RU2105137C1 - Device for perforation of well bore - Google Patents

Abstract

FIELD: oil and gas production industry. SUBSTANCE: this relates to drilling and repair of oil wells, for creation of perforated passages in casing string. Device is of high reliability, reduced diameter and simplified design. It is intended for conditions of depression of productive bed. Device has tubular and supporting bodies, wedge pusher with cutter holder and working cutters, working piston with return spring. In addition, also provided is starting spool piston with supplementary return spring. Piston can be moved reciprocally on tubular body. There is housing which connects starting spool piston with working piston. Supporting body can interact with cutter holder. EFFECT: higher efficiency. 2 dwg

Description

 The invention relates to the oil and gas industry, namely to the field of drilling and repair of oil wells to create perforation channels in the casing.

 A device for perforating a wellbore [1] is known, including a tubular body with a cutting tool placed therein with a shaping surface driven by a wedge. In this case, the cutting element is made in the form of knurled rollers with an additional surface conjugated at the base with the forming part of the knurled roller.

 The disadvantage of this device is that it: firstly, is difficult in design; secondly, it cannot be used in casing: small-diameter columns, because, due to its design features, when manufacturing it in a reduced form, the length of the cutters exit is less than the thickness of the perforated pipe, in addition, it does not develop forces sufficient for cutting perforation channels .

 Closer in technical essence is the "Device for creating perforated slotted channels" [2], containing a tubular and supporting housing, a wedge pusher with tool holders and working cutters, a working piston with a return spring.

 The disadvantage of this device is that when perforating partially filled with liquid casing (this is necessary to create the difference between the annulus and the pipe pressure in the casing), the device becomes uncontrollable, that is, it extends the cutters, but cannot pick them up inside, which causes an emergency . In addition, for the formation of cracks in the casing wall, the device requires a reciprocating motion of the cutter, which complicates the technology of perforation and operation of the device, and the creation of perforation channels in the form of longitudinal slots mechanically weakens the string, which can lead to emergency situations.

 The objective of the invention is to provide a device for perforating casing strings of high reliability, small diameter and simple structure, in the mode of depression on the reservoir.

 The problem is solved by the described device for perforating the wellbore, including a tubular and supporting body, a wedge pusher with tool holders and working tools, a working piston with a return spring. New is that it is equipped with a trigger spool piston with an additional return spring placed with the possibility of reciprocating movement on the tubular body, and a casing rigidly connecting the specified trigger spool piston with a support housing, the wedge pusher is rigidly connected to the working piston, and the support housing made with the possibility of interaction with toolholders.

 The analysis of patent and scientific and technical literature did not reveal technical solutions with a similar set of essential features, which allows us to conclude that the criteria for "novelty" and "significant differences" of the proposed solution are met.

 In FIG. 1 schematically shows the proposed device in its original position; in FIG. 2 is a sectional view of the device along AA.

 The device comprises a tubular housing 1 with an internal partition dividing its internal cavity into two cavities 2 and 3 with transfer channels 4 and 5. On the outer surface of the housing 1 there is a starting spool piston 6, with seals 7 and 8, two working surfaces 9 and 10. Between the starting spool piston 6 and the tubular body 1, an additional return spring is placed 11. The starting spool piston 6 is rigidly (on the thread) connected to the casing 12 in the body of which the discharge channel 13 is made. The casing 12, in turn, is rigidly (on the thread) soy inen with a supporting housing 14. Inside the casing 12, between it and the tubular housing 1, a working piston 15 with seals 16 and 17 and a return spring 18 is placed. On the tubular housing 1 and the working piston 15 there are reciprocal holding technological beads (not numbered in Fig.) . The working piston 15 is rigidly (on the thread) connected to the wedge pusher 19, in the grooves of which the dovetail connection is fixed to the tool holders 20 with the working cutters 21. In its upper part, the wedge pusher 19 is provided with a transfer channel 22. The supporting housing 14 is made to interact with toolholders 20.

 During operation, the device is connected to the tubing string (tubing) and lowered into the well (not shown in the diagram).

 The device operates as follows.

 After the device is lowered into the well to a predetermined depth, the fluid there is removed from the well (by compressor, swabbing, or other known method), then fluid is pumped into the tubing string, which through the transfer channel 4 begins to act on the working surface 9 of the starting spool piston 6. The latter under this action begins to move up (see Fig. 1), overcoming the resistance of the additional return spring 11. Together with the piston 6, the casing 12, which is rigidly connected to it, rises, supporting the housing 14 and, under the influence of the return spring, the piston 15 with a wedge pusher 19. When the working surface 10 reaches the overflow channel 5, the fluid pressure is transmitted to the working surface of the piston 15, as a result of which the pistons 6 and 15 begin to move apart, with the piston 15 moving mainly and the piston 6 remains in place. The movement of the piston 15 causes the wedge pusher 19, which is rigidly connected with it, to move, which, in turn, pushes the toolholders 20 apart, keeps the bottom of the support housing 14 from axially moving them. The cutters 21 pierce the casing. After the casing is punctured, the difference in the annulus and in-pipe pressure (more than 100 atm or more depending on the thickness of the uncoupling cement ring between the aquifer and oil reservoirs) in the casing drops in a jump, this causes a water hammer, pushing the reservoir fluid into the casing and simultaneously cleans the resulting channel and bottomhole formation zone. Upon reaching the working surface of the piston 15 of the transfer channel 5, the fluid pressure is discharged through the cavity 3 and the transfer channel 22 into the casing space and the device returns to its initial state, that is, it is ready for re-operation.

 If necessary, lifting the device to a predetermined height, the perforation process is repeated.

 The use of the device will allow perforation of the casing strings with reduced pressure in the annulus (since its performance does not depend on external pressure), and this, in turn, will cause fluid to flow into the casing immediately after perforation, washing the channels obtained by perforation and eliminating additional operations to cause the influx of fluid (oil) into the well.

 Technical appraisal and economic advantages of the device. Possibilities have appeared to perforate production cores of small diameter, which is especially important in wells with horizontal bottom hole. The use of the device reduces material costs, time for perforation, the duration of well development, increases productivity by cleaning the bottomhole zone as a result of creating a deep depression on the formation during perforation, maintains the support of the well by creating a gentle opening mode (creating holes without blast waves), which in turn, prevents premature flooding of the well.

Claims (1)

 A device for perforating a wellbore, including a tubular and supporting body, a wedge-shaped pusher with tool holders and working cutters, a working piston with a return spring, characterized in that it is equipped with a starting spool piston with an additional return spring placed with the possibility of reciprocating movement on the tubular body and a casing rigidly connecting the specified starting spool piston with the supporting housing, the wedge pusher is rigidly connected to the working piston, and the supporting housing is made En with the ability to interact with toolholders.

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