阅读说明：本技术 一种适用于老油区调整井固井的触变胶凝体系 (Thixotropic gelling system suitable for adjusting well cementation in old oil zone ) 是由 李足平 刘会斌 李延伟 刘东清 石鸿传 陈险峰 郭泉 杜治澎 郑延华 古峰 马雪 于 2020-05-22 设计创作，主要内容包括：本发明公开了一种适用于老油区调整井固井的触变胶凝体系,涉及油田化学及油气井固井材料领域,包括水泥2-6份；粉煤灰2-4份；矿渣2-4份；球壁开孔的空心微球1-3份。本发明胶凝体系配置的浆体具备早期高强度、低粘度和强触变的性能,可以有效的防止水侵,能提高老油区调整井固井质量。(The invention discloses a thixotropic gelling system suitable for adjusting well cementation in an old oil zone, which relates to the field of oilfield chemistry and oil-gas well cementing materials and comprises 2-6 parts of cement; 2-4 parts of fly ash; 2-4 parts of slag; 1-3 parts of hollow microspheres with holes on the sphere walls. The slurry prepared by the gelling system has the properties of high strength, low viscosity and strong thixotropy at the early stage, can effectively prevent water invasion, and can improve the well cementation quality of the adjustment well in the old oil zone.)

1. A thixotropic gelling system suitable for adjusting well cementation in old oil zones is characterized by comprising the following components in parts by weight:

2-6 parts of cement; 2-4 parts of fly ash; 2-4 parts of slag; 1-3 parts of hollow microspheres with holes on the sphere walls.

2. The thixotropic gelling system for cementing wells in old oil zones according to claim 1, wherein: the optimal weight parts of the components are as follows: 3 parts of cement; 3 parts of fly ash; 3 parts of slag; 1 part of hollow microspheres with holes on the sphere wall.

3. The thixotropic gelling system for cementing wells in old oil zones according to claim 1, wherein: the weight parts of the components are as follows: 4 parts of cement; 3 parts of fly ash; 2 parts of slag; 1 part of hollow microspheres with holes on the sphere wall.

4. The thixotropic gelling system for adjusting well cementing in old oil zones according to claim 2 or 3, wherein: the cement is G-grade oil well cement.

5. The thixotropic gelling system for cementing wells in old oil zones according to claim 4, wherein: the fly ash is ultrafine fly ash with the particle size of 1000-1250 meshes.

6. The thixotropic gelling system for cementing wells in old oil zones according to claim 4, wherein: the slag is superfine slag with the particle size of 1000-1250 meshes.

7. The thixotropic gelling system for cementing wells in old oil zones according to claim 4, wherein: the hollow microspheres with the holes on the spherical wall are hollow ceramic particles with the holes on the spherical wall.

8. The thixotropic gelling system for use in conditioning well cementing in old oil zones according to claim 7, wherein: the particle size of the hollow ceramsite with the opening on the spherical wall is 100-150 meshes.

9. The utility model provides a slurry suitable for old oil zone adjustment well cementation which characterized in that: the cement mortar comprises solids and water, wherein the solids comprise 2-6 parts of cement; 2-4 parts of fly ash; 2-4 parts of slag; 1-3 parts of hollow microspheres with holes on the sphere wall, wherein the water-solid ratio is 0.50.

Technical Field

The invention relates to the field of oilfield chemistry and oil and gas well cementing materials, in particular to a thixotropic gelling system suitable for adjusting well cementing in an old oil area.

Background

In old oil areas, due to long-term water injection development, particularly high-pressure water injection exploitation in recent years, formation pressure systems become quite complex, and the formation structure is damaged. The water content of a reservoir is large and the stratum is seriously flooded due to long-term water injection development. The water interlayer between reservoirs is more, the oil-water interlayer is thin, even has no interval, and interlayer fluid is easy to flow. And a plurality of oil-water layers exist, the layer position connectivity is good, most of the oil-water layers are flooded by water, and water invasion is easy to occur. The formation water is in a dynamic balance, and the flowing formation water can interfere and damage the cementation between the underground cement-waiting slurry and the well wall, so that the well cementation quality is difficult to ensure. And the development layer system is subdivided and water injection is carried out for a long time, so that the underground pressure layer system is complex, the contradiction between pressure stability and leakage prevention is prominent, particularly, after the well body structure is simplified, a target layer and a leakage-prone layer need to be simultaneously sealed, and if the density of cement paste is simply improved, the cement paste is easy to leak when penetrating through the stratum, so that the cement paste is lost.

Chinese patent CN101445720A discloses a preparation method of a travertine cementing material for well cementation in oil and gas fields. The preparation method comprises the following steps: 0-45% of cement clinker, 55-95% of granulated blast furnace slag and 0-5% of fly ash are ground together after being mixed according to the weight percentage; 30-59.5% of ground mixed material, 40-60% of one of fly ash, coal-fired furnace slag, clay or red mud and 0.5-10% of diagenetic agent are mixed according to weight percentage and ground together; 85-95% of the obtained mixed material and 5-15% of the ground expanded vermiculite sheets are mixed according to the weight percentage and uniformly mixed, and then the cementing material for well cementation is obtained. The invention is not only beneficial to solving various problems in oil gas well cementation, but also can greatly reduce the emission of CO2 and other pollutants compared with the production of the traditional oil well cement. But do not have the properties of early high strength, low viscosity and strong thixotropy.

Chinese patent CN102093862A discloses a salt-tolerant latex cement slurry for well cementation, which comprises the following components: the cement comprises 4-40% of salt-tolerant latex, 3-4% of fluid loss additive, 0-2% of retarder, 0.5-3% of dispersant, 18-51% of salt water or seawater with concentration not higher than 15% and 0.5-1.3% of defoamer by mass. The salt-tolerant latex cement slurry system provided by the invention overcomes the defect that common latex does not resist salt, so that the salt-tolerant latex cement slurry system can be applied to the well cementation of complex wells such as salt rock strata (salt strata, salt paste strata and salt water strata); in addition, the salt-tolerant latex cement slurry provided by the invention can be directly prepared by seawater, so that the fresh water transportation burden of the well cementation operation of an offshore drilling platform is reduced, and the operation cost is reduced. But do not have the properties of early high strength, low viscosity and strong thixotropy.

Currently, although measures such as stopping injection, relieving pressure, releasing overflow and the like are required before drilling a target layer and cementing, a downhole water injection layer is still in an active state in general, and the stopping injection can seriously affect the oil and gas yield. The thixotropic gelling system can enable the cement paste to quickly form a certain gelling strength, and can effectively prevent water invasion. Therefore, the development of the thixotropic gelling system suitable for adjusting well cementation in the old oil area has great significance for the efficient development of the old oil field.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a thixotropic gelling system which is suitable for adjusting well cementation in old oil zones and has the properties of high strength, low viscosity and strong thixotropy in early stage.

The invention also provides slurry suitable for well cementation of the adjusting well in the old oil zone.

The technical scheme of the invention is as follows: a thixotropic gelling system suitable for adjusting well cementation in old oil zones is characterized by comprising the following components in parts by weight:

2-6 parts of cement; 2-4 parts of fly ash; 2-4 parts of slag; 1-3 parts of hollow microspheres with holes on the sphere walls.

Preferably, the optimal parts by weight of the components are as follows: 3 parts of cement; 3 parts of fly ash; 3 parts of slag; 1 part of hollow microspheres with holes on the sphere wall.

Preferably, the weight parts of the components are as follows: 4 parts of cement; 3 parts of fly ash; 2 parts of slag; 1 part of hollow microspheres with holes on the sphere wall.

Preferably, the cement is grade G oil well cement.

Preferably, the fly ash is ultrafine fly ash with the particle size of 1000-1250 meshes.

Preferably, the slag is ultrafine slag with the grain size of 1000-1250 meshes.

Preferably, the hollow microspheres with the holes on the spherical wall are hollow ceramic granules with holes on the spherical wall.

Preferably, the particle size of the hollow ceramsite with the open pores on the spherical wall is 100-150 meshes.

Compared with the prior art, the invention has the following advantages: the thixotropic gelling system consists of G-grade oil well cement, superfine fly ash, superfine slag and hollow microspheres with holes on the spherical walls. Wherein the G-grade oil well cement is a basic cementing material; the superfine slag can enable a gelling system to realize better early high strength; the ultrafine fly ash can enable the cement paste to achieve a better thixotropic effect; the hollow microspheres with the holes on the spherical wall can effectively reduce the viscosity of slurry due to the ball effect. The cementing system has the properties of low viscosity and strong thixotropy, can effectively prevent leakage and water invasion, and also has high early strength, thereby improving the well cementation quality.

Drawings

FIG. 1 shows thixotropic properties of slurry with different addition amounts of ultrafine fly ash.

Detailed Description

The invention is further illustrated below with reference to the figures and examples.

A thixotropic gelling system suitable for adjusting well cementation in old oil zones comprises the following components in parts by weight: 2-6 parts of cement; 2-4 parts of fly ash; 2-4 parts of slag; 1-3 parts of hollow microspheres with holes on the sphere walls.

Wherein the cement is G-grade oil well cement. The fly ash is ultrafine fly ash with the particle size of 1000-1250 meshes. The slag is superfine slag with the grain diameter of 1000-1250 meshes. The hollow microspheres with the holes on the spherical wall are hollow ceramic granules with the holes on the spherical wall. The particle size of the hollow ceramsite with the open pores on the spherical wall is 100-150 meshes. The specific embodiment is as follows:

example 1

The slurry of the invention is composed of the following components:

a gelling system: 3 parts of G-grade oil well cement, 3 parts of ultrafine fly ash, 3 parts of ultrafine slag and 1 part of hollow microspheres with open pores on spherical walls; the water-solid ratio is 0.50. The slurry is designated C1.

The preparation method of the slurry comprises the following steps:

the G-grade oil well cement, the superfine slag, the superfine fly ash and the hollow microspheres with open pores on the spherical wall are dry-mixed, and then the cement paste is prepared according to the GB/T10238-2015 standard.

Example 2

The slurry is composed of the following components:

a gelling system: 4 parts of G-grade oil well cement, 3 parts of ultrafine fly ash, 2 parts of ultrafine slag and 1 part of hollow microspheres with open pores on spherical walls; the water-solid ratio is 0.50. The slurry is designated C2.

The preparation of the cement slurry system is as described in example 1.

Example 3

The slurry is composed of the following components:

a gelling system: 3 parts of G-grade oil well cement, 4 parts of ultrafine fly ash, 2 parts of ultrafine slag and 1 part of hollow microspheres with open pores on spherical walls; the water-solid ratio is 0.50. The slurry is designated C3.

The preparation of the cement slurry system is as described in example 1.

Example 4

The slurry is composed of the following components:

a gelling system: 3 parts of G-grade oil well cement, 3 parts of ultrafine fly ash, 2 parts of ultrafine slag and 2 parts of hollow microspheres with open pores on spherical walls; the water-solid ratio is 0.50. The slurry is designated C4.

The preparation of the cement slurry system is as described in example 1.

Comparative example 1

The slurry is composed of the following components:

a gelling system: 4 parts of G-grade oil well cement, 3 parts of ultrafine fly ash and 3 parts of ultrafine slag; the water-solid ratio is 0.50. The slurry is designated C5.

The preparation of the cement slurry system is as described in example 1.

Comparative example 2

The slurry is composed of the following components:

a gelling system: 6 parts of G-grade oil well cement, 3 parts of superfine slag and 1 part of hollow microspheres with open pores on the spherical wall; the water-solid ratio is 0.50. The slurry is designated C6.

The preparation of the cement slurry system is as described in example 1.

Comparative example 3

The slurry is composed of the following components:

a gelling system: 6 parts of G-grade oil well cement, 3 parts of ultrafine fly ash and 1 part of hollow microspheres with open pores on the spherical walls; the water-solid ratio is 0.50. The slurry is designated C7.

The preparation of the cement slurry system is as described in example 1.

The slurry thixotropy test method comprises the following steps:

after the cement slurry is prepared according to the GB/T19139-2012 oil well cement test method, the reading of phi 3 is recorded as R when the test is carried out for 10s by adopting a six-speed rotational viscometer, and then the reading of phi 3 is recorded as R1 when the slurry is placed for 10min by adopting the six-speed rotational viscometer, as shown in Table 1. The greater R1 is greater than R, the better the thixotropy of the slurry.

The cement density, strength and rheological property of the cement are tested according to the GB/T19139-.

The properties of the slurries described in examples 1-4 and comparative examples 1-3 are shown in table 1 below:

table 1.

As can be seen from Table 1, the slurries of examples 1 to 4 according to the invention have both low viscosity and strongly thixotropic properties at the same test temperature compared to comparative examples 1 and 2, and in particular when compared the readings at 10s and 10min at a speed of Φ 3, the early low viscosity properties are seen, whereas the viscosity increase is greater with time, and the strongly thixotropic properties are achieved, whereas comparative example 1 is significantly thickened at the early stage and comparative example 2 is not significantly thixotropic.

The density and strength properties of the slurries described in examples 1-4 and comparative examples 1-3 are shown in Table 2:

TABLE 2

As can be seen from Table 2, the gelled systems described in examples 1-4 of the present invention have the property of high early strength.

Therefore, the cementing system disclosed by the invention has the properties of low viscosity and strong thixotropy, can effectively prevent leakage and water invasion, and also has high early strength, so that the cementing quality is improved.

The present invention is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention, and the contents of the changes still fall within the scope of the present invention.