METHODS AND SYSTEMS FOR TRIPPING PIPE

Abstract

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.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

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.

FIELD

The present application relates to the well drilling industry and particularly to methods and systems for tripping pipe on a drill rig.

BACKGROUND

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.

SUMMARY

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.

BRIEF DESCRIPTION OF THE DRAWINGS

The best mode of carrying out the invention is described herein, with reference to the following drawing figures.

FIG. 1 is a flow chart illustrating one example of a method of tripping in hole according to the present application.

FIG. 2 is a flow chart illustrating one example of a method of tripping out of hole according to the present application.

FIG. 3 is a schematic illustrating an exemplary system for tripping on a drill rig.

FIG. 3A is a view of Section 3A-3A taken in FIG. 3.

FIG. 3B is a view Section 3B-3B taken in FIG. 3.

FIG. 4 is the schematic shown in FIG. 3, wherein a drill pipe to be tripped is being raised towards the drill rig.

FIG. 5 is the schematic shown in FIG. 4, wherein the drill pipe is raised above a drill string by a clearance distance.

FIG. 6 is a detailed view of the drill rig shown in FIG. 5 showing a hoisting device in a raised position.

FIG. 7 is the schematic shown in FIG. 5 showing the hoisting device in a lowered position, wherein the drill pipe extends above a rig floor by a stick-up height.

DETAILED DESCRIPTION OF THE DRAWINGS

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.

FIGS. 1 and 2 depict exemplary method steps for completing a tripping in process according to the present application and a tripping out process according to the present application, respectively. The steps set forth in FIGS. 1 and 2 are described with reference to FIGS. 3-7 herein below.

FIG. 3 schematically depicts an exemplary system for completing the method steps set forth in FIGS. 1 and 2. A drill rig 10 includes a conventional framed substructure 12 and a conventional framed mast structure 14. The substructure 12 defines a rig floor 16 having a rotary table (not shown) positioned over a hole 15 to be drilled in the ground 17. The mast structure 14 is positioned over the rig floor 16. A drill string 18 extends out of the hole 15 and includes an uppermost drill pipe 20 having its upper end 22 extended above the rig floor 16 by a predetermined stick-up height S. The drill pipe 20 is maintained in the position shown by conventional means such as for example a slip mechanism (not shown). The upper end 22 of the pipe 20 includes a conventional tool joint 24 (i.e. a “box”), which has a larger outer diameter than the outer diameter of the body 23 of the drill pipe 20. The tool joint 24 is configured to mate with and removably connect with a corresponding tool joint (e.g. 40; i.e. a “pin”) on another drill pipe (e.g. 30), as will be described further below. A hoisting device 26 having for example a traveling block and clamp is supported on the mast structure 14 and is configured to move vertically up and down above the upper end 22 of the drill string 18. The hoisting device 26 is configured to be attached to a new drill pipe (e.g. 30), which is to be attached to the upper end 22 of the drill string 18, as will be discussed further below.

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 (FIGS. 3A and 3B) on the catwalk 27. The drill pipe 30 has a first (upper) end 34 and a second (lower) end 36, each of which have conventional tool joints 38, 40, respectively attached thereto and configured in a manner similar to that described above. Tool joint 38 has a box and tool joint 38 has a box and tool joint 40 has a pin 51, as is conventional. A stopper mechanism 41 (FIG. 3B) which can alternately be a brake or the like is positioned in the groove 32 at one end of the lifting mechanism 28. A skate mechanism 39 (FIG. 3A), or the like, is disposed in the groove 32 at the other end of the lifting mechanism 28. A feeler gauge 44 (FIG. 3B), or like measuring instrument is positioned proximate the end 34 of the drill pipe 20 and so as to engage with the enlarged outer diameter of the tool joint 38, the enlarged outer diameter of the tool joint 40, and the smaller inner diameter of the pin 51, as will be described further below.

A controller 42 containing a memory and suitable programmable computer logic is also provided and is shown schematically in FIGS. 3, 4, 5 and 7. The controller 42 is configured to control conventional machinery associated with the drilling rig 10 for drilling the hole 15 and for completing pipe tripping processes, as described herein. The controller 42 is shown schematically as a box, however it can be configured in a variety of different ways and can include separate controller devices located apart from each other. In one example, one part of the controller 42 can be located on the rig floor 16 and be configured to control the overall drilling rig machinery. A second part of the controller 42 can be located away from the rig floor 16 and be configured to control the lifting mechanism 28, store length characteristics of the drill pipes to be tripped, and communicate the same with the first part of the controller 42. The lifting mechanism 28; a hoisting mechanism 26 such as the illustrated pulley having a clamp and traveling block; a torque-making machine such as a mechanized wrench, tongs or the like (not shown); and/or a slip mechanism (not shown) for holding the uppermost pipe (e.g. 20) in the drill string 18 in place are provided and can all be operationally controlled by one or more parts of the controller 42.

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 FIGS. 3 and 4 is capable of elevating and supporting the drill pipe 30 in a vertical, raised orientation (P1; FIG. 5) on the mast structure 14 according to conventional practices. For example, the system can include a lifting mechanism 28, which can include for example a hydraulic ramp or V-door, and a hoisting device 26 having a traveling block and a clamp that is configured to engage with and grasp the body 31 of the drill pipe 30 immediately below the tube joint 38. Once the lifting mechanism 28 is raised, the hoisting device 26 is clamped to the body of the pipe 30. Thereafter, the hoisting device 26 is raised into the vertical position shown, and the weight of the drill pipe 30 causes the enlarged outer diameter of the tool joint 38 to engage with a smaller diameter opening on the clamp, thus supporting the drill pipe 30 in a vertical orientation P1 (FIG. 5). It should be recognized however that the methods and systems described herein are also applicable with other conventional systems for elevating and supporting drill pipes in a vertical orientation. That is, the structures shown, such as the lifting mechanism 28, hoisting device 26 and drill rig 10 are shown for illustrative purposes only.

At Step 100 of the exemplary method (FIG. 1), drill pipe 30 is rolled into the groove 32 in catwalk 27. Skate mechanism 39 is operated to push the drill pipe 30 against stopper mechanism 41 in the direction of arrow 33. Once the drill pipe 30 is seated between the skate mechanism 39 and stopper mechanism 41, the distance between the skate mechanism 39 and the stopper mechanism 41 equates to a first measured length characteristic A of drill pipe 30, which in this example is the entire longitudinal length (i.e. the length from the upper end 34 to the lower end 36) of the drill pipe 30. Alternate conventional means for conducting this measurement could be used, such as for example optical, laser or motion sensors, and/or the like.

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 (FIG. 3B). Stopper mechanism 41 is removed from the groove 32 and skate mechanism 39 is operated to push drill pipe 30 longitudinally along the groove 32 towards the drill rig 10 in the direction of arrow 33. As the drill pipe 30 moves past the feeler gauge 44, the enlarged diameter of the tool joint 38 engages with and actuates the feeler gauge 44. Specifically, the feeler gauge 44 is activated upon engagement with the tool joint 38 and deactivated upon disengagement with tool joint 38 as the skate mechanism 39 pushes the drill pipe 30 past the feeler gauge 44 in the direction of arrow 33. This same process can also be employed to measure the length of the tool joint 40 and the length P of pin 51 on tool joint 40. The feeler gauge 44 is a conventional device such as a stroke counter, proximity device adapted to measure the distance between the actuations made by engagement and disengagement with the large outer diameter of the tool joint 38, which distance correlates to the entire longitudinal length B (FIG. 3B) of tool joint 38. Measurement of the length B of the tool joint 38 can be accomplished by many other alternative conventional apparatus and methods, such as optical, laser or motion sensors, and/or the like. The feeler gauge 44 or other measurement device is similarly configured to measure the length of tool joint 40 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 (FIG. 1), an elevation distance D necessary to raise the drill pipe 30 above the uppermost end 22 of drill pipe 20 into a position wherein a predetermined clearance distance C exists between the lower end 36 of the drill pipe 30 and the upper end 22 of the drill pipe 20 is calculated. In the example shown in FIGS. 5 and 6, the measured length characteristics A, B, P and the stick-up height S are inputted into the controller 42 via either the link 46 or the user input device 44. The controller 42 then calculates, based upon the length characteristics A, B and the stick-up height S, the elevation distance D (FIG. 6) necessary to raise the drill pipe 30 above the upper end 22 of the drill pipe 20 so that the lower end 36 of the drill pipe 30 and the upper end 22 of the drill pipe 20 are separated by a predetermined clearance distance C.

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 (FIG. 1), the drill pipe 30 is raised to the calculated elevation distance D to achieve the clearance distance C. In the example shown in FIGS. 4 and 5, the controller 42 communicates with the lifting mechanism 28 to actuate the lifting mechanism 28 and raise the drill pipe 30 to a position proximate the hoisting device 26. The controller 42 then actuates the hoisting device 26 to clamp the body 31 of the drill pipe 30 and to raise the hosting device 26 into a raised position, P1 (FIG. 6), and thus raise the upper end 34 of the drill pipe 30 the elevation distance D. Thus, as shown in FIG. 6, the drill pipe 30 is moved into the raised position P1 wherein the desired clearance distance C exists between the upper end 22 of the drill pipe 20 and the lower end 36 of the drill pipe 30.

At Step 106 (FIG. 1), the upper end 22 of the drill pipe 20 and the lower end 36 of the drill pipe 30 are connected. This step can be conducted by a conventional torque making machine, such as a mechanized wrench, tongs, and/or the like, positioned at the well center to engage and torque the upper end 22 of the drill pipe 20 and the lower end 36 of the drill pipe 30 together. In a preferred example, the controller 42 is configured to communicate with and control the torque making machine. Unlike conventional methods, operation of the torque making machine without manual intervention is possible because the controller 42 operates based upon the measurements A, B and the stick-up height S to ensure that the predetermined clearance distance C is achieved and to confirm that the stick-up height S is always constant and within operating parameters for the torque-making machine. This allows the torque-making machine to operate in one axis only, moving a fixed distance each time, allowing it to be part of the automated sequence managed by controller 42.

At Step 107 (FIG. 1), the position H (not shown in drawings) of the hoisting device 26 after connection of the drill pipes 20, 30 is calculated by the controller. In a preferred example, the controller 42 is configured to calculate this value by adding the stick-up height S to the free hanging length E and subtracting the measured pin length P for the particular pin 51 associated with the drill pipe 30. In equation form, this logic presents as follows:

H=S+E−P

At Step 108 (FIG. 1), the distance F necessary to move the drill pipe 30 downward into a lowered position P2 (FIG. 7) wherein a predetermined stick-up height S exists for the upper end 36 of drill pipe 30 is calculated. In the example shown in FIG. 7, the calculation of this distance is accomplished by subtracting the lowered position P2 of the hoisting device 26 from its raised position P1. The initial raised position P1 as noted in FIG. 6 for the hoisting device 26 or more specifically the clamp is P1=E+C+S while final lowered position P2 required for the clamp to maintain constant stick up S is P2=S−B. The distance F necessary to move the drill pipe 30 is hence the difference between these two positions given as:

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 (FIG. 1), the drill rig 10 is operated to move the drill pipe 30 the calculated distance F or to move the machinery to the position G. In the example, shown, the controller 42 communicates with and controls the slip mechanism (not shown) to release the drill string 18 and controls drilling machinery to move further into the hole 14. Once the hoisting device 26 reaches the reaches the stop point G (or once the drill pipe moves the drilling distance F), the controller 42 causes the movement to cease and the slip mechanism (not shown) to re-engage with and maintain the drill string 14 in a stationary position. As shown in FIG. 7, the drill pipe 30 is placed in a position so that it has the predetermined stick-up height S, allowing for the above-described process for tripping into the hole to repeat.

The following table provides exemplary output data for a method of tripping five drill pipes having different length characteristics.

							Final Position of
							Lift Mechanism After
							(Recorded Connection
				Clearance Desired	Stick-Up Height		by Controller)
				Between Lower	Desired for Upper		“H” = S + E − P
	Measured	Measured		End of Drill Pipe	End of Upper-	Elevation Distance	“P” = Pin Length	Stop Poin Required
	Length of	Length of		and Upper End	most Drill Pipe	Required to	(P will vary from pipe to	to Attain Stick-Up
	Drill Pipe	Tool Joint	Upset Length	of Drill Pipe	in Drill String	Attain Clearance	pipe-assuming 0.5′ for this	Height for Drill Pipe
Stand	“A”	“B”	A − B = “E”	“C”	“S”	“D” = (S + C + E)	column for each pipe)	“G” = S − B
1	61.54	0.75	60.79	.5	8	69.29	68.29	7.25
2	61.26	0.76	60.50	.5	8	69.00	68.00	7.24
3	62.12	0.89	61.23	.5	8	69.73	68.73	7.11
4	61.72	0.92	60.80	.5	8	69.30	68.30	7.08
5	62.70	1.10	61.60

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 (FIG. 2), the upper end 22 of the drill pipe 20 and the lower end 36 of the drill pipe 30 can be disconnected. This step can be conducted by a conventional torque making machine, such as a mechanized wrench, tongs, and/or the like, positioned at the well center to engage and torque the upper end 22 of the drill pipe 20 and the lower end 36 of the drill pipe 30 together. As described above, the controller 42 can be configured to communicate with and control the torque making machine, thus eliminating the need for human intervention. The torque making machine will need to move in one axis only, allowing it to become part of the automation process.

In one embodiment, and with reference to FIGS. 2 and 3, the controller 42 may regulate the speed of raising the drill string 18 at Step 114 based on a hookload associated therewith (e.g., the weight of the hoisting device 26 and drill string 18 less any force that reduces that weight). In that embodiment, and at Step 114, the controller 42 measures or receives an indication of the hookload from a conventional weight measuring device attached to the hoisting device 26 (not shown) and compares a calculated hookload to the measured hookload. The calculated hookload is generally a summation of the presumed weights of the hoisting device 26, the drill string 18, and the frictional drag of the drill string 18 against the hole 15 as the drill string 18 is raised, each of which may be provided to the controller 42 via the input device 44. The frictional drag of the drill string 18 against the hole 15 is a function of several factors including, for example, one or more properties of a drilling fluid in the hole 15 (e.g., viscosity of the drilling fluid), the geometry of the hole 15, and the drill string 18 configuration.

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.

Claims

1. A method of adjusting a velocity at which a drill string is moved within a well, comprising:

determining 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;

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; and

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.

2. The method of claim 1, wherein reducing the velocity at which the drill string is moved within the well includes reducing the velocity at which the drill string is removed from the well.

3. The method of claim 1, wherein reducing the velocity at which the drill string is moved within the well includes reducing the velocity at which the drill string is inserted into the well.

4. The method of claim 1, wherein the second hookload is calculated based upon user input indicating a configuration of the drill string.

5. The method of claim 1, wherein the second hookload is calculated based upon user input indicating a weight associated with the drill string.

6. The method of claim 1, wherein comparing the first hookload to the second hookload includes calculating a deviation between the first hookload and the second hookload.

7. The method of claim 1, further comprising halting the introduction of a fluid to the well.

8. The method of claim 1, further comprising increasing the velocity at which the drill string is moved within the well when the first hookload no longer deviates from the second hookload by at least the target weight limit.

9. The method of claim 1, further comprising, in response to determining that the first hookload does not deviate from the second hookload by at least the target weight limit, maintaining a velocity at which the drill string is moved with respect to the well.

10. A method of adjusting a velocity at which a drill string is moved within a well, comprising:

determining an actual velocity at which a drill string is moved within a well;

determining a target velocity at which the drill string is to be moved within the well;

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; and

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.

11. The method of claim 10, wherein reducing the actual velocity at which the drill string is moved within the well includes reducing the actual velocity at which the drill string is removed from the well.

12. The method of claim 10, wherein reducing the actual velocity at which the drill string is moved within the well includes reducing the actual velocity at which the drill string is inserted into the well.

13. The method of claim 10, wherein the target velocity is determined from user input.

14. The method of claim 10, wherein the target velocity is selected to prevent swabbing within the well.

15. The method of claim 10, wherein the target speed limit is zero.

16. The method of claim 10, further comprising halting the introduction of a fluid to the well.

17. The method of claim 10, further comprising increasing the actual velocity at which the drill string is moved within the well to the target velocity when the actual speed is less than the target velocity.

18. A method of adjusting a velocity at which a drill string is moved within a well, comprising:

determining 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;

comparing the first volume to the second volume to determine whether the first volume is greater than the second volume; and

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.