US2408558A - Mud screen - Google Patents

Description

Oct r. E. HUTCHISON 2,408,

MUD SCREEN Filed Dec. 13, 1943 3 Sheets-Sheet l Oct. 1, 1946.

F. E. H'UTC HIS ON MUD SCREEN FiledDec 1:5, 1943 a Sheets-Shed 2 QW M 361M! /MJW;

Oct. 1, 1946. E. HUTCHISON MUD SCREEN 15, 1943 3 Sheets-Sheet 3 Filed Dp.

mm 3 mm mm (O /2M H i Lust Patented Oct. 1, 1946 MUD SCREEN 7 Frank E. Hutchison, Houston, Tex. Application December 13, 1943, Serial No. 514,182

3 Claims. (01. 210-149) This invention relates to a mudscreen.

An object of the invention is to provide equipment of the character described which has been specially designed for removing foreignmatter from drilling fluid, or drilling mud.

Another and more specific object of the invention is to provide equipment of the character desoribedvwhereby a large percentage of fine sand will be separated from the drilling fluid as well as the shale and other coarser particles.

As is well known,ja special type of drilling fluid is usedin well drilling. This fluid is circulated down through the drill stem and back up to the ground surface around the stem. It carries away the drill cuttings, keeps the drill cool and maintains the walls of the well bore. In order to keep the drilling fluid pure and to maintain its specific gravityand viscosity within the required range it is common practice to pass the fluid through screening equipment, commonly known as a mud screen as the fluid returns from the 'well into the pit for reuse. Screening equipment for this purpose now in common use will remove a large portion of the shale and other coarseparticles but a relatively small portion of the fine sand. The present invention, however, has been designed for the purpose of extracting from the returning fluid a greater proportion of the fine sand than will be removed by equipment now commonly used.

Another object of the invention resides in a novel process employed for removing the sand from the drilling fluid.

With the above and otherobjects in view, the invention has particular relation to certain novel features of construction, operation. and arrangement of parts and to a novel method, an example of which is given in this specification and illustrated in the accompanying drawings, wherein:

Figure 1 shows a side elevation of th mud screen, partly in section.

Figure 2 shows a plan view.

Figure 3 shows a fragmentary sectional viewtaken on the line 3-3 of Figure 1.

Figure 4 shows a fragmentary cross sectional view of the screen and frame and v Figure 5 shows an enlarged, fragmentary, longitudinal sectional view.

Referring now more particularly to the drawings, wherein like numerals of reference designate the same parts in each of the figures, the numerals I, I designate spaced side members forming the base of the main frame work which are an- 2 chored togetherby a suitable number of tubular cross members 2.

There is an upper rectangular frame formed of the side members 3, 3 which decline forwardly and which are supported by the front, intermediate and rear standards 4, 5, 6, as more clearly shown in Figure 1. The side members 3 are preferably formed of angle iron with their horizontal flanges turned outwardly as shown in Figure 3.

The stationary frame work above described is preferably formed of metal.

1 There is a screen frame formed of the side members I, I which are anchored together by the upper and lower angle iron cross bars 8 and 9. The horizontal flanges of the side member 1 extend outwardly from the vertical depending flanges thereof, as shown in Figur 3.

Between the horizontally extended flanges of. the side members 3 and I are the resilient blocks l I, l l, on each side which are seated in the retainers l2 carried by the side members 3 and ried by the horizontal flanges of the side memover which are fitted the inverted hoods l3 carbers l. i

The screening frame is thus resiliently supported on the main frame.

There is a mud box supported by the framework having the side walls I4, I4, the rear wall l5 and the bottom [6. The front portion lBa of the bottom inclines forwardly and merges in the front wall H, which declines forwardly, as shown in Figure 1 and is secured at its lower margin to the transverse angle iron 18 which is secured to the side members I.

This mud box is of substantially the same width and length as the main frame work and is suitably secured thereto. It has side discharge chutes l9, l9 controlled by suitable gates 20, 20 whereby the reclaimed mud may be delivered from the mud box back to the pit for re-use.

As will be noted from an inspection of the drawings, the screen frame is mounted over the mud box.

Beneath the screen frame, and anchored thereto, there is a screen 2| formed of suitable foraminated material.

The side margins of this screen are clamped between the upper and lower clamp plates 22 and 23.

There are the side tension bars 24, 24 extending from end to end of the screen frame and substantially U-shaped in cross section. The upper flanges of these bars rest against the inside of the corresponding side members I and retaining plates 25 are welded to the top of the side members l and overlie the tension bars 24 to retain the latter in place, as shown in Figures 2 and 3. The outer margins of the clamp plates 22, 23, are retracted and engaged over the lower flange of each tension bar 24, as shown in Figure 4.

There are the tension bolts 2 6 fitted outwardly through holes in th webs of th bars 24 and Whose inner ends have the heads 2'! which engage with said webs. These bolts also fit throu h holes in the depending flanges of the side members 1 and have tension nuts 253 threaded on to the outer ends thereof whereby said bolts may be placed under tension to pull the tension bars 2 1 out- I wardly to regulate the tension on the screen 2L The screen frame has a central longitudinal T-iron 29 extending from the upper to the lower end thereof and suitably secured to the upper and lower ends of the screen frame. Its lower margin has a V-groove to receive a rod 3:3 which extends from end to end thereof and which is formed of resilient material. es beneath the rod 3?) and when under tension is drawn tightly thereagainst. The screen is slightly curved downwardly from side to side as shown in Figure 3.

It will thus be observed that the screen 2| declines forwardly from end to end of the screen frame and over the mud box and is completely unobstructed on its underside so that the drops of liquid forming on the underside. of the screen may move downwardly along the underside of the screen without meeting with any obstructions.

Mounted on the main frame, at the rear end. is a receiving chute 3| which receives the mud returning from the well, through the return pipe 32, and which delivers said mud onto the screen as illustrated in Figure 1.

Mounted on the side members i and the central member 29 of the screen frame are the transversely alined clamps 33 which are firmly secured to the screen frame and which contain the annular, resilient shock absorbers a l which surround the transverse tubular housing This housing is closed at one end by the cap 3'6 which is secured thereon.

Within the housing 35 there is a shaft 3M having coaxial end spindles 3! and 33 which are eccentric with respect to the axis of the shaft and which are mounted in anti-frictionbearings 39 and 4t suitably retained within the housing. The spindle 38 is extended outwardly through the cap 4| screwed on to the corresponding end of the housing. The extended end of the spindle 38 has a sheave t2 splined thereon through which the shaft may be rotated. The inside diameter of the shock absorbers is somewhat less than that of the clamps 33 so that there will be no metal to metal contact of the housing 35 with said clamps.

As the shaft 37a is rotated, it will impart vibration to the housing 35, by reason of its eccentricity, which vibration will be imparted through the shock absorbers l and will not be transmitted to the main frame.

The vibration imparted to the screen will therefore not be violent but on the other hand will be a rather gentle vibration.

The fluid returning from the well will be cast onto the screen as hereinabove stated and pass on into the mud box and the shale and coarse particles will pass down over the screen and be discharged from the lower end thereof beyond the mud box but the fine sand will pass through the screen.

A substantial portion of the liquid will form in drops on the underside of the screen, as shown The screen 2| passin Figure 5 and will be retained suspended from the screen by adhesion thereto and will gradually move on down along the underside of the screen. As above stated, these drops will meet with no obstructions to cause them to drop back into the mud box. They will assume a sack-like shape which shape will be preserved by the surface tension of the liquid forming the drops and the fine sand will collect in them and be carried along with them. Of course some of the drops will be released from the screen before they reach the lower margin of the screen out beyond the forwardly declining front wall H, but a high percentage of the drops containing the fine sand will adhere to the smooth underside of the screen until they have passed out beyond the forwardly declining front wall, or deflector l1 and then they will be released from the screen and will fall outside of the mud box.

As herein before stated, the screen 2| is slightly convexon its underside and is drawn tightly around the cushioning rod 38. The screen is stretched uniformly so as to give a smooth, uniform under surface area.

As the drilling fluid flows through the screen, small drops of the fluid will form over the entire underside of the screen. This action takes place about halfway up the screen, but the exact location depends upon the volume of drilling fluid being handled at the time. If the volume is large, the action starts further down the screen giving less flotation separation, and when the volume is decreased, the action starts closer to the top of the screen giving more sand separation by flotation.

As the drops move down along the underside of the screen, the willcollect more and more sand and when they reach the lower end of the screen, the sand will predominate over the liquid in the drop so that while not all of the sand will be removed from the fluid being screened a substantial portion thereof will be extracted.

The drawings and the description are illustrative, only, while the broad principle of the invention Will be defined by the appended claims.

What I claim is:

1. In a vibrating screening unit a mud box having vertical side walls, a vertical end wall at one end and a horizontal bottom, a portion of the bottom inclining toward the other end of the box, and a wall at said other end of the box which declines outwardly and whose upper margin merges with the adjacent end of the inclined portion of the bottom; and a vibratory, forwardly declining, screen mounted above the mud box and extending transversely, approximately from side to side, and longitudinally, approximately from end to end, of the box, with its upper, or feed, end above one end of the mud box and with its lower end positioned over and adjacent said outwardly declining portion.

2. In a vibrating screening unit, a screen comprising a frame formed with side members, means for anchoring said side members together in spaced relation, a flat, sheet-like foraminated screening element, tension bars along the inner sides of said side members having outwardly turned flanges, clamp means engageable over said flanges and over the side margins of the screening element and clamping the margins of said element to said tension bars, a longitudinal tension rod above the screening element which bears against said element approximately midway between its side margins, tension bolts passing through said tension bars and side members and tension nuts threaded onto the outer end of said bolts whereby tension may be applied to the screening element transversely to draw it tightly against said rod.

3. In a vibrating screening unit, a substantially rectangular screen frame formed with side members, means'for anchoring the side members together in spaced relation, tension bars along side the inner sides of said side members and extending approximately from end to end of the frame, a substantially flat, sheet-like screen extending across the frame and approximately from end to end thereof, clamp means clamping the side margins of the screen to the tension bars, a longitudinal tension rod above the screen which bears against the screen approximately midway between its side margins, tensioning means securing the tension bars to the side members and adjustable whereby tension may be applied to the screen transversely to draw it tightly against said 10 rod.

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