US2372575A - Method of freeing pipe jammed in a well - Google Patents

Description

March 27, 1945. J. T. HAYwARD MTHOD OF FREEING PIPE JAMMED IN A WELL Filed oct. 1o, 195s nlv y w` W Q w m v m U .In n f .w 2 HH \|\\|,l. M

Patented Mar. 27, 1945 v METHOD 0F FREEING IIPE-'JAMM IN A WELL John T. Hayward, Tulsa, Okla.4

Application October i0, 1938, Serial No. 234,223

(Cl. 20d-180) 2 Claims.

This invention relates to a method of controlling the deposition of solid matter on objects immersed in uids containing solid or semi-solid matter in suspension therein, and more particularly to an electrical method of controlling the deposition of earthy particles on objects immersed in an earthy suspensoid.

In numerous industrial operations, streams or bodies of fluids containing solid matter are handied or subjected to treatment in various-ways which involve immersing in the fluids, objects,

such as thermometers, hydrometers, electrodes, pressure gages, viscosimeters, meters and similar apparatus for the several purposes normally served by these objects. 4In Amany ofthese operations, the tendency of solid or semi-'solid matter contained in the fluid to deposit on the immersed objects adversely affects the emciency of these f objects to fulfil their normal functions, and may thus seriously impair the efciency of the operations being conducted. For example, in the drilling of wells by the rotary method, which involves the continuous circulation of a stream of mud laden fluid to and from the well, the physical.

and chemical characteristics of the fluid must be carefully watched and controlled throughout the drilling operations in order that dangerous and expensive blow-outs may be prevented and in order to study the nature of the strata traversed by the drill by* observing and measuring the changes which occur in the character of the circulating fluid. Such study and observation requires the use of various indicating, recording and measuring instruments which are ordinarily keptv immersed in the stream of mud fluid. Such instruments may be electrical or non-electrical, depending upon the character of the test to be made. In practically every case, however, such instruments, when immersed in the mud fluid, become caked or clogged by deposits thereon .of the mud particles carried by the uid, and are rendered completely inoperative, or ineflicient in perfomance 'of their normal functions, For example, frequently desired, when a thermometer bulb, whether of glass, metal or other material, is immersed in the mud stream for this purpose, it

quickly becomes,l caked with a layer of mud particles which acts to insulate the bulb and thus render the temperature readings incorrect and unreliable. Or it may be desired to measure the electrical resistance of the mud stream, which operation involves immersion of a pair of spaced electrodes in the stream and. again deposits of mud matter will form on the electrodes, at least partially'- insulating them, and render incorrect the resulting resistance readings e In still another case, the viscosity of the mud stream isa physical property, the close control of which ishighly important, and for best results should be continuously observed, However, sev- 'eral otherwise practical forms of viscosimeters for obtaining continuous measurements of this property have been ydeveloped but all involve the immersion of some part, s'uch as a rotating metal cylinder or a tube, in the mud stream whereby the viscosity of the mud uid is obtained. All such viscosimeters have lproven generally inoperative in practice because of the adherence of the mud particles to the immersed parts, thereby rendering theV viscosity readings meaninglesa'and since no way had heretofore been found to prevent the 'deposition of mud on such parts, these continuous methods of Y. measuring viscosity had to be abandoned in favor of intermittent sampling of the mud stream and testing the viscosity of the individual samples. This method is rather unsatisfactory becauseA of the frequently rapid and marked changes effected in the mud stream by. contact with subsurface strata, and the individual'samples thus are very often not at all representative of any substantial portion of the `mud stream and the viscosities of such samples, therefore, may be entirely misleading and inaccurate.

Numerous other examples of like-nature may be found in both well-drilling operations and in other types of operations, but it is thought that the foregoing examples are sufficiently illustrative of some of the problems which are solvedv by this invention.y

The method contemplated by this invention is based upon the phenomenon of electrophoresis f which is defined as the migration of suspended temperatures of the mud stream are solid, liquid, or gaseous colloidal particles under the influence of an external electrombtiye force. As most solid particles in suspension inl'liquids generally carry an electric charge, it is found that if an E. M; F. is impressed upon an 4object'in'imersed ina fluid containing such particles, an velectric field is created' in the fluid about the object causing a migration of the charged particles through the fluid in a directionl in accordancer with the direction of the field and with'the sign of the charge'on the particles. Thus. if the particles are negatively` .charged and the `field direction is toward the object, the negatively charged particles will move oppositely to the direction ofthe field and away from the object. If the particles are positively charged, they will move toward theobject, but if the eld is reversed, the positively charged particles will move in the direction of the fleld and away from the object. In other words, if an lobject is immersed in a fluid containing negatively charged particles, in order to prevent deposition of the particles on the object, an electric circuit is established including the object and the fluid, and an E. M. F. is applied to the circuit to create an electric field, the direction of which will be toward the object, and

- the negatively charged particles will then migrate way from, or will be repelled from, the object. If the particles are positively charged, the field direction will be directedr away from the object and the particles will be repelled therefrom under the influence of the externally applied E. M. F. vStated in still another way, the method comprises making the object of like electrical sign relative to the charge on the particles in order to repel the particles from the object and of unlike eiectrical Sign to cause deposition of the particles on the object whenever such action may be desired.

Another important application of this invention is in releasing objects which, when immersed in fluids containing solid or semi-solid stuck or jammed by the settling of the solid or semi-solid matter about the object, or by the formation of gel-like masses in the fluid, .to such an extent that the objects cannot easily be withdrawn from the iluid.

A very common example of this condition is found -in the well drilling industry, where drilling tools, pipe and similar objects become stuck in the drill hole, when for various reasons cuttings and other solid matter carried by the drilling or well iluids, known in the art as a mud uid, and generally comprising water anda gelforming component such as clay suspended in such a fluid, precipitate from the fluids and settle about the tools orpipe, or when the mud iluid forms a semi-solid gel of such consistency that removal of the tools or pipe becomes exceedingly difficult. By impressing an E. M. F. on the'tool or other object to create an electrical field in the fluid in proximity to the object, and by suitably controlling the direction of the field relative to the charg'e on the particles in the iluid; these particles will be repelled from the object, resulting in its release and permitting easy withdrawal thereof Afrom the fluid and the drill hole.

This application of the present invention was described in my former application, Serial Number 199,831, filed April 4, 1938, for Methods of controlling well fluids, and the present application is, therefore, a continuation-impart of ,my former application'. Y Therefore, a principal object A more specific object -is to provide an 'elecl trical method for preventing the deposit ofmud solids on objects. immersed in oil well muds.

`matter, particularly in conned spaces, become tion through the well.

An additional ,object is to provide an electrical method for releasing objects which become stuck or jammed in iluids containing solid .or semisolid matter,

A further' object is to provide an electrical method for releasing drilling tools, pipe and the like which has become stuck in the mud lluids within well bores.

Other and-more specific objects of this invention will be readily apparent from the following detailed description thereof and the accompanying drawing which illustrate more or less generally apparatus suitable for practicing the new invention.

In the drawing:

' Fig. 1 illustrates a portion of the ilow of a streamof mud uid in conventional rotary well drilling operations and showing an object immersed in the mud stream and the electrical circuit employed in conjunction therewith for accomplishing the aforementioned objects of the present invention. y

Fig. 2 is an enlarged detail of the significant portion of the apparatus shownk in Fig. l.

Fig. 3 is a view similar to Fig. 2 but showing a diierent object immersed in the mud stream.

Fig. 4 is a view showing an assembly of apparatus for releasing a drilling tool and pipe from the fluid in a' well bore.

Referring to the drawing and to Figs. l and 2 in particular, the numeral I designates a conventional well casing through which extends a pipe`2, such as a Conventional string of drill pipe. Mud fluid 3, such as is usually used in well/drilling operations and consisting ordinarily of a suspension of finely ground clay or other earthy matter in vWater or similar aqueous suspensoid. is circulated through the well lay-introducing the fluid through pipe 2 throughwhich it ows to the bottom of the well, returning through the annular space between pipe- 2 and casing i whence it is` discharged at the surface of the ground through a pipe "lnto a conduit such as a mud ditch 5, thence to a settlingpipe 6 where drill cuttings -and other matter are separated from the mud fluid, which'is then drawn through a suction pipe 'I'to 'a pump, not shown, which returns-the mud fluid to pipe 2 for recircula- An object, such as a vapor pressure thermomeier 8, has its bulb 9 immersed in the mud fluid for the purpose of *observing the temperatures of the fluid as it leaves the well and flows through ditch E. A source of direct current IB, which may be a battery, generator or rectifier, has one terminal connected by a lead H to the bulb 9 of this inventionlis to provide a method for controlling the depo- .and the other terminal by a lead I2 to ground.

The described apparatus is operated in the fol'- low'ing manner in order to control the deposition of solid or semi-solid mud particles on the bulb. In this case, it is desired to prevent the deposition of the solid matter on the bulb. Asv

1 positive terminal vto ground. ',Ihe mud ditch 5 is. o f course, also grounded. By means of the electric circuit thus established, an. E. M; F. is

impressed upon bulb 9 and an electric field es- .tablished through the mud fluid. The surface charged solid particles of the mud fluid, shown in exaggerated size in Fig. 2, will be repelled from l mud matter, andnly very low voltages are required. In the above example, where thebulb il relatively good conductor, a small standard sized ash light battery cell supplied sufficient voltage to keep the bulb clean. Actually only about l to 2 volts was all that was required to keep clean not only the described thermometer bulb, but also several additional instruments which were connected in parallel with the thermometer. Generally speaking, the voltage required will be such as is sufficient only to create an electric field in the fluid about the objects to be'kept free of deposits, and will be relatively low, ordinarily,

.. is constructed of metal, such a's iron, which is a but may be increased, depending upon the intensity of the action desired in keeping Athe objects clean.

Fig. 3 shows the invention applied to prevent deposition of mud matter on electrodes immersed in the mud fluid. The electrodes, designated I3-l3, are connected to a separate electrical circuit, designated generally by the numeral I4, which is` employed for the purpose of obtaining electrical measurements of a certain properties of the mud fluid, such as its electrical resistivity. "ll'hisl circuit includes a source of alternating current, a variable resistance, and an alternating r current voltmeter, as shown in yligure 3. requires that current flow through circuit I4, which is independent of the cleaning E. M. F. applied in accordance with this invention. In order to prevent the deposition of mud matter on the electrodes I3-|3,`whlch'would tend to in sulate them and adversely effect the resistivity measurements obtained therefrom, the negative terminal of current'source l0 is connected to circuit l and thepositive terminal of source l0 is then connected `to ground, as inthe above example. A small E. M. F. is thiis impressed on circuit I4 including electrodes I3 and by means of this E. M. F. the electrodes become negatively charged and thus repel the negatively charged particles of mud uid 3. The impressed E. M. F. is analogous to that referred t'o in the electrical arts as a bias E. M. F. having no direct effect upon the action of the current flowing in the cir. cuit it.

in this case, again, the voltage required will be relatively low but may be varied or increased depending upon the intensity of the action desiredv to keep the electrodes clean.

Fig. 4 illustrates a modification in which cleaningE. M. F. may be applied, as above described, to a drilling string l5 immersed ir'i the mud fluid in a well.

The action is the same as that previously described, in that, by application of suilicient F., the particles of the mud fluid are repelled from'the surface of the drilling string and the frictional and electrical drag ofthe mud fluid thereon is greatly reduced,v

since the movement of the solid matter away from the string will leave the string surfaces in contact 'with \a film of lrelatively clean water, which would, of course, offer little resistance vto the movement of the string, either longitudinally or rotatively.

However, a very important applicationof this tools or'pipe which have become stuck in the well. The mud fluids commonly used xin drilling operations are colloidal suspensions of finely ground clay orotherl similar earthy matter in water or similar aqueous suspensoid. Ordinarily the nature of the colloid is so controlled that the fluid will have relatively low viscosity and yield strength, suillcient to carry cuttings. from the well but low enough to permit rapid setting o f the cuttings from the fluid .after removal from the well. The colloid comprising the mud fluid is frequently of such a nature that it will remain iluid and relatively non-viscous as long as it is agitated by movement through the well, but when allowed to become quiescent, as by stoppage of the circulating pumps, forms a gel of quite considerable strength. The gelling of the fluid may yalso occur frequently as a result of chemical changes produced in the fluid by certain of the materials removed from the sub-surface formations by the drill. 'For exam-ple, bentonitic materials frequently encountered in wells sharply increase the viscosity'and gelling of the mud fluid.

When gelling or thickening of the mud fluids occur in a well, the consistency of the fluids may become such that the drilling tools or pipe become firmly stuck in the well bore, and'become very difllcult'to remove from the well, sometimes even causing complete loss of the Well. In other cases, the colloidal character of the mud fluid may be destroyed by action of materials encountered in the well withthe result that the clay particles'precipitate from-'the colloidal mud fluid and, upon stoppage of the mud pump, may settle about the tools or^pipe and pack sufllciently to. prevent ready removal thereof from Til invention in connection with drilling tools and -l pipe which must be frequently removed from the wen and reinseri-.ed therein during the course of the drilling operations, is in the releasing of such `of tools or pipe into a well containing mud uid, the mud particles tend to build up on the adjacent surfaces of the tools or pipe and the wall of the well to such an extent that masses of mud particles are rubbed-off of these surfaces by the longitudinal movement of the tools or pipe in the well and cause same to be jammed in the well. This action is commonly known in the art as balling-up and causes a great deal of dimculty in the running of pipeand tools in and out of a Well.

In such cases, the present invention is successfully applied to release. the toolsor pipe which has become stuck in the well. This is accomplished by connecting the negative terminal of the current source I0 tothe tool or pipe and applyingl a suitable E. M. F. and making the tool or pipe negative relative to the particles of the fluid. Immediately,l by electrophoresis, those particles which are contact with the surfaces of the tools or pipe are repelled therefrom, and are replaced by a sheath of the aqueous suspensoid, thereby releasing both the frictional and electrical drag of the solid matter upon the tools or pipe and permitting ready withdrawal thereof from the well. A

The E. M. F. may be applied to the entire string cf tools or pipe as illustrated in Fig. 4, or to a portion thereof as may be desired.

In` this case, also, the voltage required will be rele-tively low and may be varied as desired to hasten the releasing action thereof on the tools. In most cases, 5 to l5 volts per inch of fluid, perpendicular to the surface of the immersed object. will be suicient to release the object.

As previously noted, in most known cases inticles in a liquid suspensoid, the particles will bear a negative charge and in order to .keep immersed objects clean or to release objects stuck in masses ofrsuch particles, it is necessary to apply a negative potential to the objects. However, in the event a suspension contains positively charged particles,`it is only necessary to apply a l positive potential to the objects to accomplish the same purposes.

, is only necessary to direct the field applied to the objects, so as to makethe objects of unlike polarity relative to the particles of solid matter and thereby cause attraction and deposit of the matter on the objects.

' It will be evident from the foregoing', that l y I have disclosed, in general, a method of controlling the deposition of solid or semi-solid matter, bearing electrical charges, on objects .im-

mersed in a fluid containing such matter, and

particularly an electrical method of preventing the deposition' of such matter on objects immersed in uid suspensions of said matter, by-

creating an electric field in the uld adjacent to the objects and controlling the direction of the field .to cause the particles of the fluid to migrate away from the objects. In like manner, objects, which havebecome stuck or jammed in masses of solid matter, may be released therefrom.

It should be understood that the electric field, wherever used herein, may be produced by a cell, a thermo-couple, a conductor moving in a magnetic field, or electrostatically.

What I claim and desire to secure by Letters Patent is: 1. In a well drilled-in an earthy formation, the method of releasing a pipe-which has become stuck or jammed in the well, which comprises, establishing an electric field between said pipe and ground by applying the negative terminal of a source of unidirectional E. M. F. to said pipe and applying` the positive terminal of said source to ground whereby sol-id particles are caused to migrate away from said pipe and release same.

2. The method of -freeing a drill pipe embedded in drill mud in a bore hole which comprises connecting said drill pipe to the negative ter'- minal of a source of direct electric current, grounding the positive terminal of said-.source -of electrical current and maintaining Said drill pipe at sufficiently highl negative vpotential with respect to the surrounding mud to cause repulsion of the mud particles from the surface of and to free the pipe.

. JOHNl T. HAYWARD.

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