US2080406A - Well and method of constructing and cementing same - Google Patents

Description

J. W. ALLEN May 18, 1937.

WELL AND METHOD OF CONSTRUCTING AND CEMENTING SAME Fil ed Sept 12, 19s;

Junentor attornegs Patented May 18, 1937 NlTED STATES PATENT OFFICE WELL AND METHOD OF CONSTRUCTING AND CEMENTING SAME 8 Claims.

The present invention relates to drilled wells such as water or oil wells, gas wells, artesian wells and the like and more particularly to a cement or concrete pipe (or casing) therefor and to the method of constructing same.

In such wells as conventionally constructed there is usually provided ametallic pipe of from two to six inches, more or less, in diameter extending substantially the length of the bore of the well, which bore may vary from one hundred feet or less to several thousand feet. Such pipe, or casing as it generally termed, is employed in the transmission of fluid (gas, water or oil) from the well. It is generally necessary, particularly in the upper portion of the well, also. to use a metallic casing of a diameter slightly smaller than the earth bore of the well, to serve as a support preventing the sides of the well from caving in, this being in addition to the pipe or casing first above described. These metallic pipes and casings are expensive particularly in the larger sizes where the price often runs several dollarsv per foot of easing.

It has long been customary to use cement mixtures for coating the sides of dug wells, by which is meant those wells of a diameter sufiicient to allow a man to descend into them to do the necessary plastering of the well sides. But, because of the impossibility of such method being used in the case of drilled wells, due to their small bore, steel casing or pipe has always been used and considered the only means to accomplish the end in view-namely, to support the sides of the well andto provide a suitable passageway' for the gas or fluid from the well.

One of the objects then, of this invention is to provide a practical method by which concrete or cement may be used in lieu of the customary pipes and casings.

To the attainment of this object, a removable form is provided; a means of holding the form in center of the well so that the walls will be of uniform thickness is suggested; a means of placing the concrete or cement so that no porous cavities will result, is utilized; means providing for the removal of the form, means for drying and curing the concrete, and means for treating the surface so as to make it more impervious to water, oil or gas and thereby increase its usefulness and lasting qualities, are contemplated. The method by which this is accomplished will appear as the description proceeds, in which reference is made to the accompanying sheet of drawings in which:

Figure 1 is a vertical longitudinal section through the bore of the well just prior to the construction of a cement or concrete pipe therein, and showing apparatus used in carrying out the method;

Figure 3 is a similar view showing the cement or concrete pipe immediately after being poured;

Figure 3 is a similar view showing the cement or concrete pipe after removal of the temporary metallic form;

Figure 4 is a section on the line 4-4 of Figure 1;

Figure 5 is an enlarged fragmentary longitudinal section illustrating details of the form and the medium between the form and outer edge of the well.

In describing my method and the well structure resulting therefrom specific reference will be made to the accompanying sheet of drawings in which like reference numerals designate like parts.

When the bore I0 is drilled and it has been ascertained what size of finished opening is desired in the well, a hollow tubular form, which has been previously coated externally with a suitable meltable material M, which issolid at normal well temperatures, such as asphalt, paraflln, heavy grease, sulphur or the like, is lowered into the well; This form is of such a size that the external diameter of the coated form, including the coating, will be the same as the desired diameter 22 of opening in the finished well, and is of suflicient length to extend substantially from the top to the bottom of the well. Ordinary casing or pipe is practical for the form. It is necessary that the coating material have a low melting point but be solid at ordinary well temperature and said coating be of uniform thickness and of suflicient thickness to extend slightly beyond all raised places on the form, such as conplings, etc. If desired, the couplings may be of a kind to go inside the form or casing.

While reasonably straight in actual practice, drilled wells and more especially deep wells, deviate more or less from the vertical,- nor is a long string of pipe perfectly straight, so that a string of pipe when lowered into the well, though much smaller than the bore of the well, may at one depth come in contact with one side of the well, and at a lower depth be in the center of the bore, and-at a still lower depth touch the opposite side, possibly for a distance of many feet.

To overcome this difliculty and to serve certain other purposes as will appear there are secured about the form, externally of the asphaltic coating, and at suitably spaced intervals a series of spacing collars it, of metal, or any long lasting material subject to use in concrete or cement construction. They have a diameter less than the bore of the well and a curved under-surface as shown in Figure 1, so as not to impede lowering of the form into the well. As shown by Figure 4, hollow circular openings extend vertically through these spacing collars so as to allow free passage of the concrete or cement. Also if it is necessary to use reinforcing rods H! or other equivalent means for strengthening the cement or concrete these spacing collars [6 will form a convenient means of securing same, by placing reinforcing rods through the holes made for that purpose inthese collars, as illustrated in Figures 1 and 4 and, if thought necessary, annular sections of perforated or expanded metal may be used and secured to the spacing collars. The collar illustrated contains four openings for cement passage and four'for reinforcing rods but these collars may be constructed with more or less holes and only with openings for cement passage where no reinforcing rods are used. Use of the collars will tend to prevent formation of thin spots when cement is subsequently poured about the form.

When the form I2 is in position cement or concrete in a liquid or semi-liquid state will be forced down thru the inside of the form by any conventional pressure apparatus so as to flow out at the bottom of the form and be caused to fiow upwardly within the annular space between the form and the walls of the well l0 to the top of the well. The cement remaining within the form can be displaced in any convenient manner as by forcing sufiicient fluid under pressure down the form to drive the concrete out and thereafter lowering the form slightly to the bottom of the well shutting off all communication between the interior of the form and the space outside to prevent flow of cement or concrete back into the form. In deep wells where the opening within the, form is sufliciently large a smaller pipe 20 as shown in Figure 1 may be used for forcing the concrete thru to the bottom of the well following the same method as above. The purpose of forcing the cement or concrete in a liquid or semiliquid state to the bottom of the well and causing it to rise to the top around the form is to prevent the formation of air pockets and insure a solid formation. However in certain wells, particularly shallow wells, it may be possible where the space between the form and sides of the well is sufficient and the cement used is sufficiently liquid to introduce the cement or concrete into the annular space from the top and insure a solid formation void of air pockets. Also where conditions permit the cement or concrete may be introduced through a pipe running from top of the well to bottom between the form and sides of the well which may be gradually withdrawn as the well is filled, this latter method preventing any necessity of the cementever entering the inside ,of the form.

Any suitable arrangements may be made in pump wells for seating pump cylinders and in artesian, gas or oil wells for drilling through the final distance or plug after the concrete has set and necessary arrangements at bottom and top of well for controlling as well as arrangements for placing a strainer' pipe at the bottom of the well may be made.

The cement or concrete will flow up through and around the spacing collars l6 and the reinforcing, if any is used, to completely enclose same and they will remain embedded in the concrete.

Thereafter steam is introduced into the form l2 to help cure the cement or concrete, and cause the asphaltic coating on the outside of the form to. melt. This will release the form from the concrete, and the material will tend to coat and penetrate the concrete, thus greatly aiding in making same impervious to water, oil or gas to serve the double purpose of lengthening its life by protecting it from direct contact with water, oil or gas as well as preventing any loss of products from the well by seepage through the concrete or cement. Any suitable heating medium such as hot air, hot water or electric heating device may be used for the same purpose as the steam.

The asphaltic substance having melted around the form, the form can now be withdrawn leav-v ing the completed concrete or cemented well ready for the transmission of gas, oil or water as the case may be, through the bore 22, and the single concrete casing thus will take the place of both metallic casings used in prior practice.

Aside from the great saving in cost over the conventional use of metal casing and metal pipe, another important feature is, that in those sections of the country Where at present periodic replacement of metal casing is required, due to metallic corrosion, this method of constructing a cement or concrete pipe in the well will do away with replacement expense, as concrete becomes stronger with age.

Wherever the term cement is used Portland cemen is suggested, though any other type of cement might be used if suitable, but what is known to well men as cement grout, will probably be most desirable; It is contemplated, that if desired such chemical reagents as calcium chloride or calcium oxychloride may be used in the cement mixture where Portland cement is used to hasten hardening and increase early strength, though in deep wells it will probably not be desirable except where the particular conditions are such as to recommend it. Arrangement may be made to slightly alternately raise and lower the coated form while the cement is being forced into the well to aid in securing a solid and impervious cement formation.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of constructing concrete or cement pipe in drilled wells for the transmission of fluid from within the earth to the surface which comprises coating a tubularform externally with a meltable substance which is solid at ordinary temperatures, drilling a well bore of greater diameter than the form, positioning the said coated form within said drilled bore and in evenly spaced relation to the walls thereof, forcing a cementitious substance into the space between said form and sides of the well from the bottom of the well upwardly, heating said form to a degree sufiicient to melt said substance with which the form is coated, and releasing the form from the cement, and withdrawing said form.

2. The method of constructing wells which comprises coating a tubular form externally with a meltable substance which becomes hardened at ordinary temperaturesdrilling a well bore of greater diameter than the form, positioning said coated form within said bore and in spaced relation to the walls thereof, forcing a cementitious substance into the space between said form and walls, heating said form to a degree sufficient thereof by said meltable substance, by heating said form to a degree suflicient to melt said substance and release the form from the cement, and withdrawing said form, thereby leaving a cement casing having a fluid impervious bore.

4. The method of constructing wells which comprises coating a tubular form externally with a meltable substance which is solid at ordinary temperatures, drilling a well bore of greater diameter than the form, applying to said form a spacing collar, and securing a reinforcing member to said collar, positioning said coated form,

collar and reinforcement within said bore whereby said collar will maintain the form in spaced relation to the walls of the bore, forcing a cementitious substance into the space between said form and walls, heating said form to a degree suflicient to' melt said substance and release the ,form from the cement and from the collar and reinforcement, and withdrawing said form.

5. In a drilled well a hollow form, about which a cementitious substance may be poured, a removable reinforcing collar about said form having an external configuration tapering inwardly from top to bottom and effective to space the walls of said form. from the drilled bore of the well, means to force a cementitious substance 40 between the walls of said form and the walls of the drilled bore, and means to free said form from sticking to said cementitious substance.

6. The method of constructing wells which comprises coating a tubular form externally with a meltable substance which is hard at ordinary temperatures, drilling a well bore, positioning said form within said bore and in spaced relation to the walls thereof, forcing a cementitious substance into the space between said form and walls, applying heat to the interior of said form to cure the cementitious substance and to meltthe coating about the form whereby to release the form from the cementitious substance, and withdrawing the form.

7. The method of constructing wells which comprises coating a tubular form externally with a meltable substance which is hard at ordinary temperatures, drilling a well bore, positioning said form within said bore and in spaced relation to the walls thereof, forcing a cementitious substance into the space between said form and walls, applying heat to the interior of said form to melt the coating about the form and to cause a permeation of the cementitious substance with the material of said coating, and withdrawing said form after said coating has melted.

8. The method of constructing wells which comprises drilling a bore, inserting in said bore a hollow form having thereabout a reinforcing collar shaped with an external configuration tapering inwardly from top to bottom and effective to space the walls of said form from the walls of the drilled bore, forcing a cementitious substance between the walls of said form and the walls of said bore, freeing said form from the cementitious substance, and withdrawing said form from the cementitious substance and reinforcing collar, thereby toleave said collar embedded in the cementitious substance.

JACK W. ALLEN.

Images