The present application relates to the well drilling industry and particularly to methods and systems for tripping pipe on a drill rig.
Drill pipes, tubulars, and the like are often used to drill holes for oil and gas wells. A series of drill pipes are attached end to end to form an elongated drill string. A rotatable bit for making new hole is attached to the lowermost end of the string. Assembly and disassembly of the string is accomplished by a process called “tripping”. To “trip in” to a hole being drilled, new pipes are sequentially added to the upper end of the string to allow the string to be run further into the hole. To “trip out” of a hole once it has been drilled, pipes are sequentially removed from the upper end of the string as it is removed from the hole.
Conventional systems for performing a tripping process include a drill rig having a floor and a rotary table positioned over a hole to be drilled in the ground. A mechanized catwalk is configured to move new drill pipes towards the rig floor. The drill pipe “in the hole” extends above the rotary table by a height called the “stick-up”. A hoisting device, such as a winch or pulley system having a traveling block, is supported on a mast assembly above the rig floor. To trip a new pipe into the hole, the hoisting device is clamped to the new pipe and then moved upwards to allow the pipe to swing freely above the stick-up section of the drill pipe in the rotary table. The lower end of the pipe is then aligned with and stabbed into the upper end of the drill pipe in the rotary table. Thereafter, joystick controls are manually operated to move a torque-making machine, such as a mechanized wrench, tongs, and/or the like, to the well center and to engage with and torque the pipe to the string or the drill pipe is torqued manually using conventional tongs. Thereafter a slip mechanism holding the string in place is released and the string is run further into the hole. The above process is continued repeatedly to trip into the hole, and repeatedly in reverse order to trip out of the hole.
The present application recognizes that conventional systems and methods for tripping pipe are inefficient. For example, it is currently necessary to manually control several items of machinery during the tripping process to ensure that the stick-up height of the drill string and the clearance distance between the drill string and a pipe to be tripped are both within operational parameters of the torque making machine. That is, a typical torque making machine can only engage with the drill string and the pipe to be tripped at a predetermined vertical location above the drill floor. In conventional systems, it is necessary to use manual control to achieve the correct stick-up height and clearance distance necessary to facilitate attachment of the torque-making machine. Manual control of the hoisting device is often required to achieve the correct clearance distance between the upper end of the drill string and the lower end of the pipe to be tripped. Also, manual control of the torque making machine is often required to move the torque making machine to the correct location at the well center and to cause the torque making machine to engage with and connect or disconnect the drill string and pipe to be tripped. Each of these interventions is time consuming, expensive, and can unfortunately result in operator error and/or operator injury.
The present application provides improved methods and systems for tripping pipe that overcome disadvantages of the prior art. In several of the examples, methods of adjusting a velocity at which a drill string is moved within a well are provided. One method includes adjusting the velocity at which the drill string is moved within the well based upon a hookload associated therewith. Another method includes adjusting the velocity at which the drill string is moved within the well based upon the actual velocity at which the drill string is moved within the well. Another method includes adjusting the velocity at which the drill string is moved within the well based upon the volume of fluid displaced by the drill string flowing from the well as it is lowered into the well.
In one embodiment, a method of adjusting a velocity at which a drill string is moved within a well is provided. The method includes measuring a first hookload associated with a drill string indicative of a weight associated with the drill string, calculating a second hookload associated with the drill string indicative of a presumed weight associated with the drill string, and comparing the first hookload to the second hookload to determine whether the first hookload deviates from the second hookload by at least a target weight limit. The method further comprises, in response to determining that the first hookload deviates from the second hookload by at least the target weight limit, reducing a velocity at which the drill string is moved within a well.
In another embodiment, another method of adjusting a velocity at which a drill string is moved within a well is provided. The method includes determining an actual velocity at which a drill string is moved within a well, determining a target velocity at which to the drill string is to be moved within the well, and comparing the actual velocity to the target velocity to determine whether the actual velocity exceeds the target velocity by at least a target speed limit. The method further comprises, in response to determining that the actual velocity exceeds the target velocity by at least the target speed limit, reducing the actual velocity at which the drill string is moved within the well.
Yet another embodiment includes a method of adjusting a velocity at which a drill string is moved within a well. The method includes measuring a first volume of fluid flowing from a well in response to lowering at least a portion of a drill string therein, calculating a second volume of fluid indicative of a volume of fluid displaced by lowering the at least a portion of the drill string within the well, and comparing the first volume to the second volume to determine whether the first volume is greater than the second volume. The method further comprises, in response to determining that the first volume is greater than the second volume, reducing the velocity at which the at least a portion of the drill string is lowered into the well.
Further examples are provided herein below.
The best mode of carrying out the invention is described herein, with reference to the following drawing figures.
In the following description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The different systems and method steps described herein may be used alone or in combination with other systems and method steps. It is to be expected that various equivalents, alternatives, and modifications are possible within the scope of the appended claims.
A mechanized frame or catwalk 27 is located adjacent the drill rig 10 and includes a lifting mechanism 28 for lifting drill pipes to be added to the drill string 18. In the example shown, a drill pipe 30 to be tripped is positioned in a groove 32 (
A controller 42 containing a memory and suitable programmable computer logic is also provided and is shown schematically in
One or more user input devices 44 such as a keyboard or the like can also be included to facilitate input of user commands and associated data into the controller 42 via one or more links 43. Alternately, command inputs and data can be transmitted to the controller 42 via a wired or wireless link 46 connected to measuring equipment or other controller devices or parts of controller 42. Output from the controller 42 to the above described machinery can be transmitted for example via a wired or wireless link 48.
The system depicted in
At Step 100 of the exemplary method (
In the example shown, Step 100 also includes measurement of additional length characteristics of drill pipe 30, namely the length B of tool joint 38 and length P of pin 51 (
Once the measurements of Step 100 are completed, the measured values (e.g. A, B, P) are communicated to the controller 42 via for example the input device 44 or the link 46.
At Step 102 (
In this example, calculation of the elevation distance D is accomplished in two steps (managed in real time by the controller 42). First, the length B of tool joint 22 is subtracted from the total length A of pipe 30 to determine the free hanging length E. The free hanging length E is then added to the desired clearance distance C and to the stickup height S to obtain the distance D. In equation form, this logic presents as follows:
E=A−B
D=E+C+S
At Step 104 (
At Step 106 (
At Step 107 (
H=S+E−P
At Step 108 (
F=E+C+S−(S−B)
F=E+C+B
F=A+C
Alternately, a position for the point of attachment of the traveling block associated with the hoisting device 26 to the body 31 of the drill pipe 30 can be determined. Thus the necessary position of the traveling block and a drill pipe 30 in the vertical direction can be determined. In this example, the stop point G can be calculated by subtracting the tool joint length B from the stick-up height S. In equation form, this logic presents as follows:
G=S−B
At Step 110 (
The following table provides exemplary output data for a method of tripping five drill pipes having different length characteristics.
The above described method steps also provide the ability to raise the drill string 18 out of the hole 15 so that the break out point or the upper end of each drill pipe in the string 18 is sequentially positioned at the predetermined stick-up height S, thus eliminating the need for manual control of the slip mechanism and the torque making machine. In the example shown, the controller 42 is configured to calculate at Step 112 a retrieval distance necessary for the uppermost drill pipe (here the drill pipe 30) to travel out of the well so that the upper end 34 of the drill pipe 30 is positioned so as to extend above the rig floor 16 by the predetermined stick-up height S. In effect the controller 42 uses the input during “trip in” to create a stack of length statistics for drill string components and uses the stack in “Last in First out” basis while “trip out” to move the hoisting device 26 to a pre-calculated height allowing to maintain constant stick of next drill pipe. In the example shown, the controller 42 utilizes the calculated position H of the lifting mechanism 26 to raise the drill string 18 while also halting the introduction of of drilling fluid to the hole 15 (e.g., to maintain the integrity thereof as the drill string 18 is raised) at Step 114.
At Step 116 (
In one embodiment, and with reference to
In any event, the measured hookload and the calculated hookload are compared to determine a deviation therebetween. The deviation between the calculated hookload and the measured hookload is compared to a pre-set raising limit (i.e., a “target weight” limit). If the pre-set raising limit is met or exceeded, the controller 42 stops raising the drill string 18 and proceeds to Step 110. The controller 42 continues lowering the drill string 18 into the hole 15 at Step 110 until a target length of the drill string 18 is lowered into the hole 15. Upon lowering the target length of drill string 18 into the hole 15, fluid circulation is re-established and the drill string 18 is rotated at maximum rpm at least until the deviation between the calculated hookload and the measured hookload no longer meets or exceeds the pre-set raising limit. Alternatively, the drill string 18 may be rotated at maximum rpm until the deviation between the calculated hookload and the measured hookload is within a pre-set recovery limit. In any event, once the deviation is acceptable, the controller 42 proceeds to Step 114 to again raise the drill string 18 out of the hole 15.
Additionally and/or alternatively, the controller 42 may regulate the speed of lowering the drill string 18 based on the drill string 18 hookload. In that embodiment, and at Step 110, the controller 42 compares the value of the calculated hookload to the value of the measured hookload. The deviation between the two values is calculated and compared to a pre-set lowering limit. If the pre-set lowering limit is met or exceeded, the controller 42 stops lowering the drill string 18 into the hole 15 and proceeds to Step 114 until a target length of the drill string 18 is raised from the hole 15. Upon lowering the target length of drill string 18 into the hole 15, fluid circulation is re-established and the drill string 18 is rotated at maximum rpm at least until the deviation between the calculated hookload and the measured hookload no longer meets or exceeds the pre-set lowering limit. Alternatively, the drill string 18 may be rotated at maximum rpm until the deviation between the calculated hookload and the measured hookload is within a pre-set recovery limit. In any event, once the deviation is acceptable, the controller 42 proceeds to Step 110 to again lower the drill string into the hole 15.
In another embodiment, the controller 42 regulates the speed at which the drill string 18 is raised in Step 114 based on velocity. In that embodiment, and at step 114, the controller 42 measures or receives an indication of the velocity of the drill string 18 as it is raised out of the hole 15 (i.e., an “actual” velocity). The controller 42 then compares the measured velocity to an acceptable velocity (i.e., a “target” velocity). The acceptable velocity may be either calculated by the controller 42 based upon information associated with the drill string 18 or hole 15 (e.g., based upon the calculated or measured weight of the drill string 18 or the geometry of the hole 15, to name a few characteristics) or be pre-set (e.g., such as entered through the user input 44). In some embodiments, the acceptable velocity is a speed that is selected to avoid damage to the drill rig 10, hole 15, or drill string 18. In a specific example, the acceptable velocity may be one that is selected to avoid swabbing, in which the drill string 18 is pulled from the hole 15 at speed that causes a drop in pressure sufficient to collapse or otherwise damage the hole 15.
Such damage can take the form of the removal of mud cake, pressure instability in the hole 15, or unwanted fluids entering the hole 15.
In any event, the measured velocity is compared to the acceptable velocity. If the measured velocity deviates from the acceptable velocity by more than a target speed difference, the controller 42 may be configured to slow the speed at which the drill string 18 is raised from the hole 15 at Step 114 (e.g., such as by decreasing the speed at which the hoisting device 26 operates). Alternatively, the controller 42 may be configured to decrease the speed at which the drill string 18 is raised from the hole 15 at Step 114 to prevent the measured velocity from meeting or exceeding the acceptable velocity.
In a still further embodiment, the controller 42 regulates the speed at which the drill string 18 is raised in Step 114 based on the volume of fluid flowing into or out of the hole 15. In that embodiment, and at Step 114, the controller 42 measures the volume of fluid flowing into the hole 15, such as through a conventional flow meter (not shown). The controller 42 also calculates the volume of the drill string 18 being removed from the hole 15. The controller 42 then compares the measured volume of fluid flowing into the hole 15 to the calculated volume of drill string 18 being removed. If the measured volume deviates from the calculated volume by a pre-set limit, the controller 42 stops removing the drill string 18 at step 114. In response to stopping the removal of the drill string 18, the controller 42 positions the drill string 18 such that a conventional blow out preventer (BOP) (not shown) can close against the pipe body 31. Once in position, the controller 42 performs a flow check to confirm whether the flow of the drilling fluid is continuing at its normal pace. If flow is confirmed, the controller 42 closes the BOP.
Moreover, and in another embodiment, the controller 42 may regulate the speed at which the drill string 18 is lowered in Step 110 based on the volume of fluid flowing into or out of the hole 15. In that embodiment, and at Step 110, the controller 42 measures the volume of fluid flowing from the hole 15. The controller 42 also calculates a volume of drill string 18 being lowered into the hole 15. The controller 42 then compares the measure volume of fluid flowing from the hole 15 to the calculated volume of drill string 18 being lowered into the hole 15. If the measured volume is exceeds the calculated volume, the controller 42 stops lowering the drill string 18 at Step 110 and positions the drill string 18 such that the BOP can close against the pipe body 31. Once in position, the controller 42 performs a flow check to confirm whether fluid continues to flow from the hole 15. If flow is confirmed, the controller 42 closes the rig BOP.
Alternatively, the controller 42 may be configured to merely reduce the velocity at which the drill string 18 is lowered into the hole 15 at Step 110 when the measured volume is less than the calculated volume. In that embodiment, if the difference between the measured volume and the calculated volume meets or exceeds a pre-set deviation, or if the velocity at which the drill string 18 is lowered reaches a pre-set limit, the controller 42 stops lowering the drill string 18 into the hole 15 in Step 110 and starts pumping fluids in the hole 15 to maintain the integrity thereof.
Moreover, one having ordinary skill in the art will appreciate that the invention, in its broader aspects, is not limited to the specific details shown and described above. For example, and at Step 106, the controller 42 may perform a flow check to detect any influx from the hole 15. If an influx is detected, the controller 42 may stop connecting the drill pipe 30 to the drill pipe 20 and close the BOP. By way of further example, and at Step 116, the controller 42 may perform a flow check to detect any influx from the hole 15. If an influx is detected, the controller 42 may stop disconnecting the drill pipe 30 from the drill pipe 20 and close the BOP.
The above described steps can be continued repeatedly to trip into the hole 15 or trip out of the hole 15.
This application is a continuation-in-part and claims the benefit of application of U.S. Ser. No. 12/326,727 filed Dec. 2, 2008, the disclosure of which is incorporated by reference in its entirety herein.
Number | Date | Country | |
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Parent | 12326727 | Dec 2008 | US |
Child | 13099015 | US |