Mud flow indicator and system therefor

May 23, 1961

B. e. taylor 2,985,731 mud flow indicator, and system therefor

Filed March 3, 1958

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United States Patent Office . , _M^2,985,731

Patented May 23, 1961

2,985,731

MUD FLOW INDICATOR AND SYSTEM THEREFOR Ben E. Taylor, P.O. Box 92, Weatherford, Tex.

Filed Mar. 3, 1958, Ser. No. 718,623

Claims. (CI. 200—81.9)

My invention relates to indicator devices and systems, and more particularly to devices and systems for giving indications of drilling mud flow conditions in an oil well drilling operation. This application is a continuation-inpart of my co-pending application S.N. 658,841, filed May 3, 1957, now abandoned.

In an oil well drilling operation, a special composition known in the industry as “drilling mud,” is circulated in the drilled hole. The drilling mud is pumped down the hole via the drilling pipe, and is forced back up the hole in the space between the drilling pipe and the hole bore or casing pipe. The mud serves to enhance the cutting action of the drill bit, seal the hole walls, carry the cuttings up out of the hole, and also to keep formation pressures under control. The quantity of mud required for the circulating system of a drilling operation is obviously quite large, and the money value of this quantity of mud is substantial, amounting to many hundreds of dollars. When drilling in locations where porous formations are encountered, it often happens that the drill breaks into a porous strata and a large quantity of mud is pumped out into the cavities of the formation and irretrievably lost before the driller realizes what has occurred. Loss of mud circulation can also occur as a result of clogging in the drill bit nozzles or openings. When this happens, the cutting efficiency of the bit is greatly reduced. If there were some way to appraise the driller immediately when mud circulation is being lost, much waste could be prevented. It has been reliably estimated that several thousand dollars per well could be saved in some locations, by effectively minimizing mud waste. The problem of mud waste has been approached a number of ways in the prior art of which I am aware, but no effective solution has yet been found.

Another problem encountered in oil well drilling operations is that of “blow-outs.” A “blow-out” is a condition resulting from excessive gas pressure acting to force the drilling mud back up out of the hole. Since a “blowout” can cause serious difficulty, it is common practice to provide devices known as “blow-out preventers,” which are valve or plug type devices which when closed, act to seal the top of the hole. In most cases it is necessary to pull up the kelly before the blow-out preventer can be closed. The problem has been that of providing sufficient advance warning of imminent blow-out to enable the drilling crew to carry out the steps necessary for closing the blow-out preventer.

It is accordingly a general object of my invention to devise effective means for minimizing drilling mud waste.

More specifically, it is an object of my invention to devise an arrangement and system wherein an alarm will be actuated immediately upon loss of mud.

Another object of my invention is to provide a simple and effective mud flow sensing and alarm actuating device.

Another object of my invention is to provide an economical and effective mud flow sensing and alarm actuat2 ing device which can be readily installed in the return line of mud circulating systems.

Another object of my invention is to provide a simple and effective blow-out sensing and alarm actuating device. 5 Another object of my invention is to devise an arrangement and system wherein an alarm will be actuated immediately upon excessive drill bit clogging or plugging.

Another object of my invention is to devise an arrange10 ment and system wherein an alarm will be actuated immediately to indicate abnormal mud circulating conditions.

These and other objects are effected by my invention as will be apparent from the following description taken 15 in accordance with the accompanying drawing, forming a part of this application, in which:

Fig. 1 is a block diagram showing a typical mud circulating system embodying my invention;

Fig. 2 is a schematic perspective view showing a sensing 20 and alarm actuating device in accordance with a preferred embodiment of my invention;

Fig. 3 is a schematic side elevational view partly in section of the device of Fig. 2 in its alarm actuating positions; and

Fig. 4 is a schematic block diagram illustrating the electrical circuit of the alarm system.

In the mud circulating system shown in Fig. 1, mud is taken from the mixing pit 11 to the pump 13 which pumps it down the drilling pipe 15. The mud then goes 30 down to the drill bit (not shown) and is forced back up in the space between the drilling pipe 15 and the hole bore casing 17, from whence it is piped to the shale shaker 19, and from the shale shaker to the return pit 21, and from the return pit back to the mixing pit 11. 35 The indicator actuator device of my invention is inserted in the mud return line just ahead of the shale shaker 19.

A section of the return line 23 at the indicator actuator location is shown in Fig. 2. The return line is prepared for installation of the indicator actuator device by weld40 ing onto the top of the return line a receptacle 25 which is a short section of pipe, one end of which is shaped to conform to the outer surface of the return line pipe 23. The return line pipe is also provided with a slot 27 extending along a diameter of the receptacle 25 and longitu45 dinally of the return pipe 23. The indicator actuator device comprises a body portion 29, a pendulum paddle 31, a pendulum arm 33, a support shaft 35, and a pair of mercury (Hg) switches 37, 39. The body portion 29 has the shape of a short cylinder having an outside diam50 eter which is just less than the inside diameter of the receptacle 25, so that the body will nest into the receptacle. The upper end portion of the body exterior is of increased diameter to form a shoulder 41, and carries threads 43. The body is provided with a pair of bear55 ing slots 45, 47 located at the upper portion of the body 29, one at each end of a body diameter. Each slot 45, 47 is open at the top, extends downward to a point just above the lower extent of the threads 43, and has a semicircular bottom. The lower portion of the body 29 car00 ries four pins 49 90 degrees apart at a common level near the body lower end. The pins 49 project a short distance outwardly from the body 29. The receptacle 25 is provided with four crankshaped slots 51 located 90 degrees apart and opening to the upper end of the receptacle 25. _6g The pins 49 on the body portion are adapted for co-operation with the crank-shaped slots 51.

The pendulum paddle 31 is a relatively heavy piece of metal plate material shaped to conform generally with the inner surface of the return line 23, with enough clear70 ^{ance a}^^ow f°r adequate swinging movement. The pendulum arm 33 is a metal rod which is fixed at one end to the paddle 31 by suitable means, such as by weld3;98δ,731 ³ ing or brazing. The support shaft 35 is a cylindrical metal rod. The shaft has a central portion 53 which spans a diameter of the body portion aforementioned, and; end portions of reduced: diameter just less, than the width of the body bearing slots. One· shaft end portion 5 55 . terminates at the body exterior surface, while the other shaft end portion 57 extends- outwardly beyond the body exterior to serve as a mount for the mercury switches 37, 39, as will be hereinafter- more, fully explained. The free end of the pendulum; arm. 33 is fixed 10 to the center of the shaft central portion 53 by suitable means, e.g., by welding or brazing,. Thus; the pendulum paddle 31 acts as a variable obstruction, in. the return line 23. and the pendulum arm 33 can swing on the support shaft 35 in a vertical plane bisecting the return pipe. The 15 pendulum arm 33 is curved so that the paddle, obstruction of. the return line 23. is maximum; at. one extreme; position of the arm and minimum at the other extreme position of the arm. The bulbs of the. mercury switches 37, 39 are contained in respective weatherproof housings 59, each 20 having contacts which are brought, out; to. a pair of terminals 61 at the housing exterior. The housings. 59 are each provided with a bore of proper size to fit the shaft end portion 57. The housings 59 are also, each; provided with a. threaded bore adapted for receiving a- shaft lock 25 screw 63. Thus, the housings 59 may be fixed, in. any radial position on the shaft end portion 57. The indicator actuator device may be closed at its upper end by means of a cap 65 which is adapted for threading onto the top of the body 29. To install the,indicator actuator 30 device, the paddle of the indicator actuator is passed down through the return line slot 27 and then the indicator actuator is rotated so that the pins 49 are over the slots 51, and then it is lowered and rotated, to seating position. The paddle is of course oriented properly with 35 respect to the mud flow direction. In Figs. 2 and 3, the mud flow direction is from left to-right. The electric alarm circuit for the indicator actuator system is shown by Fig. 4. One terminal of each mercury switch 37, 39 is.connected through a battery 64 to ground at 66. The ⁴⁸other, terminal of each mercury switch 37, 39 is connected in series with a respective, single pole switch 67, 73 and a respective alarm device 69, 75 to a ground at 71. The alarm devices 69; 75 may be of any suitable electrically energized noise; maker type, such as buzzers, 45 bells, or horns. The alarm devices-69, 75 and single pole switches 67, 73 are preferably installed at a location convenient, to the drilling rig operator. The purpose of the single pole switches is to provide for manual energization: and de,-energization of the respective alarm circuit. 50

As hereinbefore stated, the device of my invention performs three important functions; namely, it provides adequate warning in cases of mud loss, drill bit plugging, and incipient blow-out conditions. In operation, with mud flowing normally in the return line, the paddle 31 55 floats on top of the mud stream in an intermediate position, which :is. approximately that shown in Fig. 2. Under these conditions, the housing of the first mercury switch 37 is adjusted on the shaft end portion 57 to a position such that its contacts are open, and then is locked in posi- 60 tion by means of the lock screw 63. The housing of the first, mercury switch 37 is placed on the shaft end portion 57 in the position such that its contacts will be closed by clockwise movement of the shaft 35. The second mercury switch 39 is also adjusted on the shaft end. portion 65 57 to a. position such that its contacts are open; during the normal: mud flow condition, but it is placed on the shaft end portion 57 in the position such that its contacts will be closed by counter clockwise movement of the shaft 35.; Now. if a. porous strata is encountered in· the hole 70 being drilled, so that mud will flow into the strata instead of being forced .back up and out; of the hole, or if there is bit plugging, or if for any reason the mud flow in the return line decreases from normal, the paddle 31 will be mp.ved by action: of its own weight and gravity toward 75 the maximum, obstruction position (for example, as shown by the solid lines in Fig. 3). The first mercury switch 37 is at the same time rotated, or tilted, to cause its contacts to close to energize its alarm circuit, while the contacts of the second mercury switch 39 remain open. Now if a region of excessive gas pressure is encountered in the hole presaging, a potential blow-out, it will have the effect of applying additional pressure on the returning mud,, thus causing the- mud flow level in the return pipe 23 to increase, which in turn causes the paddle 31 to ride at a higher level, which rotates the shaft 35 counter clockwise, tilting the second mercury switch 39 to the closed contacts position (for example, the position shown by dotted lines in Fig. 3), while at the same time the contacts of the first mercury switch 37 remain open. The alarm circuit of the second mercury switch 39 is thus energized. When either alarm circuit is energized, of course the respective alarm, device will be actuated, alerting, the drilling rig operator, who can then immediately take the necessary precautionary actions and effect appropriate corrective measures..

It is understood that the amount of paddle- swing- required to cause the contacts of a respective, mercury switch to close can be predetermined, and. the sensitivity of respective switch, actuation can be,selected as desired.

The indicator actuator device, and system disclosed herein has proved to be very effective in; actual operation. It is estimated, that in. many cases as much as several thousand dollars per well could, be saved by utilizing, the device and system, of. my invention to minimize drilling mud losses. Also, my. invention, may be utilized, to. enhance drilling efficiency, since it provides indication of bit plugging. Furthermore, my invention-may- be utilized to minimize the possibility of danger and heavy losses due to blow-outs, I have found that: under most; conditions it is not essential to employ the indicator actuator body cap 65, because no significant amount of mud: passes up through the return, line slot 27. While the shaft construction which I have shown is a convenient; form, obviously the shaft could be constructed in other forms. Also, the shape of the pendulum paddle could take any form which would provide sufficient: obstruction and. have sufficient weight to operate properly.

While I have shown, my invention in only one form; it will be obvious to those skilled in the art that, it is: not: so limited, but is susceptible to various changes and modifications without departing from the spirit thereof.