US2576283A - Process of separating shale cuttings from drilling mud containing plastering agents - Google Patents

Description

Nov. 27, 1951 P, CHANEY 2,576,283

PROCESS OF" SEPARATING SHALE CUTTINGS FROM DRILLING MUD CONTAINING PLASTERING AGENTS Filed July 28, 1944 2 SHEETS-SHEET l m/mwrm Nov. 27, 1951 P. E. CHANEY 7 2,576,283

I PROCESS OF SEPARATING SHALE CUTTINGS FROM DRILLING MUD CONTAINING PLASTERING AGENTS Filed July 28, 1944 2.SHEETSSHEET 2 ArM/F/VEXS.

Patented Nov. 27, 1951 PROCESS OF SEPARATING SHALE CUTTINGS FROM DRILLING MUD CONTAINING PLAS- TERING AGENTS Preston E. Chaney, Beaumont, Tex, assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Application July 28, 1944, Serial No. 547,028

11 Claims.

In the normal course of rotary drilling, mud fluid is pumped by means of a slush pump into the drill pipe (or drill stem). The mud fluid proceeds to the bit at the bottom of the drill pipe and passes through the eyes of the bit at high velocity. The mud fluid then returns to the surface through the annulus between the drill pipe and the wall of the bore hole or the casing, carrying in suspension any shale cuttings which have been drilled by the rotary motion of the bit. At the surface, the mud is delivered into a flow line which usually conducts it to a shale shaker. of the vibrating screen type, which serves to separate the mud fluid from the shale cuttings. The shale-free mud falls through the vibrating screen into a suitable mud ditch'or trough, through which it is delivered to the mud storage tank. The mud fluid is then picked up by the slush pump for recirculation to complete the cycle.

' While this is the normal procedure in rotary drilling, conditions are encountered which necessitate variation in both the mechanical equipment and in the properties of the mud fluid. For example, a sand containing gas, oil, or salt water under high pressure may be encountered comes necessary to increase the density of the mud fluid in order to maintain a hydrostatic pres- 4 Frequently, however, this increase in mud.

weight or density is limited by the loss of mud to uncased porous formations in the bore hole. Thus, for example, it might be found that a mud weight of 16 pounds per gallon would be necessary to prevent the flow of fluid from a high pressure zone into the bore hole, but at the same time a mud weight exceeding 15 pounds per gallon would cause loss of the mud fluid to some lower pressure zone in the well.

In such case, it is necessary to add various mechanical plastering agents, such as shredded cellophane, flsh scales, mica flakes, or sugar cane flber, to the mud fluid in order to plaster over, or wall oi," the zone to which the mud fluid is being lost. However, at present there is a serious objection to the use of these plastering agents, in that they, together with the shale cuttings, are separated from the mud by the shale shaker. It is then necessary to discontinue the use of the shale shaker in order to continuously circulate mud fluid containing such plastering agents.-

However, failure to utilize the shale shaker results in the accumulation of shale cuttings in the mud fluid, which is objectionable inth'at the concen- 2 tration of shale cuttings may become sufliciently high to cause sticking of the drill pipe, and consequent loss of the bore hole. The object of my invention is to enable certain plastering agents to be added to the drill mud and to circulate the drilling mud continuously and effect the removal therefrom of the shale cuttings without loss of the plastering agent from the stream of drilling mud conveyed by the slush pump to the drill pipe. The invention comprises continuously separating the plastering agent and the shale cuttings from the stream of drilling. mud flowing from the bore hole, continuously separating, as hereinafter described, the plastering agent from the shale cuttings, and continuously conveying the separated plastering agent to the mud stream beyond the locus therein at which the plastering agent and the shale cuttings were removed therefrom.

In one preferred way of practicing the process, the return mud, containing shale cuttings and any added plastering materials, flowing from the well, is conducted over a vibrating screen type of shale shaker in a conventional manner. The shale cuttings and any added plastering materials are screened from the mud and collected at the lower end of the shale shaker. The mud falls through the screen and, thus freed from shale cuttings and plastering agent, is collected in a suitable mud trough or ditch, through which it flows back to the mud storage pit. The mixture of plastering material and shale cuttings collected at the end of the shale shaker is then subjected to an upwardly directed fluid (liquid or gas), the velocity of which is so regulated as to selectively lift the plastering material to an elevation at which the mixture of plastering material and fluid are removable from the zone of separation, while the shale cuttings will not be lifted to such elevation. The separated plastering agent is then returned to the mud stream at a locus beyond the locus of removal therefrom of the plastering agent and shale cuttings; that is, it is conveyed to the trough or ditch through which the mud (freed iromshale cuttings and plastering agent) flows back to the mud storage pit, or it is conveyed direct to the mud storage pit.

The success of that part of the process which separates the plastering agent from the shale.

cuttings depends upon the possession by the plastering agent of a ratio of surface area to particle weight substantially higher than the ratio of surface area to particle weight characteristic of the shale cuttings. Such relation is characteristic of most plastering agents. Where, however, the particular material used has a ratio of surface area to particle weight not substantially different from that of shale cuttings, the process herein described for efiecting their separation is not applicable. This limitation on the operativeness of the process is not aserious one, since effective and eco nomical plastering materials having the above,

specified high ratio of surface area to particle H that I have found to be not only practicable but which practices the process with especial efficiency; it being understood, however, that the I process is not limited to being carried on in the particular apparatus so illustrated and hereinafter described.

In the drawings: a Fig. 1 is a perspective view of such an apparatus associated with a known well drilling means and mud fluid circulating system. Fig. 2 is a perspective .view of part of a modified system for Fig. 3 is a side view of practicing the process. the means forming part of the apparatus of Fig. 2, for cleaning and drying the separated mixture of shale cuttings and plastering agent and for sepa-I rating the constituents of the mixture. Fig. 4 is an end iew or section on the line 4-4 of Fig. 3.

From thestorage tank a the drilling mud fluid, carrying in suspension at plastering agent, is pumped through a pipe b into'the drill pipeor drill stem c, through which it proceeds to the bit at the bottom of the drill pipe, there passing through the eyes of the bit and thence returning to the surface through the annulus between the drill pipe and the walls of the bore hole and casing d, carrying in suspension shale" cuttings as well as the plastering agent. At the surface this mud fluid is delivered to a flow linee, which conducts it to a shale shaker f. of the known vibrating screen type, which separates the shale cuttings and plastering material from the mud fluid.

The mud fluid returns through the trough orditch g to the storage tank a.

The mixture of plastering agent and shale'cuttings collected at the discharge end of the shale shaker 1 passes through a pipe, tube or other suitable flow channel h that communicates with a chamber 7' through a side opening therein. Below this side opening is a fluid distributor it connected with an inlet pipe 2' for admission of water or other fluid. The water pressure or velocity is so regulated as to cause the plastering materials to be carried upward with the water stream to an overflow pipe m, while permitting the shale cuttings, by reason of their lower ratio of surface area to particle weight, to fall through the 'up-" wardly moving water stream. to below the distributor 10. Here the shale cuttingsare collected by a screw conveyor n and raised to a level above the normal water level in the chamber 9' in order that they may be continuously removed without loss of appreciable amounts of water through the pipe of the screw conveyor.

The plastering agent, together with the water carried out therewith, is delivered to a traveling endless screen belt 0, through which the water falls into a suitable collecting trough (not shown) which prevents its entry into the mud stream. The substantially dry and clean plastering material is then conveyed by the traveling screen into the trough or ditch y (or direct to the storage tank a), thus being returned to the circulating system.

It is practicable to utilize, in the chamber 9', a gas, instead of a liquid, for separating the plastering materials from the shale cuttings without substantialchange in the apparatus, and it is practicable to design means quite different from the apparatus shown in Fig. 1 for carrying out the process, utilizing, as a selective lifting agent, either a liquid or a gas. -In Figs. 2, 3' and 4, a different specific apparatus is illustrated in which a gas is used as the agent for selectively lifting the plastering material and thus separating it from the shale cuttings. In this modification the mixture of shale cuttings and plastering material "delivered. from the shale shaker 1 falls onto one end of theupper reach of an endless screen belt II which travels around end rollers I and [2, one of which is driven by any suitable power means. Therotary screen belt is shown as inclined to the horizontal, its lower end adjoining the shale shaker f-and its upper reach moving upwardly and away from the shale shaker. The angle of a; V V veyed beneath a water spray l3, which removes ,over a number of steam jets l5.

rise of the screen'belt Ill to'the horizontal is not criticaland may be of any value between and'60' degrees, but I prefer an angle of inclination to the horizontal of to degrees. a

Themixture of v shale cuttings and plastering' material, in its travel along with the belt, is con-'- from the particles of shale cuttings and plaster-- ing material the small quantity of mud fluid and mud solids remaining on their surfaces.

The mixture, in its further travel, is conveyed beneath a row of steam jets M. The high ve locity steam acts to remove most of the wash water and thus to dry thesurfaces of the par-' ticles of plastering material and'shale cuttings. This drying process renders the materials more susceptible to separation by the procedure that follows, although it may not be absolutely essential to the satisfactory operation of the device.

The dried mixture, in its continued travel; is then conveyed to a zone beneathfa hood i6 and The velocity of the steam from jets l5 is so regulated as to lift the particles of plastering materials withinthis zone from the screen belt into the hood l6, while permitting the shale cuttings to remain on the screenbelt and to be conveyed beyond the hood to the higher end of the screen, whence they fall into a shalepit Hlarranged for their reception.

The plastering agents, after entering the hood I6, are delivered into a pipe or duct l1, through which they are conveyed to the trough g, wherein they mix with the mud fluid flowing toward the storage tank a. The end of the pipe or ductl'! adjoining the hood may be open and steam from a pipe l8 may be injected into, the open end to propel the separated particles of plaster-, ing materials through the duct l1.

For the steam jets may be, substituted a current of air or any other gas which may be given the required velocity by any suitable means.

The process is not dependent for its operationon the use of the specific mechanical instrumentalities shown and described. For example,; any known means for separating particles hav-- ing substantially different ratios of surface area to particle weight may be substituted for the specific separating apparatus herein disclosed. This application is a. continuation in part of s an application filed by 'me'November 6, 19. .3, Serial No. 509,186, now abandoned.

. What I claim .and desire. to protect by'Letters Patent is:. 1 1

1. In the process of rotary gdrilling wells involving circulation of drilling mud fluid, with removal from the bore hole of shale cuttings, to which mud fluid has ,been added a plastering agent the particles Ofwhich have a ratio of sur face ,areato particle wei htsubstantially higher than the ratio of surface area to particle weight of the cuttings, the improvement which comprises separating from the" drillingimud fluid the mixture of said plastering agent and shale cuttings contained in the stream of such mud fluid plastering agent from'the shale cuttings by subjecting the mixture to the action of a fluid stream adapted to carry away only the particles having a high ratio of surface area to particle weight and conveying the separated plastering agent to the mud stream at a locus beyond the locus of the removal therefrom of the plastering agent and shale cuttings, whereby a drilling mud substantially free of shale cuttings, but with the removed plastering agent restored thereto, is conveyed to the drill stem, thereby effecting continuous circulation of the mud fluid without accumulating therein shale cuttings and without substantial loss from the stream of any plastering agent not utilized to plaster the bore hole.

2. The process defined in claim 1 in which the separation of plastering agent from the drill cuttings, after their separation from the drilling mud fluid, is effected by feeding the mixture into an enclosed space of substantial height and allowing it to fall therein countercurrent to an upwardly directed fluid stream at a velocity adapted to carry the plastering material to the upper part of the space while allowing the shale cuttings to fall to the lower part of the space and separately removing from said space the shale cuttings and plastering material.

3. The process defined in claim 1 in which a liquid is utilized as the agent for separation of plastering agent from the drill cuttings, and in which, after the plastering agent and the drill cuttings are separated from the drilling mud fluid, the separation of the plastering agent from the drill cuttings is eifected by feeding the mixture into an enclosed space of substantial height and allowing it to fall therein countercurrent to an upwardly directed liquid stream at a velocity adapted to carry the plastering material to the upper part of the space while allowing the shale cuttings to fall to thelower part of the space, separately removing from said space the shale cuttings and the mixture of plastering material and actuating liquid, and then removing from the plastering material a substantial proportion of the liquid before conveying it to the mud stream.

4. The process defined in claim 1 in which a gas is utilized as the agent for separation of plastering agent from the drill cuttings, and in which, after the plastering agent and the drill cuttings are separated from the drilling mud fluid, the separation of the plastering agent from the drill cuttings is effected by feeding the mixture into an enclosed space of substantial height and allowing it to fall therein countercurrent to an upwardly directed gaseous stream at a velocity adapted to carry the plastering material to the upper part of the space while allowing the shale cuttings to fall to the lower part of the space and separately iremoving'ifrom" said":

space the sha'lecuttings and i-plastering material. 5. The'process defined in claim 1 in which theseparation of plastering agent from the drill cuttings, after their separation'from the drilling mud fluid, is effected by delivering them to, and distributing them: over, a gas-permeable surface and there subjecting them to the action of upflowing gas having a velocity adapted to-eifecti such separation by lifting substantially all the and shale cuttings, after its separation from the drilling mud fluid and before separatingthe constituents of the mixture, to the action of an impinging fluid adapted to remove adherent fluid and solid mud.

7. The process defined in claim 1 comprising delivering of the mixture of shale cuttings and plastering agent, separated from the outflowing mud stream, to, and distributing it over, a moving surface, removing, by means of an impinging fluid, from the particles of said mixture in the course of its travel adherent fluid and solid mud and subjecting the thus treated moving mixture, in the course of its further travel, to upwardly directed gas under pressure adapted to separate the particles of plastering agent from the cuttings by selectively lifting substantially only the plastering agent within the area of said mixture subjected to the action of said gas into position to be conveyed to the mud stream.

8. The process defined in claim 1 comprising also subjecting the mixture of plastering agent and shale cuttings, after its separation from the drilling mud fluid and before separating the constituents of the mixture, to the action of a water spray adapted to remove fluid and solid mud remaining on the surfaces of said constituents and then to the action of steam jets adapted to dry said surfaces.

9. The process defined in claim 1 comprising delivering the mixture of shale cuttings and plastering agent, separated from the outflowing mud stream, to, and distributing it over, a moving surface, subjecting the traveling mixture first to the action of a water spray adapted to remove mud fluid and solids remaining on the surfaces of the shale cuttings and plastering agent particles, then to the action of steam jets adapted to dry said surfaces, and then to the action of an upwardly directed gas blast adapted to selectively lift the particles of plastering agent from the area of the moving surface subjected to said blast.

10. The process defined in claim 1 in which separation of plastering agent and drill cuttings is effected by delivering the mixture thereof to, and distributing it over, a moving gas-permeable surface and blowing a stream of gas upward plastering agent from the drill cuttings, and in which, after the plastering agent and the drill cuttings are separated from the drilling mud 7. fluid, the separation-of the plastering agent. 13mm the drill cuttings is effected. by feeding the mix-- ture into. an enclosed space of substantial height and. allowing it to fall thereincountercurrent to anupwardly directed, liquid-stream at a velocity adapted to carry thepl'astering material to the upper part of the space while allowing the shale cuttings to fall to the lower part of the space, and separately removing :from said space the shale cuttings and plastering material. A

' PRESTONE'. CHANEY.

REFERENCES CITED UNITED'STATES PATENTS;' I

Number Date "Name 1 779,615 Martin Jan. 10, 1905 1,807,082 Boynton May 26, 1931 2,025,841 Young Dec. 31, 1935 2,156,333 Cross et' al. May 2, 1939 2,169,675 Bays Aug. 15, 1939 2,219,312 Hayward et a1. Oct. 29, 1940 2,276,075

Wuensch Mar. 10, 1942 OTHER REFERENCES Core: Application-of Cellulose Foil, etc., The

Oil Weekly, September 13, 1943, pp. 25, 26, 28.

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