US2053448A - Depth gauge control and lead plug - Google Patents

Description

L. T. STAjRR DEPTH GAUGE CONTROL AND LEAD PLUG Sept. 8, 1936.

2 Sheets-Sheet 1 Filed March 18, 1935 INVENTOR ATTORNEY Patented Sept. 8, 1936 UNITED STATES PATENT OFFICE 2,053,448 DEPTH GAUGE CONTROL AND LEAD PLUG Lewis T. Starr, Dallas, Tex.

Application March 18, 1935, Serial No. 11,663

Claims. (6i. 166-1) This invention relates to the art of cementing wells and it has particular reference to a depth gauge control and lead plug.

The principal object of the invention is to 5 improve upon conventional methods of cementing wells'by providing means for accurately determining the depth at which cement is to be pumped and which provision iseiiective not only in the saving of cement and the time usually required to complete the job of cementing but is likewise effective in insuring proper disposition of the cement at the lower end of the well casing. For all practical purposes, the cementitious material should be held under a uniform pressure until it attains a mechanical set. Also, it is required that the mud within the casing be forced out preparatory to the introduction of the cement and further, it is important that the cement does not rise to any great extent within the well casing and to prevent this, the invention provides means capable of being forced to a predetermined depth within the well casing by fluid under pressure and this means is instrumental both in preventing the cementitious material from rising in the casing and separating the material from the pressure fluid.

The invention further aims to provide means which may be secured in spaced relation to the bottom of the well casing and at a predetermined depth therein to function as an operating means I for the depth gauge control,'the latter, as stated,

being the means by which the cement is prevented from rising within the casing.

With the foregoing objects as paramount, the

invention has particular reference to its salient features of construction and arrangement of parts which will become manifest as the description proceeds, taken in connection with the accompanying drawings, wherein:--

Figure 1 is a vertical section at the bottom of a well showing the two units of the invention in position, the depth gauge control being shown under fluid pressure.

Figure 2 is a detail view of the depth gauge away.

Figure 8 is a perspective view of one of the expansible segments carried adjacent the upper' Figure 10 is a fragmentary elevation showing one of the prongs of the plug in solid and in dotted lines which is the operative and inoperative positions respectively of the prong.

' Figure 11 is a fragmentary viewv in vertical section of a joint between two sections of the casing showing a spider which is used in lieu of the plug shown in Figures 9 and 10.

Figure 12 is a fragmentary view in section of the lower end of a casing where a conventional casing guide shoe is used and which element obviates the necessity for using the lead plug or the spider shown in Figure 11, and

Figure 13 is a modified form of the device shown in Figure 11.5

Continuing with a more detailed description of the drawings, reference is made primarily to Figures 2 to 8 inclusive. In Figure 2 is shown the mounting for the expansible elements, to be described in detail later and the expansible wings 2. This mounting is shown also in Figure 3 with both the elements 8 and wings 2 removed and as apparent, the mounting is comprised of a series of spaced, parallel members 3, the spacing being better shown in Figure 6. Above the spaced members 3 there is a box t and on each of its four sides there is aflixed pairs of members 5, each pair defining a channel in which the wings 2 are received. Springs 6 are disposed behind each of the wings in order that they will be normally urged outward. Each wing is faced with a strap of leather or other suitable material], the purpose of which will be described presently.

The lower portion of the gauge control is formed into a box like structure 8 which is hollow to receive a squared expanding element or trigger 9, shown in detail in Figure 4. A slot H! is provided in the box 8 longitudinally thereof and in which slides a dowel pin it secured to the trigger 9 and which arrangement prevents the trigger 8 from dropping out of the box 8 when the gauge control is suspended in a well. Secured to the bottom of the trigger 9 is a guide formed of light angular members it, each of which may be faced with a strip of leather or other material Hi. This guide serves to maintain the control gauge in concentric relation to the casing as it is forced downwardly therein but it does not interfere with upward passage of cement, the latter being stopped by the packing washers it, one of which is disposed below the expanding elements I, another immediately thereabove and still another above the expanding wings 2. Annular recesses I5 are provided to accommodate these washers.

Referring specifically to the expansible elements I, reference is made to Figure 8 in which the elements are shown to be segmental so that the group will embrace the mounting on all sides. Each element has a tongue I6 receivable in the spaces between the members 3 of the mounting. When the segments I are expanded by the trigger 9, which operation will be later described, there will be a space between each of the segments and to cover which, strips of leather or similar material I! are affixed to one segment whereby the free portion thereof will lie within recesses I8 in a companion segment. Thus the spaces are closed against the upward passage of cement likely to escape the wiping action of the lowermost packing washer I4. When the segments I are all assembled in operative relationship on the mounting, they are embraced by a sleeve I9 of resilient material such as rubber. It will be understood however that the purpose of the sleeve is to retain the segments I in proper relationship on the mounting and to return them to their original inoperative position after having been expanded.

It is of course apparent that the sleeve has some effect in preventing the device from floating upwardly and serves to secure the-same in position in the casing. However, the rubber sleeve may be substituted by a coiled spring or any equivalent means which will retain the segment in place and return them to their original position. The wings 2 are in fact the means by which the device is held against undue upward movement in the casing since the facing I thereon serves to grip the walls of the casing with suflicient firmness as to resist any back pressure should for any reason the fluid pressure be relieved.

The foregoing substantially describes the depth gauge control and a description of the construction' and operation of the lead pl will now be made.

Reference is made to Figures 9 and 10 in which is shown paired members 20, each pair defining a vertical groove or channel 2I in which reposes a prong 22. Normally each of the prongs 22 are disposed in the manner shown in dotted lines in Figure 1 0 and being pivoted at 23 they are capable of being extended to the dotted position shown in Figure 10 or as shown in Figures 1 and 9. 'A spring 24 serves to extend the prongs 22 when the latter are released and in each of the channels 2| there is a stop 25 which holds the prongs at right angles to the longitudinal axis of the plug when they are extended.

At either end of the plug there is a packing washer 26 and at its base there are a series of flexible members 21 which engage the pointed ends of the prongs in the manner shown in Figure 10 to prevent them from springing out of the channels or recesses 2| predeterminately.

The pointed ends of each of the prongs are reinforced by metal tips 28 and intermediate the ends of the prongs there is provided a protuberance 29, preferably of rubber which engages the walls of the casing and serves to guide the same therein.

.In cementing wells in the manner described, it is preferable that the devices used to control the Cement be constructed of wood or perhaps soft metal in order that there will be no difliculty or -;injury.to the drill bit when it becomes necessary to proceed with the completion ofthe well subsequent to cementing and since this is true, some parts of the devices are reinforced with metal when they are constructed of wood. such as the tips of the prongs 22. It will be observed in Figure 4 that the upper portion of the trigger 9 is reinforced at 30.

In operation, the lead plug shown in Figures 9 and 10 is first inserted into the casing and a proper mixture of neat cement is afterwards in-, troduced under pump pressure. Mud is driven out of the casing and passes upwardly outside the walls of the casing as the plug is forced toward the lower end thereof. This mud sometimes rises which are driven into the walls of the well by,

pump pressure from the surface. thus held against displacement.

The depth gauge control shown in Figures 1 to 8 inclusive, is then introduced into the casing and backed by fluid under pressure such as indicated at 3| in Figure 1.. The depth gauge is thus forced downward against the cement in the casing and the latter is forced upwardly exteriorly of the casing as shown at 32 in. Figure 1. In thus passing upwardly, the cement urges the mud and water toward the surface and the cement effectively closes any leaks in the casing.

When the depth gauge is forced down to a point where the guide members I2 engage the lead plug as shown in Figure 1, further pressure upon the depth gauge will force the mountin downward while the trigger. 9 remains stationary against the plug. The pointed end of the trigger 3 is thus urged against the curved lower ends of the tongues I6 formed upon the slips I, thereby causing the slips to move outwardly, expanding the rubber sleeve I9 against the walls of the casing. As soon asthisaction takes place, the operator will be immediately apprised due to the fact that there will be a sudden rise on the pressure indicator at the surface and the fluid The plug is pressure will be maintained at a uniform degree for a predetermined period of time to allow the cement to attain a mechanical set after which the pressure is relieved and the drilling operation may proceed. The elements described remain in the hole and are drilled out as the drilling proceeds.

In some cases, especially deep wells, a casing guide shoe 33 such as shown in Figure 12 is employed and this will obviate the necessity of using the lead plug shown in Figures 9 and 10 since the depth is known and the shoe 33"serves as an actuating means for the depth gauge control, cement being pumped through the opening 34 in the shoe 33 in advance of the depth gauge.

Some drilling contractors prefer that a column of cement of a predetermined height be left in the casing. In cases of this kind, a device of the character shown in Figure i1 is employed. This device consists of a spider 35 having set screws 36 in each of its arms which are interposed between the contiguous ends of two sections of casing, one or more sections from the :bottom of the hole as indicated by the contractor. The spider does not interfere with the down- 2,068,448 wardly against the cement. When the depth gauge reaches the spider 35, the segments are expanded as described in the foregoing and the depth gauge is maintained in a stationary posltion by fluid pressure until the cement attains a mechanical set.

As a modification of Figure 11, the device Shown in Figure 13 is provided and is comprised of the sleeve 31 of ,wood or other material having three or more leaf springs 38 secured at spaced points to its periphery. The upper ends of these springs are bent outwardly as shown and are adapted to lie between the joints of the casing and thereby suspend the sleeve 31 in vthe casing.

Manifestly, the construction shown is capable of considerable modification and such modification as is considered within the scope and mean ing of the appended claims is also considered within the spirit and intent of the invention.

What is claimed is: 1. In combination with an anchor plug in a well cementing assembly, a follower plug includ ing a body having a plunger axially movable therein and radially expansible means actuated by said plunger to secure said follower plug in a well.

2. In combination with an anchor plug in a a well cementing assembly, a follower plug including a body having a plunger axially movable therein and radially expansible means actuated by said plunger to secure said follower plug in a well, and resilient means surrounding said expansible means for holding the same against displacement.

3. In combination with the lead plug of a well cementing assembly, a depth gauge control plug comprising a group of members disposed radially about a common axis, a plunger movable through said axis to radially expand said members upon engagement with said lead plug and packing means carried by said control plug.

4. In combination with the lead plug of a well cementing assembly, a body having an axially movable plunger, a plurality of members grouped radially about the longitudinal axis of said body and capable of outward movement upon upward thrust of said plunger when the latter impinges said lead plug, expansible means for limiting the movement of said members, packing means-carried by said body and means to limit the axial movement of said plunger.

5. In combination with the lead plug in a well cementing assembly, a depth gauge control plug comprising a body, the upper section of which is surrounded by a plurality of radially expansible segments, resilient means surrounding said segments to limit the degree of radial displacement of said segments, an axially movable plunger, a guide therefor in the lower section of said body, said plunger having means to engage and expand said segments upon engagement thereof with said lead plug in a well.

LEWIS T. STARR.

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