US1803057A - Plug for use in the process of cementing oil wells - Google Patents

Description

April 28, 1931.

z. A. DYER PLUG FOR USE IN THE PROCESS OF CEMENTING OIL WELLS Filed Dec. 10, 1928 gnwntoz Patented Apr. 28, 1931 UNITED STATES ZEB ALLEN DYER, OF WHITTIER, CALIFORNIA PL'U'G FOR USE IN THE PROCESS OF CEMENTING OIL WELLS Application filed December 10, 1928. Serial No. 324,910,

This invention relates toa plug for use in following fluid cement down a well casing and separating fluid cement from the hydrau-.

lic fluid which is employed for forcing the cement into place.

In the cementing of oil wells, when it is necessary to de os1t cement back of a well casing to shut o the formations above and at the bottom of the well casing from the well bore below the well casing, it is the practice to introduce fluid cement, before the same has come to set, into the well casing and then force the cement by hydraulic fluid, such as water or fluid mud, down through the 15 Well casing, whereupon discharging below the well casing, it is forced upwardly around the exterior of the well casing.

It is the usual rocess to introduce a plug into the well be ore the cement is inserted ac to keep the cement from bein admixed with the fluids in the well and a ter the cement has been placed in the well casing, to put upon the top of the cement, a plug for separating the cement from the water or hydrau-- 2 lie mud which is used to force this cement into lace. One important function of the top p ug used in the cementing process is to stop the downward travel of the fluids when this plug reaches the bottom or near the bot- 80 tom of the well hole and then to ofl'er a seal against further downward passage of circulating fluid. in this way, the operator at the top of the well, by the pressure that is built up against the circulating means, recognizes that the cement has been lodged in position.

It has been the current practice prior to the present invention, to use for this top plug, a plug made mainly of wood with small rubber sealing cups surrounding the same. The difficulties with these plugs are that the well casing which is being cemented has not an entirely smooth internal surface, but at various places, there are projections from the well casing or enlargements of the well casing bore, and if the plug should happen to be arrested at one of these positions, a fluidtight seal is not made and the plug does not properly perform its function, and further, with the plugs which have been generally used prior to the present invention, after the cementing operation, it was necessary to drill out the plugs and cement from the bottom of the well hole when further drilling was to be performed. The wooden cementing plugs deposit fiber in the well hole which works back into the valves of the circulating pumps and holds these valves open.

It is the primary object of the present invention to provide a well cementing plug which consists in the main part of a substantially cylindrical outer walling of suflicient length to bridge any irregularities that ma exist in a well hole and to form this cylindrical Walling of a material sufliciently flexible that it may form a fluid-tight seal around any such well casing irregularity, and to provide such a well cementing plug with a substair tially hollow interior for the entrance of the fluidbeing pumped, so that the sealing wallin is held tightly against. the Well casing wa ls by the hydraulic pressure of the fluids being pumped. By the plug of the present invention danger of loss of the seal by stopping the plug at an irregularity in the caslng is avoided, and at the same time, the sealing means of the plug does not need to be supported or mounted upon a body of material, such as wood, which does not properly grind up when it is desired to remove the plug from the well hole.

Various further objects and advantages of the present invention will be apparent from a description of a preferred form of well plug embodying the invention. For this purpose, there is hereafter described one form or forms of a well plug embodying the present invention, description being given in reference to the accompanying drawings, in which- Figure 1 is an elevation in vertical section through a well hole showing the plug of the present invention in operative position, and

Figure 2 is an enlarged fragmentary section of the well plug.

Referring to the drawings, 2 generally 1ndicates a well hole in which there is disposed a well casing 3 of the conventional type. At the bottom of the well casing 3, there may 4 be employed any suitable means for arresting a plug, such as a guide shoe (not shown).

The well casing 3 at times consists of a riveted casing and therefore its inner surface is made irregular by the rivet heads or other couplings or the well casing 3 maybe of the coupled type, as shown having the couplings 4 connecting proper.

adjoining sections 5 and 6 of pipe 11 such a case, the endsof the sections 5 and 6 of the well casing pipe do not come together and so there are formed between the ends of this pi e and the couplings 4 connecting them toget er, annular grooves or enlargements of the well bore. It is essential that the plug employed for cementin through a well casing of this kind be provide with a sealing means which is effective to provide a seal over the irregularities thus-described. he well casin also ordinaril includes, at its top, a hea 8 connected wlth a pipe 9 by which fluid such as liquid mud, may

be introduced into t, e well casing after the cement for forcing the cement and plug downwardly through the well casing.

10 indicates generally the well cementing plug-of the present invention which, in this instances, is illustrated as serving as the to plug of theusual cementing process. ThlS plug 10 comprises, generally, speakin an outer side wallin 11, generally cylin rical in shape, althoug it may ossess a slight 80 downward taper, as indicate This outer cy- 85 formed by the coupling 7 in the well casing.

pose lindrical walling 11 of the lug is made of sufiicient height to insure that an adequate amount of sealing material will be resent at both sides of any irregularity, suc as that The cylindrical wall 11 of the cementing plug is formed of a flexible material adapted to be pressed against the well casing 3 by hydraulic pressure a plied to its inner surface,

10 and the material ound best suitable for this purpose is soft rubber. While other materials may be substituted for rubber, the should possess a flexible propert and shoul be preferabliy free of fiber or su ciently solidly comof fiber, that all of the fiber will be adequatel ground up when it is necessary to r111 t e plug from the well hole.

The plu 10 has a general hollow interior or i bore 12 w ich is open to communicate with hydraulic fluid, such as indicated at 13, which In certain cases, where the lug is be r diaphragm 14,

revious y hardened cement is most satis-- actory. 4

By means of the cement plug herein described the fluid cement Whlchis indicated at 16, below the plug, is ade uately sealed from the hydraulic fluid 13 use to force such cement and plug 10 down the well bore 2. The long cylindrlcal sealing walling 11 of the plug provides an adequate seal operatlve under all conditions, even those where the plug is stop ed opposite an irregularity in the surface 0 the well casing.

While the articular form of the well plug herein descri ed is well adapted to carry out the objects of this invention, it will be understood that various modificatlons may be made in the well plug all coming within the scope of the present invention and this mvention includes all such modifications and chan es as come within the scope of the appen ed claim.

I claim p A plug for following cement down a well casing under hydraulic pressure, said plug comprising an integral body of soft rubber having a substantially-tubular outer wall-' ing of suflicient height to form a surrounding seal whenever the lug is stopped opposlte an irre ularity in t e well caslng, the plug also being provided with a cross-wall for forming a fluid barrier against the passage of fluid through the well casin by the plug, the hollow space within the tu ular outer walling of the plug being adapted to recelve'h draulic fluid for ex ending the tubular wa 1- ing and pressing t e same against the well casing wall, and a disc of solidified cement within the tubular walls of the plug and restin upon said cross-wall.

igned at Whittier, Californ1a,th1s 1st day of December, 1928.

ZEB ALLEN DYER.

employed for cementing a well ole of large

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