RU2432457C1 - Device for development of well with swabbing - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: device consists of swab, of production string with arrester of swab run, with filter for communication with reservoir, and of packer set above reservoir. According to the invention the production string has a row of through holes above the packer but below the swab run arrester. In an initial position the holes are closed with a hollow bush fixed with a shear element relative to the production string and equipped with a valve spring loaded downwards. The hollow bush performs limited travels downwards under force of excessive pressure created in production string till its rest against an internal circular recess of the production string; successively the hollow bush is fixed with a spring split retaining ring by an upper end of the hollow bush thus communicating internal space of the production string with an above-packer zone. Also, the swab is equipped with a safety valve spring loaded upwards and opening at force of 80-90% of critical allowed force.

EFFECT: simplified design of device, increased efficiency of well development due to elimination of inflow of well fluid from annular space above packer between production string and tubing string; elimination of break of swab cable.

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Description

The invention relates to the field of oil and gas industry and can be used in well development after drilling and during operation.

A device for developing a wellbore by swabbing is known (see E.P. Soldatov, I.I. Kleshenko, V.N. Dudkin. Swabbing is a resource-saving technology. Scientific and Technical Library "Construction of oil and gas wells on land and at sea." 6-7 1997. p.27-29), including a tubing string installed in the well, tubing swab lowered into the tubing string with a stroke limiter, as well as with or without a packer installed above the formation.

The disadvantage of this device are:

firstly, when swabbing a well without a packer, a very low depression on the formation is created (0.6-0.8 MPa) and a significant number of (8-12) swab cycles are necessary, which in time leads to significant labor costs and reduces the efficiency of the device ;

secondly, when swabbing a well with a packer, on the contrary, high (7-8 MPa), very sharp depressions on the formation are created, which negatively affects the state of the bottomhole zone of the well when an inflow from weakly cemented reservoirs, oil-saturated reservoirs, etc. is caused. In all cases, the swab performance increases with increasing frequency and stability of the swab lowering-raising operations;

thirdly, if there is a packer in the device, upon completion of development, when the packer breaks down, the borehole fluid located in the annular space flows back into the formation, clogging the bottom-hole zone of the formation, as a result, the well is jammed and development is reduced to zero.

The closest in technical essence is the method of swabbing the well (patent RU No. 2181830, IPC ⁸ ЕВВ 43/00, published in Bulletin No. 12 of 04/27/2002), which consists in lowering the pressure of the killing fluid on the reservoir by periodic fluid withdrawal from the production casing and lifting it to the surface with a swab, in which at least one of the swabs moved in the casing is removed from the production casing in a well separated in depth by a packer unit installed below the static liquid level pump-compressor pipes in the sub-packer area, and the selection of liquid from the over-packer area and its supply to the surface is carried out by another swab moving in the string of tubing located in the over-packer area.

A device for implementing this method includes two swabs, two tubing strings (tubing) with stroke limiters of the corresponding swabs and a filter for communicating with the formation of one of the tubing columns equipped with a packer installed above the formation.

The disadvantages of this device are:

- firstly, the design complexity associated with the presence of two tubing columns and two swabs;

- secondly, at the end of swabbing, it is necessary to unpack the packer and remove two tubing strings, while the wellbore column located above the packer in the annulus between the production string and tubing string enters the developed reservoir, provided that the pressure created by the hydrostatic level a column of well fluid above the packer is greater than reservoir pressure. As a result, the borehole fluid located in the annulus above the packer enters the reservoir, i.e. there is a killing of the developed well and the bottom-hole zone of the formation is clogged, reservoir properties of the formation deteriorate and the result of well development is reduced to zero;

thirdly, there is a high likelihood of a breakage of the rope pulling the swab in the seal or along the body of the rope, which leads to a complication in the well, the elimination of which requires additional financial costs.

The objective of the invention is to simplify the design of the device and the technology of work with its use, as well as to increase the efficiency of well development by eliminating the ingress of well fluid located in the annulus between the production string and the tubing string above the packer, as well as the guaranteed elimination of the breakage of the rope pulling the swab.

The problem is solved by a device for developing a wellbore by swabbing, including a swab, a tubing string with a swab limiter and a filter for communicating with the reservoir, a packer installed above the reservoir.

What is new is that the tubing string is higher than the packer, but below the swab stroke limiter, it is equipped with a number of through holes, in the initial position hermetically closed by a hollow sleeve, fixed by a shear element relative to the tubing string and equipped with a spring-loaded valve downward, while the hollow sleeve has the possibility of limited axial downward movement under the action of the generated excess pressure in the tubing string up to the stop in the inner annular selection of the tubing string with subsequent fixation by a spring split retaining ring behind an open end face of the hollow sleeve and the internal space of the tubing string with an overpacker zone, while the swab is equipped with a safety valve, spring-loaded upward and opening with a force of 80-90% of the critically permissible force.

In figures 1, 2 and 3, a sequence diagram of an implementation of a method for developing a reservoir by swabbing and an apparatus for its implementation are shown.

Figure 4 is a sectional view schematically shows a swab with a safety valve.

The device for reservoir swab development 1 consists of a tubing string 3 lowered into the well 2 (see FIGS. 1 and 2), as well as a packer 5 isolating the annulus 4, which is installed 10-15 m above the reservoir 1. Swab 6 on the cable 7 is lowered into the tubing string 3. The stroke limiter 8 of the swab 6 is fixed inside the tubing string 3 by any known method, for example, on a thread. The packer 5 hermetically divides the annulus 4 into a subpacker 9 and a superpacker 10 zone.

At the end of the tubing string 3, a filter 11 is installed, plugged from below and serving to communicate the interior of the tubing string 3 with formation 1.

The tubing string 3 is higher than the packer 5, but below the travel limiter 8, the swab 6 is equipped with a number of through holes 12, in the initial position hermetically closed by the hollow sleeve 13. The hollow sleeve 13 with a shear element 14 is fixed relative to the tubing string 3 and is equipped with a spring-loaded valve 15.

The hollow sleeve 13 has the possibility of limited axial movement downward under the action of the generated overpressure in the tubing string 3 until it stops in the inner ring sample 16 of the tubing string 3, followed by fixing by a spring split retaining ring 17 located in the inner ring sampling 18 of the tubing string 3, behind the upper the end face 19 of the hollow sleeve 13 and the message of the inner space of the tubing string 3 with nadpakernym 10 zone.

The necessary tightness during operation is provided by sealing elements (Figs. 1, 2, 3, 4 are shown conditionally).

Swab 6 is equipped with a safety valve 20, while its design may be the same as shown in figure 4.

The safety valve 20 is spring-loaded upward by means of a spring 21 and opens with a force of 80-90% of the critically permissible for closing (not shown in FIGS. 1, 2, 3, 4) swab 6, while the liquid inside the tubing string 3 above the swab 6 flows through the opened safety valve 20 into the tubing string 3 under swab 6.

For example, the critical force to seal the swab 6 is 4 tons. Thus, the spring 21 is adjusted to (80-90%) × 4 tons = 3.2 ÷ 3.6 tons, upon reaching which the safety valve 20 opens.

The device operates as follows. The device is mounted in the well 2 (see figure 1), while the packer 5 can be of any design, for example, focusing on the bottom, for example, ABM. The packer is planted in the well 2 10-15 m above the top of the formation 1, while the row of through holes 12 of the tubing string 3 in the initial position is sealed by a hollow sleeve 13 fixed by a shear element 14.

Then, the swab 6 is lowered into the tubing string 3 on the rope to the calculated depth. Next, begin the process of development of the reservoir 1 by swabbing using a ground drive, for example, an aggregate for swabbing (not shown in Figs. 1, 2, 3).

The fluid is sampled along the tubing string 3 (see FIG. 1) by swabbing from the sub-packer zone 9 through the filter 11 until a stable inflow of the formation 1 is obtained by periodically lifting the fluid along the tubing string 3 using the swab 6, certain portions of fluid from the well 2 stepwise lowering of the liquid level and the corresponding change in the depth of descent of the swab 6 with each subsequent stroke. The height of the raised column of liquid and, accordingly, the volume of liquid raised in one cycle, are determined by the immersion depth of the swab 6 under the liquid level in each cycle. In the process of swabbing, the safety valve 20 (see Fig. 4) opens if the force created by the liquid column located inside the tubing string 3 above the swab 6 exceeds the aforementioned 3.2 ÷ 3.6 t. For example, the liquid column in the tubing string 3 creates a swab force of 3.7 tons, while the safety valve 20 is open.

With a decrease in the force generated by the liquid column inside the tubing string 3 to swab 6 to 3.2 ÷ 3.6 t, the safety valve 20 closes.

After receiving a stable influx of products from the reservoir 1, swab 6 is removed from the tubing string 3 from the tubing string 7, while the above-packer 10 and subpacker 9 zones remain separated by a hollow sleeve 13 that overlaps the through holes 12 of the tubing string 3 in the initial position.

Then tie the injection line of the pump unit (not shown in FIGS. 1, 2, 3, 4) with the tubing string 3 at the wellhead 2. Using the pumping unit installed at the wellhead 2, excess hydraulic pressure is created in the tubing string 3, for example up to 6-7 MPa, at the same time, the shear element 14 is first destroyed, and the hollow sleeve 13 together with the valve spring-loaded downward are moved down to the stop by the lower end of the hollow sleeve 13 into the inner ring sample 16, while the hollow sleeve 13 is locked by the locking ring 17 located inward renney annular sample 18 tubing 3, its upper end 19, thus avoiding the axial displacement of hollow sleeve 13 upwardly with the overlapping of a number of through holes 12 in the subsequent swabbing the well 2.

As a result, there is a message of the annular space 4 in the above-packer zone 10 and the inner space of the tubing string 3 and the height of H ₁ liquid column is aligned in them (see Fig. 2).

The pump unit is disconnected from the tubing string 3 at the wellhead 2 and the swab 6 on the rope 7 is again lowered into the tubing string 3.

The fluid is sampled along the tubing string by swabbing from the sub-packer 9 and overpacker 10 zones until the fluid level decreases by ΔН = Н ₁ -Н ₂ (see Figs. 2 and 3) in the overpacker zone of the annular space until the pressure exerted by hydrostatic the level of N ₂ (see figure 3) of the borehole fluid, will not be lower than the reservoir pressure (P _PL ).

where R _PL - reservoir pressure, MPa;

ρ is the density, kg / m ³ ;

g is the acceleration of gravity, m / s ² ;

N ₂ - the height of the liquid column in the above-packer zone of the annular space and to the roof of the reservoir, m;

or

Then, the packer 5 is unpacked (removed) and removed together with the tubing string 3.

The proposed device has a simple design and technology of work with its application. In addition, it can improve the efficiency of well development by eliminating the ingress of well fluid above the packer in the annulus between the production string and the tubing string into the developed reservoir after unpacking the packer. In addition, the proposed device eliminates the breakage of the rope pulling the swab, which avoids the additional financial costs of eliminating the complication.

Claims (1)

A device for developing a wellbore by swabbing, including a swab, a tubing string with a swab limiter and a filter for communicating with the reservoir, a packer installed above the reservoir, characterized in that the tubing string is higher than the packer but below the swab limiter a number of through holes, in the initial position hermetically closed by a hollow sleeve, fixed by a shear element relative to the tubing string and equipped with a valve spring-loaded downward, while the hollow sleeve has the possibility of limited of downward movement under the action of the generated overpressure in the tubing string up to the stop in the inner annular sampling of the tubing string, followed by fixing with a spring split retaining ring behind the upper end of the hollow sleeve and the message of the inner space of the tubing string with an over-packer zone, while the swab is equipped with a safety valve, spring-loaded up and with the possibility of opening with an effort of 80-90% of the critical allowable effort.

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