CN111307690A

CN111307690A - Packing performance testing device and method for annular cement ring of oil-gas well cylinder

Info

Publication number: CN111307690A
Application number: CN202010286338.3A
Authority: CN
Inventors: 刘健; 薛元陶; 李早元; 黄盛�; 苏东华; 吴旭宁; 宋伟涛; 郭小阳
Original assignee: Southwest Petroleum University
Current assignee: Southwest Petroleum University
Priority date: 2020-04-13
Filing date: 2020-04-13
Publication date: 2020-06-19
Anticipated expiration: 2040-04-13
Also published as: CN111307690B

Abstract

A device and a method for testing packing performance of an annular cement ring of an oil-gas well cylinder are provided. The device is internally provided with an internal pressure sleeve, a cement sheath and an external pressure cylinder. The device is provided with a heating sleeve, a temperature sensor, a nitrogen inlet interface, a permeability detection module joint, an internal pressure joint, an equivalent crack width detection module joint, an annular pressure conduction coefficient detection module joint, an annular pressure inlet joint, a flow monitoring meter joint, an annular pressure outlet joint, an annular pressure control system, an annular pressure conduction coefficient detection module, an equivalent crack width detection module, an internal pressure control system, a nitrogen bottle, a permeability detection module, a temperature control system, a flow monitoring meter, a valve and a computer control system. The method and the device solve the problems of physical equivalence of the load of the cement sheath and quantitative monitoring of the packing performance of the cement sheath.

Description

Packing performance testing device and method for annular cement ring of oil-gas well cylinder

Technical Field

The invention relates to the technical field of integrity testing of petroleum and natural gas shafts, in particular to a packing performance testing device and method for an annular cement ring of an oil-gas shaft.

Background

Regarding the packing performance test or evaluation of the annular cement sheath of the oil and gas shaft, in recent years, many related technologies exist at home and abroad, some are called sealing characteristic simulation evaluation, some are called the integrity evaluation of the cement sheath, some are called the mechanical sealing characteristic evaluation of the cement sheath, some are called the packing capability test of the cement sheath, and the like, the purpose is to evaluate the performance of the annular cement sheath of the shaft, and the experimental evaluation technology for the annular packing performance of the cement sheath is developed quickly. Because the actual shaft casing has various sizes and layers, the cement sheath has various materials, is greatly influenced by temperature and pressure, has various formation lithology and complex ground stress, has irregular well track and well shape, and has various complex influence factors such as the diversity and the complexity of shaft operation working conditions, the load process of the actual cement sheath under the service working condition is really simulated to test the change of the annular space packing performance of the actual cement sheath, so that the method is a challenge which is not small, and the solution way is a progressive way for continuous development. At present, devices or systems for testing the packing performance of cement rings are mainly divided into two types: full-scale devices and non-full-scale devices are described below with respect to the problems currently existing in these two types of devices.

The full-size cement sheath packing performance testing device has the following problems: 1) the combination of the casing and the cement sheath is large and heavy, the experimental operation is inconvenient, mechanical hoisting is required, and the requirement on the installation site is high; 2) the pipe has large pressure sealing area, large sealing difficulty and high processing cost; 3) for casings with different well structures and various sizes, casings with the same size are respectively processed, one-to-many simulation cannot be realized, large-length and large-volume cement cemented pipes are difficult to reuse, and the experiment cost is high; 4) the requirement of the underground confining pressure of the cement sheath between the experimental casings on the pump is very high, so that the environment of the cement sheath under the high confining pressure is difficult to simulate; 5) the early-stage sample preparation amount is large, the sample preparation is troublesome, cement is filled between the two long sleeves, and if the foam is not completely discharged and the tamping is not uniform, the cement sheath is easy to generate initial defects; later stage is expected to get experimental back cement sheath appearance and is done further experiment, can relate to the sleeve pipe cutting, and the sample degree of difficulty is big, and is with high costs. Although the full-scale device has the advantage of easily reproducing the physical process of bearing and damaging the actual cement sheath of the shaft, the full-scale device can only be used as a special testing tool and cannot be used as a testing device used in a daily laboratory according to the defects, and is difficult to popularize.

The size of the product is reduced to be developed towards a non-full-size direction in order to be popularized, used daily and close to the field. The core problem that present non-full-size cement sheath packing performance testing arrangement exists is exactly: the method is used for uniformly equating the physical process of the actual cement sheath damaged by underground loading to the experimental small-size cement sheath. The scholars propose geometric similarity which is not a sufficient condition for physical equivalence and cannot ensure physical equivalence; the inventor proposes that the equivalent stress of the cement sheath is equal to realize physical equivalence, the equivalent stress is synthesized by three main stresses, and the shape of a main stress space cannot be determined. The further development of non-full-size devices is only motivated by the core problem mentioned above.

The same problem exists with current technology, whether full-size or non-full-size devices: the quantitative characterization parameters of the packing performance of the cement sheath are lacked, most of the devices detect the pressure point or the time point of the damage of the cement sheath by testing flow or sound wave data, and the parameters are used for characterizing the depth and the connotation of the packing performance of the cement sheath, so that the depth and the connotation are not comprehensive enough, and the requirement of the characterization performance is not met.

Disclosure of Invention

The invention aims to solve the defects in the prior art, provides a test system and an experimental method for the whole-process simulation of the service working condition of a cement sheath of an oil-gas well and the quantitative monitoring of the packing performance of the cement sheath, and provides a non-full-size test system for the packing performance of the cement sheath so as to solve the problems of physical equivalence of underground loading of the cement sheath and the quantitative monitoring of the packing performance.

The utility model provides an oil gas well casing ring space cement ring's packing capability test device, includes: a top cover, a base, an internal pressure sleeve, a cement sheath, an external pressure cylinder, a pressure bearing cylinder, a heating sleeve, a temperature sensor, a nitrogen inlet interface, an upper joint of a permeability detection module, an internal pressure inlet joint, an upper joint of an equivalent crack width detection module, an upper joint of an annular pressure conduction coefficient detection module, an annular pressure inlet joint, a joint of a flow monitor, a lower joint of the permeability detection module, an internal pressure outlet joint, a lower joint of the equivalent crack width detection module, a lower joint of the annular pressure conduction coefficient detection module, an annular pressure outlet joint, an annular pressure control system, an annular pressure conduction coefficient detection module, an equivalent crack width detection module, an internal pressure control system, a nitrogen bottle, a permeability detection module, a temperature control system, a flow monitor, a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a first three-way valve, a second three-way valve, A computer control system;

the top cover is connected with the pressure-bearing cylinder in a sealing way through upper threads, and the base is connected with the pressure-bearing cylinder in a sealing way through lower threads;

the inner pressure sleeve, the cement sheath and the outer pressure cylinder form a simulated shaft assembly;

the heating sleeve is wrapped on the outer wall of the pressure-bearing cylinder; the temperature control system is provided with three connecting ports which are respectively connected with the heating sleeve, the temperature sensor and the computer control system;

the ring pressure control system is provided with two connecting ports, one end of the connecting port is connected to the ring pressure inlet connector through a second valve, and the other end of the connecting port is connected to the computer control system;

the internal pressure control system is provided with two connecting ports, one end of the internal pressure control system is connected to the internal pressure inlet connector through a first valve, and the other end of the internal pressure control system is connected to the computer control system;

the permeability detection module is provided with three connecting ports which are respectively connected with the upper joint of the permeability detection module, the lower joint of the permeability detection module and the computer control system; the permeability detection module is used for determining the permeability of the cement sheath by three testing methods, namely a gas channeling method, a pressure drop method and a pulse method;

the equivalent crack width detection module is provided with three connecting ports which are respectively connected with an upper joint of the equivalent crack width detection module, a lower joint of the equivalent crack width detection module and a computer control system;

the annular pressure conduction coefficient detection module is provided with three connecting ports which are respectively connected with an upper joint of the annular pressure conduction coefficient detection module, a lower joint of the annular pressure conduction coefficient detection module and a computer control system;

the external pipeline of the nitrogen cylinder is connected to the nitrogen inlet joint through a third valve;

the flow monitoring meter is provided with three connecting ports which are respectively connected with the flow monitoring meter connector and the computer control system, and the other end of the flow monitoring meter is sequentially connected with the first three-way valve and the second three-way valve and then is communicated with the atmospheric environment;

the metal pipeline connected with the internal pressure outlet joint is communicated to the atmospheric environment through a fourth valve, a first three-way valve and a second three-way valve;

and a metal pipeline connected with the annular pressure outlet joint is communicated to the atmospheric environment through a fifth valve and a second three-way valve.

Further, the packing performance test device for the annular cement sheath of the oil and gas well shaft as described above, the simulated well shaft assembly comprises: 4 combinations for testing the packing capability of the cement ring body under high temperature and high pressure, combinations for testing the packing capability of the cement ring under non-uniform ground stress, combinations for testing the packing capability of the cement ring under the tie-back of the casing and combinations for testing the packing capability of the cement ring-two interface under the formation surrounding rock.

Further, as above oil gas pit shaft annular space cement sheath seal and separate capability test device, the combination body of cement sheath body seal and separate ability under the test high temperature high pressure is: a circular cement sheath is additionally arranged outside the internal pressure sleeve, and the external pressure cylinder is a high-temperature resistant rubber cylinder.

Further, as above mentioned oil gas pit shaft annular cement sheath seal and separate capability test device, characterized in that, the assembly of cement sheath seal and separate ability under the test inhomogeneous ground stress is: an elliptical cement sheath is additionally arranged outside the inner pressure sleeve, non-uniform load is simulated by changing the ratio of the major axis and the minor axis of an ellipse, and the outer pressure cylinder is a high-temperature-resistant rubber cylinder.

Further, the packing performance testing device for the oil and gas well casing annulus cement sheath as described above is characterized in that the combination for testing the packing capacity of the cement sheath in the casing tieback comprises: the internal pressure sleeve is additionally provided with a circular cement sheath, the circular cement sheath is additionally provided with an outer sleeve, and the external pressure cylinder consists of the outer sleeve and a high-temperature-resistant rubber cylinder.

Further, as above oil gas pit shaft annular space cement sheath seal performance test device, its characterized in that, the assembly of test formation country rock cement sheath second interface seal ability test is: the external circular cement sheath of interior pressure sleeve pipe, the external simulation country rock of circular cement sheath, the simulation country rock comprises the multistage country rock ring to scribble impermeably coating on every section country rock anchor ring, prevent that gas from invading inside the simulation country rock, an external pressure section of thick bamboo by simulation country rock + high temperature resistant rubber section of thick bamboo is constituteed.

A packing performance test method for an annular cement ring of an oil-gas well casing comprises the following steps:

1) before an experiment, an actual cement sheath is equivalent to an experimental cement sheath through three processes of geometric similarity, equal stress and same working procedure, the pressure value which is required to be added inside an inner pressure sleeve and outside an outer pressure cylinder under the condition that the load of the experimental cement sheath and the load of the actual cement sheath are equal under each working condition is calculated, an inner and outer experimental pressure value table is formed, the experiment is started, corresponding cement paste is prepared according to the experimental requirements and the AP I standard, the cement paste is injected into a cement sheath maintenance mold, the mold is placed in a high-temperature high-pressure maintenance kettle for maintenance for a regular period, and a sleeve-cement sheath or sleeve-cement sheath-outer pressure cylinder combination is taken out;

2) tightly connecting the base with the pressure-bearing cylinder through lower threads, sleeving a cured combined body with a rubber sleeve, then placing the rubber sleeve in the pressure-bearing cylinder, and screwing a top cover;

3) respectively connecting the temperature control system to the heating sleeve, the temperature sensor and the computer control system; one end of a ring pressure control system is connected to a ring pressure inlet joint through a valve, and the other end of the ring pressure control system is connected to a computer control system; connecting one end of an internal pressure control system to an internal pressure inlet joint through a valve, and connecting the other end of the internal pressure control system to a computer control system; respectively connecting the permeability detection module to an upper joint of the permeability detection module, a lower joint of the permeability detection module and a computer control system; respectively connecting the equivalent crack width detection module to an upper joint of the equivalent crack width detection module, a lower joint of the equivalent crack width detection module and a computer control system; the annular pressure conductivity coefficient detection module is respectively connected to an upper joint of the annular pressure conductivity coefficient detection module, a lower joint of the annular pressure conductivity coefficient detection module and the computer control system; connecting an external pipeline of a nitrogen cylinder to a nitrogen inlet connector through a valve; respectively connecting the flow monitoring meter to a flow monitoring meter connector and a computer control system, and connecting the other end of the flow monitoring meter connector to a first three-way valve and a second three-way valve to the atmospheric environment; the metal pipeline connected with the internal pressure outlet joint is communicated to the atmospheric environment through a valve, a first three-way valve and a second three-way valve; the metal pipeline connected with the annular extrusion outlet joint is communicated to the atmospheric environment through a valve and a three-way valve;

4) closing the third valve, the fourth valve and the fifth valve, opening the first valve and the second valve, filling a liquid medium into the inner cavity of the sleeve from the internal pressure inlet joint by using an internal pressure control system, filling water into an annular space between the pressure-bearing cylinder and the rubber sleeve from the annular pressure inlet joint by using an annular pressure control system, starting the temperature control system, setting the temperature rise time, heating the pressure-bearing cylinder by using an annular heater, increasing the internal pressure and the annular pressure along with the increase of the temperature, controlling the temperature to be at a target temperature after the temperature rise is finished, starting the internal pressure control system and the annular pressure control system, setting the target pressure, and uniformly and continuously pressurizing the inner cavity and the annular space of the sleeve by using the internal pressure pump and the annular pressure pump until the pressure rises to the target pressure;

opening a third valve, opening a nitrogen cylinder, starting a flow monitor, a permeability detection module, an equivalent crack width detection module and an annular pressure conduction coefficient detection module to start detection, simulating pressure rise and fall inside a sleeve and outside a cement ring under different working conditions, starting an internal pressure control system and an annular pressure control system, carrying out pressure rise and fall according to the same procedure steps, and monitoring the sealing performance change condition of the cement ring in real time according to the permeability, the equivalent crack width and the annular pressure conduction coefficient detected by the three modules;

5) after the experiment is finished, the computer control system saves experimental data, the nitrogen cylinder and the third valve are closed, the temperature control system is closed, after the device is cooled down, the pressure of the inner cavity of the sleeve and the annular space is removed by using the internal pressure pump and the annular pressure pump, the internal pressure control system, the annular pressure control system, the first valve and the second valve are closed, the permeability detection module is closed, the equivalent crack width detection module and the annular pressure conduction coefficient detection module are opened, the fourth valve and the fifth valve are opened, water in the inner cavity of the sleeve and the annular space is discharged, all pipelines of each control system and each detection module are removed, the top cover and the base are removed, and the cement ring assembly is taken out. The cement sheath assembly structure can be further subjected to microscopic detection experiments, and microscopic failure mechanisms of the cement sheath material can be observed.

Has the advantages that:

(1) the method uses the cement sheath as a research target, reduces the bearing process and the stress state of the cement sheath under the actual shaft operation, monitors the development process of mechanical damage of the cement sheath, and enables the actual cement sheath load to be equivalent to the experimental cement sheath through three methods of geometric similarity, stress equality and process identity, thereby solving the problem of physical equivalence of the cement sheath load.

(2) The packing performance of the cement sheath is represented by three parameters of permeability, equivalent crack width and pressure conductivity coefficient of the cement sheath, and the problem of quantitative monitoring of the packing performance of the cement sheath is solved.

Drawings

FIG. 1 is a schematic structural diagram of a packing performance testing device of an annular cement sheath of an oil-gas well shaft according to the invention;

FIG. 2 is a schematic diagram of the permeability of a cement ring measured by a pulse method;

FIG. 3(a) is a schematic diagram of an assembly for testing the packing capacity of a cement ring body under high temperature and high pressure;

FIG. 3(b) is a cross-sectional view of FIG. 3 (a);

FIG. 4(a) is a schematic diagram of a combination for testing the packing capacity of a cement ring under non-uniform ground stress

FIG. 4(b) is a cross-sectional view of FIG. 4 (a);

FIG. 5(a) is a schematic diagram of a combination for testing the packing capacity of a cement ring under the tie-back of a casing

FIG. 5(b) is a cross-sectional view of FIG. 5 (a);

FIG. 6(a) is a schematic diagram of an assembly for testing the cement ring-two interface packing capability in the formation surrounding rock;

FIG. 6(b) is a cross-sectional view of FIG. 6 (a);

reference numerals:

1-top cover, 2-base, 3-internal pressure sleeve, 4-cement sheath, 5-external pressure barrel, 6-pressure bearing barrel, 7-heating sleeve, 8-temperature sensor, 9-nitrogen inlet interface, 10-permeability detection module upper joint, 11-internal pressure inlet joint, 12-equivalent crack width detection module upper joint, 13-annular pressure conductivity coefficient detection module upper joint, 14-annular pressure inlet joint, 15-flow monitor joint, 16-permeability detection module lower joint, 17-internal pressure outlet joint, 18-equivalent crack width detection module lower joint, 19-annular pressure conductivity coefficient detection module lower joint, 20-annular pressure outlet joint, 21-annular pressure control system, 22-annular pressure conductivity coefficient detection module, 23-equivalent crack width detection module, 24-internal pressure control system, 25-first valve, 26-second valve, 27-nitrogen gas cylinder, 28-third valve, 29-permeability detection module, 30-temperature control system, 31-flow monitor, 32-fourth valve, 33-first three-way valve, 34-second three-way valve, 35-fifth valve, 36-computer control system, 51-outer sleeve, 52-simulated surrounding rock.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are described clearly and completely below, and it is obvious that the described embodiments are some, not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The technical scheme adopted by the invention is as follows:

1) key method

The experiment takes the cement sheath as a research target, reduces the bearing process and the stress state of the cement sheath under the actual shaft operation, and monitors the development process of the mechanical damage of the cement sheath. The actual cement sheath load is equivalent to the experimental cement sheath by three methods of geometric similarity, equal stress and same procedure, so that the problem of physical equivalence of the cement sheath is solved.

The geometric similarity is as follows:

the stress equality is realized by converting the radial, circumferential and axial stress states of the actual cement sheath in the underground on an experimental cement sheath, namely:

σ_{r actual}＝σ_{r experiment}，σ_{Theta actual}＝σ_{Theta test}，σ_{z actual}＝σ_{z experiment}

The same procedure means that the simulation working condition of the experimental shaft is the same as that of the actual shaft operation procedure well, for example: the pressure lifting of the working procedures of casing pressure test, pressure reduction, fracturing, trial production and the like is simulated, and the experimental shaft is also lifted by adopting the same working procedure.

The packing performance of the cement sheath is characterized by three parameters of permeability of the cement sheath, equivalent crack width and pressure conductivity coefficient. The permeability of the cement sheath represents the annular packing performance, the width of the equivalent weight crack represents the damage severity of the annular packing performance, and the conductivity of the annular pressure represents the severity of annular gas channeling. The problem of quantitative monitoring of the packing performance of the cement sheath is solved by measuring and monitoring the three parameters.

The permeability of the cement sheath is measured by three testing methods, namely a gas channeling method, a pressure drop method and a pulse method.

The gas channeling flow method comprises

When testing cement sheath packing performance, insert the nitrogen cylinder at cement sheath one end, the other end inserts gas flowmeter, according to darcy's law:

wherein: a is the cross-sectional area of the end face of the cement sheath, L is the length of the cement sheath, mu is the viscosity of the gas passing through the cement sheath, Q₀For gas flow through the cement sheath, p₀Is at the atmospheric pressure and is,

is the air pressure of the upper end surface of the cement sheath,

the air pressure of the lower end face of the cement sheath, and K is the permeability of the cement sheath. When the flow measured by the flowmeter is stable, the pressure sensors measure the pressure of the upper end surface and the lower end surface of the cement sheath, and the permeability of the cement sheath is calculated.

The pressure drop method is

In testing the packing performance of the cement sheath, a gas tank of calibrated volume, a precise pressure sensor for measuring gauge pressure, an inlet valve and an inlet line are connected to the upper end face of the cement sheath, and an outlet line to atmosphere is connected to the lower end face of the cement sheath, and the outlet is provided with a valve so as to be closed after starting. Opening the inlet valve to generate pressure transient, when the pipeline pressure on the upper end surface of the cement sheath is attenuated to a certain ratio of full pressure, establishing continuous and smooth pressure change on the whole cement sheath length, starting to collect data, reading and recording the pressure at selected intervals and the corresponding time, and calculating the permeability of the cement sheath according to the axial flow pressure drop data.

The pulse method is (as shown in figure 2)

When testing the packing performance of the cement sheath, the upper end surface of the cement sheath is connected with a volume V₁The upstream gas box and the valve 1 are connected with a volume V at the lower end surface of the cement sheath₂A pressure difference sensor is connected between the two gas boxes to measure the pressure difference between the two gas boxes, and a pressure sensor P is connected to the downstream gas box₂A pressure pipeline connected with a valve 2 is connected between the two gas tanks, and a gas source and a valve 3 are connected on the pressure pipeline. Opening the valve 1, the valve 2 and the valve 3, injecting gas into the two gas boxes and the cement sheath by using a gas source, inflating for enough time to fully diffuse the gas into the cement sheath, closing the valve 3 after the gas pressure reaches a certain value, and balancing the pressure to ensure that the stable pressure is P_2iValve 1 and valve 2 are closed, valve 3 is opened, and the pressure in the upstream gas tank is measured at Δ P₁(is P)_2i2% to 3%) are increased. Equal V₁After the pressure in the process is stable, the valve 3 is closed, the valve 2 is opened, the instantaneous pressure is measured, and the permeability of the cement sheath is calculated according to the axial flow pressure attenuation data.

The equivalent crack width of the cement sheath is as follows

When the cement sheath is sealed and isolated to lose efficacy in the test process, the permeability of the cement sheath is calculated through the permeability detection module and substituted into the formula:

wherein K is the equivalent permeability when the cement sheath fails, and W is the equivalent fracture width. And characterizing the damage severity degree of the annular packing performance by the calculated equivalent fracture width.

The annular pressure conductivity is

When testing the packing performance of the cement sheath, one end of the cement sheath is connected with a nitrogen cylinder, the other end of the cement sheath is connected with a flowmeter and a timer, a differential pressure sensor is connected between the upper end surface and the lower end surface of the cement sheath to measure the differential pressure delta P of the upper end surface and the lower end surface, according to the formula:

when the cement sheath is damaged and the flow measured by the flowmeter is stable, the pressure difference delta P between the two end surfaces of the cement sheath is measured by the pressure difference sensor, the time t recorded by the timer is substituted into the formula to calculate the annular pressure conductivity coefficient α, so that the annular gas channeling severity is represented.

System architecture

The invention provides a packing performance testing device of an oil gas shaft annular cement sheath, which mainly comprises a top cover 1, a base 2, an internal pressure casing 3, a cement sheath 4, an external pressure barrel 5, a pressure-bearing barrel 6, a heating sleeve 7, a temperature sensor 8, a nitrogen inlet interface 9, an upper joint of a permeability detection module 10, an internal pressure inlet joint 11, an upper joint of an equivalent crack width detection module 12, an upper joint of an annular pressure conduction coefficient detection module 13, an annular pressure inlet joint 14, a flow monitoring meter joint 15, a lower joint of the permeability detection module 16, an internal pressure outlet joint 17, a lower joint of an equivalent crack width detection module 18, a lower joint of the annular pressure conduction coefficient detection module 19, an annular pressure outlet joint 20, an annular pressure control system 21, an annular pressure conduction coefficient detection module 22, an equivalent crack width detection module 23, an internal pressure control system 24, a nitrogen bottle 27, a nitrogen gas bottle, a nitrogen gas, The permeability detection module 29, the temperature control system 30, the flow monitor 31, the first valve 25, the second valve 26, the third valve 28, the fourth valve 32, the fifth valve 35, the first three-way valve 33, the second three-way valve 34, the computer control system 36 and the like.

The top cover 1 is tightly connected with the pressure-bearing cylinder 6 through upper threads, and is convenient to detach and install.

The base 2 is tightly connected with the pressure-bearing cylinder 6 through lower threads, and is convenient to detach and install.

The inner pressure casing 3, the cement sheath 4 and the outer pressure cylinder 5 form a simulated shaft assembly, and the simulated shaft assembly has 4 rings of assemblies: 4 combinations for testing the packing capability of the cement ring body under high temperature and high pressure, combinations for testing the packing capability of the cement ring under non-uniform ground stress, combinations for testing the packing capability of the cement ring under the tie-back of the casing and combinations for testing the packing capability of the cement ring-two interface under the formation surrounding rock.

The assembly for testing the packing capacity of the cement ring body under high temperature and high pressure is shown in fig. 3(a) and 3 (b): the internal pressure sleeve 3 is externally provided with a circular cement sheath 4, and the external pressure cylinder 5 is a high temperature resistant rubber cylinder.

The assembly for testing the packing capacity of the cement ring under the non-uniform ground stress is shown in fig. 4(a) and 4 (b): an elliptical cement sheath 4 is additionally arranged outside the inner pressure sleeve 3, and the outer pressure cylinder 5 is a high temperature resistant rubber cylinder.

The assembly for testing the sealing capacity of the cement ring under the condition that the casing is connected back is shown in figures 5(a) and 5 (b): the inner pressure sleeve 3 is externally provided with a circular cement sheath 4, the circular cement sheath is externally provided with an outer sleeve 51, and the outer pressure cylinder 5 is composed of the outer sleeve and a high-temperature resistant rubber cylinder.

The assembly for testing the cement ring two-interface packing capacity under the formation surrounding rock is shown in fig. 6(a) and 6 (b): the external pressure sleeve 3 plus circular cement sheath 4 of interior pressure, circular cement sheath plus simulation country rock 52, simulation country rock 52 comprises the multistage country rock cover to scribble the impermeabilization coating on every section of country rock cover, prevent inside gaseous invasion simulation country rock, the external pressure section of thick bamboo 5 is simulation country rock + high temperature resistant rubber tube.

The pressure-bearing cylinder 6 is a steel sleeve, and the heating sleeve 7 is wrapped on the outer wall of the pressure-bearing cylinder 6 and mainly comprises an annular heater and heat-preservation cotton.

The temperature control system 30 has three main connection ports, which are respectively connected with the heating sleeve 7, the temperature sensor 8 and the computer control system 36.

The ring pressure control system 21 has two primary connection ports, one connected to the ring pressure inlet fitting 14 via the second valve 26 and the other connected to the computer control system 36.

The internal pressure control system 24 has two main connection ports, one end connected to the internal pressure inlet connection 11 through a first valve 25 and the other end connected to a computer control system 36.

The permeability detection module 29 has three main connection ports, which are connected to a permeability detection module upper connector 10, a permeability detection module lower connector 16, and a computer control system 36, respectively. The permeability detection module is used for measuring the permeability of the cement sheath by three testing methods, namely a gas channeling method, a pressure drop method and a pulse method.

The equivalent crack width detection module 23 has three main connection ports, which are respectively connected to the equivalent crack width detection module upper joint 12, the equivalent crack width detection module lower joint 18, and the computer control system 36. The annular pressure conductivity detection module 22 has three main connection ports, which are respectively connected to an annular pressure conductivity detection module upper joint 13, an annular pressure conductivity detection module lower joint 19, and a computer control system 36.

The external line of the nitrogen cylinder 27 is connected to the nitrogen inlet connector 9 through a third valve 28.

The flow monitor 31 has three main connection ports, which are respectively connected with a flow monitor connector 15 and a computer control system 36, and the other end of the flow monitor is connected with a first three-way valve 33 and a second three-way valve 34 and then is communicated with the atmosphere.

The metal pipeline connected with the internal pressure outlet joint 17 is communicated to the atmosphere through a fourth valve 32, a first three-way valve 33 and a second three-way valve 34.

The metal pipeline connected with the ring pressure outlet joint 20 is led to the atmosphere environment through a fifth valve 35 and a second three-way valve 34.

The invention also provides a test method based on the test device, which sequentially comprises the following steps:

step 1: before the experiment, the actual cement sheath is equivalent to the experimental cement sheath through three processes of geometric similarity, equal stress and same working procedure, the pressure value which is required to be added inside the inner pressure sleeve 3 and outside the outer pressure cylinder 5 and has the same load of the experimental cement sheath and the actual cement sheath under each working condition is calculated, an inner and outer experimental pressure value table is formed, the experiment is started, corresponding cement paste is prepared according to the experimental requirements and API standards, the cement sheath is injected into a cement sheath maintenance mold, the mold is placed in a high-temperature high-pressure maintenance kettle for maintenance for a regular period, and a sleeve-cement sheath or sleeve-cement sheath-outer pressure cylinder assembly is taken out.

Step 2: the base 2 is tightly connected with the pressure-bearing cylinder 6 through lower threads, the maintained combined body is sleeved with a rubber sleeve, then the rubber sleeve is placed in the pressure-bearing cylinder, and the top cover 1 is screwed down.

And step 3: the temperature control system 30 is respectively connected with the heating sleeve 7, the temperature sensor 8 and the computer control system 36; one end of the ring pressure control system 21 is connected to the ring pressure inlet joint 14 through a second valve 26, and the other end is connected to the computer control system 36; connecting one end of an internal pressure control system 24 to the internal pressure inlet joint 11 through a first valve 25, and connecting the other end to a computer control system 36; the permeability detection module 29 is respectively connected to the permeability detection module upper joint 10, the permeability detection module lower joint 16 and the computer control system 36; the equivalent crack width detection module 23 is respectively connected to the equivalent crack width detection module upper joint 12, the equivalent crack width detection module lower joint 18 and the computer control system 36; the annular pressure conductivity coefficient detection module 22 is respectively connected to the annular pressure conductivity coefficient detection module upper joint 13, the annular pressure conductivity coefficient detection module lower joint 19 and the computer control system 36; the external pipeline of the nitrogen cylinder 27 is connected to the nitrogen inlet joint 9 through a third valve 28; the flow monitoring meter 31 is respectively connected to the flow monitoring meter connector 15 and the computer control system 36, and the other end of the flow monitoring meter is connected with the first three-way valve 33 and the second three-way valve 34 and then is communicated to the atmospheric environment; the metal pipeline connected with the internal pressure outlet joint 17 is led to the atmosphere through a fourth valve 32, a first three-way valve 33 and a second three-way valve 34; the metal line connecting the ring pressure outlet connection 20 is opened to the atmosphere through a fifth valve 35 and a second three-way valve 34.

And 4, step 4: closing the third valve 28, the fourth valve 32 and the fifth valve 35, opening the first valve 25 and the second valve 26, filling water into the inner cavity of the casing from the inner pressure inlet joint 11 by using the inner pressure control system 24, filling water into the annular space between the pressure bearing cylinder and the rubber sleeve from the annular pressure inlet joint 14 by using the annular pressure control system 21, starting the temperature control system 30, setting the temperature rise time, heating the pressure bearing cylinder by using an annular heater, wherein the inner pressure and the annular pressure can be increased along with the increase of the temperature, controlling the temperature to be at the target temperature after the temperature rise is finished, starting the inner pressure control system 24 and the annular pressure control system 21, setting the target pressure, and uniformly and continuously pressurizing the inner cavity of the casing and the annular space by using the inner pressure pump and the annular pressure pump until the pressure rises to the target pressure. And opening a third valve 28, opening a nitrogen cylinder 27, starting a flow monitor 31, a permeability detection module 29, an equivalent crack width detection module 23 and an annular pressure conduction coefficient detection module 22 to start detection, simulating the pressure rise and fall inside the sleeve and outside the cement sheath under different working conditions, starting an internal pressure control system 24 and an annular pressure control system 21, increasing and decreasing pressure according to the same procedure steps, and monitoring the permeability, the equivalent crack width and the annular pressure conduction coefficient detected by the three modules to monitor the sealing performance change condition of the cement sheath in real time.

And 5: after the experiment is finished, the computer control system 36 stores experimental data, the nitrogen cylinder 27 and the third valve 28 are closed, the temperature control system 30 is closed, after the device is cooled, the pressure of the inner cavity and the annular space of the sleeve is removed by using the internal pressure pump and the annular pressure pump, the internal pressure control system 24 and the annular pressure control system 21, the first valve 25 and the second valve 26 are closed, the permeability detection module 29, the equivalent crack width detection module 23 and the annular pressure conductivity coefficient detection module 22 are closed, the fourth valve 32 and the fifth valve 35 are opened, water in the inner cavity and the annular space of the sleeve is discharged, all pipelines of the control systems and the detection modules are removed, the top cover 1 and the base 2 are removed, the cement ring assembly is taken out, further microscopic detection experiments can be carried out on the structure of the cement ring assembly, and microscopic failure mechanisms of the cement ring material are observed.

Example one

The implementation process of testing the packing capacity of the high-temperature and high-pressure cement sheath body under the fracturing working condition is as follows:

1. before an experiment, the load of a cement sheath in an actual shaft is equivalent to the experimental cement sheath through three processes of geometric similarity, equal stress and same working procedure, the size, the stress and the load of a simulated fracturing working condition on the experimental cement sheath are calculated, then the experiment is started, corresponding cement paste is prepared according to the experimental requirements and API standards, the cement paste is injected into a cement sheath maintenance mold, the mold is placed in a high-temperature high-pressure maintenance kettle for maintenance for a certain age, and the combination of the internal pressure casing pipe and the circular cement sheath is taken out.

2. The base 2 is tightly connected with the pressure-bearing cylinder 6 through lower threads, the maintained combined body is sleeved with a rubber sleeve, then the rubber sleeve is placed in the pressure-bearing cylinder, and the top cover 1 is screwed down.

3. The temperature control system 30 is respectively connected with the heating sleeve 7, the temperature sensor 8 and the computer control system 36; one end of the ring pressure control system 21 is connected to the ring pressure inlet joint 14 through a second valve 26, and the other end is connected to the computer control system 36; connecting one end of an internal pressure control system 24 to the internal pressure inlet joint 11 through a first valve 25, and connecting the other end to a computer control system 36; the permeability detection module 29 is respectively connected to the permeability detection module upper joint 10, the permeability detection module lower joint 16 and the computer control system 36; the equivalent crack width detection module 23 is respectively connected to the equivalent crack width detection module upper joint 12, the equivalent crack width detection module lower joint 18 and the computer control system 36; the annular pressure conductivity coefficient detection module 22 is respectively connected to the annular pressure conductivity coefficient detection module upper joint 13, the annular pressure conductivity coefficient detection module lower joint 19 and the computer control system 36; the external pipeline of the nitrogen cylinder 27 is connected to the nitrogen inlet joint 9 through a third valve 28; the flow monitoring meter 31 is respectively connected to the flow monitoring meter connector 15 and the computer control system 36, and the other end of the flow monitoring meter is connected with the first three-way valve 33 and the second three-way valve 34 to be communicated with the atmospheric environment; the metal pipeline connected with the internal pressure outlet joint 17 is led to the atmosphere through a fourth valve 32, a first three-way valve 33 and a second three-way valve 34; the metal line connecting the ring pressure outlet connection 20 is opened to the atmosphere through a fifth valve 35 and a second three-way valve 34.

4. Closing the third valve 28, the fourth valve 32 and the fifth valve 35, opening the first valve 25 and the second valve 26, filling water into the inner cavity of the casing from the inner pressure inlet joint 11 by using the inner pressure control system 24, filling water into the annular space between the pressure bearing cylinder and the rubber sleeve from the annular pressure inlet joint 14 by using the annular pressure control system 21, starting the temperature control system 30, setting the temperature rise time, heating the pressure bearing cylinder by using an annular heater, wherein the inner pressure and the annular pressure can be increased along with the increase of the temperature, controlling the temperature to be at the target temperature after the temperature rise is finished, starting the inner pressure control system 24 and the annular pressure control system 21, setting the target pressure, and uniformly and continuously pressurizing the inner cavity of the casing and the annular space by using the inner pressure pump and the annular pressure pump until the pressure rises to the target pressure. And opening a third valve 28, opening a nitrogen cylinder 27, starting a flow monitor 31, a permeability detection module 29, an equivalent fracture width detection module 23 and an annular pressure conductivity coefficient detection module 22 to start detection, simulating the rise and fall of the internal pressure of the casing pipe in the fracturing process, starting an internal pressure control system 24, carrying out pressure rise and fall according to the same procedure steps, and monitoring the change condition of the packing performance of the cement sheath in real time according to the permeability, the equivalent fracture width and the annular pressure conductivity coefficient detected by the three modules.

5. After the experiment is finished, after the computer control system 36 stores experimental data, the nitrogen cylinder 27 and the third valve 28 are closed, the temperature control system 30 is closed, after the device is cooled down, the pressure in the inner cavity of the casing and the annular space is removed by using the internal pressure pump and the annular pressure pump, the internal pressure control system 24 and the annular pressure control system 21, the first valve 25 and the second valve 26 are closed, the permeability detection module 29, the equivalent crack width detection module 23 and the annular pressure conductivity coefficient detection module 22 are closed, the fourth valve 32 and the fifth valve 35 are opened, water in the inner cavity of the casing and the annular space is discharged, all pipelines of each control system and each detection module are removed, the top cover 1 and the base 2 are detached, and the cement ring assembly is taken out. The cement sheath assembly structure can be further subjected to microscopic detection experiments, and microscopic failure mechanisms of the cement sheath material can be observed.

Example two

The implementation process for testing the packing capacity of the cement sheath under the fracturing working condition and the non-uniform ground stress is as follows:

1. before an experiment, the load of a cement sheath in an actual shaft is equivalent to the experimental cement sheath through three processes of geometric similarity, equal stress and same working procedure, the size, the stress and the simulated fracturing working condition load on the experimental cement sheath are calculated, then the experiment is started, corresponding cement paste is prepared according to the experimental requirements and API standards, the cement paste is injected into a cement sheath maintenance mold, the mold is placed in a high-temperature high-pressure maintenance kettle for maintenance for a certain age, and an 'internal pressure sleeve-oval cement sheath' assembly is taken out and aims at simulating the stress environment of the cement sheath under non-uniform ground stress.

5. After the experiment is finished, after the computer control system 36 stores experimental data, the nitrogen cylinder 27 and the third valve 28 are closed, the temperature control system 30 is closed, after the device is cooled down, the pressure in the inner cavity of the casing and the annular space is removed by using the internal pressure pump and the annular pressure pump, the internal pressure control system 24 and the annular pressure control system 21, the first valve 25 and the second valve 26 are closed, the permeability detection module 29, the equivalent crack width detection module 23 and the annular pressure conductivity coefficient detection module 22 are closed, the fourth valve 32 and the fifth valve 35 are opened, water in the inner cavity of the casing and the annular space is discharged, all pipelines of each control system and each detection module are removed, the top cover 1 and the base 2 are detached, the cement ring assembly is taken out, and the cement ring assembly is taken out. The cement sheath assembly structure can be further subjected to microscopic detection experiments, and microscopic failure mechanisms of the cement sheath material can be observed.

EXAMPLE III

The implementation process for testing the packing capacity of the cement sheath under the cyclic loading working condition and the casing tie-back is as follows:

1. before the experiment, the cement sheath load in the actual shaft needs to be equivalent to the experimental cement sheath through three processes of geometric similarity, equal stress and same working procedure, the size, stress and simulated cyclic loading load on the experimental cement sheath are calculated, then the experiment is started, corresponding cement paste is prepared according to the experimental requirements and API standards, the cement paste is injected into a cement sheath maintenance mold, the mold is placed in a high-temperature high-pressure maintenance kettle for maintenance for a certain age, and the combination of the internal pressure sleeve, the circular cement sheath and the outer sleeve is taken out, and the combination aims at simulating the stress environment of the cement sheath connected back with the sleeve.

4. The third valve 28, the fourth valve 32 and the fifth valve 35 are opened, the first valve 25 and the second valve 26 are opened, the inner pressure control system 24 is used for filling water into the inner cavity of the sleeve from the inner pressure inlet joint 11, the ring pressure control system 21 is used for filling water into the annular space between the pressure bearing cylinder and the rubber sleeve from the ring pressure inlet joint 14, the temperature control system 30 is started, the temperature rise time is set, the pressure bearing cylinder is heated by the ring heater, the inner pressure and the ring pressure can be increased along with the increase of the temperature, the temperature is controlled to be at the target temperature after the temperature rise is finished, the inner pressure control system 24 and the ring pressure control system 21 are started, the target pressure is set, the inner pressure pump and the ring pressure pump are used for uniformly and continuously pressurizing the inner cavity of the sleeve and the annular space until the target pressure is increased, and the inner pressure is greater than the ring pressure to. And opening a third valve 28, opening a nitrogen cylinder 27, starting a flow monitor 31, a permeability detection module 29, an equivalent crack width detection module 23 and an annular pressure conductivity coefficient detection module 22 to start detection, continuing for a period of time, then reducing the pressure in the inner cavity of the casing by using an internal pressure pump, increasing the annular pressure by using an annular pressure pump, forming a negative pressure difference when the internal pressure is smaller than the annular pressure, continuing for a period of time, then repeating the process for N weeks to simulate a cyclic loading process, and monitoring the change condition of the sealing performance of the cement ring in real time according to the permeability, the equivalent crack width and the annular pressure conductivity coefficient detected by the three modules.

5. After the computer control system 36 stores the experimental data, the nitrogen cylinder 27 and the third valve 28 are closed, the temperature control system 30 is closed, after the device is cooled, the pressure of the inner cavity and the annular space of the sleeve is removed by using the internal pressure pump and the ring pressure pump, the internal pressure control system 24 and the ring pressure control system 21, the first valve 25 and the second valve 26 are closed, the permeability detection module 29, the equivalent crack width detection module 23 and the annular pressure conductivity coefficient detection module 22 are closed, the fourth valve 32 and the fifth valve 35 are opened, the water in the inner cavity and the annular space of the sleeve is discharged, all pipelines of each control system and each detection module are removed, the top cover 1 and the base 2 are detached, and the cement ring assembly is taken out. The cement sheath assembly structure can be further subjected to microscopic detection experiments, and microscopic failure mechanisms of the cement sheath material can be observed.

Example four

The implementation process of simulating the cyclic loading working condition and testing the cementing capacity of the two interfaces of the cement ring is as follows:

1. before an experiment, the load of a cement sheath in an actual shaft needs to be equivalent to the experimental cement sheath through three processes of geometric similarity, equal stress and same working procedure, the size, the stress and the simulated cyclic loading load on the experimental cement sheath are calculated, then the experiment is started, corresponding cement paste is prepared according to the experiment requirements and API standards, the cement paste is injected into a cement sheath maintenance mold, the mold is placed in a high-temperature high-pressure maintenance kettle for maintenance for a fixed period, and an 'internal-pressure sleeve-circular cement sheath-simulated surrounding rock' assembly is taken out, and the assembly aims at testing the cementing capacity of a cement sheath interface.

4. Closing the third valve 28, the fourth valve 32 and the fifth valve 35, opening the first valve 25 and the second valve 26, filling water into the inner cavity of the casing from the inner pressure inlet joint 11 by using the inner pressure control system 24, filling water into the annular space between the pressure bearing cylinder and the rubber sleeve from the annular pressure inlet joint 14 by using the annular pressure control system 21, starting the temperature control system 30, setting the temperature rise time, heating the pressure bearing cylinder by using an annular heater, wherein the inner pressure and the annular pressure can be increased along with the increase of the temperature, controlling the temperature to be at the target temperature after the temperature rise is finished, starting the inner pressure control system 24 and the annular pressure control system 21, setting the target pressure, uniformly and continuously pressurizing the inner cavity and the annular space of the casing by using the inner pressure pump and the annular pressure pump until the target pressure is increased, and forming a positive pressure difference when the inner pressure is greater than the annular pressure. And opening a third valve 28, opening a nitrogen cylinder 27, starting a flow monitor 31, a permeability detection module 29, an equivalent crack width detection module 23 and an annular pressure conductivity coefficient detection module 22 to start detection, continuing for a period of time, then reducing the pressure in the inner cavity of the casing by using an internal pressure pump, increasing the annular pressure by using an annular pressure pump, forming a negative pressure difference when the internal pressure is smaller than the annular pressure, continuing for a period of time, then repeating the process for N weeks to simulate a cyclic loading process, and monitoring the change condition of the sealing performance of the cement ring in real time according to the permeability, the equivalent crack width and the annular pressure conductivity coefficient detected by the three modules.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. The utility model provides an oil gas well casing ring space cement ring's packing capability test device which characterized in that includes: the device comprises a top cover (1), a base (2), an internal pressure sleeve (3), a cement sheath (4), an external pressure barrel (5), a pressure-bearing barrel (6), a heating sleeve (7), a temperature sensor (8), a nitrogen inlet interface (9), a permeability detection module upper joint (10), an internal pressure inlet joint (11), an equivalent crack width detection module upper joint (12), an annular pressure conduction coefficient detection module upper joint (13), an annular pressure inlet joint (14), a flow monitor joint (15), a permeability detection module lower joint (16), an internal pressure outlet joint (17), an equivalent crack width detection module lower joint (18), an annular pressure conduction coefficient detection module lower joint (19), an annular pressure outlet joint (20), an annular pressure control system (21), an annular pressure conduction coefficient detection module (22), an equivalent crack width detection module (23), The device comprises an internal pressure control system (24), a nitrogen gas cylinder (27), a permeability detection module (29), a temperature control system (30), a flow monitor (31), a first valve (25), a second valve (26), a third valve (28), a fourth valve (32), a fifth valve (35), a first three-way valve (33), a second three-way valve (34) and a computer control system (36);

the top cover (1) is connected with the pressure bearing cylinder (6) in a sealing mode through upper threads, and the base (2) is connected with the pressure bearing cylinder (6) in a sealing mode through lower threads;

the inner pressure casing (3), the cement sheath (4) and the outer pressure cylinder (5) form a simulated shaft assembly;

the heating sleeve (7) is wrapped on the outer wall of the pressure-bearing cylinder (6); the temperature control system (30) is provided with three connecting ports which are respectively connected with the heating sleeve (7), the temperature sensor (8) and the computer control system (36);

the ring pressure control system (21) is provided with two connecting ports, one end of the connecting port is connected to the ring pressure inlet joint (14) through a second valve (26), and the other end of the connecting port is connected to the computer control system (36);

the internal pressure control system (24) is provided with two connecting ports, one end of the internal pressure control system is connected to the internal pressure inlet joint (11) through a first valve (25), and the other end of the internal pressure control system is connected to the computer control system (36);

the permeability detection module (29) is provided with three connecting ports which are respectively connected with the permeability detection module upper joint (10), the permeability detection module lower joint (16) and the computer control system (36); the permeability detection module is used for determining the permeability of the cement sheath by three testing methods, namely a gas channeling method, a pressure drop method and a pulse method;

the equivalent crack width detection module (23) is provided with three connecting ports which are respectively connected with the equivalent crack width detection module upper joint (12), the equivalent crack width detection module lower joint (18) and the computer control system (36);

the annular pressure conduction coefficient detection module (22) is provided with three connecting ports which are respectively connected with an upper joint (13) of the annular pressure conduction coefficient detection module, a lower joint (19) of the annular pressure conduction coefficient detection module and a computer control system (36);

the external pipeline of the nitrogen cylinder (27) is connected to the nitrogen inlet joint (9) through a third valve (28);

the flow monitoring meter (31) is provided with three connecting ports which are respectively connected with the flow monitoring meter connector (15) and the computer control system (36), and the other end of the flow monitoring meter is connected with the first three-way valve (33) and the second three-way valve (34) in sequence and then is communicated with the atmospheric environment;

a metal pipeline connected with the internal pressure outlet joint (17) is communicated to the atmosphere environment through a fourth valve (32), a first three-way valve (33) and a second three-way valve (34);

and a metal pipeline connected with the annular pressure outlet joint (20) is communicated to the atmosphere environment through a fifth valve (35) and a second three-way valve (34).

2. The device for testing packing performance of an oil and gas well bore annulus cement sheath as claimed in claim 1, wherein the simulated well bore assembly comprises: 4 combinations for testing the packing capability of the cement ring body under high temperature and high pressure, combinations for testing the packing capability of the cement ring under non-uniform ground stress, combinations for testing the packing capability of the cement ring under the tie-back of the casing and combinations for testing the packing capability of the cement ring-two interface under the formation surrounding rock.

3. The oil and gas well casing annulus cement ring packing performance testing device of claim 2, wherein the assembly for testing the packing capacity of the cement ring body under high temperature and high pressure is as follows: a circular cement sheath (4) is additionally arranged outside the internal pressure sleeve (3), and the external pressure cylinder (5) is a high-temperature resistant rubber cylinder.

4. The device for testing packing performance of annular cement rings of oil and gas well barrels according to claim 2, wherein the combination for testing packing capacity of cement rings under non-uniform ground stress comprises: an elliptical cement sheath (4) is additionally arranged outside the inner pressure sleeve (3), non-uniform load is simulated by changing the ratio of the long axis and the short axis of an ellipse, and the outer pressure cylinder (5) is a high-temperature-resistant rubber cylinder.

5. The oil and gas well casing annulus cement ring packing performance testing device of claim 2, wherein the combination of cement ring packing capacity under test casing tieback is: the internal pressure sleeve (3) is externally provided with a circular cement sheath (4), the circular cement sheath is externally provided with an outer sleeve (51), and the external pressure cylinder (5) consists of the outer sleeve and a high-temperature-resistant rubber cylinder.

6. The device for testing packing performance of annular cement rings of oil and gas well barrels according to claim 2, wherein the assembly for testing the packing capacity of the cement rings in the formation surrounding rocks at the interface between the two interfaces is as follows: interior pressure sleeve pipe (3) plus circular cement sheath (4), circular cement sheath plus simulation country rock (52), simulation country rock (52) comprise the multistage country rock ring to scribble impermeably coating on every section of country rock anchor ring, prevent inside gas invasion simulation country rock, external pressure section of thick bamboo (5) by simulation country rock + high temperature resistant rubber tube constitute.

7. A packing performance test method for an annular cement ring of an oil-gas well casing is characterized by comprising the following steps:

1) before an experiment, an actual cement sheath is equivalent to the experimental cement sheath through three processes of geometric similarity, equal stress and same working procedure, pressure values which are required to be added inside an inner pressure sleeve (3) and outside an outer pressure cylinder (5) and have equal load of the experimental cement sheath and the actual cement sheath under each working condition are calculated, an inner experimental pressure value table and an outer experimental pressure value table are formed, the experiment is started, corresponding cement paste is prepared according to experimental requirements and API standards, the cement sheath is injected into a cement sheath maintenance mold, the mold is placed in a high-temperature high-pressure maintenance kettle for maintenance for a regular age, and a sleeve-cement sheath or a sleeve-cement sheath-outer pressure cylinder combination is taken out;

2) tightly connecting the base (2) with the pressure-bearing cylinder (6) through lower threads, sleeving a cured combined body on a rubber sleeve, then placing the rubber sleeve in the pressure-bearing cylinder, and screwing the top cover (1);

3) the temperature control system (30) is respectively connected to the heating sleeve (7), the temperature sensor (8) and the computer control system (36); one end of a ring pressure control system (21) is connected to a ring pressure inlet joint (14) through a second valve (26), and the other end of the ring pressure control system is connected to a computer control system (36); one end of an internal pressure control system (24) is connected to an internal pressure inlet joint (11) through a first valve (25), and the other end is connected to a computer control system (36); respectively connecting a permeability detection module (29) to a permeability detection module upper joint (10), a permeability detection module lower joint (16) and a computer control system (36); respectively connecting the equivalent crack width detection module (23) to an equivalent crack width detection module upper joint (12), an equivalent crack width detection module lower joint (18) and a computer control system (36); the annular pressure conductivity coefficient detection module (22) is respectively connected to the annular pressure conductivity coefficient detection module upper joint (13), the annular pressure conductivity coefficient detection module lower joint (19) and the computer control system (36); connecting an external pipeline of a nitrogen cylinder (27) to a nitrogen inlet joint (9) through a third valve (28); respectively connecting a flow monitoring meter (31) to a flow monitoring meter connector (15) and a computer control system (36), and connecting the other end of the flow monitoring meter (31) to a first three-way valve (33) and a second three-way valve (34) to be communicated with the atmospheric environment; a metal pipeline connected with the internal pressure outlet joint (17) is led to the atmosphere environment through a fourth valve (32), a first three-way valve (33) and a second three-way valve (34); the metal pipeline connected with the annular pressure outlet joint (20) is communicated to the atmosphere environment through a fifth valve (35) and a second three-way valve (34);

4) closing a third valve (28), a fourth valve (32) and a fifth valve (35), opening a first valve (25) and a second valve (26), filling water into the inner cavity of the sleeve from an internal pressure inlet joint (11) by using an internal pressure control system (24), filling a liquid medium into an annular space between the pressure-bearing cylinder and the rubber sleeve from an annular pressure inlet joint (14) by using an annular pressure control system (21), starting a temperature control system (30), setting the temperature rise time, heating the pressure-bearing cylinder by using an annular heater, increasing the internal pressure and the annular pressure along with the temperature increase, controlling the temperature to be at a target temperature after the temperature rise is finished, starting the internal pressure control system (24) and the annular pressure control system (21), setting the target pressure, and uniformly and continuously pressurizing the inner cavity of the sleeve and the annular space by using an internal pressure pump and an annular pressure pump until the target pressure is increased;

opening a third valve (28), opening a nitrogen cylinder (27), starting a flow monitor (31), a permeability detection module (29), an equivalent crack width detection module (23) and an annular pressure conductivity coefficient detection module (22) to start detection, simulating the pressure rise and fall of the inside of the sleeve and the outside of the cement ring under different working conditions, starting an internal pressure control system (24) and an annular pressure control system (21), carrying out pressure rise and fall according to the same steps of the process, and monitoring the sealing performance change condition of the cement ring in real time according to the permeability, the equivalent crack width and the annular pressure conductivity coefficient detected by the three modules;

5) after the experiment is finished, the computer control system (36) stores experiment data, the nitrogen cylinder (27) and the third valve (28) are closed, the temperature control system (30) is closed, after the device is cooled down, the internal pressure pump and the ring pressure pump are used for removing the pressure of the inner cavity of the sleeve and the annular space, the internal pressure control system (24) and the ring pressure control system (21) as well as the first valve (25) and the second valve (26) are closed, the permeability detection module (29), the equivalent crack width detection module (23) and the annular pressure conduction coefficient detection module (22) are closed, the fourth valve (32) and the fifth valve (35) are opened, the water in the inner cavity of the sleeve and the annular space is discharged, all pipelines of each control system and each detection module are removed, the top cover (1) and the base (2) are removed, the cement ring assembly is taken out, and further microscopic detection experiments can be carried out on the structure of the cement ring, observing the microscopic failure mechanism of the cement sheath material.