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BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present invention generally relates drilling and, in particular, to activation of downhole safety devices. 
         [0003]    2. Description of the Related Art 
         [0004]    Boreholes are drilled deep into the earth for many applications such as carbon sequestration, geothermal production, and hydrocarbon exploration and production. In all of the applications, the boreholes are drilled such that pass through or can allow for access to a material (e.g., a gas or fluid) contained in a formation located below the earth&#39;s surface. Many different types of tools and instruments may be disposed in the boreholes to perform various tasks and some of these can be utilized to take measurements of various values while the borehole is being drilled. 
         [0005]    One disadvantageous phenomenon that can arise while drilling is referred to as “drilling kick” or simply “kick.” Kick generally refers to the condition where a formation fluid or formation gas flows from the formation into the borehole while drilling. Kick can occur when formation pressure exceeds the hydrostatic pressure exerted on the formation by drilling mud utilized in drilling the borehole. This type of kick is generally referred to as “underbalanced kick.” Another type of kick referred to as “induced kick” can occur when movement of the drill sting or casing causes the pressure in the borehole to fluctuate. 
         [0006]    Regardless of the cause, the kick can, in extreme cases, result in an uncontrolled flow of formation fluid or gases into the atmosphere at the surface in a phenomenon referred to as “blowout.” To prevent blowout, a blowout preventer is typically installed in the space between the drill pipe and the casing at the surface. The blowout preventer is activated when a kick is detected and seals off the annulus between the drill pipe and the casing to prevent the fluid or gasses from escaping. Early detection of a kick is required to effectively operate the blowout preventer and typically includes visual observation of bubbles in the drilling mud at the surface. 
       BRIEF SUMMARY 
       [0007]    Disclosed is a drilling system for drilling a borehole that includes a drill string including a bottom hole assembly and a telemetry system coupled together. The system also includes a communication device coupled to the drillstring configured to transmit sensor data to and receive control data from a control unit located at a surface location through the telemetry system and a sensor coupled to the drillstring, the sensor providing the sensor data to the communication device. The system also includes a downhole safety device coupled to the drill string and in operable communication with the communication device, the downhole safety device configured to actuate after receiving an activation signal initiated by the control unit. 
         [0008]    Also disclosed is a method of actuating a downhole safety device in a drilling system that includes collecting information indicative of borehole conditions at a downhole location; transmitting the information to a surface control unit; determining that the downhole safety device should be actuated; sending an actuation signal through a telemetry system to the downhole safety device; actuating the downhole safety device using the actuation signal. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
           [0010]      FIG. 1  illustrates a drilling system in which embodiments of the present invention may be implemented; and 
           [0011]      FIG. 2  is flow chart illustrating a method according to one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    A detailed description of one or more embodiments of the disclosed apparatus and method presented herein is by way of exemplification and not limitation with reference to the Figures. 
         [0013]      FIG. 1  illustrates  FIG. 1  is a schematic diagram of an exemplary drilling system  100  that includes a drill string having a drilling assembly attached to its bottom end that can be operated according to the exemplary methods apparatus disclosed herein.  FIG. 1  shows a drill string  120  that includes a drilling assembly or bottomhole assembly (“BHA”)  190  conveyed in a borehole  126 . The drilling system  100  includes a conventional derrick  111  erected on a platform or floor  112  which supports a rotary table  114  that is rotated by a prime mover, such as an electric motor (not shown), at a desired rotational speed. A tubing (such as drill pipe)  122  having the drilling assembly  190  attached at its bottom end extends from the surface to the bottom  151  of the wellbore  126 . The tubing  122  is so-called wired pipe in one embodiment and allows for high-speed bi-directional communication through it. 
         [0014]    A drill bit  150 , attached to drilling assembly  190 , disintegrates the geological formations when it is rotated to drill the borehole  126 . The drill string  120  is coupled to a drawworks  130  via a Kelly joint  121 , swivel  128  and line  129  through a pulley. Drawworks  130  is operated to control the weight on bit (“WOB”). The drill string  120  can be rotated by a top drive (not shown) instead of by the prime mover and the rotary table  114 . The prime mover/rotary table  114  combination or a top drive or any other means of turning drill string  120  shall be referred to as drill string actuator herein. The operation of the drawworks  130  is known in the art and is thus not described in detail herein. 
         [0015]    A suitable drilling fluid  131  (also referred to as “mud”) from a source  132  thereof, such as a mud pit, is circulated under pressure through the drill string  120  by a mud pump  134 . The drilling fluid  131  passes from the mud pump  134  into the drill string  120  via a de-surger  136  and the fluid line  138 . The drilling fluid  131  discharges at the borehole bottom  151  through openings in the drill bit  150 . The returning drilling fluid  131   b  circulates uphole through the annular space  127  between the drill string  120  and the borehole  126  and returns to the mud pit  132  via a return line  35  and drill cutting screen  185  that removes the drill cuttings  186  from the returning drilling fluid  131   b.    
         [0016]    In some applications, the drill bit  150  is rotated by rotating the drill pipe  122 . However, in other applications, a downhole motor  155  (mud motor) disposed in the drilling assembly  190  also rotates the drill bit  150 . The rate of penetration (“ROP”) for a given drill bit and BHA largely depends on the WOB or the thrust force on the drill bit  150  and its rotational speed. 
         [0017]    A surface control unit or controller  140  receives signals from downhole sensors and devices and processes such signals according to programmed instructions provided from a program to the surface control unit  140 . The surface control unit  140  displays desired drilling parameters and other information on a display/monitor  141  that is utilized by a human operator to control the drilling operations. The surface control unit  140  can be a computer-based unit that can include a processor  142  (such as a microprocessor), a storage device  144 , such as a solid-state memory, tape or hard disc, and one or more computer programs  146  in the storage device  144  that are accessible to the processor  142  for executing instructions contained in such programs to perform the methods disclosed herein. The surface control unit  140  can process data relating to the drilling operations, data from the sensors and devices on the surface, and data received from downhole and can control one or more operations of the downhole and surface devices. 
         [0018]    The drilling assembly  190  also contains formation evaluation sensors or devices (also referred to as measurement-while-drilling, “MWD,” or logging-while-drilling, “LWD,” sensors) determining borehole pressure, formation pressure, resistivity, density, porosity, permeability, acoustic properties, nuclear-magnetic resonance properties, corrosive properties of the fluids or formation downhole, salt or saline content, and other selected properties of the formation  195  surrounding the drilling assembly  190 . Such sensors are generally known in the art and for convenience are generally denoted herein by numeral  165  and can include, for example, resistivity sensors, density sensors, porosity sensors, permeability sensors, temperature sensors, pressure sensors, vibration sensors, bending moment sensors, rotation sensors, orientation sensors and shear sensors. The drilling assembly  190  can further include a variety of other sensors and communication devices  159  for controlling and/or determining one or more functions and properties of the drilling assembly (such as velocity, vibration, bending moment, acceleration, oscillations, whirl, stick-slip, etc.) and drilling operating parameters, such as weight-on-bit, fluid flow rate, pressure, temperature, rate of penetration, azimuth, tool face, drill bit rotation, etc. 
         [0019]    A suitable telemetry sub (communication device)  180  using, for example, two-way telemetry, is also provided as illustrated in the drilling assembly  190  and provides information from the various sensors to the surface control unit  140  through the wired pipe  122 . The telemetry sub  180  can also provide control or activation data received from the control unit  140  to the sensors or other devices located at or near the BHA  190 . In one embodiment, the telemetry sub  180  provides activation signals to downhole safety devices  167 . 
         [0020]    Still referring to  FIG. 1 , the drill string  120  further includes an energy conversion device  160 . In an aspect, the energy conversion device  160  is located in the BHA  190  to provide an electrical power or energy, such as current, to sensors  165  and/or communication devices  159 . Energy conversion device  160  can include a battery or an energy conversion device that can for example convert or harvest energy from pressure waves of drilling mud which are received by and flow through the drill string  120  and BHA  190 . Alternately, a power source at the surface can be used to power the various equipment downhole. 
         [0021]    The drill string  120  further includes one or more downhole safety devices  167 . These safety devices  167  can include, for example, blowout preventers (BOPs). The BOPs, as is known in the art, are operated to seal incoming fluid from the formation  169  from traversing up the annulus between the drill pipe  122  and the borehole  126 . It shall be understood that the safety devices  167  can receive an activation signal from the control unit  140  through the telemetery sub  180 . In some cases, a surface BOP can also be provided that seals fluid from escaping into the atmosphere. 
         [0022]    According to one embodiment of the present invention, the sensors  165  can sense one or more of formation pressure, flow rate of the drilling mud and composition of the drilling mud. Information collected by the sensors  165  is provided to the controller  140  through wired pipe  122 . At the controller  140  it is determined if a kick is about to or has occurred. The determination can be automatic or based on analysis of the data by an operator. If kick has or is about to occur, the controller  140  can transmit a signal through the wired pipe  122  to safety devices  167  that cause them to activate. 
         [0023]    In prior art applications, after detection of a kick at the surface, an activation of the safety devices  167  has heretofore been initiated manually with significant time delay from surface by dropping a ball or the like or sending a downlink. In either case, the safety devices  167  are actuated independent of the other portions of the drilling system  100 . Such activation, while suitable for reducing or eliminating the effects of kick, is not very effective due to the time delay and can create additional problems. For instance, if the safety device  167  is activated before the rotary table  114  is stopped, the drill string  120  could be damaged. In some cases a blow-out will not be even recognized (underground blow-out) at surface. 
         [0024]    By making the determination of a kick condition based on downhole information at the surface, other related systems can be stopped or altered in the correct order. For instances, if the sensors detect conditions indicative of kick, the rotary table  114  could be stopped, a surface BOP (not shown) activated, and then the controller  140  could then transmit the signal to cause the safety devices  167  to actuate. In short, due to the high speed communication capabilities of e.g. wired pipe, the correct sequencing of a kick related shut-down can be controlled from the surface in real-time. 
         [0025]    Such safety device can also be used in case of mud losses to shut-in the annulus and prevent an underbalanced condition causing borehole instability or a kick initiation. 
         [0026]      FIG. 2  is a flow chart showing a method according to one embodiment. At process  200  current drilling conditions are monitored by sensors located on or near the BHA of a drill string. The conditions can include, for example, the flow rate or composition of the drilling mud and hydrostatic pressure of the formation to name but a few. At process  202  the drilling conditions are transmitted to the surface. At the surface, the drilling conditions are provided to a control unit as indicated at process  204 . It shall be understood that the control unit can be located at the same location as or remote from the location where the drilling is being conducted. That is, the control unit could be remote from the drilling rig in one embodiment. 
         [0027]    Regardless of where the control unit is located, at block  206  a determination is made that a downhole safety device located along the drill string needs to be actuated. This determination can be made either by an operator, fully automatically by the control unit using an expert system approach, or combinations of operator determined and automatic control. At process  208  at least one other portion of the drilling system (e.g., the rotary table) is provided a command to cause it vary its operation (e.g., stop). After process  208  is completed, at process  210 , an activation command is sent to from the control unit to the downhole safety device. In some instances, downhole conditions are further monitored to determine is the activation command achieved the desired result or if further safety devices need to be actuated or other actions taken. 
         [0028]    Elements of the embodiments have been introduced with either the articles “a” or “an.” The articles are intended to mean that there are one or more of the elements. The terms “including” and “having” are intended to be inclusive such that there may be additional elements other than the elements listed. The conjunction “or” when used with a list of at least two terms is intended to mean any term or combination of terms. The terms “first,” “second,” and “third” are used to distinguish elements and are not used to denote a particular order. 
         [0029]    It will be recognized that the various components or technologies may provide certain necessary or beneficial functionality or features. Accordingly, these functions and features as may be needed in support of the appended claims and variations thereof, are recognized as being inherently included as a part of the teachings herein and a part of the invention disclosed. 
         [0030]    While the invention has been described with reference to exemplary embodiments, it will be understood that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications will be appreciated to adapt a particular instrument, situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Summary:
A drilling system for drilling a borehole includes a drill string including a bottom hole assembly and a telemetry system coupled together and a communication device coupled to the drillstring configured to transmit sensor data to and receive control data from a control unit located at a surface location through the telemetry system. The system also includes a sensor coupled to the drillstring, the sensor providing the sensor data to the communication device and a downhole safety device coupled to the drill string and in operable communication with the communication device, the downhole safety device configured to actuate after receiving an activation signal initiated by the control unit.