US2281414A - Combined bridge plug and drilable whipstock - Google Patents

Description

April 28, 1942. J. M. CLARK -COMBINED BRIDGE PLUG AND DRILLABLE WHIPSTOCK Filed NOV. 7, 1940 lNVENTOk 23. 5%. 1. James M 6/0/16 5 ATIOR Y Fatente d Apr. 28, 1942 stares ZQMAM COMBINED BRIDGE PL US: AND DRILL-ABLE WHIPSTOCK poration of Delawar Application November 7, 1940, Serial No. 364,667

1 Claim.

My invention relates to a combined bridge plug and drillable whipstock.

Trouble with crooked holes is almost an every= day occurrence with rotary drilling. I do not mean to imply that every rotary drilling operation results in a crooked hole. Such trouble is encountered, however, in one hole out of twenty or thirty drilled by rotary drilling. This crooked hole trouble need not be serious, although it may be expensive.

Sometimes it is desirable to drill a crooked hole purposely. A straight hole may be drilled to a water sand. The producing sand may be under a river or other body of water through which a well cannot be drilled. In such case acrooked hole is purposely drilled in order to reach the desired producing sand.

Controlled directional drilling is most frequently practiced with a deflecting tool known as a removale whipstock. The knuckle joint may also be used, but is employed less frequently.

Whipstocks known to the art consist of one piece including a chisel point to engage the bottom of the hole and prevent turning, a tapered concavity to guide the bit into the wall and a ring on the top of the tool by means of which it may be withdrawn from the hole.

Many failures are had directional drilling operations. In the customary mode of procedure the old hole is plugged backand a whipstock set which deflectsthe drill bit in the desired direction. Many cement plugs fail to set due to the large annular space between the drill pipe and the hole. This induces channeling and prevents sumcient scrubbing of the walls. After obtaining a normal cement plug, sidetracking attempts frequently fail because the plug is still soft and more drillable than the formation surrounding it. Because of ,the softness of the cement plug when the bend in the sidetrack hole is reamed the cement plugis frequently drilled into.

' One object of my invention is to provide a combined drillable whipstock and cement plug which will make for greater certainty in sidetracking operations.

Another object of my invention is to provide a combined bridge plug and whipstock which may be set in the hole and need not be removed, saving the necessity of removing the whipstock from the hole. 1

Other and further objects of my invention will appear from the following description.

In the accompanying drawing which forms part of the instant specification and is to be read with sidetracking or in .coniuinction therewith, and in which like reference numerals are 'used to indicate like parts in the various views:

Fig. 1 is a diagrammatic view of a crooked hole showing a. combined bridge plug and whipstock of my invention in use.

Fig. 2 is an enlarged sectional view of my combined bridge plug and drillable whipstock.

Fig. 3 is a sectional view taken on the line 3-3, Fig. 2.

Fig. 4 is a sectional view taken on the line 4-4, Fig. 2.

Referring now to Fig. 1, it is desired to drill a hole 2 to a producing sand I. The hole deviated and the lower portion 3 of the hole missed the producing sand I. A fish or bridge 4 was placed in the hole and the combined bridge plug and whipstock 5 of my invention cemented on top of the fish 4. The whipstock then deflects the drill bit 6 along the proposed path indicated by the construction lines I.

The combined whipstock and bridge plug 5 is constructed of cement in which there is an aggregate of particles 8 of gravel, cast iron frag-- ments, and the like to give suflicient hardness to the whipstock. A pipe 9 of drillable material is embedded in the whipstock body 5,. and provided at its upper portion with a left hand thread Hi. The lower portion of the whipstock is provided with ducts H communicating with the pipe 3.

In operation, a bridge or lower portion 3 of the old hole, and the whipstock supported on the bridge oriented in the desired direction. The drill bit is removed from the drill pipe I3 and the end of the drill pipe secured to the whipstock by means of the left handed thread it. It is understood, of course,

that any suitable connecting means may be employed, suchas a J slot connection or shear pin. The plug is lowered to the desired position by means of the drill pipe. After it is in the desired position, cement is run through the drill pipe and the drillable pipe 9 in the whipstock, out of the ducts H into the hole above the fish i2. Cement It fills the hole around the whipstock, which acts as aplug in addition to performing the duties of a whipstock.

It will be observed that the cementing operation will be more successful because of the small annular space between the plug 5 and the walls of the hole 3. Due to the fact that the whipstock is made of harder material than the surrounding formation, sidetracking operations will be more successful. Furthermore, reaming of the hole at the point of deviation will likewise be fish I2 was set in the possibIe because of the hardness of the plug and whipstock.

If for any reason the plug sticks in the hole placed in the proper position, it could before it is without damage to be drilled with light weight, the hole.

After the cement threaded from the left drill bit 6 again placed on the drilling string. Drilling operations then proceed, the drill bit being deflected by the inclined deflecting surface 15 formed on the whipstock.

In a hole which has an internal diameter of 9% inches, for example, the whipstock would be 20 feet long from tip to tip. The upper tapered surface l5 would be 6 feet long. The lower tapered surface would be 1Vz feet long. The main body of the whipstock would be 8 inches in diameter while the pipe 9 made of drillable alloy would be 2 inches in diameter. The diameter of the ducts ll would be 1 inch. It is understood, 01 course, that any reasonable length may be run, and the above dimensions are given by way of illustration and not by way of limitation.

has set the drill pipe is unhanded thread l0 and the ing in combination a body member formed of concrete, said concrete comprising cement and an aggregate of hard material, a pipe formed of relatively soft drillable alloy fixedly embedded axially of said body member, aligning transverse ducts formed in said body member and said pipe adjacent the lower end of the body. said pipe being formed adjacent its upper portion with a left hand thread, said .body member provided with an inclined surface at its upper end.

JAMES M. CLARK.

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