Cement paste system for well cementation

Abstract

The invention relates to a cement paste system for well cementation. The cement paste system is prepared from the following raw materials in parts by weight: 100 parts of oil well cement, 20-45 parts of micro-silicon, 20-50 parts of active lightening material, 2.5-3.5 parts of a fluid loss agent, 0.5-1 part of a dispersing agent, 0.9-1.8 parts of a retarder, 1.5-3 parts of an early strength agent, 1-1.5 parts of a de-foaming agent and 112-250 parts of water. The cement paste system has the advantages that the active lightening material is added into the cement paste system, so that the cement paste density is reduced, and meanwhile, the active lightening material can chemically react with and is integrally fused with cement hydration product, so that the early strength of low-density set cement can be promoted, and the problem of high probability of breaking of floating beads under high-pressure fast stirring conditions can be solved; the retarder is a compound ionic retarder and has a temperature self-adaption characteristic, and under a low-temperature environment, the molecular chain is curled, and adsorption groups are under a bound state, so that the adsorption to cement grains is reduced and the retarding property is weakened; under a high temperature condition, the molecular chain is unfolded, more adsorption groups are exposed and the retarding property is enhanced.

Description

technical field

[0001] The invention relates to the technical field of deep well and ultra-deep well cementing, in particular to a cement slurry system for well cementing. Background technique

[0002] At present, most shallow oil and gas resources in China are close to depletion after long-term exploitation, and recoverable and easy-to-recover reserves are limited. In order to increase crude oil production and support the development of the national economy, exploration and development work has begun to expand to deep oil and gas reservoirs, especially in recent years. The discovery of a large number of deep wells and ultra-deep wells has brought people gratifying oil reserves, but also brought great challenges to cementing operations;

[0003] The existing cement slurry has a high water-solid ratio, and its own stability is poor. Due to the great disparity between the density of the lightening material and the cement particle, it is easy to cause the slurry to settle due t...

Examples

Embodiment 1

[0024] Preparation of cement slurry systems with different densities:

[0025] The preparation density is 1.3g / cm 3 The cement slurry system, this experiment is named No. 1:

[0026] Take 100 parts of G grade oil well cement, 45 parts of micro silicon, 50 parts of lightening material, 3.5 parts of fluid loss reducer, 0.8 part of dispersant, 0.9 part of retarder, 3 parts of early strength agent, 1.5 parts of defoamer, 250 parts Water, prepare cement slurry according to API specification Spe-10A, standby;

[0027] The preparation density is 1.4g / cm 3 The cement slurry system, this experiment is named No. 2:

[0028] Take 100 parts of G-grade oil well cement, 25 parts of micro-silicon, 35 parts of lightening material, 3 parts of fluid loss reducer, 0.5 part of dispersant, 1.2 parts of retarder, 1.5 parts of early strength agent, 1 part of defoamer, 175 parts Water, prepare cement slurry according to API specification Spe-10A, standby;

[0029] The preparation density is 1.5g...

Embodiment 2

[0032] Evaluation of cement slurry properties

[0033] Taking Example 1 as the test object, the basic performance test and evaluation of cement slurry was carried out according to GB / T 19139-2012 "Test Methods for Oil Well Cement". The test results are shown in Table 1.

[0034] Table 1 Test results of basic performance of cement slurry under different densities

[0035]

[0036] As can be seen from Table 1, the fluidity of the cement slurry prepared with the cement slurry formulation of the invention is between 21 and 24 cm, indicating that the pumpability of the cement slurry is good. The free water content is less than 0.1%, which shows that the cement slurry prepared by the present invention has good stability and takes into account the stability and rheological properties of the whole system. In addition, the water loss of the whole system is within 75mL, so it can effectively control the water loss during the construction process, thereby avoiding the change of cemen...

Embodiment 3

[0038] Evaluation of Thickening Time and Compressive Strength of Cement Slurry

[0039] Taking Example 1 as an example, according to GB19139-2003, the compressive strength of the top of the cement column is tested by the high-temperature dynamic prefabrication method, that is, the cement slurry is mixed and loaded into a high-temperature and high-pressure thickening instrument, and enters the high-temperature constant temperature section according to the thickening test plan. Lower it to the resting temperature at the top, remove the thickener pulp cup, remove the oil, and then make a mold and place it at the top temperature to maintain it until it ages. The test results are shown in Table 2:

[0040] Table 2 Thickening time and compressive strength test results of cement slurries with different densities

[0041]

[0042] It can be seen from Table 2 that the thickening time of the cement slurry system prepared by the invention is greater than 300 minutes at a high tempera...

technical field

[0001] The invention relates to the technical field of deep well and ultra-deep well cementing, in particular to a cement slurry system for well cementing. Background technique

[0002] At present, most shallow oil and gas resources in China are close to depletion after long-term exploitation, and recoverable and easy-to-recover reserves are limited. In order to increase crude oil production and support the development of the national economy, exploration and development work has begun to expand to deep oil and gas reservoirs, especially in recent years. The discovery of a large number of deep wells and ultra-deep wells has brought people gratifying oil reserves, but also brought great challenges to cementing operations;

[0003] The existing cement slurry has a high water-solid ratio, and its own stability is poor. Due to the great disparity between the density of the lightening material and the cement particle, it is easy to cause the slurry to settle due t...

Examples

Embodiment 1

[0024] Preparation of cement slurry systems with different densities:

[0025] The preparation density is 1.3g / cm 3 The cement slurry system, this experiment is named No. 1:

[0026] Take 100 parts of G grade oil well cement, 45 parts of micro silicon, 50 parts of lightening material, 3.5 parts of fluid loss reducer, 0.8 part of dispersant, 0.9 part of retarder, 3 parts of early strength agent, 1.5 parts of defoamer, 250 parts Water, prepare cement slurry according to API specification Spe-10A, standby;

[0027] The preparation density is 1.4g / cm 3 The cement slurry system, this experiment is named No. 2:

[0028] Take 100 parts of G-grade oil well cement, 25 parts of micro-silicon, 35 parts of lightening material, 3 parts of fluid loss reducer, 0.5 part of dispersant, 1.2 parts of retarder, 1.5 parts of early strength agent, 1 part of defoamer, 175 parts Water, prepare cement slurry according to API specification Spe-10A, standby;

[0029] The preparation density is 1.5g...

Embodiment 2

[0032] Evaluation of cement slurry properties

[0033] Taking Example 1 as the test object, the basic performance test and evaluation of cement slurry was carried out according to GB / T 19139-2012 "Test Methods for Oil Well Cement". The test results are shown in Table 1.

[0034] Table 1 Test results of basic performance of cement slurry under different densities

[0035]

[0036] As can be seen from Table 1, the fluidity of the cement slurry prepared with the cement slurry formulation of the invention is between 21 and 24 cm, indicating that the pumpability of the cement slurry is good. The free water content is less than 0.1%, which shows that the cement slurry prepared by the present invention has good stability and takes into account the stability and rheological properties of the whole system. In addition, the water loss of the whole system is within 75mL, so it can effectively control the water loss during the construction process, thereby avoiding the change of cemen...

Embodiment 3

[0038] Evaluation of Thickening Time and Compressive Strength of Cement Slurry

[0039] Taking Example 1 as an example, according to GB19139-2003, the compressive strength of the top of the cement column is tested by the high-temperature dynamic prefabrication method, that is, the cement slurry is mixed and loaded into a high-temperature and high-pressure thickening instrument, and enters the high-temperature constant temperature section according to the thickening test plan. Lower it to the resting temperature at the top, remove the thickener pulp cup, remove the oil, and then make a mold and place it at the top temperature to maintain it until it ages. The test results are shown in Table 2:

[0040] Table 2 Thickening time and compressive strength test results of cement slurries with different densities

[0041]

[0042] It can be seen from Table 2 that the thickening time of the cement slurry system prepared by the invention is greater than 300 minutes at a high tempera...

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