RU2156355C1 - Device for selective implosive treatment of producing formation - Google Patents

Abstract

FIELD: oil and gas producing industry. SUBSTANCE: device has tubular body with fastening thread and radial holes. Installed at body ends are upper and lower packer units. Lower part of body hollow is closed by plug. Relief valve for discharge of liquid from tube hollow is installed in body plug. Body internal walls and plug form low-pressure chamber for instantaneous filling of it with well and formation fluids. Lower packer member is made in form of self- sealing collar located in case is connected with pusher by means of pins through longitudinal recesses of body. Case comes in contact with shanks of anchoring slips provided with compression spring and friction lining. Tail part of lower stop of upper packer member is conical with radial holes. At full relieving of device, body radial holes coincide with radial holes of tail part of lower stop. Conical tail part of lower stop is engageable with slips. EFFECT: simplified design of device, provided deep differential pressure onto formation. 2 dwg

Description

 The proposal relates to the field of the oil and gas industry, in particular for implosive stimulation of the formation in order to increase the productivity of the formation, and can also be used for the development of oil, gas, water intake and injection wells.

 A device is known for processing the bottom-hole zone of a well by implosion method (see ed. St. USSR N 1004624, class E 21 B 43/26, 1981), including a packer, a cylinder connected to it, a tubing string, tubing with a valve and a device for communicating the cylinder cavity with the under-packer zone.

 The effect on the formation is achieved by creating a series of hydraulic shocks by the device.

 The disadvantage of this device is the lack of effectiveness on the reservoir, since the power generated by hydraulic shocks is small.

 There is also known a device for implosive treatment of a productive formation (see book: Popova A.A. Implosion in oil production processes.- M .: Nedra. 1966, p. 115), containing a packer, a cylinder connected to it, a tubing string, a piston with a pressure valve, a drive to the piston and a device for communicating the cylinder cavity with the under-packer zone.

 However, this device also has low efficiency due to the execution of the piston drive in the form of a rope. The rope has a limited load capacity, and when the piston is lowered down, it freezes due to friction in the seals and the viscosity of the liquid. It should also be noted that the device does not provide a strong and deep implosive effect on the reservoir due to the small diameter of the piston, and an increase in its diameter is not possible due to the limited diameter of the well. In addition, there is a risk of sealing failure due to rapid damage to the piston seal, since the hole communicating the cylinder cavities with the under-packer zone is in the way of the piston.

 It is also known "Device for stimulating the formation" (see the description of the patent of the Russian Federation N 2023875, 6 E 21 B 43/25, published in BI N 22, 1994), containing a tubular body with a connecting thread and radial holes, two packing units, installed at the ends of the body, and a valve.

 The specified device is structurally closer to the proposed one and can be adopted as a prototype.

 Without detracting from the advantages of this device, we note that it is difficult in design (to create depression, the use of pumping equipment, packers of complex design, which, when launched into the well, partially become unusable, especially the unprotected sealing elements of the top packer assembly), and most importantly it does not provide the creation of deep depression on the reservoir, as a result of which a sharp increase in the productivity of the reservoir is not achieved.

 The technical result of the proposed device is to ensure the creation of a deep depression on the reservoir, as well as simplifying its design.

 The required technical result is achieved by the described device, including a tubular body with connecting thread and radial holes, upper and lower packer units installed at the ends of the body, and a valve.

 New is that the lower packer element is made in the form of a self-sealing cuff placed in the casing. The latter is connected to the pusher by pins passing through the longitudinal through grooves of the housing and is in contact with the shanks of the anchor dies equipped with compression springs with functional overlays, while the tail of the lower stop of the upper packer element is made with a conical surface with radial holes in response to the radial holes of the housing and is installed with the possibility of interaction when working with dice.

 Another difference is that the lower part of the housing cavity in the area where the dies are located is covered by a plug with an overflow valve installed and forms a low pressure chamber together with the internal walls of the housing.

 Preliminary patent research on the patent fund of the TatNIPIneft Institute, as well as the study of scientific and technical literature, showed the absence of similar technical solutions with such distinctive features as the proposed device, creating a new positive effect - creating a deep depression on the formation. Therefore, it can be assumed that it has novelty, and its industrial applicability is confirmed by a description of its work.

 The following drawings explain the essence of the invention, where in FIG. 1 shows the proposed device, lowered into the well on the tubing string using an adapter, in the context.

 In FIG. 2 is a sectional view of the lower packer element when it is in the working position after it has been released from the casing.

 The proposed device comprises a tubular housing 1 with a connecting thread 2 and radial holes 3. It is in the upper part made thickened with a transition to a conical surface 4. Packing units are placed at the end sections of the housing. The sealing element 5 of the upper packer assembly is supported by a stop 6 with a radial hole 7 in response to the radial hole 3 of the housing. The tail of the specified emphasis is also made thickened and with a conical surface 8 and it is fixed relative to the housing with a shear pin 9.

 The sealing element 10 of the lower packer unit is made in the form of a self-governing cuff and is placed in the protective casing 11. The latter is connected to the pusher 12 with pins 13 passed through the longitudinal, through grooves 14 of the housing 1. The upper end of the casing contacts the shanks 15 of the anchor dies 16 with serrated notches. The shanks 15 of the dies are connected to the housing by cut-off pins 17 and are equipped with compression springs 18 with friction linings 19. The cavity of the housing in the area of its lower part is blocked by a plug 20 with a bypass type one-way spring-loaded valve, the shut-off element of which is made in the form of a ball 21. The plug 20 with the inner walls of the housing 1 forms a low pressure chamber 22.

 The device operates as follows.

 It is lowered into the well 23 on the tubing string 24, attaching to its lower part via a sub 25, until it stops at the bottom. In this case, the pusher 12, rising upwards, releases the casing 11 from the lower sealing element, at which the pins 17 are cut off and the shanks 15 of the dies 16 are unlocked. Then the device is raised to a height of approximately 0.5-0.6 above the top of the reservoir , after which the device is again lowered down until the conical surface 8 of the stop 6 rests against the dies 16, which are prevented from moving by the compression springs 18 due to the friction linings 19. Thus, the device is anchored by the dies 16 in the well. With further loading of the tubing string and, consequently, the device, the pins 9 are cut off, connecting the stop of the stop 6 to the housing 1. At the same time, the latter with the lower packer assembly moves downward, while the conical surface 4 of the housing expands the sealing element 5 of the upper packer assembly and thereby overlaps annular space at the roof of the reservoir. When the device is completely unloaded, the openings 3 of the housing and the openings 7 of the stop of the stop 6 coincide, forming a network of channels communicating the low pressure chamber 22 with the annulus in the interval of the reservoir. In this case, due to the pressure difference in the formation and chamber 22, the fluid located in the interval of the formation rushes into the cavity of the chamber 22, there is a strong and deep depression on the formation, in which all the pollutants of the formation together with the formation fluid exit the formation, thereby cleaning pores and channels of formation flow. Due to the separation by the packing elements of the interval of the reservoir from above and below the underlying reservoirs, the maximum effect is selectively only on the reservoir, a deep instantaneous depression on the reservoir can destructively affect the wellhead due to a sharp decrease in pressure on the bottom.

The allowable pressure reduction at the bottom can be determined based on the strength of the cement stone behind the column according to the following formula:
P _c = P $\genfrac{}{}{0ex}{}{\text{waters}}{\text{pl}}$ -hσ,
where P _PL ^water - reservoir pressure of the aquifer, MPa,
h is the thickness of the section between oil-saturated and aquifers, m,
σ is the maximum allowable pressure per 1 m of the height of the cement ring, MPa.

 The value of σ depends on the conditions of the opening of the reservoir, the quality and technology of cementing the well. And this value for oil fields in Tatarstan averages 2.4 MPa.

 The calculation of the energy of the depression pulse can be made according to the isothermal law.

E _Depr = P • W,
where P is the bottomhole pressure, MPa,
W is the volume of the low-pressure chamber, m ³ ,
W = πR ² L,
where π = 3,14 constant value,
R is the radius of the tubular body, m,
L is the length of the low-pressure chamber, m

 To prevent this, the force of depression on the formation is regulated by adding fluid to the cavity of the chamber 22 through the tubing, thereby ensuring the integrity of the well support between the layers.

 In the process of lifting the tubing string with the device, the liquid is drained from it through the bypass valve 21 installed in the plug 20. After flushing the well, it is put into operation.

 The technical and economic advantage of the proposed device is to increase the productivity of the formation by about 30-40%, due to the strong, deep and selective depression on the formation, therefore, in increasing the production rate of the well. The device is simple in design.

 The widespread use of the device in the oil fields will provide tangible economic benefits.

Claims (1)

 A device for selective implosive treatment of a reservoir containing a tubular body with connecting thread and radial holes, upper and lower packing units installed at the ends and a valve, characterized in that the lower packing element is made in the form of a self-sealing sleeve located in a casing associated with the pusher with pins passing through the longitudinal through grooves of the housing, and in contact with the shanks of the anchor dies, equipped with compression springs with friction pads, at ohm, the tail of the lower stop of the upper packer element is conical with radial holes in response to the radial holes of the housing with the possibility of their coincidence when the device is completely unloaded and installed to interact when working with dies, and the lower part of the cavity of the housing is blocked by a plug with a valve installed in it and forms together with the inner walls of the housing, a low-pressure chamber.

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