RU2741882C1 - Method for multi-stage cuff cementing of wells - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention can be applied for the collar stage cementing of casing strings in oil and gas wells. The method is characterized in that a collar cementing packer is installed above the filter part, consisting of a sleeve part designed to close the annulus of the well, and a collar part designed to fill the annular space above the packer with cement slurry of the first stage of cementing. At a predetermined depth, a cementing sleeve is installed to fill the annulus with cement slurry of the second stage of cementing. The sealing element of the packer is inflated until it contacts the borehole wall. The cementing holes in the packer sleeve portion open for performing the collar cementing. The first volume of cement slurry is pumped in and the first squeeze plug is placed. Drilling fluid is pumped over the plug and the plug is pushed, while simultaneously displacing the cement slurry from the pipe space into the annular space. A second squeeze plug is placed in the pipe space and two plugs are simultaneously pushed at a predetermined distance from each other until the first squeeze plug fits into the saddle located in the collar cementing packer. After the first displacement plug has been seated, the cementing windows are closed. The technological windows located in the cementing sleeve are opened, to provide communication between the pipe and annular spaces, and the second cementing plug is pushed through until it fits into the landing seat of the cementing sleeve. Excessive pressure is created over the second displacement plug and the cementing holes in the cementing sleeve are opened to receive the second stage cement slurry. After the cement slurry of the first stage has set, a second volume of cement slurry is pumped into the pipe and a third squeeze plug is placed. It is pushed through until it fits into the saddle located in the cementing sleeve, while the cement slurry of the second stage is squeezed out into the annulus. After the third plug is seated in the landing seat, overpressure is created and the cementing holes in the cementing sleeve are closed.

EFFECT: increased reliability and simplified method of collar step cementing of wells without cementing the filter section in the zone of the productive formation.

1 cl, 1 dwg

Description

Technology area

The invention relates to the oil industry and can be used for collar cementing of casing strings in oil and gas wells in two or more stages. In soft soils prone to formation hydraulic fracturing or with low internal pressure, the cuff method of strengthening the well walls is practiced. This method provides for cementing not along the entire length of the casing, but exclusively in the upper part, in order to completely eliminate the effect of pressure of the backfill (cement) slurry on the productive lower layers.

Prior art

The known method of multistage well cementing, characterized in that the casing is equipped with the first and second cementing couplings, which are set from each other at a distance corresponding to the distance between the abnormal zones of the well, lower the casing to a given depth with intermediate flushing, pump the estimated volume of cement solution of the first stage of cementing, let the lower plug, push the lower plug before landing in the stop-pipe of the casing string, let the first plug-bomb, made with the possibility of free fall before landing in the lower saddle of the first cementing sleeve, create an overpressure in the pipe space to a predetermined value to open the cementing windows of the first cementing sleeve, cut off the excess cement slurry of the first stage and pause while waiting for the cement slurry to set in the first stage, inject the estimated volume of the cement slurry of the second stage cement cement a dividing plug is put in, the dividing plug is pushed through before it fits into the upper seat of the first cementing sleeve, an overpressure is created in the pipe space to a predetermined value to close the cementing holes of the first cementing sleeve, the second bomb plug is put into the lower seat of the second cementing sleeve, create an overpressure in the pipe space up to a predetermined value to open the cementing windows of the second cementing sleeve, cut off excess cement slurry of the second stage and pause while waiting for the cement slurry of the second stage to set, then pump the estimated volume of cement slurry of the third stage, start the upper plug and its squeezing before landing in the upper saddle of the second cementing sleeve, create an excess pressure in the pipe space to a predetermined value to close the cementing windows of the second cementing sleeve and pause while waiting for the cement slurry to set ra of the third stage (see. RU 2576253, publ. 02/27/2016).

The disadvantages of the known method for multistage well cementing are the complexity and limited application. Bomb plugs are used only in vertical and directional wells with an inclination angle of no more than 30 degrees.

Disclosure of invention

The technical result achieved during the implementation of the claimed invention is to increase the efficiency of the method for multistage well cementing, due to the ability to control the cementation process at each stage and to ensure the guaranteed success of the operation for pumping cement slurry during sleeve cementing.

The technical result achieved by the implementation of the claimed invention is the ability to carry out multi-stage well cementing without cementing the filter section in the zone of the productive formation.

The technical result of the invention is achieved due to the fact that in the method of multi-stage collar cementing of wells, the bottom of the casing assembly is equipped with a shoe, above which a check valve is installed, above which a filter part is located, above which a collar cementing packer is installed, consisting of a sleeve intended to cover the annulus of the well, and the sleeve designed to fill the annular space above the packer with cement slurry of the first cementing stage, casing is installed above the collar cementing packer, then, at a given depth, a cementing sleeve is installed to fill the annular space with cement slurry of the second cementing stage, above the cementing sleeve a string of casing pipes is installed up to the wellhead, after lowering the specified assembly to a predetermined depth, a ball is placed inside the casing pipes and the ball is pushed through the drilling fluid pumped into the well before landing in the saddle located in the packer, after the ball is in the saddle, a closed cavity is formed above it, in which excessive pressure is created, as a result of the creation of excess pressure, the packing element of the packer is inflated until the outer part of the sealing element contacts the borehole wall, excessive pressure is created to open the cementing holes in the collar part of the packer for collar cementing, after opening the cementing holes, the first volume of cement slurry is pumped into the pipe and the first squeezing plug is placed, a pump is connected, and, pumping drilling fluid over the plug, the plug is pushed through, simultaneously displacing the cement slurry from the pipe space into the annulus, after pumping out a specified amount of drilling fluid, the pump is turned off, a second squeezing plug is placed in the pipe space and the pump is turned on again, simultaneously pushing two plugs located at a given distance from each other, displacing the cement slurry pressure from the pipe space to the annulus before the first displacement plug fits into the saddle located in the collar cementing packer, after the first displacement plug fits into the saddle, the pump builds up pressure, and, exceeding the allowable pressure, the screws holding this saddle in the packer are cut off, the cementing windows are closed, thereby preventing the backflow of cement slurry from the annular space into the pipe, with an increase in excess pressure above the second displacement plug, the pressure increases and under the plug, overcoming the permissible shear pressure of the screws, the technological windows located in the cementing sleeve open and the communication of the pipe and annular spaces is restored, allowing push the second cement plug before landing in its seat located in the cementing sleeve, create excess pressure above the second displacement plug, exceeding the permissible shear pressure of the screws and open the cementing holes in the cementing m uft for receiving cement slurry of the second stage, after setting the cement slurry of the first stage, a second volume of cement slurry is pumped into the pipe and a third squeezing plug is placed, the pump is turned on and, pumping drilling fluid over the plug, it is pushed through until it lands in the saddle located in the cementing sleeve with by simultaneously squeezing out the cement slurry of the second stage into the annulus, after the third plug is seated in the landing seat, an excess pressure is created, which exceeds the allowable shear force of the screws that hold the plug with the seat from axial movement, and close the cementing holes in the cementing sleeve. The number of casing pipes in the assembly is selected based on the geological conditions of the wells.

When conducting patent research, no solutions were found identical to the declared one, therefore, the proposed solution meets the criterion of "novelty". The essence of the invention does not follow explicitly from the known solutions, therefore, the proposed invention meets the criterion of "inventive step".

Brief Description of the Drawing Figures

The essence of the invention is illustrated by a drawing, where figure 1 shows a diagram (layout) of the arrangement of equipment during the construction of a well by the method of multi-stage collar cementing of wells.

FIG. 1 the following designations are adopted:

1 - shoe;

2 - check valve;

3 - filter part;

4 - collar cementing packer;

5 - casing pipe;

6 - cementing sleeve.

Best Mode for Carrying Out the Invention

The method for multistage sleeve cementing of wells is carried out as follows. The bottom of the casing assembly 5 is equipped with a shoe 1, the purpose of which is to guide the string while running along the well. Above the shoe 1 (or through a pipe 8-10 meters), a check valve 2 is installed, the purpose of which is to prevent the flow of liquid from the annular space into the pipe space. Above the check valve 2 there is a filter part 3, the purpose of which is to exclude the ingress of solid impurities (sand) carried by the well fluid from the productive formation during production. Above the filter part 3 to separate the cemented part of the well from the uncemented part, a collar cementing packer is installed 4. Conventionally, the packer can be divided into two parts - sleeve - to cover the annular space of the well and exclude the possibility of cement slurry sinking into the filter part 3 and the sleeve - to fill the annular space above the packer 4 with cement slurry of the first stage of cementing. Above the collar cementing packer 4, the N-th number of casing 5 is installed. The number is selected based on the geological conditions of the well. Then, at a given depth, a cementing sleeve 6 is installed. Above the cementing sleeve 6, a string of casing pipes 5 is installed up to the wellhead (exit to the surface).

After the assembly has been lowered to a predetermined depth and all the necessary technological washes have been carried out, the equipment is activated. Inside the pipe 5 is placed a ball supplied with the packer for collar cementing 4 and connect the pressure line to the pump. By pumping the drilling mud into the well, the ball is pushed until it lands in the seat located in the packer 4. After the ball lands in the seat, an excess pressure is created above the ball, which acts on the plug located in the seat and is kept from axial movement by shear screws. When the pressure exceeds the allowable pressure, the screws shear and the plug moves, opening access to the valve system of the packer 4. The drilling fluid flows through the valve mechanism and fills the under-sleeve space, inflating the packing element 4 until the outer part of the packing element contacts the borehole wall (packer). By creating an excess pressure exceeding the shear pressure of the screws holding the sleeve that closes the cementing holes, the cementing holes are opened in the sleeve part of the packer 4 for collar cementing. Packer 4 is ready for first stage cementing.

First stage cementing:

The first portion of the cement slurry is pumped into the pipe 5 and the first displacement plug is placed. The pump is connected, and, pumping the drilling fluid over the plug, the plug is pushed, while simultaneously displacing the cement slurry from the pipe space into the annulus. After pumping out a predetermined amount of drilling fluid, the pump is turned off, a second squeeze plug is placed in the pipe space and the pump is turned on again, simultaneously pushing two plugs (located at a given distance from each other) and displacing the cement slurry from the pipe space into the annulus until the first squeezing plug fits into a saddle located in a packer for collar cementing 4. After the displacement plug has been seated in the saddle, the pump builds up pressure, and, exceeding the allowable pressure, shear off the screws holding this saddle in the packer 4, close the cementing holes, thereby preventing the backflow of cement slurry from the annulus into the pipe. The second cementing plug has not yet reached its seat, located in the cementing sleeve, therefore, as the excess pressure above the plug increases, the pressure under the plug also increases. Overcoming the permissible shear pressure of the screws, the technological windows located in the cementing sleeve 6 are opened and the communication between the pipe and annular spaces is restored, allowing the second cementing plug to be pushed through before it fits into its landing seat located in the cementing sleeve. By creating excess pressure above the second cementing plug, the permissible shear pressure of the screws is exceeded and the cementing holes in the cementing sleeve are opened. The coupling is ready to receive the second stage slurry. The well is left for the time of the cement slurry hardening.

Second stage cementing:

A second portion of the cement slurry is pumped into the pipe 5, and a third cement plug is placed, having the same design as the second cement plug. The pump is switched on and, pumping the drilling fluid over the plug, it is pushed through until it fits into the saddle located in the cementing sleeve with the simultaneous squeezing of the second stage cement slurry into the annulus. After the third plug is seated in a special landing seat, an excess pressure is created that exceeds the allowable shear force of the screws holding the bushing with the seat from axial movement, and the cementing holes in the cementing sleeve are closed. Closing the windows prevents the movement of the cement slurry from the annular space into the pipe space. The well is left for the time of the cement slurry hardening.

The proposed method for multistage sleeve cementing of wells is efficient, simple and allows for the efficient cementing of complex wells, for example, drilled in soft soils, prone to formation hydraulic fracturing or with low internal pressure, the sleeve method of strengthening the walls of wells is practiced.

Claims (2)

1. The method of multi-stage collar cementing of wells, characterized in that the bottom of the casing assembly is equipped with a shoe, above which a check valve is installed, above which a filter part is located, above which a collar cementing packer is installed, consisting of a sleeve part designed to close the annulus of the well, and a sleeve designed to fill the annular space above the packer with cement slurry of the first cementing stage, casing is installed above the collar cementing packer, then a cementing sleeve is installed at a given depth to fill the annular space with cement slurry of the second cementing stage, a casing string is installed above the cementing sleeve up to the wellhead, after lowering the specified assembly to a given depth, a ball is placed inside the casing pipes and the drilling fluid pumped into the well pushes the ball until it lands in the saddle located in the pack ere, as a result of excessive pressure, the packing element of the packer is inflated until the outer part of the packing element contacts the borehole wall and an excess pressure is created to open the cementing holes in the collar part of the packer for collar cementing; after opening the cementing holes, the first volume of cement slurry is pumped into the pipe and the first displacement plug, connect the pump, and, pumping the drilling fluid over the plug, push the plug, while simultaneously displacing the cement slurry from the pipe space into the annulus, after pumping out a predetermined amount of drilling mud, the pump is turned off, a second squeezing plug is placed in the pipe space and the pump is turned on again, simultaneously pushing through two plugs located at a given distance from each other, displacing the cement slurry from the pipe space into the annulus before the first displacement plug fits into the saddle located in the collar cementing packer, after the first selling The pump builds up pressure in the seat plug and, exceeding the permissible pressure, shears off the screws holding this seat in the packer, closes the cementing holes, thereby preventing the backflow of cement slurry from the annular space into the pipe space; when the excess pressure over the second displacement plug increases, the pressure increases and under the plug, overcoming the permissible shear pressure of the screws, the technological windows located in the cementing sleeve are opened and the communication between the pipe and annular spaces is restored, which allows the second cement plug to be pushed through before landing in its seat located in the cementing sleeve, create an excess pressure over the second displacement plug exceeding the permissible shear pressure of the screws, and open the cementing windows in the cementing sleeve to receive the cement slurry of the second stage, after the cement slurry of the first stage has set, the second volume of the cement slurry and soil is pumped into the pipe the third displacement plug is turned on, the pump is turned on and, pumping the drilling fluid over the plug, it is pushed through until it lands in the saddle located in the cementing sleeve with simultaneous squeezing of the second stage cement slurry into the annulus, after the third plug is seated in the landing saddle, an excess pressure is created, which exceeds the allowable shear force of the screws holding the plug with the seat from axial movement and close the cementing holes in the cementing sleeve. 2. The method according to claim 1, characterized in that the number of casing in the assembly is selected based on the geological conditions of the wells.

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