SU1240879A1 - Device for attaching deep-well instrument to cable - Google Patents

Description

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The invention relates to geophysical studies of wells and can be used when working with a reservoir tiltmeter, microprobe and other devices that have irim-Hi.ie blocks. The purpose of the invention is to improve the accuracy of measuring the current depth of the instrument by reducing the irregularity of its movement.

Figure 1 shows a device for connecting a downhole tool to a cable; figure 2 - the device in operation with uniform motion; fig.Z - the same, with accelerated motion; Fig, 4 - the same, with slow motion.

The device contains a power rod 1 with an airtight end for connection with a cable head 2. The piston 3 is rigidly fixed on the rod with a small throttle bore 4 made in it, a disc valve 5 pressed against a weak compression spring 8, scooter 6 and 7, between which there are mt large holes 9.

The rod 1 with the piston 3 is located inside the sealed cylinder 10, the cavities A and B of which are filled with oil. Both ends of rod I have the same cross section and exit through the cylinder walls into the drilling fluid. In this case, the rod with the piston 3 can move in the cylinder 10, and the hydrostatic pressure of the drilling mud does not prevent this movement.

To unload the walls of the cylinder 10 from the well pressure of its cavity through the hole 11 in the rod 1, they are connected to the cavity of the rubber pressure compensator 12, to which drilling fluid flows out through the windows 13. The front wall of the cylinder 10 and the piston 3 are preloaded with a compression spring 14, the initial force of which is close to the weight of the downhole tool 15 The piston can rest against the rubber stop J6.

The power wires 17 are routed inside the stem 1 and through the sealing plug 18 are inserted into the cavity C of the cylinder 10 filled with drilling mud. Further, these wires, mounted on a conical coil spring 19, are passed into a sealed pipe.

nechnik 20 to which the downhole tool 15 is connected ..

Cavities A and B of cylinder 10 are sealed to stem 1 from drilling mud 5 with rubber o-rings 21, axial movement; the piston at the maximum compression of the force spring is limited by the stop 22, and a possible reversal of the rod relative to the cylinder when operating in the borehole. the pin is fixed by a pin 23.,

The device works as follows.

When descending and stopping at the bottom of the well 15, the shock absorber does not work, because the initial force of the spring 14 piston 3 is pressed against the stop 16.

When the instrument is lifted in the measurement mode with the constant cable speed of 20 liters, the following cases are encountered at the mouth.

In the first case, a move is made. cable under the action of a logging winch (FIG. 2), the cable is then stretched - 25, then the point K starts to go down. Rod 1 is stemmed. The rod together with the piston 3 smoothly compresses the spring 14, the oil from the cavity A into cavity B through the throttle the hole 30 4, until it reaches a point located at a distance c from the stop 16, while the spring force becomes equal to

F, p + F

 r-r r tP.nOf,

 where P is the weight of the device;

. Tr. Pok force of friction

The second case. The device began to move. The friction of movement is less, the check is the friction of peace. The change in the Q value of the friction coefficient occurs in a jump-like manner and if the point K was rigidly fixed with the downhole tool, the tension of the cable spring would decrease, would cause the device to move with acceleration, and then with

deceleration, - As a result, the movement of the device would be spasmodic (bouncing - stopping, etc. J

The device at this moment works as follows.

As soon as the device acquires an accelerated motion, due to the smaller mass of the piston rod with the piston, compared with the mass of the device, the piston rod with the relatively heavy instrument is fired. This opens valve 5 and the piston, without resistance, tends to move

3

under the action of the spring 14 to the point at a distance C from the stop 16 (FIG. 3), in which the condition is fulfilled.

 Ff P + RTR.L. where g is the strength of the motion training

Piston oscillation damping when approaching the specified point occurs due to one-sided throttling of the oil through the opening 4 when the rod moves in the direction of compression of the spring 14. The spring return damping of the cable is performed by throttling the oil flow through the opening 4.

The point K of the rod advances the movement of the device relative to the point of suspension of the cable and the device, moving with less acceleration, acquires a uniform movement as soon as the piston takes a position determined by the distance tz

40879 -4

When tightening the instrument or changing the parameters of the drilling fluid, increase the density or viscosity, etc. the load increases from the bottom to the spring of the cable and the piston moves to a point remote from the stop 20 at a distance, and when the load is reduced to the initial level, Gili below is quickly thrown downwards, acquiring a velocity V (Fig. 4) relative to the housing and then smoothly set to the ta position. Due to its kinetic energy, the piston can be 5 well below point 2, and the piston can hit the stop 20, therefore the stop is equipped with a rubber shock absorber - limit it to prevent breakdowns and further dampen its oscillations.

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Compiled by N. Krivko Editor N. Kelemesh Tehred L. Oleinik Proofreader G. Reshetnik

Order 3464/26 Circulation 548. Subscribe.e VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, Projecto st., 4

Claims (2)

1. A device for connecting a downhole tool to a cable, comprising a unit for recording the current depth, connected by cable to the cable head of the downhole tool, characterized in that, in order to improve the accuracy of measuring the current depth of the device by reducing the unevenness of its movement, it is equipped with a hydraulic shock absorber, made in the form of a cylinder rigidly connected with the downhole tool, passed through the cylinder and spring-loaded relative to it rod connected with the cable head, while stem gidrokompensirovannogo formed as a cylinder whose both ends have the same cross section, and fastened on the rod seal relative to the cylinder piston, wherein a throttle formed and mounted otvers- term disc valve. 2. Device pop. 1, characterized in that a hole is made in the wall of the hydrocompensated cylinder to connect its cavity to the cavity of the cylinder of the hydraulic shock absorber.