Abstract:
A system for jetting a borehole in a seafloor, the system including a tubular, and a jetting tool inserted into the tubular and having an end from which fluid is selectively discharged to excavate the borehole. An electrical inclination sensor is attached to the stem of the tubular, and is in communication a transmitter. A receiver is positioned proximate the sea surface and is in communication with the transmitter through the fluid in a drill pipe, so that when the jetting tool is excavating the borehole, an inclination of the tubular is sensed by the inclination sensor, which inclination is communicated from the transmitter to the receiver.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This technology relates to subsea oil and gas wells. In particular, this technology relates to measurement of inclination of running, setting, and testing tools during the primary phase of jetting a subsea well. 
         [0003]    2. Brief Description of Related Art 
         [0004]    Typical subsea drilling operations include a drilling vessel and an arrangement of equipment to accomplish the first drilling phase of a well. Where the sea floor is sandy, the first phase of the drilling operation may include jetting. Jetting is a process wherein a jetting tool, enclosed within a casing, is placed adjacent the sea floor. Fluid is sprayed through the end of the jetting tool and directed at the sand on the sea floor. The fluid is turbulent and stirs up the sand, which mixes with the fluid and is carried up the casing away from the bottom of the casing. When the sand is thus removed, the casing is lowered into the void left behind. This process is continued until the casing reaches a predetermined depth, after which equipment related to the next phase of drilling (i.e. a high pressure housing, blow out preventer, marine riser, etc.) is connected. 
         [0005]    It is beneficial for the equipment used in this first stage of drilling to be vertically oriented while the well is created. Such a vertical orientation allows for straight and proper connections of equipment used in subsequent phases of drilling. Accordingly, monitoring the inclination of the jetting equipment used during the first phase of drilling may be beneficial to help ensure that a vertical orientation is maintained. 
       SUMMARY OF THE INVENTION 
       [0006]    Disclosed herein is a system for jetting a borehole in a sea floor. In an example, the system includes a tubular having a stem, a housing running and jet tool, and a jetting tool inserted into the tubular and having an end from which fluid is selectively discharged to excavate the borehole. An electrical inclination sensor is attached either to the stem of the tubular, or to the housing running and jet tool. The electrical inclination sensor measures vertical inclination of the jetting tool and the housing running and jet tool. 
         [0007]    A transmitter is attached to the electrical inclination sensor that receives information related to the inclination of the jetting tool and the housing running and jet tool from the electrical inclination sensor. The transmitter than transmits either a mud pulse signal or an acoustic signal, depending on the placement of the transmitter, containing information about the inclination of the jetting tool and the housing running and jet tool. 
         [0008]    A receiver is located at the drilling vessel and is configured to receive the mud pulse or other acoustic signal from the transmitter. If the transmitter is attached to the stem of the jetting tool, the receiver may be attached to a receptor at the top of the drill string. If the transmitter is attached to the housing and drill tool, so that is transmits acoustic signals into the sea water, the receiver may be positioned near the drilling vessel and submerged in the sea. 
         [0009]    Also disclosed herein is a method for jetting a borehole in a sea floor. The method includes the steps of jetting a borehole by selectively discharging fluid our of a jetting tool directed at the sea floor, and providing an electrical inclination sensor that measures the inclination of the jetting tool. The method also provides monitoring the inclination of the jetting tool with the electrical inclination sensor prior to and during drilling activities, acoustically transmitting a signal containing information about the inclination of the jetting tool via a transmitter attached to the electrical inclination sensor, and receiving the signal with a receiver proximate the sea surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The present technology will be better understood on reading the following detailed description of nonlimiting embodiments thereof, and on examining the accompanying drawings, in which: 
           [0011]      FIG. 1A  is a perspective view of a jetting assembly according to an embodiment of the present technology; 
           [0012]      FIG. 1B  is an enlarged view of the area indicated by the circle  1 B in  FIG. 1A ; 
           [0013]      FIG. 2  is a side view of the jetting assembly of claim  1  in operation during a primary phase of drilling a well; 
           [0014]      FIG. 3A  is a perspective view of a system for running, setting, and testing subsea jetting tools according to an embodiment of the present technology; 
           [0015]      FIG. 3B  is an enlarged side view of a portion of the jetting equipment shown in  FIG. 3A , as indicated by the area  3 B of  FIG. 3A ; 
           [0016]      FIG. 4  is a side view of a the jetting assembly according to an embodiment of the present technology, with a known analog inclination sensor and a remotely operated vehicle; 
           [0017]      FIG. 5A  is a side view of the jetting assembly according to an embodiment of the present technology, including an electrical inclination sensor attached to the stem of the housing running and jet tool; 
           [0018]      FIG. 5B  is an enlarged side view of the electrical inclination tool attached to the stem of the housing running and jet tool, as indicated by area  5 B of  FIG. 5A ; 
           [0019]      FIG. 6  is a perspective view of components of a system for running, setting, and testing subsea jetting tools according to an embodiment of the present technology, including a transmitter and receiver configured to communicate via mud pulse data transmission; 
           [0020]      FIG. 7A  is a side view of components of a system for running, setting, and testing subsea jetting tools according to an embodiment of the present technology, including a transmitter and receiver configured to communicate via acoustic data transmission; and 
           [0021]      FIG. 7B  is a side view of a portion of the jetting assembly, including an electrical inclination sensor and a transmitter configured for acoustic data transmission, as indicated by area  7 B of  FIG. 7A . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    The foregoing aspects, features, and advantages of the present technology will be further appreciated when considered with reference to the following description of preferred embodiments and accompanying drawings, wherein like reference numerals represent like elements. In describing the preferred embodiments of the technology illustrated in the appended drawings, specific terminology will be used for the sake of clarity. However, the technology is not intended to be limited to the specific terms used, and it is to be understood that each specific term includes equivalents that operate in a similar manner to accomplish a similar purpose. 
         [0023]      FIG. 1A  shows a jetting assembly  10  according to an embodiment of the present technology, including a low pressure housing  12 , a casing string  14 , a housing running and jet tool  16 , drill pipe  18 , and a jetting tool  20 . The housing running and jet tool  16  has a stem  21 . Jetting assembly  10  is configured to accomplish the first phase of a drilling program, by beginning drilling a wellbore into the sea floor. As shown in  FIG. 1B , when the jetting assembly  10  is assembled, the end  22  of the jetting tool  20  is positioned a predetermined distance D from the bottom of the casing string  14 . In one embodiment, this distance D may be about 18 inches. Before initiating jetting operations, and during the course of jetting the first phase of the well, it is desirable for the jetting assembly  10 , and in particular the drill pipe  18  and the casing  14 , to be vertically oriented. Such a vertical orientation allows for the successful connection and operation of equipment during subsequent drilling phases. 
         [0024]      FIG. 2  shows the jetting assembly  10  in practice. Once the jetting assembly  10  is positioned vertically adjacent the sea floor  24 , the jetting tool  20  ejects fluid downward toward the sea floor  24 . The ejection of fluid causes turbulence at the end of the casing string  14 , which turbulence stirs up the sand and sediment on the sea floor  24 . As the sand and sediment is stirred up, it is carried by the fluid upwardly through the casing string  14 , along the path indicated by arrows A. In the embodiment shown, the sand and sediment may be discharged into the sea through the low pressure housing  12 . As the sand and sediment is stirred and carried upward by the drill fluid, a void space is created immediately below the casing string  14 . The casing string  14  then travels downward to fill the void space. This sequence of operation (i.e., jetting, removal of sand and sediment, and lowering of the casing string) is repeated as needed until the assembly  10  achieves a predetermined depth. The fluid may be incontaminable, to minimize or eliminate environmental hazards when the fluid is discharged in the sea along with the sand and sediment. 
         [0025]    Referring to  FIG. 3A , there is shown a system for running, setting, and testing subsea jetting tools, including equipment used to carry out subsequent phases of drilling after the first phase is completed. Specifically,  FIG. 3A  shows a drilling vessel  26 , located at the surface of the sea, and additional subsea drilling equipment located at the sea bed  24 . Although the drilling vessel  26  is shown to be a ship, it could also be a drilling platform, such as, for example, a floating platform, tension leg platform, etc. An enlarged view of some of this additional subsea drilling equipment is shown in  FIG. 3B , and includes the low pressure housing  12 , a high pressure housing  30  configured for insertion inside the low pressure housing  12 , and a pressure management device  32 , such as, for example, a blowout preventer (BOP). As shown, the subsea drilling equipment may be connected to the drilling vessel  26  by a marine riser  28 . 
         [0026]    In practice, the jetting assembly  10  may be assembled on the drilling vessel  26 . To accomplish this, the housing running and jet tool  16  is inserted and locked into the low pressure housing  12 . Drill pipe  18  is also attached to the housing running and jet tool  16 . This may be accomplished by connecting a bottom thread of the housing running and jet tool  16  to a top thread of the drill pipe  18 . Similarly, the jetting tool  20  may then be attached to the drill pipe  18  by, for example, connecting a bottom thread of the drill pipe  18  with a top thread of the jetting tool  20 . The casing string  14  is also connected to the low pressure housing  12 , and is configured so its bottom end is a predetermined distance D from the bottom end  22  of the jetting tool  20 , as discussed above. Once the jetting assembly  10  has been assembled, it is lowered to the sea floor. The jetting assembly  10  remains connected to the drilling vessel  26  by a drill pipe (not shown) which extends upwardly through the marine riser  28  from the jetting assembly  10  to the drilling vessel  26 . The fluid to be ejected by the jetting tool  20  is delivered to the jetting tool  20  from the drilling vessel  26  via the drill pipe  18 . 
         [0027]    As discussed above, it is desirable that the jetting assembly  10  maintain a vertical orientation through the jetting phase. Accordingly,  FIG. 4  shows one known method of verifying such a vertical orientation that includes an analog inclination measuring device  34  attached to the jetting assembly  10 . In an example, an analog inclination measuring device  34  is of the type known as a “Bullseye” device in the industry that includes liquid in a sealed chamber, and a ball floating in the liquid. Reference lines are drawn on surfaces of the chamber, and as the equipment inclines, the liquid pushes the floating ball to a corresponding reference line. Association of the ball with a particular reference line indicates how much the device is inclined. Options exist where the analog inclination measuring device  34  is attached to or formed integrally with, the housing running and jet tool  16 . 
         [0028]    In practice, the use of such an analog inclination measuring device  34  requires that an inclination reading be taken between each iteration of jetting (i.e., between each sequence of jetting, sand and sediment removal, and lowering of the casing string). Such an inclination reading requires use of a remotely operated vehicle (ROV)  36 , and can be time consuming and inefficient. This is because the ROV  36  can only read the analog inclination measuring device  34  from close proximity, as shown in  FIG. 4 . During the actual jetting operation, however, the ROV  36  must be positioned relatively far away from the jetting assembly  10  so as not to interfere with operations. This means that between each iteration of jetting, the ROV  36  must move into close proximity of the analog inclination measuring device  34 , take the inclination reading, transmit the reading to an operator on the drilling vessel  26 , and move back away from the jetting assembly  10  a safe distance. 
         [0029]    A better way to measure the inclination of the jetting assembly  10  is through the use of an electrical inclination sensor  38 , as shown in  FIGS. 5A and 5B . One example of such an electrical inclination sensor  38  is disclosed in U.S. Pat. No. 4,937,518, which is hereby incorporated by reference herein. As shown, the electrical inclination sensor  38  is attached to the jetting assembly  10 , and is configured to send an inclination signal to an operator on the drilling vessel  26  in real time. In some embodiments, the electrical inclination sensor  38  may be attached to the stem  21  of the housing running and jet tool  16 . In other embodiments, the electrical inclination sensor  38  may be attached to the low pressure housing  12  (as shown in  FIG. 7 ). 
         [0030]    The real time transmission of inclination data from the jetting assembly  10  to an operator on the drilling vessel  26  is advantageous because it eliminates the need to stop jetting between each jetting iteration to allow the ROV  36  to take an inclination reading. Furthermore, the real time transmission allows an operator to detect a problem with the inclination immediately when the problem occurs, rather than waiting for the next break between jetting iterations. Thus, the jetting process is more efficient, and potential problems can be identified and remedied more rapidly. 
         [0031]    Signal transmission from the electrical inclination sensor  38  to the operator on the drilling vessel  26  can be accomplished in at least two different ways. For example, the data signal from the electrical inclination sensor  38  can be sent via mud pulse transmission (shown in  FIG. 6 ) or acoustic data transmission (shown in  FIG. 7 ). In each case, the data signal is transmitted from the electrical inclination sensor  38  by a transmitter  40 , and received by a receiver  42 . 
         [0032]    In the case of mud pulse transmission, shown in  FIG. 6 , the electrical inclination sensor  38  may be attached to the stem  21  of the housing running and jet tool  16 . The transmitter  40  may also be attached to the stem  21  of the housing running and jet tool  16 , and may be connected to the electrical inclination sensor  38  by a wire (not shown). Coupled with the drill pipe  18 , proximate the drilling vessel  26 , is a receptor stem  44 . The receptor stem  44  may be attached to the drill pipe  18  by engaging a top thread of the drill pipe  18  with a corresponding bottom thread of the receptor stem  44 . A receiver  42  is attached to the receptor stem  44  and in communication with a display  46  that is viewable by an operator. 
         [0033]    In practice, the electrical inclination sensor  38  determines the inclination of the stem  21  of the housing running and jet tool  16 , which corresponds to the inclination of the entire drill assembly  10 . The inclination sensor  38  then communicates the inclination data to the transmitter  40 . Next, the transmitter  40  transmits an inclination data signal upward in a pulse through the mud surrounding the stem  21  and the drill pipe  18  to the receptor stem  44 . At the receptor stem  44 , the receiver  42  receives the signal, and communicates the inclination data to the display  46 . In certain embodiments, the inclination data is generated constantly by the electrical inclination sensor  38  and transmitted in real time to the receiver  42 . Thus, the operator receives continuous real time data about the inclination of the drill assembly  10  throughout the primary jetting process. 
         [0034]    In an example of acoustic data transmission, as shown in  FIGS. 7A and 7B , the electrical inclination sensor  38  is attached to an outer face of the low pressure housing member  12 . Likewise, the transmitter  40  is attached to the outer surface of the low pressure housing member  12 , and is connected to the electrical inclination sensor  38  by a wire (not shown). Receiver  42  is positioned near the drilling vessel  26  (shown as a floating platform in  FIG. 7 ), and is connected to a display  46  (shown in  FIG. 6 ) that is viewable by an operator. 
         [0035]    In an example of operation, the electrical inclination sensor  38  senses an inclination of the low pressure housing  12 , which corresponds to the inclination of the entire drill assembly  10 . The inclination sensor  38  then communicates the inclination data to the transmitter  40 , which transmits an inclination data signal into the surrounding sea water that is received by receiver  42 . Based on the received signal, the receiver  42  communicates the inclination data to the display  46 . In certain embodiments, the inclination data is generated constantly by the electrical inclination sensor  38  and transmitted in real time to the receiver  42 . Thus, the operator receives continuous real time data about the inclination of the drill assembly  10  throughout the primary jetting process. In this embodiment, the receiver  42  is submerged in the sea water proximate the vessel so that it can better intercept the acoustic signals transmitted by the transmitter  40 . 
         [0036]    In certain embodiments, the receiver  42  can communicate with an analysis device or system, such as a computer, processor, network, software, analytics engine, etc. Such communication may be by means of a wire, or wireless transmission signals. The analysis device or system may be adapted to react to certain data received from the receiver  42  by, for example, sounding an alarm, sending a message, or sending control signals to automatically or semi-automatically control the equipment. In addition, the analysis device or system could be located near the receiver  42  or remote from the receiver  42 , such as, for example, at a distant location. 
         [0037]    While the technology has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention. Furthermore, it is to be understood that the above disclosed embodiments are merely illustrative of the principles and applications of the present invention. Accordingly, numerous modifications may be made to the illustrative embodiments and other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.