US2140072A - Well graveling apparatus - Google Patents

Description

Dec.A 13, 193s.

R. L. CHENAULT WELL GRAVEL I NG APPARATUS Filed Aug. 26, 1938 REZZZZZZZEZEEZEE .a A

Patented Dec. 13, 1938 PATENT OFFICE WELL GRAVELING APPARATUS Roy L. Chenault, Penn Township,A Allegheny County, Pa., assignor'to Gulf Research & De-

velopment Company, ration of Delaware Pittsburgh, Pa., a corpo- A Application August 26, 1938, Serial No. 226,983

7 Claims.

This invention or discovery relates to apparatus for placing gravel or sand in well bottoms; and it comprises, in combination, a sleeve-like base member and screen adapted to be xedly positioned at the producing level of a well, means i'or holding gravel and adapted to be lowered to the top of said base member, valve means adjacent the bottom of the gravel holding means, constructed and arranged to be normally closed m and retain the gravel, and to open on contact with the top of the base member, and graveldistributing means below said valve means, for distributing gravel flowing from the holding means, to the outside of the base andy screen.

One object of `the invention is the provision of apparatus for methodically depositing gravel or sand around the outer face of a well strainer or screen, in which deposition of gravel within the strainer is precluded. Another object is the provision of such apparatus wherein gravel is caused to be deposited downwardly, from outside the screen, in reverse circulation, while the hazards ordinarily attendant upon reverse circulation are precluded. A third object is the improvement of gravel pack systems generally, as

regards elciency and reliability. Another object is the provision of a graveling system in which only the exact amount of gravel required need be introduced into the well bottom.

In completing oil wells, a tubular strainer or f screen is set in the oillproducing formation, and it is customary in many cases to provide a gravel or sand pack around the strainer, to prevent caving of the surrounding rock and to preclude plugging of the strainer by any mud in the formation. which may tend to migrate toward the strainer face. By so doing, the effective permeability of the region surrounding the screen can be greatly increased, making it possible to use a larger mesh screen than otherwise, and

. also increasing production where the producing sand is excessively fine or has a very low permeability. Known methods of providing such packs leave much to bedesired in theway of efciency and reliability. In one conventional method, the strainer is ilrst installed in the well bottom, the strainer base having a lower opening protected with a check valve arranged to pre- Y clude iiow of fluids into the interior of the strainer. A string of tubing is seated on the strainer bottom, and a gravel slurry forced down the tubing, flowing past the check valve outside the strainer. The only way the operator has of knowing when the cavity is 'lled is when the 1 pump pressure begins to rise.` At that time the tubing may be completely iilled with gravel. When graveling is completed, the tubing is raised. Necessarily, the gravel left in the tubing all flows out into the interior of the strainer and has to be removed by hailing. In another wellknown procedure, reverse circulation is employed, so as to avoid getting any gravel inside the strainer. In such method, a gravel slurryA is forced down through the casing outside. the tubing, and the liquid part of the slurry ows backvthrough the strainer and up the tubing. I'hus no gravel gets inside the strainer. The disadvantage of this procedure is that the gravel may bridge betweenthe casing and the tubing, making it impossible to remove the tubing. Such a mishap sometimes ruins the well.

According to the present invention there is provided a system for graveling wells which has the advantage that bridging between the tubing and casing is obviated in all cases, while at the same time gravel is kept from getting inside the strainer. In operating under the invention, gravel is let down to the well bottom by a bailer or tubing, and is distributed outside the screen by suitable means, and a valve arrangement is provided for cutting oiT efiiux of gravel from the tubing or bailer Yimmediately upon raising the bailer. Only the exact amount of gravel necessary to iill the well cavity need be introduced into the well. The functioning of the system will be apparent from the extended description to follow.

In the accompanying drawing there are shown, more or less diagrammatically, two examples of specific embodiments of apparatus within the purview of thek invention. In lthe drawing,

Fig. 1 is a view partly in vertical section, partly in elevation, of one system, employing tubing for carrying gravel; and

Fig. 2 is a similar view of a modification in which the gravel is carried by a special bailer.

Fig. 3 is an elevational view of the special bailer used in Fig. 2 .with parts broken away to show details of construction.

Referring to the drawing, Fig. 1 shows the lower portion of an oil well cased) at I0 down to the upper level of the producing stratum II which is shown as including a mud stratum I2. A cavity 9 is formed in the producing sand, as shown, lby washing or otherwise. Within the cavity is located a screen-liner or strainer I 3 perforate as at i4 and coupled at I5 to the lower end of an inner string of casing I6 extending up the well to-a point above a packer I1 which forms a seal between casings I0 and IIS` The lower end of the screen-liner carries a footpiece or base comprising a cylindrical sleeve attached to the screen at 2| and closed by a plug 22, resting on the 'rock 8 below the producing stratum. An annulus 23 is arranged in the container as shown, having a conical upper seat 24 for reception'of tubing (described below) and a lower valve seat. 25 cooperating with a puppet valve 26, slidably mounted by supports 21 and 28 in the footpiece. The valve is normally urged upward by a spring 29. A plurality of perforations 3||l are provided in thefootpiece so that gravel is directed out from the footpiece to the well bottom when valve 26 is open. Ordinarily the assemblage is located at the well bottom, as described, but sometimes is located at a higher level, the lower portion `of the well being blocked off.

The assemblage described is installed in the well by operations familiar to those skilled in the art and requiring no detailed description.

For graveling the well, a string of tubing 35 vis' provided, adapted to-be let down the well. 'Ihe lower end of the tubing is chamfered at 36 to make a i-lrm, centered seal with seat 24. Within the tubing is a poppet valve 31, having a tapered head 38 and a tapered seat portion 39, engaging a seat 40 xed to the tubing, as shown. 'I'he valve is slidably mounted in spiders 4I and 42 as shown.

In operation, the tubing is lowered down the well until it rests in the position shown in the drawing. The lower end of valve 31 rests on the head of valve 26. A slurry of gravel or sand in water, mud or other medium is now pumped down the tubing. Valve 26 is shown as opened by a small projection 34 on spider 42 though'the vweight of the gravel slurry can be relied upon for opening it. Gravel issues through openings 30, being thereby distributed outside the screen as shown. When the bottom hole cavity 9 is lled, as evidenced by a rise in pressure at the gravel pumping means, the tubing 351s simply raised. Valve 31 instantly. closes on raising the tubing from annulus 23, thus no( gravel gets into the casing. Valve 26 likewise closes against any influx of substances to the interiorfof the strainer.

Figs. 2 and 3 show a modification using a bailer as the gravel-transporting means and arranged to provide a downward gravel flow outside the screen. This is advantageous in some conditions. The baileris of special construction to cooperate with the rest of the graveling arrangement. vAs shown, the lower end of casing I0 is protected by a bottom piece |40, and there is set-inside `the casing a screen-liner or strainer having an upper sleeve extension |4| and a lower perforate section I3,

capped at 2| as shown. The liner is centered in the easing by means of a plurality of radial fins |42, conveniently arranged at 120 degree angles Four of these ns show in the figure. N

The screen-liner (elements |3,`I4I. and 2|) is lowered into the position shown by meansl of a string of tubing (not shown), attachment being made by left-hand threads 43 so that the tubing s can readily be unscrewed and removed after the liner has been set in place.

Gravel or sand is carried by means of a bailer comprising a casing 44 with' bail 45 for attachment to a lowering cable or wire 46. At the lower end of the bailer casing is a sleeve 41 having a constricted interior throat portion 48. VA sleeve 49 is attached to sleeve 48 as shown, and has a plurality of perforations 50. A double-ended spearhead valve is provided as shown, comprising an )that the graveling job iscomplete.

interior of the screen is sealed off by spear-head l 55 as shown, and gravel runs out into the well, outside the screen-liner, as indicated by arrows. 'I'he various elements of the bailer and the screenliner cooperate to distribute the gravel with a minimum of obstruction to flow, as will be apparent from Fig. 3.

Usually'several bailerfuls of gravel are required to form the pack. When the well cavity is filled, the gravel will be deposited in the annular zone between the liner and the casing until it reaches the level of the outlet ports (50). When the pack reaches this level, no more gravel will ilow out of the bailer, and when the bailer is withdrawn it will be found not vcompletely empty, indicating When the bailer is raised partly full of gravel, none flows out into the line, because the bailer valve closes immediately on raising the bailer. Bridging is obviated with this arrangement, yet the advantages of the conventional reverse circulation procedure are maintained. That is, the gravel is fed downwardly outside the liner; not upwardly.

While the invention has been described with reference to placing gravel or sand it is equally Well adapted for placingQany other desired mateapplicable to wells other than oil wells, where formation of a gravel pack is required.

. The apparatus is embodied in the usual mate- 35 rial around the screen, e. g., shot, and is of course having a tubular screen set at the producing level thereof, for the purpose of depositing divided material such as gravel outside of said screen, comprising in combination a sleeve connected coaxially with the screen and communicatingtherewith, gravel-holding means adapted to be lowered in the well to the top of the sleeve, valve means adjacent the bottom of the gravel-holding means,

constructed and arranged to benormally closed l and retain the gravel, and to open on contact with the top of the sleeve, and valve means, below said gravel-retaining valvev means, const'ructed and arranged to distribute gravel flowing from the gravel-holding means, `outside the sleeve and screen.

2. The apparatus of claim 1 wherein the sleeve and the gravel-distributing means are below the screen, so that gravel ows upwardly outside the screen.

3. The apparatus of claim 1 wherein the sleeve and the gravel-distributing means are above the screen, so that gravel ilows downwardly outside the screen.

4. vThe apparatus of claimv 1 wherein the gravf el-holding means isa bailer, vadapted to be lowered in the well by a cable."`

5. The apparatus .of claim 1 wherein the gravel-holling means is a string of tubing,adapted to carry a flow of gravel downward therein.r

6. Apparatus for placing gravel outside 'a tubular screen set at the producing level of a well,

comprising in combination a sleeve at thev upper end of the screen, a bailer for holding gravel and 15 thereof, and means for opening having a normally closed valve the bottom d valve and distributing the gravel over said sleeve and screen, upon lowering of the bailer to the top of the sleeve.

'7. Apparatus for placing gravel outside 'a tubular screen set at the producing level otra well,

comprising in combination a sleeve attl lower end of the screen, a. normally closed valve in the sleeve preventing flow of lsubstances into the interior of the screen, a string of tubing adapted to hold gravel and to be lowered d'own the well, and a valve in the lower end o1 the tubing constructed and arranged to be normally1 closed and to open whenthe tubing contacts the sleeve so as to let gravel flow outside the sleeveand the screen.

ROY L. CHENAULT.

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