阅读说明：本技术 油井水泥自愈合能力评价装置及方法 (Oil well cement self-healing capability evaluation device and method ) 是由 高飞 田宝振 党冬红 和建勇 张伟 刘渐强 霍磊磊 张峰 陈欣彤 刘宁泽 张鑫 于 2019-10-08 设计创作，主要内容包括：本发明公开了一种油井水泥自愈合能力评价装置及方法,其装置包括由柱形筒体及位于两侧开口处的两个端盖、以及一根设置在柱形筒体内且设置在筒体中轴线上的钢丝构成的水泥试块模具,分别位于模具两侧的声波发生器和声波接收器,分别通过导线与声波发生器和声波接收器相连接的时间测量仪,以及固定在水泥试块模具底部的升降支架；其相应方法包括:将待测水泥浆注满外筒、端盖和钢丝组合形成的环形空间中,养护至初凝,抽出钢丝,继续养护至终凝,人工制造出圆柱形通孔来模拟水泥石在井下环境中产生的微间或裂缝,通过测量不同凝期水泥石通孔声波传送时间,作为评价水泥石自愈合能力的指标,其原理可靠,操作简单,对比性强,能够量化评价,且适用范围广,具有广阔的应用前景。(The invention discloses an oil well cement self-healing capability evaluation device and a method, wherein the device comprises a cement test block mold, a sound wave generator and a sound wave receiver, a time measuring instrument and a lifting support, wherein the cement test block mold consists of a cylindrical barrel, two end covers positioned at openings on two sides, and a steel wire arranged in the cylindrical barrel and arranged on the central axis of the barrel; the method comprises the steps of filling cement slurry to be measured into an annular space formed by combining an outer cylinder, an end cover and a steel wire, curing to initial setting, drawing out the steel wire, continuing curing to final setting, artificially manufacturing a cylindrical through hole to simulate micro or cracks generated by the cement stone in an underground environment, and measuring the sound wave transmission time of the cement stone through hole in different setting periods to serve as an index for evaluating the self-healing capability of the cement stone.)

1. An oil well cement self-healing capability evaluation device is characterized by comprising a sound wave generator, a cement test block mold, a sound wave receiver, a time measuring instrument and a lifting bracket; wherein the content of the first and second substances,

the cement test block mould consists of a cylindrical barrel, a first end cover and a second end cover which are respectively arranged at two sides of the cylindrical barrel, and a steel wire arranged in the cylindrical barrel; axial through holes with the aperture matched with the diameter of the steel wire are formed in the centers of the first end cover and the second end cover, so that two ends of the steel wire are respectively inserted into the axial through holes of the first end cover and the second end cover and are superposed with the central axis of the cylindrical barrel;

the lifting support is arranged below the horizontally placed cement test block mould and is fixed in the middle of a cylindrical barrel of the cement test block mould, so that the cement test block mould is driven to move up and down in a reciprocating manner;

the sound wave generator and the sound wave receiver are symmetrically arranged on two sides of the horizontally placed cement test block mould, and the probe needle of the sound wave generator, the probe needle of the sound wave receiver, the axial through hole of the first end cover and the axial through hole of the second end cover are kept to be positioned on the same axis in an initial state;

the time measuring instrument is respectively connected with the sound wave generator and the sound wave receiver through leads and is used for obtaining the time required from the moment when the sound wave generator emits the sound waves to the moment when the sound wave receiver receives the corresponding sound waves.

2. The method for evaluating the self-healing capability of oil well cement according to claim 1, wherein the diameter of the steel wire is matched with the self-healing capability of the cement paste to be tested.

3. The method for evaluating the self-healing capability of oil well cement according to claim 1, wherein the first end cap and the second end cap are respectively screwed at openings at two ends of the cylindrical barrel, and at least one sealing ring is arranged at the screwed joint, so that the cylindrical barrel, the first end cap and the second end cap form a closed mold cavity.

4. An oil well cement self-healing ability evaluation method implemented by the oil well cement self-healing ability evaluation device according to claim 1, characterized by comprising the steps of:

s1, filling cement slurry to be tested into a closed mold inner cavity formed by the cylindrical barrel, the first end cover and the second end cover, placing a steel wire into the cylindrical barrel, and respectively inserting two ends of the steel wire into axial through holes formed in the centers of the first end cover and the second end cover;

s2, curing the cement test block mould which is poured with the cement paste to be tested and is obtained in the step S1, and after the cement test block mould is in an initial setting state, drawing out the steel wire to enable the cement paste to be tested and positioned in the inner cavity of the closed mould to form a cylindrical cement stone with a small-size pore passage in the center; then continuing to maintain to final set;

s3, fixing the cement test block mould which is cured to be finally set in the step S2 on a lifting support, simultaneously clamping a sound wave generator and a sound wave receiver in clamping grooves of a first end cover and a second end cover respectively, and keeping two probe needles of the sound wave generator and the sound wave receiver and the small-size pore canal of the cylindrical cement stone on the same axis; starting the sound wave generator, the sound wave receiver and the time measuring instrument, recording the moment when the sound wave generator sends the sound wave and the moment when the sound wave is transmitted to the sound wave receiver through the cement stone pore passage to receive the sound wave, and obtaining the time t used for transmitting the sound wave through the cement stone through hole₁，ms；

S4, adjusting the distance of one end of the cement test block mould moving upwards by using the lifting support, so that the two probe needles of the sound wave generator and the sound wave receiver are no longer positioned on the same axis with the small-size pore channel of the cylindrical cement stone; then starting the sound wave generator, the sound wave receiver and the time measuring instrument, recording the moment when the sound wave generator sends the sound wave and the moment when the sound wave is transmitted to the sound wave receiver through the set cement to receive the sound wave, and obtaining the time t used for the sound wave to be transmitted through the set cement₂，ms；

S5, placing the cement test block mould under a preset condition, maintaining for a period of time, placing the cement test block mould on the lifting support again, clamping the sound wave generator and the sound wave receiver in the clamping grooves of the first end cover and the second end cover respectively, and keeping the two probe needles of the sound wave generator and the sound wave receiver and the small-size pore canal of the cylindrical cement stone on the same axis; starting sound wave generatorThe generator, the sound wave receiver and the time measuring instrument are used for recording the moment when the sound wave generator sends the sound wave and the moment when the sound wave is transmitted to the sound wave receiver through the cement stone pore channel to receive the sound wave, and obtaining the time t used for transmitting the sound wave through the cement stone through hole_X，ms；

S6, calculating the self-healing capacity K of the cement stone formed by the slurry to be measured after a period of time according to the data measured in the steps S3-S5:

and S7, repeating the steps S5 and S6 to obtain the self-healing capacity K of the cement stone formed by the slurry to be tested after different time.

5. The oil well cement self-healing ability evaluation device according to claim 4, wherein the sound wave generated by the sound wave generator is a sound wave having a wavelength of 0.1mm to 1mm in steps S3 to S5.

Technical Field

The invention relates to the technical field of petroleum and natural gas exploration and development, in particular to an oil well cement self-healing capability evaluation device and method.

Background

The oil-gas well cementing water mixed ring can generate damage such as micro-gap or micro-crack under the action of external force, and if the damage continues to develop, serious problems such as the sealing failure of the cement ring and the like are likely to occur. The well cementation industry has proposed solving this problem with self-healing cements which are capable of autonomously responding to micro-spaces or micro-cracks and plugging micro-gaps or micro-cracks. Through years of development, research on self-healing cement at home and abroad is greatly improved, but a recognized evaluation method for evaluating the self-healing capacity of the cement is not formed yet.

Through the literature search of the conventional self-healing capacity evaluation device and method, the conventional evaluation method for the self-healing capacity of the cement mainly comprises a compressive strength recovery method, an seepage rate method and an electric conductivity method. The compressive strength recovery method is characterized in that cracks are prefabricated on the set cement under certain pressure, the set cement is maintained for a certain age period, the compressive strength of the set cement is tested, and compared with the set cement without the self-healing agent, the compressive strength recovery degree of the set cement is obtained to evaluate the self-healing capacity. The seepage permeability method is characterized in that cement stones after being maintained for several days are manually placed back to original molds for continuous maintenance after being maintained for a certain age period, and then are taken out for permeability experiments to be compared with the permeability before the cracks are manufactured. The two methods have the main problems that the distribution, the size and the number of the cracks which are manufactured manually in the water-mixed stone cannot be controlled, so that the result deviation among test pieces is large, the repeatability is poor, and the measuring steps are complicated and time-consuming. The conductivity method has high measurement accuracy, but certain errors still exist.

Disclosure of Invention

The invention aims to provide an oil well cement self-healing capability evaluation device for quantitatively evaluating the self-healing capability of cement paste.

The invention also aims to provide an oil well cement self-healing capacity evaluation method realized by adopting the oil well cement self-healing capacity evaluation device.

Therefore, the technical scheme of the invention is as follows:

an oil well cement self-healing capability evaluation device comprises a sound wave generator, a cement test block mold, a sound wave receiver, a time measuring instrument and a lifting support; wherein the content of the first and second substances,

the cement test block mould consists of a cylindrical barrel, a first end cover and a second end cover which are respectively arranged at two sides of the cylindrical barrel, and a steel wire arranged in the cylindrical barrel; axial through holes with the aperture matched with the diameter of the steel wire are formed in the centers of the first end cover and the second end cover, so that two ends of the steel wire are respectively inserted into the axial through holes of the first end cover and the second end cover and are superposed with the central axis of the cylindrical barrel;

the lifting support is arranged below the horizontally placed cement test block mould and is fixed in the middle of a cylindrical barrel of the cement test block mould, so that the cement test block mould is driven to move up and down in a reciprocating manner;

the sound wave generator and the sound wave receiver are symmetrically arranged on two sides of a horizontally placed cement test block mould, and a probe needle of the sound wave generator, a probe needle of the sound wave receiver, an axial through hole of the first end cover and an axial through hole of the second end cover are kept to be positioned on the same axis in an initial state;

the time measuring instrument is respectively connected with the sound wave generator and the sound wave receiver through leads and is used for obtaining the time required from the moment when the sound wave generator emits the sound waves to the moment when the sound wave receiver receives the corresponding sound waves.

Further, the diameter of the steel wire is matched with the self-healing capacity of the cement paste to be tested.

Furthermore, the first end cover and the second end cover are respectively in threaded connection with openings at two ends of the cylindrical barrel, and at least one sealing ring is arranged at the threaded connection position, so that the cylindrical barrel, the first end cover and the second end cover form a closed mold inner cavity.

The oil well cement self-healing capacity evaluation method realized by adopting the oil well cement self-healing capacity evaluation device comprises the following specific steps:

s1, filling cement slurry to be tested into a closed mold inner cavity formed by the cylindrical barrel, the first end cover and the second end cover, placing a steel wire into the cylindrical barrel, and respectively inserting two ends of the steel wire into axial through holes formed in the centers of the first end cover and the second end cover;

s2, curing the cement test block mould which is poured with the cement paste to be tested and is obtained in the step S1, and after the cement test block mould is in an initial setting state, drawing out the steel wire to enable the cement paste to be tested and positioned in the inner cavity of the closed mould to form a cylindrical cement stone with a small-size pore passage in the center; then continuing to maintain to final set;

s3, fixing the cement test block mould which is cured to be finally set in the step S2 on a lifting support, simultaneously clamping a sound wave generator and a sound wave receiver in clamping grooves of a first end cover and a second end cover respectively, and keeping two probe needles of the sound wave generator and the sound wave receiver and the small-size pore canal of the cylindrical cement stone on the same axis; starting the sound wave generator, the sound wave receiver and the time measuring instrument, recording the moment when the sound wave generator sends the sound wave, and the moment when the sound wave is transmitted to the sound wave receiver through the cement stone pore passage to receive the sound wave, so as to obtain the sound wave channelTime t for propagation of the through-hole of the cement stone₁，ms；

S4, adjusting the distance of one end of the cement test block mould moving upwards by using the lifting support, so that the two probe needles of the sound wave generator and the sound wave receiver are no longer positioned on the same axis with the small-size pore channel of the cylindrical cement stone; then starting the sound wave generator, the sound wave receiver and the time measuring instrument, recording the moment when the sound wave generator sends the sound wave and the moment when the sound wave is transmitted to the sound wave receiver through the set cement to receive the sound wave, and obtaining the time t used for the sound wave to be transmitted through the set cement₂，ms；

S5, placing the cement test block mould under a preset condition, maintaining for a period of time, placing the cement test block mould on the lifting support again, clamping the sound wave generator and the sound wave receiver in the clamping grooves of the first end cover and the second end cover respectively, and keeping the two probe needles of the sound wave generator and the sound wave receiver and the small-size pore canal of the cylindrical cement stone on the same axis; starting the sound wave generator, the sound wave receiver and the time measuring instrument, recording the moment when the sound wave generator sends the sound wave and the moment when the sound wave is transmitted to the sound wave receiver through the cement stone pore passage to receive the sound wave, and obtaining the time t used for transmitting the sound wave through the cement stone through hole_X，ms；

S6, calculating the self-healing capacity K of the cement stone formed by the slurry to be measured after a period of time according to the data measured in the steps S3-S5:

and S7, repeating the steps S5 and S6 to obtain the self-healing capacity K of the cement stone formed by the slurry to be tested after different time.

Further, in steps S3 to S5, the sound wave generated by the sound wave generator is a sound wave having a wavelength of 0.1mm to 1 mm.

To sum up, the evaluation device for the self-healing capacity of the self-healing cement adopts the artificial through holes to simulate micro annular gaps or micro cracks in the set cement, so that the cracks are standardized, thereby reducing the influence on the test result caused by factors such as the number, the width, the spatial distribution and the like of the cracks; compared with the prior art, the method has the advantages of reliable principle, simple operation, strong contrast, capability of quantitative evaluation, wide application range and wide application prospect

Drawings

FIG. 1 is a schematic structural diagram of an oil well cement self-healing capability evaluation device according to the present invention;

fig. 2 is a curve showing the self-healing capability of plugging a 1mm crack with cement slurry to be tested by using the oil well cement self-healing capability evaluation device of embodiment 1 according to the invention, as a function of curing time in embodiment 2.

Detailed Description

The invention will be further described with reference to the following figures and specific examples, which are not intended to limit the invention in any way.