RU56464U1 - DEVICE FOR WORKING THE BORE BEFORE FIXING A WELL - Google Patents

Abstract

The invention relates to the oil and gas industry, in particular to the preparation of the walls of the wellbore for launching and cementing the casing string. The device includes a three-cone bit with lateral hydromonitor nozzles, lowered into the interval of drilling on the drill pipe string, two of which are made with an inclined axis, the outlet openings of which are directed at an acute angle to the borehole wall, while the length of the flooded stream from the outlet openings of the aforementioned nozzles to contact with the wall wells are selected from the following conditions:

L = 7-8 d _n , where

L is the length of the flooded stream, mm;

d _n - the diameter of the outlet nozzles with an inclined axis, mm

When using the device, a more complete removal of the clay crust and colmatation of the channels and pores is achieved, which eliminates the re-formation of the crust due to decolmatization. The technical result achieved by using the utility model ensures a trouble-free descent of the production string into the well, the quality of its fastening increases, while the reservoir properties of the reservoir are preserved, and the time spent on well construction is reduced.

Description

The invention relates to the oil and gas industry, namely to downhole equipment used in the preparation of a wellbore for launching and cementing a casing string.

Known devices for working out the wellbore before fixing (1-4), which consists in removing the clay cake from the walls of the wellbore by cleaning devices — scrapers of various designs, lowered on the drill pipe string and flushing by creating circulation until the well is fastened.

The disadvantage of these devices is the complexity of the design of the technical means used to remove the clay cake, which often does not completely solve the problem, since the wellbore is not strictly cylindrical, therefore part of the clay cake, especially in irregularities and cavities, is preserved after processing, thereby reducing the quality of cementing. In order to increase the completeness of removing the clay cake and displacing the drilling fluid, various buffer fluids are usually used, and the production casing is additionally equipped with scrapers before the well is launched, and its descent is accompanied by pacing of the casing. However, this also does not completely solve the problem, since after removing the clay crust, its re-formation in permeable areas is not ruled out due to the formation of new and opening of old channels, in addition, all these operations require a lot of time and material resources, as well as equipment borrowing and labor.

A device is also known for processing the walls of the well (5), which describes the technology for working through the walls of the wellbore with a stream of liquid flowing out of the nozzles directed perpendicularly to the walls of the well, as well as using calibrating blades and cleaning scrapers.

The described method partially solves the problem of removing the clay crust deposited on the permeable walls of the wellbore. Its disadvantage is that the stream of fluid flowing out of the hydraulic nozzles under high pressure and speed, along with the colmatation of the pores of the formation, leads to the destruction and expansion of the walls of the well, which creates additional difficulties in removing the mud cake in case of its re-formation.

It is also known a device for the mudding of the walls of the well (6), including the descent into the interval of drilling on the drill pipe string of a tricone bit with side nozzles, one of the nozzles of which is made with an inclined axis, the outlet opening of which is directed at an acute angle to the wall of the well with the aim of exposing it to the walls of the well a stream of liquid to remove the filter cake and to clog the pores and cracks of the permeable formation when washing the well while rotating the bit and feeding the tool.

This device by technical nature and the achieved result is closer to the proposed one and can be adopted as a prototype.

It is used in the process of drilling a well when opening permeable formations, in which a number of positive results are achieved, for example, a number of complications when drilling a well are excluded, such as flushing fluid leaving the formation, sticking, tightening of the drilling tool, as a result of preventing the formation of a filter cake due to clogging of pores and cracks.

However, it is also not without flaws. For example, an outflowing jet from a nozzle with an inclined axis, having the maximum kinetic energy at which the length of the flooded jet is equal to:

L = (5-6) d _H , where

L is the length of the flooded stream, mm;

d _N - diameter of the nozzle outlet, mm.

not only clogs the pores of the permeable formation, but also leads to the destruction of the walls of the well. It is known that with repeated tripping operations, alternating loads are created on the well walls, which leads to the removal of muds back into the cavity of the well, and thereby to the opening of pores and cracks, which is the reason for the re-formation of clay crust on permeable sections of the well. This makes it necessary to re-develop the well wall before lowering the production casing to cement it.

An object of the present invention is to provide a device with increased efficiency for removing mud cake and clogging pores and fractures of a permeable formation when preparing a well for casing and cementing without damaging the well wall.

The problem is solved by the described device, which includes a three-cone bit with lateral hydraulic nozzles, which is lowered into the interval of drilling on the drill pipe string, one of which is made with an inclined axis, the outlet opening of which is directed at an acute angle to the well wall.

What is new is that the second side nozzle is also made with an inclined axis, similar in design to that of the first, while the length of the flooded stream from the outlet openings of the above nozzles to contact with the well wall is selected from the following condition:

L = 7-8 d _n , where

L is the length of the flooded stream, mm;

d _n - the diameter of the outlet nozzles with an inclined axis, mm

The above figures explain the essence of the invention, in which Fig. 1 shows the proposed device in the form of a three-cone hydraulic monitoring bit, lowered into the well on a drill pipe string, in which two lateral hydraulic nozzles are made with an inclined axis, the process of cleaning the walls of the well from mud cake and simultaneous mudding.

Figure 2 - nozzle inclined axis, mounted in the body of the bit in longitudinal section, is increased.

A device for developing a wellbore includes a three-cone bit 1 (see FIG. 1) lowered on a string of drill pipes with side hydromonitor nozzles 2, two nozzles 3 of which are made with an inclined axis 4 (see FIG. 2) directed at an acute angle α "to the wall 5 of the wellbore.

The angle "α" is determined taking into account the length "L" of the flooded stream, which is chosen from the conditions:

7 d _n ≤L≤8 d _n , where

L is the length of the flooded stream, mm;

d _n - the diameter of the outlet nozzles 3 with an inclined axis 4, mm

At this length, the flooded stream has reduced hydraulic energy, which does not destroy the borehole wall, but is sufficient to remove the filter cake.

The operation of the device is as follows.

Before fixing the well by the workers of the geological service of the drilling enterprise, according to the data of the final geophysical research complex, the intervals of the section to be worked out and other parameters of the well, such as the depth of the bottom, the installation depth of the technical equipment of the column, the intervals of the section with cavities, their diameter, and the zenith angle of the axis of the well , the pressure value of the separated formations.

Then the above-described device is lowered into it on the drill pipe string into the well to a predetermined depth.

Next, the drill pipe string with the device is rotationally rotated or using a downhole motor (screw or turbine type). Its rotation is necessary for uniform removal of a filter cake from the entire surface of the borehole walls with irregularities and cavities there. In the process of rotation of the device while creating a circulation of the fluid and feeding the tool, the teeth b of the bit cutters partially destroy the clay crust structure. At the same time, part of the circulating fluid is directed to the bottom, destroying slurry plugs, and the other part of the side nozzles 3 with an inclined axis 4, with a speed of 70-100 m / s is directed at an acute angle “a” to the well wall. The outflowing jets of fluid from these nozzles, under high pressure, flooded in the upward flow of flushing fluid, create a shock force at the well wall that is sufficient to destroy and remove the clay cake from the well walls and simultaneously block

clay particles, as well as solid particles of pore wash liquid and cracks of the developed permeable layer, thereby eliminating the re-formation of clay cake, which impedes the descent of the production string into the cementing well and leading to other complications.

Numerous field trials have established that the greatest results are achieved when developing a wellbore at a speed of 10-20 m / h.

After all planned sections of the well have been worked out according to the described technology, the device is lifted to the surface, and the pipes are folded onto bridges, after which control geophysical measurements of the diameter of the wellbore are carried out by caliper or profilometry. Next, the production casing is lowered into the well and cemented. After waiting for the cement to harden (OZC), geophysical surveys are carried out by acoustic cement logging (ASC) or SGDT - 3 in order to determine the quality of fastening, after which they draw up an act on the work performed.

The technical and economic advantage of the proposal is as follows: When using the inventive device, a more complete removal of the clay crust and colmatation of the channels and pores is achieved, which eliminates the re-formation of the crust due to decolmatization. The technical result achieved by using the utility model ensures a trouble-free descent of the production string into the well, the quality of its fastening increases, while the reservoir properties of the reservoir are preserved, and the time spent on well construction is reduced.

Information sources:

1. Patent R.F. No. 2057905, Е 21 В 33/14, B.I. No. 10, 96 g.

2. A. S. No. 1098796, B 21 V 37/02, B.I. No. 19, 84 g.

3. A. S. No. 1.723311, E 21 B 37/02, B.I. No. 12, 90 g.

4. Patent R.F. No. 2194609, Е 21 В 33/14, B.I. No. 2,2000 g.

5. A. S. No. 1.627672, E 21 V 37/100, 33/138 B.I. No. 6, 91 g.

6. Patent R.F. No. 2168600, Е 21 В 10/18, B.I. No. 16, 2001 (prototype).

Claims (1)

A device for working through the wellbore before mounting the well, including a three-cone bit with lateral hydromonitor nozzles being lowered into the interval of drilling on the drill pipe string, one of which is made with an inclined axis, the outlet opening of which is directed at an acute angle to the well wall, characterized in that the second side nozzle also made with an inclined axis similar to that of the first, while the length of the flooded jet from the outlet openings of the above nozzles to contact with the wall of the well zhiny choose from the following conditions: L = 7-8 d _n , where L is the length of the flooded stream, mm; d _n - the diameter of the outlet nozzles with an inclined axis, mm