US2033561A - Method of packing wells - Google Patents

Description

March 10, 1936. w T. WELLS METHOD vOF PACKING WELLS Original Filed Nov. l

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Patented Mar. 10, 1936 UNITED STATES METHOD F PACKING WELLS Walter T. Wells, Glendale, Calif., assignor to The Technicraft Engineering Corporation, Los Angeles, Calif., a corporation of California Original application November 12, 1932, Serial No.

Divided and this application July '1, l1934, Serial No. 734,1707L 9 Claims. (Cl. 16S- 21) The present invention relates to a method of packing wells and is a division of my co-pendlng application entitled: Means for packing oil wells and the like; illed: November 12, 1932, Serial No. 642,369. l

The objects of my present invention are:

First, to provide a method of this character which has a wide range of application, it being useful inperforming for such operations as formation testing or testing for shoe leaks, location of water intrusion in oil or gas wells, fractures in cement jobs, and segregation or orientation of oil or water producing zones in bores of great depth, breaking up cement that has been set to facilitate its removal, cleaning the well bore of mud accumulations, and many other uses;

Second, to provide a method of this character which is readily adaptable to and usable in conjunction with present-day oil well practice and requires a minimum of special equipment for its execution; and 4 Third, to provide a method of this character which may be easily and quickly executed.

With these and other objects in view as may appear hereinafter, attention is directed to the accompanying drawing in which Figure 1 is a vertical cross sectional view of an apparatus designed to execute my method, showing the apparatus in position within a well bore; Figure 2 is an enlarged sectional view thereof taken through 2-2 of Figure 1 illustrating particularlyV the check valve incorporated 'in the sampler means; and Figure 3 is a diagrammatical view illustrating a modification of my method wherein hydraulic pressure is utilized.

Referring to the drawing, the numeral I indicates a tubing string lowered into a well bore 2, here shown as open formation, filled with drilling iiuid 3, and terminating below an oil producing stratum 4.

The device hereinafter describedis operated in association with a divided tubing string wherein two sections of said tubing are provided with means permitting relative movement of the sections and said movement is utilized to expel a refrigerating agent for the purpose of solidifying all water bearing matter cognate to said tubing string.

But one string of tubing is employed and it serves several purposes. the well dry", that is to say, closed at the bottom to keep it empty of iluid as it is lowered into drilling iiuid or the like.

It thus provides a conduit for the discharge refrigerating agent at substantially atmospheric Said string is run intol pressure. When subsequently opened, it affords a means of communication with the producing zone below the frozen area for the recovery of a sample of fluid therefrom, and for circulating, from the mouth of the well, a stream of liquid to expedite thawing or to create hydraulic pressure in the zone below the frozen core. 'Ihe lower end of tubing I, (upper section) is threaded to receive collars 6 and 'I. Between said collars is a piston 8, provided with rings 9 and cup leathers II.

Slidable within the tubing is the upper end member I2 of the lower section of tubing string I.

. Welded or suitably secured to member I2 is a cylinder head I3 to which is threaded, at I4, one end of a cylinder I6, the opposite end of which is threaded at Il to a cylinder head I8, provided with a packing gland I3 through which slides the tubing I.

The structure so far described provides a cylindrical chamber 2| which is loaded, before the device is lowered into the well 2, with a refrigerant 22, which may be anhydrous ammonia, carbon dioxide, sulphur dioxide or other suitably equivalent.

The member I2 is threaded into a bore 23 in a connector 24. Said bore is enlarged from below and tapped to admit therein a threaded collar 26, a valve cage 21, and one end of a pipe 28 provided with perforations 23.

A rigid connection is thus formed between perforated pipe 28 and member I2 and it results from this that, when pipe 28 encounters the bottom of well 2, cylinder I6 is held stationary and the weight of the entire upper section of the tubing string I is eiective to move piston 8 through said cylinder and expel the refrigerant 22 through an expansion valve 3| which, under urge of -a spring 32, normally closes one end of a pipe coil 33, here shown as a double coil surrounding the member I2 and terminating in a valve cage 34.

As the weight of tubing string -I moves piston 8 downwardly the space behind said piston is illled with drilling uid 36, from well bore 2, which enters through passages 31 and 38 normally closed by a spring actuated check valve 39.

Therefrigerant 22, under pressure, unseats expansion valve 3|, passes through coil 33, lifts a flapper valve 4I (in valve cage 34) to its dotted line position and exhausts into member I2 of the dry tubing string.

The rapid expansion of the refrigerant, thus released, congeals the liquid surrounding the coil 33 and solidiiles an area of considerable size in the adJacent formation as indicated by the broken line shaded area A in Figure 1.

'I'his method of sealing or packing an open hole or formation bore, which has no casing, assures a fluid tight seal betwen the tubing string and a surrounding wall which is completely effective, irrespective of inequalities or irregularities of surface, or formation characteristics, which so often defeat mechanically operated packers.

'I'he tubing string I has been kept dry up to this point by a. membrane or disc 42 compressed between collar 26 and pipe 23 in a manner obstructing passage of liquid into member I2.

When the refrigerating action has taken place, a go-devil indicated in dotted lines at 43 is dropped through tubing string I, from the mouth of the well, and it strikes the top of a piston valve 44, which rests on said disc 42 and is thereby prevented from seating in its cage 21 until said disc is broken out as described.

As soon as said disc is broken, fluid in the zone below the frozen area is released at substantially atmospheric pressure, and it rushes into member i2 of the tubing string, lifting piston 44 until it abuts collar 26. Said piston is provided with quadrilaterally disposed channels 46, Figures 2 and 3, which communicate with a bore 41 in collar 26. f

Fluid continues to rise in the' tubing string until it reaches its normal head, being relieved of hydrostatic pressure of drilling fluid in the well by the frozen area 33.

When the pack thaws 33 suillciently to permit raising of the tubing string, piston valve 44 acts as a foot valve, entrapping the fluid content of the tubing, as the lower tapered end of said valve seats in cage 21 and closes channels 46.

Check valve 31 prevents escape of drilling fluid from cylinder I6 and said fluid, being entrapped, forms a connecting link between the upper and lower sections of tubing string I, automatically responsive to the first lifting strain.

Said check valve 31 also provides a means for applying pump pressure to piston 3 as shown in Figure 3. Should it be desirable to augment the pressure provided by the weight of tubing string I, a pump 43 is connected, by a pipe line 49, to the well 2 which is closed at the mouth as indicated at 5|. As the pump increases the pressure in the Well valve 3| is unseated and piston 3 moved downwardly to discharge refrigerant 22.

It is of course recognized that heat resulting from compressing of the refrigerant before opening of valve 3| must be dissipated to obtain an efficient refrigerating action in coil 33. This may be accomplished in several ways. First, the refrigerant may be introduced in the cylinder 2| under pressure; but such pressure being lower than that necessary to open valve 3|. Then upon applying additional pressure either through tubing string I or hydraulically through valve 31 the valve 3| is caused to open. The additional pressure need not be such as to heat the refrigerant materially; furthermore, the chamber 2| is quite elongated and the pressure therein may be maintained fairly uniform after the valve 3| is open so that a large percentage of such additional heat will be dissipated through the walls of the cylinder. Very little of this heat will be absorbed by the chilling coil as heat tends to be dissipated upwardly.

Second, as the refrigerator is lowered, the liquid in the well bore tends to maintain an equality `53 under urge of a spring 54.

of pressure between the exterior of the refrigerator and the upper end of the piston 3, providing valve 31 does not offer too much resistance. This pressure increase lifts the refrigerator structure relative to the tubing string moving the piston relatively downwardly and compressing the refrigerant. In this case as in the first, valve 3| is designed to withstand this pressure. The movement of the piston is gradual and the heat of compression is dissipated to the well fiuid as fast as it is generated so that the temperature of the refrigerant does not increase materially. When the refrigerator is in position, additional prure either hydraulically or by gravity is applied to open valve 3|.

Third. valve 31 may be designed to remain closed against the pressure of the well nuid. After the refrigerator is in position the tubing string is moved downwardly shifting the piston a predetermined distance calculated to compress the refrigerant but not open valve 3|, and is then held until the resulting heat is dissipated; whereupon the additional pressure is applied.

Pump pressure can also be applied to tubing string I to ush the formation below the frozen zone, or to increase pressure at that point.

A check valve 52 is provided in the piston valve v44 and said valve normally closes a port However when said check valve is unseated fluid enters the port 53 and finds its way through passages I3 which open into a bore l1 in valve cage 21, when the piston valve is seated in said cage.

'I'he piston valve 44, check 82, and cage 21 are also shown and described in my co-pending application for patents, filed September 6, 1932, Serial Number 631,781.

In order to prevent accumulation of frost around expansion valve 3| and its orifice I load coil 33 with an inert iiuid containing-no moisture. Said fluid is also placed in the lower portion of pipe I2 to a level indicated by the dotted line 5B, Figure 1. Said fluid is driven out of coil 32 by the release of refrigerant 22 ahead of piston 3.

It will be seen that pipe 23 can be removed from the foot member 24 and other anchoring means substituted therefor.

I employ a standard thread which makes possible the interchangeable use of either a rathole packer of the type illustrated in my copending application Serial Number 634,599, filed September 23, 1932, or a hook-wall packer such as is described in my application Serial Number 614,731, filed June 1st, 1932.

The operation of my invention is as follows:

Formation test-During the drilling of an oil well, the bit progresses into the ground or formation, passing through various strata. The object is to temiinate the well when a formation has been reached containing a supply of oil or gas in quantity suilicient for practical production. While the well is being drilled it contains a quantity of mud laden fiuid, known as drilling fluid.

This fluid exerts pressure, dependent upon the height of the fiuid, which opposes the natural pressure of the oil or gas contained in the formation through which the well is being drilled.

Oil is usually encountered in formations at considerable depth and at pressures insumcient to overcome the pressure of the fluid in the well.

As the driller does not know the depth at which oil may be present, and to prevent drilling on past an oil bearing stratum of formation without knowledge of its existence, a formation test is made to determine the productivity at a given depth. y

My apparatus is assembled as shown in Figure 1 and lowered into the well 2 on the lower end of tubing string I, the lower section of which is movable with respect to the upper section.

said movement being limited to .the degree of travel of piston 8 in cylinder I6.

When the lower end member 2l of the bottom section encounters the bottom of the well, the weight of the upper section moves piston 3 and displaces the refrigerant 22, the rapid dissipation of which lowers the temperature in the zone surrounding the coil 33 until a pack or seal A is solidified and seals off the drilling fluid 3 from formation below.

When the well has been packed in this manner, go-devil 43 is dropped through tubing string I and -its impact shatters the frangible disc 42, opening the tubing string I to the inux of fluid from the formation 4. Said fluid, being now opposed by-no pressure other than atmospheric, rises within the tubing string I to its natural head or level.

The frozen pack A is allowed to thaw and the tubing string I is raised. Foot valve 44 seats under pressure of the entrapped fluid sample in the tubing and said sample is lifted within s the string.

Water shut op* test.-Before a well is placed on a production basis, a string of casing is set and said casing is cemented around its shoe, or bottom end, and measures must be taken to ascertain the eiilcacy of said cement seal in excluding extrusion of water from upper levels into oil Yproducing formation. Laws, enacted in the interest of the eld as a whole, require .a test furnishing proof that this water shut oil! is complete.

A cementitious material is introduced through the casing and allowed to set aroImd the casing and below its lower end for a considerable distance. The cement plug so formed is then drilled through, the bore extending beyond the casing and into formation below. As it is impracticable to bail out the casing at great depths owing to danger of collapse of casing under external pressure it is necessary to pack within the casing and near the shoe and thereafter recover a sample of the content of formation below.

In this instance, the relatively small volume of iiuid between the casing and the drill stem need be solidified to effect a pack.

A quantity of refrigerant 22 is injected through a loading bore 59, Figure l, through the cylinder head I3, and said bore is closed by a plug 6I.

The device is lowered as before and the drilling fluid solidified at a point above the shoe of the casing, go-devil 43 is dropped to open the tubing string I to admit a sample of fluid through pipe 28.v The seal is allowed to thaw and the entrapped sample recovered as previously described. Y

Removing coated accumulations from formation MIL- Formation walls become plastered or encrusted with drilling fluid which impedes filtration of oil into the bore. The weight of the column of dense fluid and the action of the boring tool combine to produce this effect.

As the accumulation contains water it can be removed by submitting it 'to -alternate freezing and thawing and the solid content of the encrustation will gravitate to the bottom of the well-leaving` the. formation wall in a better condition to exude oil.

. Disintegrationbf cement bodies-It some-l times happens, in a cementing operation, that cement introduced in plastic state sets prematurely, or improperly, leaving an obstruction to re-cementing efforts. and not effectively preventing inilltration of water from above.

Buch bodies can be fractures by expansive treatment a batch of refrigerant isolated from the surface, restrained in an inert condition but capable upon being released to absorb a predetermined quantity of heat; and then releasing said refrigerant charge to cause it to undergo-a single refrigerating cycle.

2. The method of extracting heat from a predetermined section of ajwell bore characterized by: introducing opposite the section to undergo treatment a batch of refrigerant isolated from the surface; then influencing the. 'r frigerant body to cause it to undergo a refrigerat cycle.

3. The method of extracting heat from a predetermined section of a well bore characterized by: introducing opposite the section to undergo treatment a batch of compressed refrigerant isolated from the surface; then reducing the eifective pressure against the refrigerant body.

4. The method of forming a congelation plug in a well bore characterized by: introducing op posite a predeterminedv point in the well bore a batch of refrigerating material isolated from the surface and calculated to absorb suilicient heat from the surrounding formation while being dissipated to `divide temporarily by congelation said well bore into upper and lower zones.

5. The method of obtaining fluid samples from liquid illled well bores characterized by: causing a refrlgerating charge to undergo a single refrigerating cycle while being dissipated and temporarily divide the well bore by .congelation into an upper and a lower zone; and then collecting a sample from the lower zone while the well bore is so divided.

46. The method`of obtaining fluid samples from liquid filled well bores characterized by: introducing above the region from which the sample is desired an isolated refrigerant charge restrained in an inert condition but capable of being released to absorb a suili'cient quantity of heat to divide by congelation the well bore into an upper and a lower zone; then collecting a sample from the lower zone.

7. The method of obtaining fluid samples from liquid filled well bores characterized by: introducing above the region from which Ythe sample is desired, a compressed refrigerant body isolated from the mouth of the well bore; then reducing the effective pressure against the refrigerant body whereby the refrigerant body is caused to absorb heat, the refrlgerating capacity of said refrigerant body being calculated to provide upon completing its refrigerating action a congelation plug dividing the well bore into an upper and a lower zone; then 'collecting a sample from the lower zone.

8. In the art of obtaining fluid samples from well bores wherein the well bores are divided into upper and lower zones and the fluid samples are collected from the lower zones, the method of producing such division of a well bore charactera fluid sample from the lower zone without du. ized by: introducing at the point ot division a placement oi' nuid from the upper none, char. refrigerant charge calculated to absorb suillcient terized by: causing a relrigerant to form by `heat from the surrounding formation while the congelation a plug dividing the well bore extecharge is being dissipated to divide temporarily riorly of the sampling device and above its inlet;

said well bore into an upper and a lower zone. and discharging the dissipated refrigerant into 9. A method of dividing into an upper and the sampling device.

lower zone a well bore in which a sampling device WALTER 'n WELLS.

hasbeen positioned for the Purpose of obtaining

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