RU2614833C1 - Template cementing method during well construction - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: according to the method, a template is set into the well bore. Manometer, flow meter and rotary valve are consequently connected to the template. The rotary valve is fully opened. Cement slurry is fed into the space between the template and the well bore. The feeding solution volume is set equally to the pre-calculated amount of the space between the well bore and the template. Air flow in the upper part of the template is monitored by a flowmeter. If the volume of air displaced by the cement slurry, the amount of space between the well bore and the template are exceeded, the rotary valve is closed by the template in half. The pressure in the upper part of the template is monitored with a manometer. If the manometer pressure exceeds the predetermined value, the rotary valve is fully closed.

EFFECT: improving efficiency of the method due to reduction of the time and material inputs connected to the well cementing.

2 cl, 2 dwg

Description

FIELD OF THE INVENTION

The invention relates to the oil and gas industry, and in particular to a method for cementing a conductor in a wellbore with reverse circulation of cement.

State of the art

There is a direct cementing technique in which, in order to prepare the wellbore for running the conductor, a drill pipe string is lowered into the well to the roof of hard rocks of the Lower Perm department (according to the approved work plan).

A wellhead sealant and a lead pipe are screwed onto the upper drill pipe. The annulus between the direction and the drill pipe string is sealed by fitting the rubber element of the sealant on the upper edge of the direction.

Hydraulic examination of the wellbore is carried out by the drilling pump for excess wellhead pressure not exceeding the pressure allowed when testing the wellbore in the interval of the shoe of the previous column (direction).

The pressure is fixed by a pressure gauge mounted on the manifold of the discharge line of the mud pumps. In the absence of a wellhead sealant, work is carried out before the drill pipe string is lowered into the well through a cementing head.

If the test pressure is not reached at the mouth, the annulus is depressurized, up to 1.5 volume of the clay mud well with inert filler (cord fiber, rubber crumb, sawdust, breakage up to 10% of the clay volume is added to the well through drill pipes using a processing tank ) until the solution exits at the wellhead. Sealed annular space is carried zadavlivanie solution in the absorption zone to produce an excess pressure at the wellhead into the wellbore by pumping 4-8 m ³ slurry.

In case of failure to achieve test pressure at the mouth after completion of work, as well as if an intensive absorption zone was opened during drilling under the conductor, followed by: incomplete exit of circulation (less than 50%), opening of more than one complication zone or complete absence of circulation, presence of sediment at the bottom of more than 5 m, work on preparing the wellbore, launching and cementing the conductor is carried out according to a separate work plan drawn up after obtaining actual data for the well.

However, this technique known from the prior art leads to significant time and material costs associated with the elimination of acquisitions.

Also known from the prior art are well reverse cementing techniques.

Reverse cementing refers to a process in which a cement slurry is pumped into the annulus and a drilling fluid located in the well exits through a cemented casing string.

This method is usually used when there are fragile formations in the well section that are subject to hydraulic fracturing at low pressures, or as repair and restoration when leaks are detected in production casing strings.

The method has several advantages:

1) significantly reduced hydraulic pressure on the reservoir, which prevents hydraulic fracturing and absorption;

2) the operation time is reduced due to the absence of a stage of forcing cement mortar;

3) when grouting mortar directly into the annulus, there is no need to treat the entire volume of the mortar with reagents;

4) it is possible to supply grouting fluid in a turbulent mode, which is very important for the complete displacement of the drilling fluid by grouting.

The reverse cementing method has been known for a long time, but has not received widespread use due to its inherent disadvantages:

1) there is no reliable control over the movement of cement slurry in the annulus;

2) it is difficult to determine the end of the operation;

3) productive horizons overlap with contaminated grouting mortar, an oversized cement glass forms in the column.

Of these shortcomings, the main one is the difficulty in determining the end of the operation, i.e. the moment the cement slurry enters the shoe.

To perform reverse cementing, the annulus is sealed with a preventer. The preventer refers to the wellhead equipment and is installed on the last column of the conductor. The preventer housing consists of dies with holes for drill or casing with rubber seals and a mechanism for controlling the movement of the dies. The discharge lines of the cementing units are connected with the annulus through the crosspiece of the preventer. Drilling fluid emerging from the space pipes is guided through the waste branches into the gutter.

The amount of grout injected is controlled either by calculation or by gamma-ray logging tools. The device is lowered into the shoe of the column and an ampoule with a radioactive isotope is introduced with the first portion of the cement mortar, which makes it possible to clearly control the boundary between the drilling and grouting mortar. When an isotope-activated cement slurry of the column shoe appears, which is noted by the gamma-ray logging tool, the cementing process is considered to be completed (see http://fomen.ru/materialy/texnologiya-bureniya/cementirovanie/obratnoe/).

However, this method requires sophisticated equipment to determine the completion of cementing.

The prior art known is selected as a prototype method of reverse cementing the casing string in the well (RU 2086752, publ. 08/10/1997), including preparing the well, lowering the casing string into it with a controlled spring-loaded poppet type check valve in its lower part, configured to its opening from the effect of vertical axial force from top to bottom, for example, from the influence of a column of flushing pipes, lowering the latter into the well, equipping them at the mouth with a flow line, filling the annulus the casing and the column of washing fluid pipe, lowering column flushing pipes on the check valve to its fully open, injecting cement slurry into the well annulus and establishing the moment of its closure. To open the check valve, the free lower end of the flushing pipe string is inserted into the “stop ring” hole, which equips the casing above the check valve. When the non-return valve is open, the first buffer fluid is injected into the borehole annulus, then the drilling fluid and the second buffer in an amount equal to the internal volume of the wash pipe string, after which the cement slurry is injected, the end of which is established at the end of the first buffer fluid at the wellhead, after which the column of flushing pipes is lifted, the check valve closes.

However, this method requires sophisticated equipment to implement the method.

Disclosure of invention

In one aspect of the invention, there is disclosed a method of cementing a conductor in well construction, comprising the steps of:

- install a conductor in the wellbore;

- a manometer, a flow meter and a slewing crane are connected in series to the conductor;

- fully open the slewing crane;

- grouting mortar is fed into the space between the conductor and the wellbore, the volume of the supplied solution being set equal to the previously calculated volume of space between the wellbore and the conductor;

- monitor the air flow in the upper part of the conductor using a flow meter;

- when the volume of air displaced by the cement slurry exceeds the volume of space between the wellbore and the conductor, the slewing valve is half closed;

- monitor the pressure in the upper part of the conductor using a manometer;

- when the pressure on the manometer exceeds a predetermined value, the rotary valve is completely closed;

- add cement slurry if necessary.

In another aspect of the invention, a method is disclosed in which, before starting the supply of cement mortar, the steps are carried out in which:

establish a tank at the wellhead communicating with the annulus of the conductor,

moreover, the supply of cement is carried out in the tank.

The main task solved by the claimed invention is the implementation of a simple and effective method of reverse cementing the conductor.

The essence of the invention lies in the fact that cementing is carried out by feeding cement slurry from the mouth directly into the annulus of the conductor, the air outlet from the conductor is controlled and the conductor is half shut at the moment the cement conduit reaches the lower part of the conductor, then the pressure increase in the conductor is monitored and completely shut off when the pressure reaches a predetermined value. Thanks to this technical solution, no additional columns are required to be lowered, no check valve or other devices are required to prevent the cement slurry from rising inside the conductor barrel, all the equipment necessary to control the process is installed at the wellhead. Also provides a more efficient passage of the absorption zones, since the absorption zones are subjected to lower pressure from the grout.

The technical result achieved by the solution is to reduce the time and material costs associated with cementing the well, as well as increasing the efficiency of the passage of absorption zones during cementing of the conductor.

Brief Description of the Drawings

In FIG. 1 shows a wellbore indicating absorption zones.

In FIG. 2 depicts equipment located at the mouth for monitoring the cementing process.

The implementation of the invention

The advantages of the reverse cementing method are disclosed above, in order to overcome the difficulties encountered with this method of cementing, the authors proposed the following methodology.

The main difficulty arising from reverse cementing is the correct determination of the completion of the process. It was proposed to determine the achievement of cement slurry using a flow meter. The volume of the drilled well can be calculated quite accurately as the product of the length of the well and the cross-sectional area of the well. This section is a circle of known diameter, in general, equal to the diameter of the drill with which the well was drilled.

The volume of the annulus with approximately the same accuracy is determined as the difference between the volume of the drilled well and the volume occupied by the conductor (which is equal to the product of the length of the conductor by its cross-sectional area).

The figure 1 shows a wellbore with absorption zones that are not taken into account when determining the volume of a drilled well.

Knowing this volume and controlling the volume of air displaced from the conductor using a flow meter, it can be concluded with fairly high accuracy that the cement slurry reaches the bottom at the time of displacement, equal to the volume of the annulus.

While grouting mortar moves downward without encountering the resistance of compressed air, it essentially does not enter the absorption zones due to the action of gravity. Therefore, this assessment of the achievement of cement slurry mortar gives a fairly high accuracy.

Further, according to the method, a half-turn valve is closed at the mouth, which leads to a significant increase in the resistance to movement of the cement slurry down. The entire grouting mortar continues to move downward under pressure from the overlying layers, forming a more uniform mass, while part of the grouting fluid enters the well shoe, which will need to be drilled for further well operation.

To improve the quality of cementing, the rotary valve does not completely shut off immediately, since in this case there is a high probability of formation of a bad cement cup near the bottom, which is associated with the uneven movement of the cement slurry in the well.

In addition, incomplete valve closure provides a smooth increase in the pressure of the cement slurry on the absorption zones, which reduces the likelihood of opening them, that is, the efficiency of the method with respect to the passage of the absorption zones is increased.

The criterion for the complete overlap of the slewing crane is the increase in pressure on the manometer to a predetermined level. In general, a predetermined level is 10-12 atmospheres, but it can be set both higher and lower depending on the parameters of the absorption zones. Obviously, with a large number of absorption zones and their high injectivity, a predetermined level should be lower than with a weak injectivity of the absorption zones, which is done to save grouting mortar. Alternatively, this level can be determined empirically for a particular type of soil, one or another soil structure, or one or another area.

A specific embodiment of the method is described below.

To conduct the conductor cementing operation, a box 1 × 1 m in size, 0.3-1.0 m in height, which is installed on the mouth (the box must be sealed to the ground surface), is required. An adapter 3 is prepared from the OTTM 245 thread to the 3-147 thread (for connecting the casing to the lead drill pipe). A branch pipe 4 with a diameter of 73 mm, a pressure gauge 1 to 4 MPa and an air flow meter 2 with a rotary valve 5 are installed to the side of the adapter (see Fig. 2). The cement slurry ρ = 1800 / m ³ is fed into the box with one cementing unit CA-320M and one cement-mixing machine SMN-20 according to the estimated volume of the annular space for 245 mm conductor. Open the slewing crane - completely. Observe the level of cement in the box and monitor the air outlet using an air flow meter. As you approach the first cubic meters of cement to the conductor shoe, turn the tap on 50% and monitor the pressure gauge. With an increase in pressure on the pressure gauge by ≈10-12 atm, a conclusion is drawn about the cement mortar entering the conductor and the growth of the cement glass.

The cement slurry is stopped and at the same time a 100% slewing crane is closed. Track the level of cement behind the conductor. Produce topping up several times as the annular space is filled. Disconnect the adapter through the OZZ (waiting for the hardening of the cement) after 4 hours.

It is clear that the dimensions of the threads and the specific grades of the equipment used are not essential within the framework of the claimed method, the essence of which is to track the moment when to close the slewing crane and when to close it completely.

The steps of the method can be fully or partially automated using appropriate equipment.

Thus, the detailed sequence of actions is as follows:

1. Drill the interval of the conductor with washing with water without conducting insulation, grouting.

2. Install a pipe (a) or a box without a bottom (b) on the mouth.

The pipe or box must be sealed to the ground to prevent spillage of the cement slurry across the area.

3. Prepare the adapter from the OTTM 245 thread to the 3-147 thread (for connecting the casing to the square). Install a 73 mm branch pipe to the adapter on the side, a pressure gauge with a measuring range of 0-4 MPa, a rotary valve and an air flow meter.

4. Prepare the shoe shoe for the 245 mm casing.

5. Run a 245 mm conductor with landing (unloading) at the bottom.

6. Feed the grouting mortar ρ = 1800 / m ³ into the pipe (box) with one CA-320M + one SMN-20.

7. Open the slewing valve on the adapter 100%.

8. Observe the level of cement in the pipe (box) and monitor the air outlet using an air flow meter.

9. Continue pouring the cement mortar according to the estimated volume of the annular space beyond the 245 mm conductor.

10. As the first cubic meters of cement mortar approaches the shoe-clutch (approximately when filling 90% of the annulus), close the rotary valve by 50% and follow the pressure gauge. With an increase in pressure on the pressure gauge by ≈10-12 atm, one can judge the entry of cement into the conductor and the growth of the cement cup.

Pouring cement mortar can be stopped, at the same time close the 100% slewing crane.

11. Monitor the level of cement mortar behind the conductor by directing the beam of the flashlight. Perform topping up several times as the annular space fills.

12. To disconnect a square from the conductor, having insured an adapter a steel rope.

13. Disconnect the adapter after the cement mortar has set (see control cement sample) ≈ after 4 hours.

Embodiments are not limited to the embodiments described herein, those skilled in the art based on the information set forth in the description and knowledge of the prior art will appreciate other embodiments of the invention without departing from the spirit and scope of the present invention.

The elements mentioned in the singular do not exclude the plurality of elements, unless specifically indicated otherwise.

The functional connection of elements should be understood as a connection that ensures the correct interaction of these elements with each other and the implementation of one or another functionality of the elements. Particular examples of functional communication may be communication with the possibility of exchanging information, communication with the possibility of transmitting electric current, communication with the possibility of transmitting mechanical motion, communication with the possibility of transmitting light, sound, electromagnetic or mechanical vibrations, etc. The specific type of functional connection is determined by the nature of the interaction of the above elements and, unless otherwise indicated, is provided by well-known means using principles well known in the art.

The methods disclosed herein comprise one or more steps or actions to achieve the described method. The steps and / or actions of the method can replace each other without going beyond the scope of the claims. In other words, unless a specific order of steps or actions is defined, the order and / or use of specific steps and / or actions can be changed without departing from the scope of the claims.

The application does not indicate specific software and hardware for the implementation of the blocks in the drawings, but one skilled in the art should understand that the essence of the invention is not limited to a specific software or hardware implementation, and therefore any software and hardware known in the prior art. So, the hardware can be implemented in one or more specialized integrated circuits, digital signal processors, digital signal processing devices, programmable logic devices, user programmable gate arrays, processors, controllers, microcontrollers, microprocessors, electronic devices, and other electronic modules made with the ability to carry out the functions described in this document, a computer or a combination of the above.

Although not specifically mentioned, it is obvious that when it comes to storing data, programs, and the like, a computer-readable storage medium is meant, examples of computer-readable storage media include read-only memory, random-access memory, register, cache semiconductor storage devices, magnetic media such as internal hard drives and removable drives, magneto-optical media and optical media such as CD-ROMs and digital versatile disks (DVDs), as well as any other Gia known in the prior art storage media.

Although exemplary embodiments have been described in detail and shown in the accompanying drawings, it should be understood that such embodiments are illustrative only and are not intended to limit the broader invention and that the invention should not be limited to the particular arrangements and structures shown and described, since various other modifications may be apparent to those skilled in the art.

The features mentioned in the various dependent claims, as well as the implementations disclosed in various parts of the description, can be combined to achieve beneficial effects, even if the possibility of such a combination is not explicitly disclosed.

In the above description of examples, directional terms (such as “above,” “top,” “below,” “bottom,” “top,” “bottom,” etc.) are used to conveniently refer to the accompanying drawings. In general, “above”, “upper”, “up” and similar terms are related to the direction to the earth’s surface along the wellbore and “below”, “lower”, “down” and similar terms are related to the direction of the earth’s surface along the borehole moreover, the wellbore may be horizontal, vertical, inclined, directional, etc.

Any numerical values set forth in the materials of the present description or in the figures are intended to include all values from the lower value to the upper value in increments in one unit element, provided that there is an interval of at least two unit elements between any lower value and any upper value . As an example, if it is stated that the value of a component or a process parameter value, for example, such as temperature, pressure, time, and the like, for example, has a value from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, it is understood that values, such as from 15 to 85, from 22 to 68, from 43 to 51, from 30 to 32, etc., are expressly listed in this description of the invention. As for values that are smaller than one, if necessary, one unit element is considered to have a value of 0.0001, 0.001, 0.01 or 0.1. These are merely examples of what is specifically implied, and all possible combinations of the multiple meanings between the lowest value listed and the highest value should be considered expressly set forth in this application in a similar manner. As can be seen, the indication of the values expressed in the materials of the present description as "weight fractions" also implies the same ranges expressed in terms of percentage by weight. Thus, the expression in the detailed description of the invention of the range in terms of “x` weight fractions of the resulting composition of the polymer mixture” also implies the indication of ranges of the same stated value of `` x` as a percentage of the weight of the resulting composition of the polymer mixture ”.

Claims (13)

1. The method of cementing the conductor during the construction of wells, containing stages in which: a conductor is installed in the wellbore; a pressure gauge, a flowmeter and a slewing crane are connected to the conductor in series; fully open the slewing crane; cement slurry is fed into the space between the conductor and the wellbore, the volume of the supplied solution being set equal to the previously calculated volume of space between the wellbore and the conductor; monitor the air flow in the upper part of the conductor using a flow meter; when the volume of air displaced by the cement slurry exceeds the amount of space between the wellbore and the conductor, the slewing valve is half closed; monitor the pressure in the upper part of the conductor using a manometer; when the pressure on the manometer exceeds a predetermined value, the rotary valve is completely closed; add cement slurry if necessary. 2. The method according to p. 1, in which before starting the filing of the cement slurry, the steps are carried out in which: establish at the wellhead a container in communication with the space between the conductor and the wellbore; supply cement slurry to the tank.

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