232 results about "Cement sheath" patented technology

The invention provides high-toughness micro-expansive cement paste suitable for high-temperature well cementation. The cement paste comprises the following raw materials in parts by weight: 60-90 parts of G-grade oil well cement, 20-40 parts of an active material, 3-12 parts of a high-performance toughening agent, 3-10 parts of nano oxide, 0.5-5 parts of an expanding agent, 3-5 parts of a chemical exciting agent, 1-3 parts of a high-temperature fluid loss agent, 0.5-3 parts of a high-temperature retarder and 0.1-1 part of a dispersing agent, and 0.2-1 part by weight of a defoaming agent. By adding the active material, the high-performance toughening agent, the nano oxide and the expanding agent, the high-temperature resistance and toughness of the cement paste, the cementation quality of a cement sheath and the like are improved; through the combined action of the four components, the high-temperature resistance, toughness and surrounding rock interface cementation performance of the cement are comprehensively improved; and the cement paste is matched with other components for use, so that the cement paste has the advantages of good stability, low water loss, good rheological property and the like, is suitable for underground gas storage well cementation, can improve the well cementation quality of a stratum sealing section, and ensures the sealing integrity of a cement sheath under frequent injection and production.

The invention discloses a well cementation cement sheath seepage corrosion and mechanical property evaluation device and method, and belongs to the field of oil and gas well cementation material corrosion evaluation. The device comprises an acidic corrosive gas injection system, a formation water injection system, a high-pressure oil injection system, a control system and a corrosion and test system, the corrosion and test system comprises a main body, an upper cover and a base, and the main body sequentially comprises a metal cylinder, a simulated formation, a simulated sleeve and a center rod from outside to inside; a cement sheath maintenance-corrosion space is formed between the simulated stratum and the simulated casing, a temperature control device is arranged in an annulus formed between the simulated casing and the center rod, and the center rod is provided with a plurality of displacement meters at different positions and angles to measure deformation displacement of a simulated casing-cement sheath combination. The method for evaluating seepage corrosion and mechanical properties of the well cementation cement sheath by using the device is simple and convenient to operate, realizes three functions of cement sheath maintenance, acid medium corrosion and cement sheath mechanical integrity evaluation at high temperature and high pressure, and has a wide application prospect.

The invention discloses a vibration-CO2 corrosion coupling effect real-time monitoring system and monitoring method for a well cementation cement sheath of an oil and gas well in a high-temperature and high-pressure environment. The system comprises a kettle system which is fixed with a base of an axial loading system, and a push rod of the axial loading system extends into the kettle system from the center of a kettle cover and is pressed on a detected body; the CT detection system is mounted below a jack supporting plate of the axial loading system; the electrolytic corrosion system is connected with the lower end of a first embedded axial pipeline on the side wall of a kettle body in the kettle system so as to apply an experimental environment; the gas pressurization system is divided into two paths, one path is led into the kettle system from the lower part, and the other path is connected with the lower end of the second embedded axial pipeline; a sleeve of the kettle system is fixed in the kettle system, the nondestructive testing system is installed in the middle of the sleeve, and the vibration system in the sleeve is installed on the lower portion of the sleeve. According to the invention, axial loading, gas pressurization and heating devices are integrated, and an underground high-temperature and high-pressure environment is simulated; and CT and ultrasonic waves cooperate to realize multi-dimensional dynamic monitoring of the corrosion process.

A wellbore staged operation method includes running, after a first well drifting operation is performed on a wellbore, a pipe string (100) in the wellbore, wherein the pipe string (100) includes, along a direction from bottom to top, a floating hoop (2), a plug seat (7), a toe-end sliding sleeve (3), and a fracturing sliding sleeve (4); performing a cementing operation, wherein cement slurry pumped into an inner chamber of the pipe string (100) enters an annulus between the pipe string and the wellbore through the plug seat (7) and the floating hoop (2) to form a cement sheath, the cement sheath isolating the toe-end sliding sleeve (3) from the fracturing sliding sleeve (4); performing a second drifting operation to ensure the toe-end sliding sleeve (3) of the pipe string (100) exposed; performing a pressure test for the pipe string; and performing staged fracturing constructions.

A numerical simulation method for the integrity of cement sheath systems in oil and gas wells under alternating temperature and pressure is characterized by the use of extended finite element method (XFEM), concrete damage plasticity model theory, Cohesive element method, and bilinear traction separation criterion, based on elastoplastic theory and plastic damage theory. This method can simulate not only the failure process of the cement sheath-casing interface under alternating temperature and pressure and characterize the mechanical behavior of interface failure, but also the failure process of the cement sheath itself and characterize its mechanical behavior. By comprehensively analyzing the failure behavior of the cement sheath system integrity in oil and gas wells, this method enables a realistic evaluation, prediction, and diagnosis of the integrity of the casing-cement sheath-casing assembly system under alternating temperature and pressure, which helps optimize cement slurry systems, improve cementing quality, and prevent cement sheath integrity failure. This invention is applicable to the field of oil and gas drilling and production engineering technology.

The invention provides an old well shaft reconstruction cement sheath simulation device and simulation method, and relates to the technical field of cement sheath integrity detection. The old well shaft reconstruction cement sheath simulation method comprises the following steps: constructing a shaft stratum model; obtaining a pre-reconstruction strength parameter of the old well shaft model before shaft reconstruction; the inner side of the sleeve is filled with an expansion liner tube; secondary perforation is formed, so that an old well shaft model after shaft reconstruction is formed; and obtaining a reconstructed strength parameter of the old well shaft model after shaft reconstruction. According to the old well shaft reconstruction cement sheath simulation method provided by the embodiment of the invention, the strength parameters of the shaft model before and after reconstruction can be tested so as to evaluate the influence of shaft reconstruction on the integrity of the cement sheath.

The invention provides a cement consolidation casing pipe separation process, and relates to the technical field of petroleum engineering well repair, the process comprises the following steps: S1, ground equipment installation, pipeline connection and pressure test; s2, plugging a central through hole of the casing below the target depth, and performing a pressurizing test; s3, the inner wall of the casing pipe is cleaned, the well is washed circularly, gas lift drainage and drying are conducted, and inert gas is injected for well sealing; s4, detecting the contents of combustible gas, oxygen and inert gas in the well; s5, a high-frequency induction heating device is put down to the target depth, and the high-frequency induction heating device is moved from bottom to top to conduct induction heating on the sleeve; s6, a section milling tool is put down to conduct section milling on the casing pipe at the target depth, and the well is washed circularly; and S7, a fishing tool is put down, and the upper casing pipe is lifted out. The device can effectively destroy the binding force between the casing and set cement outside the casing, then the casing can be taken out in sections, and the device has the advantages of being high in efficiency, short in operation period, low in cost, small in environmental pollution and the like.

The invention relates to the technical field of petroleum engineering, and provides an oil and gas well cementation cement sheath integrity evaluation method which comprises the following steps: S1, simulation experiment: simulating underground environment and cement sheath stress changes under various operation conditions through an indoor physical simulation device to obtain reliable experiment data and experiment phenomena; s2, analysis and verification experiment: analyzing and verifying an experiment phenomenon through the mathematical model of the cement sheath; and S3, judgment: forming a cement sheath sealing integrity judgment method with practical significance through organic combination of a mechanical model and physical simulation. Through a method of combining a simulation experiment and mechanical model analysis, the integrity and the packing performance of the cement sheath can be evaluated more accurately, a more comprehensive and objective evaluation basis can be provided by experimental data and phenomenon acquisition and a stress analysis result, the defect of a single basis is avoided, the integrity of the cement sheath is evaluated accurately, and the sealing performance of the cement sheath is improved. And potential well cementation problems can be found in time.

According to the multi-stage opening long-acting packing device and method based on metal-cement sheath sealing, in the well cementation process of different opening times, when a casing pipe is tripped into different positions of a shaft, CO2 is injected or in the long-term storage process, when annulus pressure occurs in the shaft, according to the storage position and integrity analysis of the shaft, the sealing time of the casing pipe is shortened, and the sealing time of the casing pipe is shortened. A pre-embedded device on the upper portion of the leakage position is selected, the low-melting-point alloy is melted in the mode of injecting high-temperature steam, meanwhile, thermal expansion fluid drives the low-melting-point alloy to be squeezed into the sealing integrity failure position, and then the low-melting-point alloy flows into a micro annular space or a micro crack to achieve material blocking. The expansion effect in the solidification process of the low-melting-point alloy is used for achieving mechanical plugging on part of microfractures, so that a corresponding well barrier is established, and the sealing integrity of a shaft is guaranteed. And as time goes on, the corrosion effect of a bottom shaft is considered, when the annulus belt pressure occurs again, the pre-embedded devices at different positions are started in multiple stages, and the sealing integrity is guaranteed.

Methods of the present disclosure relate to tailoring cement compositions to withstand carbon dioxide injection. A method comprises predicting a depth of carbonation in a cement sheath; predicting spatially varying mechanical properties of the cement composition due to the carbonation; and determining a mechanical response of the cement sheath based on the spatially varying mechanical properties of the cement composition.

A risk assessment and control method for radial cracking and crack propagation and transfixion of cement sheath in fracturing wells is provided. Based on the thermo-solid coupling theoretical model of casing-cement sheath-formation combination and thick-walled cylinder theory, the tangential stress distribution of crack-free cement sheath when fracturing is obtained, the maximum tensile stress criterion is used to judge whether the cement sheath has radial initial cracking when fracturing and calculate the initial cracking length, based on the weight function method, the stress intensity factor of the tip of the radial initial cracking of the cement sheath when fracturing is calculated, the fracture mechanics criterion is used to judge whether the radial crack propagation and transfixion will occur in the cement sheath, and the performance parameters of the cement sheath are controlled by the double standards of preventing the radial cracking of the cement sheath and controlling the crack propagation.

The invention discloses a casing centralizer with a pipe diameter adjusting function, and relates to the technical field of petroleum and natural gas drilling engineering equipment, the casing centralizer comprises two fixing rings which are symmetrically distributed left and right, the outer surface of each fixing ring is provided with a plurality of fixing seats at equal intervals in the circumferential direction, and each fixing seat is rotatably connected with a connecting plate; an elastic plate is arranged between the left connecting plate and the right connecting plate in the horizontal direction, and the two ends of each elastic plate are rotationally connected with the two adjacent connecting plates respectively. By rotating the adjusting bolt, the driving screw rod and the fixing pipe are in threaded transmission, and the distance between the two fixing rings is accurately controlled, so that the annular supporting frame formed by the connecting plate and the elastic plate generates controllable radial deformation; stepless adjustment of the supporting outer diameter is achieved, different borehole sizes are accurately matched, the problem that a centralizer with a fixed size is insufficient in supporting or difficult to descend is solved, it is ensured that a casing pipe is efficiently centered, and a foundation is laid for forming a uniform cement sheath.

The invention discloses a dual-system rapid ultrahigh-pressure tracking mechanism for evaluating the sealing integrity of a cement sheath. The dual-system rapid ultrahigh-pressure tracking mechanism comprises a first high-pressure stress cabin and a second high-pressure stress cabin, the two ends of the adjusting device are connected with the first high-pressure stress cabin and the second high-pressure stress cabin through pulling assemblies correspondingly, displacement detection pieces are arranged on the pulling assemblies, and the ends, away from the adjusting device, of the first high-pressure stress cabin and the second high-pressure stress cabin are each provided with a valve assembly, a pressure detection assembly and a water supply piece through pipelines; the controller is electrically connected with the adjusting device, the valve assembly, the pressure detection assembly, the displacement detection piece and the water supply piece, the controller is used for presetting a detection numerical value of the displacement detection piece and controlling the moving distance of the adjusting device towards the first high-pressure stress cabin or the second high-pressure stress cabin according to the detection numerical value, and reciprocating control is conducted in this way; rapid liquid adding under the ultrahigh pressure condition can be achieved, the liquid adding process is continuous, and the functions of pressure gradient loading and automatic pressure tracking during alternating stress simulation are achieved.

The invention discloses an oil and gas well cement sheath interface bonding strength experimental device and a determination method, and relates to the technical field of oil and gas wells. Temperature control is performed on a cement sheath through a numerical control system, so that the temperature of the cement sheath is within a preset temperature range; according to experimental requirements, the cement sheath is subjected to circular treatment, the circular treatment comprises pressurization treatment, heating treatment, cooling treatment and pressure relief treatment, the circular treatment is repeated, the number of times of circulation is consistent with the number of times of demand of field working conditions until the cementing surface in the cement sheath fails in cementing, and the cement sheath is obtained. And determining a load-displacement curve during the cementation failure period of the cementation surface in the cement sheath, and determining the cementation strength of the cement in the cement sheath according to the load-displacement curve. The method can achieve the purposes of being closer to the actual working condition and more accurate in measurement result.

The invention provides well cementation prepad fluid for oil-based drilling fluid as well as a preparation method and application of the well cementation prepad fluid. The well cementation prepad fluid comprises the following raw materials: water, an anionic surfactant accounting for 0.1%-10% of the total mass of the water, a nonionic surfactant accounting for 0.1%-15% of the total mass of the water, a coupling agent accounting for 0.1%-2.5% of the total mass of the water, a buffering agent and / or a chelating agent accounting for 0.2%-3% of the total mass of the water, and a suspending agent accounting for 0.1%-3.0% of the total mass of the water, a defoaming agent accounting for 0.1%-3.0% of the total mass of the water; wherein the coupling agent is an amino alkyl type silane coupling agent. The prepared well cementation prepad fluid can effectively remove oil-phase substances of a casing pipe and a well wall when an oil-based drilling fluid is used for drilling, the interface cementation quality is improved, and the cement sheath packing capacity and the well cementation quality are guaranteed.

The invention discloses a hydraulic fracturing shaft leakage detection system and method, and the method comprises the steps: controlling an electro-hydraulic servo pressure regulating valve to inject a hydraulic medium into a confining pressure cavity, and simulating the pressure applied to the confining pressure cavity in a shaft environment; a high-pressure pump is controlled to inject high-pressure fluid into the shaft environment, and the hydraulic fracturing working condition is simulated; in the process of simulating the actual working condition, pressure data in the confining pressure cavity and strain data of any measuring point in the cement sheath are obtained, and when it is monitored that the strain data exceed a preset threshold value, pressure interlocking control is triggered: an electro-hydraulic servo pressure regulating valve is controlled to conduct graded pressure reduction treatment on the pressure in the confining pressure cavity; and fitting a crack propagation path of the cement sheath by adopting a least square method according to the monitored temperature data of the cement sheath and the pressure data after pressure interlock control. The simulation precision of the dynamic expansion path of the cement sheath crack can be improved, qualitative speculation of the crack expansion path is changed into quantitative reduction, and a reliable basis is provided for shaft sealing design.

The invention discloses a cement sheath thickness real-time calculation method, device, equipment, medium and product, and relates to the field of geophysical cased well acoustic logging, the method comprises the following steps: carrying out waveform extraction, frequency domain feature extraction and stoneley wave parameter calculation on standard array sound wave data to obtain corresponding processing data; forming a training sample set by taking the processed data as sample data and taking an open hole diameter corresponding to the standard array sound wave data as label data; training by using the training sample set to obtain a hole diameter prediction model; performing waveform extraction, frequency domain feature extraction and stoneley wave parameter calculation on the actually measured array sound wave data acquired in real time to obtain processing data corresponding to the actually measured array sound wave data, and inputting the processing data into the borehole diameter prediction model for prediction to obtain a real-time predicted borehole diameter; and calculating the thickness of the cement sheath in real time by combining the external diameter of the standard According to the invention, real-time prediction of the thickness of the cement sheath based on multi-data driving is realized.

The invention discloses a well cementation sealing compensation device. The method comprises the steps that limiting bosses are arranged at the two ends of a framework body respectively, and at least one hole is formed in the framework body; the framework body is sleeved with the protective sleeve, and the two ends of the protective sleeve are limited through limiting bosses. And the vulcanized colloid is filled between the outer wall of the framework body and the protective sleeve and on the inner wall of the framework body. The auxiliary sealing device can assist in well cementation conveniently and efficiently at low cost, achieves the sealing effect, provides a new auxiliary sealing method for solving the problem of annulus pressure caused by oil-gas-water channeling caused by cement sheath micro-ring gaps / insufficient cementation, effectively relieves the problem of annulus pressure, and accordingly improves well cementation quality, prolongs the service life of a shaft and guarantees well control safety of oil and gas fields.

The invention provides a monitoring system and a monitoring method for a micro annular space of an underground cement sheath. The monitoring system comprises a reaction kettle, a first injection device, a second injection device, a third injection device and a monitoring assembly, the interior of the reaction kettle is divided into a confining pressure cavity, a second annular cavity and a first annular cavity, the second annular cavity is arranged around the peripheral side of the first annular cavity, and the confining pressure cavity is arranged around the peripheral side of the second annular cavity. First liquid is injected into the first annular cavity through the first injection device to simulate the temperature and pressure in the casing pipe. Third liquid is injected into the confining pressure cavity through a third injection device, and the temperature and pressure in the stratum are simulated. And cement paste is injected into the second annular cavity through the second injection device to form a cement sheath. And the temperature information and the sound wave information of the cement sheath are monitored through the monitoring assembly, so that the expansion behavior of the micro annular space in the cement sheath in the low-temperature carbon dioxide injection process can be obtained.

The invention is suitable for the field of casing sidetrack drilling operation, and provides an elastic piece prizing type side pushing mechanism for a cement sheath knapper, the elastic piece prizing type side pushing mechanism comprises a first fixing rod, a second fixing rod, an inserting rod, an elastic piece and a movable roller shell, the elastic piece is bent to jack the movable roller shell to do lateral movement, extrusion force is applied to a casing to induce cracking of a cement sheath, and the elastic piece prizing type side pushing mechanism is suitable for the cement sheath knapper. An elastic piece prizing type lateral pushing structure is adopted, an independent driving cavity, a sealing assembly and a guiding structure do not need to be arranged, the structure of the mechanism is greatly simplified, the overall outer diameter size is reduced, miniaturization and compactness of the mechanism are achieved, the mechanism meets the tripping-in requirements of small well diameters, thin-wall sleeves and complex well conditions, meanwhile, lateral extrusion is achieved through elastic deformation of an elastic piece, and the service life of the mechanism is prolonged. Stable extrusion force is guaranteed, and the defects that an existing piston driving structure is complex and large in size are overcome.

The invention discloses a device for testing the sealing performance of a full-size sleeve-cement sheath-stratum combination of a hydrogen storage bank. Relates to the technical field of petroleum and natural gas drilling and production engineering, and is characterized in that the device comprises a sleeve-cement sheath-simulated stratum maintenance device for preparing the simulated stratum, an alternating load applying device and a sealing performance testing device; the method comprises the following steps: preparing a full-size simulated stratum through a maintenance device, constructing a'sleeve-cement sheath-simulated stratum 'integrated assembly by taking the full-size simulated stratum as a carrier, completing maintenance, and detecting the sealing integrity of the cement sheath after simulating the actual underground working condition; the simulation stratum capable of being used for testing the sealing performance of the cement sheath is prepared, the full-size simulation stratum serves as a core testing carrier, and quantitative evaluation of the sealing performance of the full-size cement sheath is achieved.

The invention belongs to the technical field of oil well windowing, and discloses a double-layer casing windowing sidetrack drilling test device and test method. The double-layer casing windowing sidetrack drilling test device comprises an inner-layer casing, an outer-layer casing, a filler, a guide piece and a drilling piece, the outer-layer casing is arranged outside the inner-layer casing in a sleeving mode, and an oil well with the double-layer casing can be simulated; the filling space between the inner-layer sleeve and the outer-layer sleeve can be filled with the filling material, and the filling material is used for simulating a cement sheath in actual construction; the guide piece fixed in the inner hole of the inner-layer sleeve is used for simulating a whipstock; a drilling part used for simulating a milling cone can move to be in contact with the guiding inclined face of the guiding part and move to be in contact with an inner-layer sleeve, a filling material or an outer-layer sleeve under the guiding of the guiding inclined face, the drilling part can mill the inner-layer sleeve, the filling material or the outer-layer sleeve through rotation so as to open windows and drill holes in the inner-layer sleeve, the filling material and the outer-layer sleeve, and the inner-layer sleeve, the filling material and the outer-layer sleeve can be driven by the drilling part to rotate. Double-layer casing windowing sidetrack drilling is simulated on the ground, and the success rate of actual windowing sidetrack drilling is increased.

The application provides a cement sheath anti-casing deformation capacity evaluation method and system for oil and gas well cementing, and the evaluation method specifically comprises the following steps: filling the annulus of a mold with cement slurry for cementing after preparation to obtain a sample; applying non-uniform extrusion or shear load to the sample by using a shear test device to simulate the displacement amount of a formation; determining the relative displacement ΔS and the radial size change amount ΔD of the inner cylinder of the mold; determining the deformation amount ΔL of the sample based on the relative displacement ΔS and the radial size change amount ΔD; and judging whether the deformation amount ΔL of the sample is greater than 25 mm, if yes, it is considered that the cement slurry belongs to a large strain cement slurry, and the cement sheath formed has the ability to inhibit casing deformation, otherwise, it is considered that the cement sheath formed by the cement slurry does not have the ability to inhibit casing deformation. The application can quantitatively evaluate the contribution of the cement slurry to reducing the degree of casing deformation, and provides technical support for selecting a cement slurry to reduce casing deformation caused by formation sliding.

The invention relates to the technical field of oil and gas field well drilling and cementing, in particular to an anti-channeling tough cement paste system and a preparation method and application thereof, and aims at effectively relieving the problem that the sealing integrity of a cement sheath is damaged in the large-volume fracturing production process. According to the anti-channeling tough cement paste provided by the invention, the flexural strength is improved, meanwhile, the rapid decline of the compressive strength can be slowed down, and relatively high compressive strength is reserved. The invention provides an anti-channeling tough cement paste system which comprises the following components in parts by weight: 100 parts of oil well cement; 1-4 parts of a toughening agent; 0.7 to 2.5 parts of a fluid loss agent; 0 to 0.5 part of a drag reducer; 0-35 parts of a stabilizer; 1-4 parts of a suspending agent; 0 to 2.5 parts of a retarder; 0.1 to 0.3 part of a defoaming agent; and 42 to 54 parts of water.

The application discloses a plastic drainage pipe fitting and a production device of a cement shell of a pipe material, belongs to the field of cement product processing equipment, and is used for the cement shell, which comprises a concrete base, a rack is installed on the concrete base, a plurality of vibration springs are distributed on the rack, the rack is connected with a vibrating table through the vibration springs, a plurality of molds are connected with the vibrating table through fasteners, and the molds are connected with cement mortar conveying pipelines respectively; a machine box is further arranged on the vibrating table, a vibrating motor is installed in the machine box, and the vibrating table moves relative to the rack under the driving of the vibrating motor. According to the technical scheme, the cement mortar can be guaranteed to be dense in the mold, the strength and service life of the cement shell are improved, and then the quality of the produced cement shell is improved.

The invention relates to the field of oil and gas well drilling and production, and discloses experimental equipment for simulating erosion corrosion of an oil and gas well at high temperature and high pressure and a use method thereof. The experimental equipment comprises an erosion corrosion fluid module, a corrosion fluid module, a reaction kettle and a damage analysis module. The erosion corrosion fluid module is used for manufacturing an erosion corrosion fluid material; the corrosive fluid module is used for manufacturing corrosive fluid materials. The reaction kettle is provided with a reaction chamber for mounting an experimental object, and the experimental object is a combined body comprising an oil pipe, a sleeve and a cement sheath; the experimental object and the reaction chamber act together to form a first chamber in the oil pipe and communicated with the erosion corrosion fluid module, a second chamber located between the oil pipe and the casing pipe and communicated with the erosion corrosion fluid module, and a third chamber located between the casing pipe and the cement sheath and communicated with the erosion corrosion fluid module. And the damage analysis module is used for analyzing the experimental object and obtaining an erosion-corrosion analysis result of the experimental object, so that the erosion-corrosion resistance test experiment of the material under the complex underground working condition is completed.

This invention discloses a method for reliability analysis of cement sheath quality in coiled tubing drilling, relating to the field of construction technology. The steps of this invention are as follows: S1: Identify the damage forms and characteristics of the cement sheath; S2: Test the impact of cement sheath loss on the external load of the casing; S3: Test the casing performance using different parameters; S4: Calculate the external load and strength data of the casing; S5: Calculate reliability data, test the failure morphology of the cement sheath after fracturing under high-pressure formation fluid and fracturing conditions, test the sealing integrity of the perforated section under fracturing operation conditions, and observe the cement sheath crack propagation morphology and microcrack propagation characteristics around the perforation channel using CT scanning. This invention, through method improvements, facilitates the visual observation of cement sheath failure morphology; evaluates the cement sheath sealing performance under different operating conditions; and analyzes the impact of different cement sheath damage degrees on the casing stress state.

The device comprises a hot melting metal packer connected between adjacent sleeves, the hot melting metal packer comprises a hot melting metal cylinder, the annular area of the hot melting metal cylinder is provided with a circulation hole used for allowing fluid to pass through, and the annular area of the hot melting metal cylinder is provided with a circulation hole used for allowing fluid to pass through. The hot melting metal cylinder is used for being heated and melted into fluid, filling the fluid into a to-be-sealed area and conducting sealing through volume expansion in the curing process. According to the device, potential gas migration and annulus pressure can be prevented, and the effectiveness of cement sheath sealing can be ensured on the basis that well repairing or cement squeezing operation is not needed in the oil and gas well production process.

This invention discloses a core-shell structure oil absorbent for cementing under oil-based drilling fluid conditions and its preparation method. The oil absorbent comprises the following components in parts by weight: 20-25 parts ester monomers, 3-7 parts modified composite materials, 1-5 parts dispersant, 20-25 parts pore-forming agent, 0.5-0.8 parts crosslinking agent, 1.3-1.5 parts initiator, and 50-70 parts water. The oil absorbent of this invention expands after absorbing oil and possesses a certain rigidity, compensating for defects without causing a decrease in the mechanical properties of the cement stone. Furthermore, the addition of this oil absorbent allows the cement stone to meet the low elasticity requirements under multi-stage fracturing conditions, enhancing the elasticity of the cement stone and improving the long-term sealing performance of the cement sheath.

The present invention discloses a device and method for evaluating the seepage corrosion and mechanical properties of cement rings in well cementing, which belongs to the field of corrosion evaluation of cementing materials in oil and gas wells. The device includes an acidic corrosive gas injection system, a formation water injection system, a high-pressure oil injection system, a control system, and a corrosion and testing system. The corrosion and testing system comprises a main body, an upper cover, and a base. The main body comprises, from the outside to the inside, a metal cylinder, a simulated formation, a simulated casing, and a center rod. A cement ring maintenance-corrosion space is formed between the simulated formation and the simulated casing. A temperature control device is provided in the annulus formed between the simulated casing and the center rod. Multiple displacement gauges are provided at different positions and angles on the center rod to measure the deformation displacement of the simulated casing-cement ring assembly. The method for evaluating the seepage corrosion and mechanical properties of cement rings using this device is simple to operate and simultaneously realizes three functions: cement ring maintenance under high temperature and high pressure, acidic medium corrosion, and cement ring mechanical integrity evaluation. It has broad application prospects.