Draw works disabling device for use with a well drilling apparatus

A device for disabling the draw works of a well drilling apparatus responsive to the locking of the drill string by a blow out prevention device. The device comprises an air-actuated valve connected for regulating the flow of air to the air-actuated clutch of the draw works. A second valve regulates the flow of pressurized air to the air actuated valve. The second valve is responsive to the actuation of the blow out prevention device by an accumulator valve.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates in general to well drilling apparatus and more 
particularly to devices for regulating the movement of a drill string or 
pipe utilized in well drilling. 
2. Description of the Prior Art 
In the past, most oil drilling apparatus have utilized a draw works 
consisting of a powered rotating drum for raising and lowering the drill 
string by means of a drilling cable. The drilling cable is carried on the 
powered rotating drum of the draw works and is received through sheaves 
located in the crown and traveling block. The traveling block is connected 
to a drill string pipe such that rotation of the draw works drum raises 
and lowers the drill string pipe. 
In most well drilling apparatus the draw works is operated by means of a 
clutch which is connected to and actuated by pressurized air from an air 
supply. An air valve regulates the supply of air from the air supply to 
the draw works clutch to engage the draw works. The air valve is generally 
located on a driller's console so that a driller operator can manually 
engage the draw works by means of this valve. 
Most well drilling apparatus also include a blowout prevention device which 
locks or freezes the drill string pipe in position. This prevents the pipe 
from being lifted out of the well due to pressure changes within the well. 
The blow out prevention device also usually cuts off the supply of mud 
which is circulated into the well during the drilling process. The blow 
out preventer includes hydraulically actuated rams which engage the drill 
string pipe when hydraulic pressure is supplied to the blow out preventer. 
Hydraulic pressure is supplied to the blow out preventer from a source of 
hydraulic fluid generally known as an accumulator. The accumulator also 
supplies hydraulic fluid for various hydraulically operated devices around 
the drilling apparatus. A particular valve on the accumulator supplies 
hydraulic pressure to the blow out preventer and engages the rams with the 
drill string pipe, locking the pipe against movement. 
In the past, a particular problem with well drilling apparatus has been 
that the blow out prevention device has often been engaged when the draw 
works has been inadvertently or absent-mindedly operated. When this 
happens, the drill string pipe will be damaged and often the pipe is 
severed. Usually various other equipment is destroyed in the effort to 
move the locked drill pipe. If severed, the pipe often falls into the hole 
and is lost either before or after the blow out preventer is disengaged. 
In most well drilling apparatus the accumulator and its valves, and the 
driller's console and the draw works valve are not located in the same 
position. This prevents immediate mechanical connection between the blow 
out prevention accumulator valve and the draw works control valve. 
Moreover, a mechanical connection would interfere with the regular 
operation of the draw works. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an improved well 
drilling apparatus and particularly an improved well drilling apparatus 
with a device for disabling the draw works when the blow out preventer is 
engaged. By this means, damage to the drill string and to other equipment 
can be prevented. 
It is also an object of the present invention to provide such a device for 
disabling the draw works which device can be easily attached to presently 
existing well drilling apparatus and which is effective in disabling the 
draw works but does not interfere with the general operation of the draw 
works. 
It is still further an object of the present invention to provide a 
disabling device for disabling the draw works of a well drilling apparatus 
which is safe and which utilizes standard pieces of equipment and does not 
require extensive alterations of the presently existing equipment. 
In accordance with these objects the present invention is utilized with 
well drilling apparatus of the type which includes a draw works for 
raising and lowering a drill string, a manual operation device connected 
to the draw works for manually operating the draw works, and an 
accumulator connected through an accumulator valve for supplying hydraulic 
fluid to a blow out prevention means which locks the drill string against 
movement. The device comprises a means for disabling the manual operation 
device which actuates the draw works. It also includes an activating means 
for activating the disabling means and this activating means is responsive 
to the actuation of the accumulator locking the drill string against 
movement. Thus, the present invention disables the manual operation of the 
draw works upon the locking of the drill string by the blow out prevention 
means. 
In most cases, the draw works is operated by a manually operated valve 
which regulates the supply of air from an air supply to an air actuated 
clutch on the draw works. Preferably, the present invention includes a 
pressure actuated valve disposed on the air supply conduit between the air 
supply and the draw works. A second air supply conduit is connected from 
the air supply to the pressure actuated valve. A second valve is connected 
to regulate the supply of air to the pressure actuated valve. This second 
valve is responsive to operation of the accumulator valve which engages 
the blow out prevention device. 
For a further understanding of the invention and further objects, features 
and advantages thereof, reference may now be had to the following 
description taken in conjunction with the accompanying drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now to FIG. 1, a well drilling apparatus is schematically shown 
generally at 11. The apparatus 11 includes a derrick structure 13 which 
rests on a drilling platform 15. One purpose of the derrick structure 13 
is to provide a support for raising and lowering a drill string pipe 17. 
The drill string pipe 17 is, of course, utilized in drilling the well and 
extends into the well. 
The upper end of the drill string pipe 17 has a collar which is attached to 
a traveling block 19 by a clamp 21. A series of sheaves 23 are journaled 
to the traveling block 19. A drilling cable 25 is wound through the 
sheaves 23 and also through a series of sheaves 27 journaled to a crown 29 
at the top of derrick structure 13. One end of the drilling cable 25 is 
wound about a cable storage spool 31. The other end of cable 25 is wound 
about a draw works drum 33. The draw works drum 33 is powered for rotation 
and by rotation raises and lowers the drill string pipe 17. The sheaves 27 
and 23 form a pulley to translate the winding of the drilling cable 25 on 
draw works drum 33 into motion for raising and lowering the drill string 
pipe 17. 
The draw works drum 33 is only one element of the draw works 35. Of course, 
an engine is provided for powering the drum rotation. A transmission and 
clutch are connected between the engine and the draw works drum 33 to 
regulate the rotation and the direction of rotation of the draw works drum 
33. The clutch is actuated by air pressure supplied through one or more 
air supply conduits 37. The conduit 37 is attached to a draw works valve 
39 which regulates the supply of air through conduits 37. A valve handle 
41 manually regulates the supply of air to conduits 37, and, therefore, 
regulates the rotation and direction of rotation of draw works drum 33. 
Air is supplied from an air supply source 43 to draw works valve 39 through 
a conduit 45. The air supply source 43 generally consists of an air 
compressor and a storage tank. 
Usually, the draw works valve 39 is mounted on a driller's console located 
on the drilling platform 15. By adjusting the position of handle 41 the 
driller regulates the operation of the draw works and the raising and 
lowering of traveling block 19 and the drill string pipe 17 attached 
thereto. 
Still referring to FIG. 1, a blow out prevention device is shown generally 
at 47. The blow out prevention device 47 includes a pair of hydraulic rams 
or jaws 49 which can engage and lock the drill string pipe 17. Hydraulic 
fluid is supplied to the rams 49 through a conduit 51. The source of 
hydraulic fluid and pressure connected to the blow out preventer 47 
through the hydraulic conduit 51 is an accumulator 53. The accumulator 53 
includes a valve 55 which regulates the flow of hydraulic fluid through 
conduit 51. Valve 55 is actuated by an accumulator valve handle 57. 
Each of the elements described above is convention and the details of each 
are well known to those skilled in the art. The schematic representation 
of FIG. 1 omits many of the details of these elements because these 
details do not specifically effect the combination and operation of the 
present invention. 
To disable the draw works 35, the present invention utilizes a valve 59 
connected to regulate the flow of air through conduit 45. When valve 59 is 
closed no air is supplied from the air supply source 43 to the draw works 
valve 39. When no air is supplied from the air supply source 43 to the 
draw works clutch through valve 39 the draw works 35 cannot be operated 
and cable 25 can not be moved. 
Valve 59 is a pressure-closed valve; i.e., a valve which closes when 
pressurized fluid is supplied to the actuation mechanism of the valve. 
Such pressure-closed valves are common and the construction of these 
valves is well known in the art. 
An air conduit 61 is connected to supply pressurized air from the air 
supply source 43 to the actuation mechanism of valve 59. One end of 
conduit 61 is connected to valve 59 and the other end is connected to the 
air supply source 43. 
A valve 63 is connected to conduit 61 to regulate the flow of pressurized 
air from the air supply source 43 to valve 59. When the valve 63 is open 
pressurized air is supplied to valve 59 through conduit 61 and valve 59 
closes. When valve 63 is closed, the portion of conduit 61 between valve 
59 and 63 is vented and valve 59 opens. 
Referring now to FIG. 2 as well as FIG. 1, valve 63 is actuated by a lever 
arm 65. This arm 65 is mechanically connected to the accumulator valve 
handle 57. The connection is such that the movement of handle 57 to supply 
hydraulic fluid from the accumulator 53 to the blow out prevention device 
47 moves arm 65 to a position which opens valve 63 and supplies air from 
the air supply source 43 to valve 59. The movement of handle 57 to a 
position which releases the rams 49 closes valve 63 and relieves the air 
pressure to valve 59. 
Arm 65 can be connected to handle 57 in a variety of ways. One method is to 
drill a hole in handle 57 through which arm 65 can extend and pivot. Other 
mechanical linkages will be apparent to those skilled in the art. Those 
skilled in the art will also recognize that valve 63 can readily be 
mounted to accumulator 53 in a manner which allows the combination to 
cooperate as described above. 
To attach the device of the present invention the valve 63 is mounted on 
accumulator 53 so that arm 65 is mechanically connected to handle 57. 
Valve 59 is connected to conduit 45. An air supply conduit is then 
connected from air supply source 43 to valve 63 and from valve 63 to the 
actuation mechanisms of valve 59. 
In operation, the present invention disables the draw works in response to 
the closing of the pipe rams 49 locking the drill string pipe 17. This 
prevents an inadvertent or absent-minded attempt to raise the drill string 
pipe 17 when the rams 49 are locked about pipe 17. 
Each time handle 57 is moved to a position which supplies hydraulic fluid 
to blow out prevention device 47 and closes rams 49 about pipe 17, valve 
63 is opened and pressurized air closes valve 59. The closing of valve 59, 
in turn, prevents air from being supplied from the air supply source 43 to 
the draw works clutch through draw works valve 39. Thus, opening valve 57 
disables the draw works 35. 
After the rams 49 have been locked about drill string pipe 17 the draw 
works can be activated only by disengaging the rams 49 by closing valve 
55. The movement of handle 57 to close valve 55 closes valve 63 and vents 
the air in conduit 61 between valve 59 and valve 63. This opens valve 59 
which, in turn, communicates the air supply source 43 with draw works 
valve 39. The draw works 35 can then be operated by the valve handle 41. 
Thus, the draw works disabling device of the present invention is well 
adapted to obtain the objects and advantages mentioned as well as those 
inherent therein. While presently preferred embodiments of the present 
invention have been described for the purpose of this disclosure, numerous 
changes in the construction and arrangement of parts can be made by those 
skilled in the art which changes are encompassed within the spirit of this 
invention as defined by the appended claims. 
The foregoing disclosure and the showings made in the drawings are merely 
illustrative of the principles of this invention and are not to be 
interpreted in a limiting sense.