the art.  FIG. 3  shows piston  210  with magnet disc  240  in relation to magnetic sensors  264 . As bearing package  15  (from  FIG. 1 ) rotates inside rotating control drilling device  10  (from  FIG. 1 ), magnet disc  240  continuously passes (shown by arrow “B”) by the multiple magnetic sensors  264  in magnetic sensing ring  260 . The number and spacing of magnetic sensors (e.g., Hall Effect sensors)  264  arranged around the circumference of the rotating control drilling device in magnetic sensing ring  260  may be determined by a person skilled in the art. For example, the speed in revolutions per minute that the bearing package rotates may determine the number of magnetic sensors  264  used and/or the amount of spacing between magnetic sensors  264   
   Referring back to  FIG. 2 , spring  220  is configured to correspond to a selected “critical” pressure in chamber  20  between upper and lower sealing elements ( 16  and  18  from  FIG. 1 ). Spring  220  has a “spring constant,” which is a measure of “stiffness” or resistance of the spring. Calculations and methods used for selecting an appropriate spring constant would be understood by a person skilled in the art. The spring constant of spring  220  may correspond to the selected critical pressure in chamber  20  such that, as the pressure approaches the selected critical level, spring  220  also compresses a known amount. 
   When the pressure in chamber  20  has reached a predetermined or critical pressure level, spring  220  will also have compressed and moved magnet disc  240  within a “critical distance” of magnetic sensing ring  260 . As used herein, “critical distance” may be defined as the distance between magnet disc  240  and magnetic sensing ring  260  when a warning signal is sent to a rig floor operator indicating a critical pressure in chamber  20 . In certain embodiments, the critical pressure in chamber  20  may be about 200 psi. In further embodiments, the critical pressure in chamber  20  may be between about 100 psi and about 500 psi. Embodiments of the present disclosure conform to meet requirements specified by the American Petroleum Institute in their guideline API 16RCD, which relates to monitoring pressure between two sealing elements, and is incorporated by reference herein. 
   Now referring to  FIG. 4A , a section view of leak detection device  200  is shown at a state when pressure in chamber  20  has not reached the critical pressure. Spring  220  is initially uncompressed, or biased to keep magnet disc  240  at a distance greater than the critical distance from magnetic sensing ring  260 . As pressure (shown by arrows “A”) increases in chamber  20  between upper sealing element  16  ( FIG. 1 ) and lower sealing clement  18  ( FIG. 1 ), the pressure forces piston  210  and magnet disc  240  to move radially outward toward magnetic sensing ring  260  causing spring  220  to compress. 
   Referring to  FIG. 4B , a section view of leak detection device  200  is shown at a state when the pressure in chamber  20  has reached the critical pressure. The pressure applied on piston  210  (shown by arrows “A”) has forced piston  220  and magnet disc  240  to move radially outward towards magnetic sensing ring  260 , causing spring  220  to become compressed, and allowing magnet disc  240  to move within the critical distance of magnetic sensing ring  260 . Magnetic sensors  264  in magnetic sensing ring  260  detect the critical distance between themselves and magnet disc  240  which indicates the critical pressure has been reached in chamber  20 . The close proximity of magnet disc  240  to magnetic sensing ring  260  at the critical distance may cause a signal to be transmitted to the rig floor operator indicating the critical pressure. A warning indicator on a control panel on the rig floor may be in the form of a blinking light, beeping horn, or other warning signals known to those skilled in the art. In certain embodiments, the warning signal may be transmitted wirelessly to the rig floor operator. 
   In certain embodiments, the upper sealing element and lower sealing element may be contained in a cartridge style system as a single unit. The cartridge system may work with existing clamping mechanisms for installation into an existing bearing assembly of the rotating control drilling device. The cartridge style system of the sealing elements may allow the sealing elements to be changed independent of the bearing assembly. Rotating control drilling device clamping mechanisms and bearing assemblies are described in detail in U.S. patent application Ser. No. 11/556,938, assigned to the assignee of the present invention, and hereby incorporated by reference in its entirety. 
   In certain embodiments, a software program may be used with the leak detection device to manage the data received from the magnetic sensors. Initially, when starting the program, a diagnostics test may be run to verify the system. During operation, the software program may be configured to recognize the distance as it changes between the magnet disc and the magnetic sensors, and to recognize the critical distance between the magnet disc and the magnetic sensors and know when to transmit a signal to the rig floor operator. 
   Further, a time delay may be integrated into the software package. The time delay may ensure that the magnet disc is at the critical distance from the magnetic sensors for a given amount of time before a warning signal is transmitted. In certain embodiments, the time delay may be about 15 seconds. In alternate embodiments, the time delay may range from about 5 seconds to about 30 seconds. The time delay may provide that pressure “spikes” are not sufficient to cause a warning signal to be transmitted, but rather, a constant critical pressure is required before a warning signal is sent. Further, the magnet disc may be configured to have a south pole facing outward, or towards the magnetic sensors in the magnetic sensing ring. Orientation of the magnet disc in such a way will be understood by a person skilled in the art. 
   Advantageously, embodiments of the present disclosure for the leak detection device may provide an early warning indication to a rig floor operator that a sealing element in the rotating control drilling device is leaking and needs to be replaced. When a primary sealing element leaks, the rig floor personnel is alerted and may take proactive steps to prevent costly repairs caused by sealing elements failing without warning. In the past, as the drillstring was raised, the operator relied more on a sight and sound method of listening for pressure leaks as they made a “burping” sound. The leak detection device enhances the operation of a dual stripper rubber system and improves the functional and sealing effect of the rotating control drilling device. 
   Further, embodiments of the present disclosure may provide a system that is easy to install and remove with existing clamping mechanisms used in the rotating control drilling devices. The leak detection device may be retrofitted on existing equipment which is significantly less expensive than acquiring new equipment with the new technology. 
   While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the disclosure should be limited only by the attached claims.