RU2434120C1 - Procedure for well stabilisation - Google Patents

Abstract

FIELD: oil and gas production. ^ SUBSTANCE: procedure consist in lowering production string with back valve and string shoe into well. Cement grout is pumped into annular space through a filling string till it emerges at a wellhead, further, it is pumped creating round circulation. Also, the filling string is equipped with lower and upper sealing units. Lower sealing unit pressurisation is performed by selection of adjustment branches to equip the filling string with the upper sealing unit and to achieve pressure tightness. ^ EFFECT: raised quality of stabilisation of wells under complicated mining geological conditions due to reliable annular space sealing; also, reduced labour input of process. ^ 2 dwg

Description

The invention relates to mining, in particular to the construction of wells, and is used when attaching production casing wells in any geological conditions, including the presence of highly permeable absorbing layers in the wellbore with different characteristics, i.e. in conditions of intense absorption of the drilling fluid or the manifestation of formation water.

A known method of cementing wells, which includes injecting a plugging mixture and a two-component system in the form of liquid and gas into the well, moreover, after injecting a two-component system, the plugging mixture is pushed into the formation, then the gas is vented at the wellhead from the condition that the pressure in the well is not more than reservoir pressure, after why the cycle of punching - etching is repeated (RF Patent No. 2010949, ЕВВ 33/14 "Method of cementing wells").

The disadvantage of this method is the imbalance of pressure in the well-formation system when flushing pipes before lifting, and the process of imbalance of pressure is uncontrolled.

There is a method of cementing wells, including lowering the casing with the shoe into the well filled with mud, forcing the cement through the drill string into the annulus of the casing and removing the drill string from the well, and removing the drill string with its preliminary disconnection from the check valve in half the waiting time for the curing of the cement slurry (RF Patent No. 2059789, ЕВВ 33/14 "Method of cementing wells").

The disadvantages of the cementing method include the complexity and complexity of the process of sealing the well.

A known method of fixing a well, including lowering the casing into the well, injecting the grout into the casing and pushing it into the annulus until it appears at the wellhead, then injecting the grout that has left the annulus of the grout back into the casing with direct or reverse circular circulation, regulation at the mouth of the properties of the cement slurry and waiting for the hardening of cement in the annulus, and the circular circulation of the solution is carried out h Res mud surge tank at the wellhead (RF Patent №2083802, E 21 B 33/14 "Method fastening hole").

However, the known method does not provide the necessary quality of well attachment in the presence of even minor leaks in the wellhead piping, which leads to emergency situations and ultimately affects the complexity of the work and the cost of well attachment.

The technical problem to which the invention is directed is to increase the efficiency and quality of well attachment in difficult geological conditions, including when there are absorbing and / or developing formations in the wellbore, and to reduce the complexity of the process.

The technical problem is solved as follows: a well is prepared, a production casing is launched into it with a check valve and a column shoe in its lower part, cement slurry is injected and pushed into the annulus until cement slurry appears at the wellhead and the subsequent injection of the annulus left at the mouth the space of the cement mortar by creating a circular circulation, which is carried out through the averaging tank installed at the wellhead, while pumping the cement Twor is made through a casting column made of tubing with upper and lower sealing units, and the lower sealing unit is sealed by fitting fittings in such a way as to equip the filling column with an upper sealing unit and sealing, and the upper sealing unit is depressurized carried out by lifting the casting column and undocking the lower sealing unit.

Thus, the proposed technical solution meets the criterion of "novelty."

A comparative analysis of the proposed technical solution, carried out according to the patent and technical literature, not only with the prototype, but also with other technical solutions in the field of engineering and technology, did not reveal signs that distinguish the present invention from the prototype, which allows us to conclude that it matches the criterion of "inventive step".

The proposed method of fastening the well is illustrated by drawings, where

- figure 1 shows the well in the cementing process;

- figure 2 presents the flushing of the well after completion of the cementing process.

Well equipment for implementing the method includes a wellbore 1 with a conductor 2, a production string 3 with a column shoe 4, a nozzle and a check valve 5 and sealing units: lower 6 and upper 7. A filling string 8 (a tubing string) is lowered into the production string 3 (Tubing)).

To carry out the work, the wellbore is being worked out by the rotary method of the drilling fluid. Next, the production casing 3 is lowered in the following sequence: the column shoe 4 is assembled and lowered into the well, a pipe, into the coupling of which a check valve 5 is installed, the coupling of which in turn is connected to the landing-sealing device of the lower sealing assembly 6 for filling casing 8 (in as a casting column, a tubing string is used). The landing-sealing device of the lower sealing assembly 6 is a pipe with a thread the size of the used production string 3 and a cone located inside the pipe, with a calculated angle, a seat for the sealing conical plug located on the lower pipe of the casting column 8. During descent on the production string 3 set centering lights (not shown in the figures).

During the descent, in accordance with the well construction project, at the specified depths, it is necessary to flush to align the parameters of the drilling fluid with constant monitoring of the parameters and, if necessary, to pace the production casing 3. At the end of the descent of the production casing 3, flushing is performed in two cycles with alignment of the parameters of the drilling fluid according to the geological and technical order. Re-checked the measure (length) of the production casing 3 and its reaching the design face.

Next, on the upper pipe of the production casing 3, wellhead fittings are installed, consisting of a pipe with a thread for the production casing 3, with bends located on it, equipped with valves for connecting the discharge line to the cementing units. At the top there is an upper sealing unit 7, which is a flange unit with a cone-shaped inside it, with an estimated angle of a seat for a cone-shaped plug, located on the upper pipe of the casting column 8, which is sealed into the flanged unit. Next, the pumping unit or mud pump flushing and pacing the well, after which the descent of the filling column 8 continues.

At the end of the descent of the casting column 8 by landing and unloading its weight to the bottom, i.e. on the landing-sealing device, the lower sealing unit 6 is sealed by selecting fittings so as to equip the casting column 8 with the upper sealing unit 7 and make sealing, after which, if necessary, it is possible to pressure test the production string 3 before grouting.

The proposed method of fixing the well is as follows.

During its implementation, the following materials and equipment are used:

- free area for the placement of grouting equipment;

- the required amount of grouting material, taking into account the preparation of the full volume of lightweight cement mortar with its subsequent weighting by additional input of cement.

Cementing production casing 3 with circular circulation:

- collect grouting lines and pressurize them with excess pressure exceeding the working pressure by 1.5 times (according to the safety rules);

- upload into production casing 3 sequentially:

- industrial water treated with TPPN (sodium tripolyphosphate);

- into the casting column 8 through the averaging tank, the estimated volume of lightweight cement mortar.

When the cement mortar exits at the wellhead 1, direct the mortar into the averaging tank and continue pumping by the circular circulation method, gradually weighting the mortar with an additional cement injection.

Upon receipt at the outlet of a homogeneous cement mortar with predetermined parameters and in accordance with the start time of setting (to control samples), stop circulation.

Determine the tightness of the check valve 5 by reducing the pressure to atmospheric. Depressurize the upper sealing unit 7 and raise the casting column 8 with undocking the lower sealing unit 6. Bind the discharge line to the annular valve of the valve, and the discharge line to the central valve.

Flush casing 3 with process water. Raise the casting column 8 and close the well at the OZZ (waiting for cement to harden).

The method of fastening the well allows you to:

- increase the efficiency and quality of processing;

- save consumables and money;

- contributes to a uniform distribution of cement mortar throughout the annular space of the well;

- control the parameters of the cement mortar and optimize the thickening and setting time;

- apply a cement mortar with the necessary parameters for a particular well;

- wash off the clay cake and form a cement cake in the wellbore during the fastening process;

The proposed method of attaching the well reduces the time for its implementation by providing the ability to pump cement of any density into the annulus of the well with both low and high specific permeability intervals of its bore.

Claims (1)

A method of attaching a well, including preparing a well, lowering a production casing with a check valve and a column shoe in its lower part, injecting the cement slurry and pushing it into the annulus until the cement slurry appears at the wellhead and then injecting the cement that has left the annulus the solution by creating a circular circulation, which is carried out through the averaging tank installed at the wellhead, characterized in that the injection of cement is discharged through a casting column made of tubing with upper and lower sealing units, and the lower sealing unit is sealed by fitting fitting pipes so as to equip the casting column with an upper sealing unit and sealing, and depressurization of the upper sealing unit is performed lifting the casting column with undocking of the lower sealing unit.

Images