Large temperature difference well cementing slurry, preparation method and application thereof

Abstract

The application belongs to the technical field of oil and gas wells, and discloses a large-temperature-difference well cementing cement slurry, a preparation method and application. The cement slurry comprises oil well cement, gypsum, red mud, sulphoaluminate cement, silicon powder, water and an additive. The application improves the large-temperature-difference adaptability of the cement slurry by generating ettringite in the hydration reaction process.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas wells, and more particularly relates to a large-temperature-difference well cementing slurry, a preparation method and application thereof. BACKGROUND

[0002] With the continuous exploration and development of oil and gas wells, the oil and gas wells are drilled deeper and deeper. At present, the deepest oil and gas well in China has exceeded 9000 meters. The construction of ultra-deep wells brings many challenges such as high temperature and high pressure. The large temperature difference between the well bottom and the wellhead brings great difficulty to well cementing construction. In normal well cementing construction, the cement slurry is pumped from the wellhead to the well bottom through the casing, and then returned to the ground or a certain depth through the annulus between the casing and the well wall. For natural gas wells, the cement slurry often needs to be returned to the ground. In order to meet the requirements of well cementing construction, the pumpable time of the cement slurry is generally required to be more than 4 hours under the circulating temperature test conditions at the well bottom. For deep and ultra-deep wells, the bottom hole temperature often exceeds 150℃. At such a high bottom hole temperature, a large amount of retarder needs to be added to the cement slurry to ensure the thickening time of the cement slurry. However, for natural gas wells, the cement slurry needs to be returned to the ground, which causes the cement slurry at the top of the annulus between the casing and the well wall to face a low-temperature environment. The conventional cement slurry with a large amount of retarder added does not solidify for a long time in a low-temperature environment, has poor adaptability to large temperature difference, and seriously affects the safety of well cementing and the construction progress. Therefore, it is of great significance to develop a large-temperature-difference cement slurry with excellent performance. SUMMARY

[0003] The present application aims at the deficiencies of the prior art and provides a large-temperature-difference well cementing slurry, a preparation method and application thereof. The present application improves the adaptability of the cement slurry to large temperature difference by generating ettringite in the hydration process.

[0004] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a large-temperature-difference well cementing slurry, which comprises oil well cement, gypsum, red mud, sulphoaluminate cement, silica powder, water and additives.

[0005] According to the present application, preferably, the cement slurry comprises the following components by weight: 95-105 parts of oil well cement, 5-15 parts of gypsum, 15-35 parts of red mud, 8-25 parts of sulphoaluminate cement, 30-50 parts of silica powder, 70-95 parts of water and 1-15 parts of additives.

[0006] Preferably, the cement slurry comprises the following components by weight: 98-102 parts of oil well cement, 6-10 parts of gypsum, 20-35 parts of red mud, 10-20 parts of sulphoaluminate cement, 30-50 parts of silica powder, 73-95 parts of water and 1-15 parts of additives.

[0007] According to the present application, preferably, the oil well cement is oil well G-grade cement.

[0008] According to the present application, preferably, the gypsum is hemihydrate gypsum.

[0009] According to the present application, preferably, the red mud is Bayer process red mud.

[0010] According to the present application, preferably, the silicon powder has a mesh size of 200-400 mesh, and the SiO2 content is greater than 99%.

[0011] According to the present application, preferably, the water is water with different degrees of mineralization, preferably at least one of fresh water, brackish water, salt water, brine and brine.

[0012] The fresh water, brackish water, salt water, brine and brine are different degrees of mineralization water known in the art, wherein (1) fresh water, the degree of mineralization is less than 1g / L; (2) brackish water (weakly mineralized water), the degree of mineralization is 1-3g / L; (3) salt water (moderate mineralization water), the degree of mineralization is 3-10g / L; (4) salt water (strongly mineralized water), the degree of mineralization is 10-50g / L; (5) brine, the degree of mineralization is greater than 50g / L.

[0013] According to the present application, preferably, the additive comprises at least one of the following components in parts by weight: 1-5 parts of a fluid loss additive, 1-2 parts of a retarder, 1-4 parts of an expansive agent and 1-4 parts of a defoaming agent.

[0014] According to the present application, preferably, the fluid loss additive is an acrylamide fluid loss additive and / or a polyvinyl alcohol fluid loss additive.

[0015] According to the present application, preferably, the retarder is a copolymer of 2-acrylamido-2-methylpropane sulfonic acid and itaconic acid.

[0016] According to the present application, preferably, the expansive agent is a calcium oxide expansive agent and / or a magnesium oxide expansive agent.

[0017] According to the present application, preferably, the defoaming agent is an organosiloxane defoaming agent and / or a polyether defoaming agent.

[0018] In the present application, oil well G-grade cement is used as a base material to ensure the strength of the cement slurry. Gypsum and red mud will react to form ettringite, and sulphoaluminate cement will also hydrate to form ettringite. Ettringite has a super-high specific surface area and will decompose at high temperatures. The super-high specific surface area of ettringite will adsorb a large amount of retarder after being formed under medium and low temperature conditions, thereby reducing the amount of retarder used to delay the hydration of cement, and shortening the setting time of cement slurry at low temperature. However, at high temperatures, ettringite will decompose, so there is no ettringite in the cement slurry at high temperatures, and the retarder can better delay the hydration rate of the cement, thereby facilitating the guarantee of high-temperature thickening time.

[0019] The second aspect of the present application provides a preparation method of the large-temperature-range well cementing slurry, which comprises uniformly mixing and stirring the oil well cement, gypsum, red mud, sulphoaluminate cement, silicon powder, water and additives to obtain the large-temperature-range well cementing slurry.

[0020] The third aspect of the present application provides application of the large-temperature-range well cementing slurry in large-temperature-range well cementing.

[0021] The beneficial effects of the technical scheme of the present application are as follows:

[0022] The present application introduces gypsum, red mud, sulphoaluminate cement and other admixtures which can additionally generate ettringite into the cement slurry formula, and improves the large-temperature-range adaptability of the cement slurry by generating ettringite in the hydration reaction process.

[0023] Other features and advantages of the present application will be described in detail in the subsequent specific embodiments. DETAILED DESCRIPTION

[0024] The preferred embodiments of the present application will be described in more detail below. Although the preferred embodiments of the present application are described below, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0025] In the following examples and comparative examples, the components used can be obtained by commercial purchase;

[0026] The mesh number of the silicon powder is 200-400 mesh, and the SiO2 content therein is greater than 99%.

[0027] Example 1

[0028] The present embodiment provides a large-temperature-range well cementing slurry, which comprises the following components in parts by weight: 100 parts of oil well cement G, 6 parts of hemihydrate gypsum, 20 parts of Bayer red mud, 10 parts of sulphoaluminate cement, 35 parts of silicon powder, 73 parts of fresh water, 2 parts of acrylamide fluid loss additive, 1 part of copolymer of 2-acrylamido-2-methylpropanesulfonic acid and itaconic acid, 1 part of calcium oxide expander, and 1 part of polyether defoaming agent.

[0029] The preparation method of the large-temperature-range well cementing slurry comprises uniformly mixing and stirring the above components to obtain the large-temperature-range well cementing slurry.

[0030] Example 2

[0031] The embodiment provides a large-temperature-difference well cementing slurry, which comprises the following components in parts by weight: oil well G-class cement 100 parts, hemihydrate gypsum 10 parts, Bayer red mud 30 parts, sulphoaluminate cement 20 parts, silicon powder 35 parts, slightly salty water 93 parts, acrylamide fluid loss additive 4 parts, 2-acrylamido-2-methylpropanesulfonic acid and itaconic acid copolymer 1.8 parts, calcium oxide type expanding agent 3 parts and polyether type defoaming agent 1 part.

[0032] The preparation method of the large-temperature-difference well cementing slurry comprises uniformly mixing the above components to obtain the large-temperature-difference well cementing slurry.

[0033] Embodiment 3

[0034] The embodiment provides a large-temperature-difference well cementing slurry, which comprises the following components in parts by weight: oil well G-class cement 100 parts, hemihydrate gypsum 13 parts, Bayer red mud 35 parts, sulphoaluminate cement 8 parts, silicon powder 35 parts, fresh water 80 parts, acrylamide fluid loss additive 3 parts, 2-acrylamido-2-methylpropanesulfonic acid and itaconic acid copolymer 1.3 parts, magnesium oxide type expanding agent 4 parts and polyether type defoaming agent 1 part.

[0035] The preparation method of the large-temperature-difference well cementing slurry comprises uniformly mixing the above components to obtain the large-temperature-difference well cementing slurry.

[0036] Embodiment 4

[0037] The embodiment provides a large-temperature-difference well cementing slurry, which comprises the following components in parts by weight: oil well G-class cement 100 parts, hemihydrate gypsum 5 parts, Bayer red mud 15 parts, sulphoaluminate cement 8 parts, silicon powder 50 parts, fresh water 73 parts, acrylamide fluid loss additive 5 parts, 2-acrylamido-2-methylpropanesulfonic acid and itaconic acid copolymer 2 parts, magnesium oxide type expanding agent 1 part and polyether type defoaming agent 2 parts.

[0038] The preparation method of the large-temperature-difference well cementing slurry comprises uniformly mixing the above components to obtain the large-temperature-difference well cementing slurry.

[0039] Comparative Example 1

[0040] The comparative example provides a well cementing slurry, which comprises the following components in parts by weight: oil well G-class cement 100 parts, silicon powder 35 parts, fresh water 60 parts, acrylamide fluid loss additive 1.5 parts, 2-acrylamido-2-methylpropanesulfonic acid and itaconic acid copolymer 1 part, calcium oxide type expanding agent 1 part and polyether type defoaming agent 1 part.

[0041] The preparation method of the well cementing slurry comprises uniformly mixing the above components to obtain the well cementing slurry.

[0042] Test Example

[0043] The cement paste of Example 1-2 and Comparative Example 1 was tested. The test method was GBT 19139-2012 Oil Well Cement Test Method, and the results are shown in Table 1.

[0044] Table 1

[0045]

[0046] According to the results of Table 1, the thickening time of Comparative Example 1 at 160℃ was 351 min, and the compressive strength at 70℃ for 48h was only 3MPa. The thickening time of Example 1 at 160℃ was 319 min, and the compressive strength at 70℃ for 48h could reach 16MPa, showing good large temperature difference adaptability. The thickening time of Example 2 at 160℃ was 379 min, and the compressive strength at 70℃ for 48h could reach 14MPa, also showing good large temperature difference adaptability. The thickening time of Example 3 at 160℃ was 335 min, and the compressive strength at 70℃ for 48h could reach 12MPa, also showing good large temperature difference adaptability. The thickening time of Example 4 at 160℃ was 402 min, and the compressive strength at 70℃ for 48h could reach 9MPa, also showing good large temperature difference adaptability. The thickening time of Example 1, Example 2 and Example 3 at 160℃ was similar, and the compressive strength at 70℃ was also similar, and the large temperature difference performance was similar in general. The thickening time of Example 4 at 160℃ was slightly longer, resulting in a slightly lower compressive strength at 70℃, but the large temperature difference performance was also better.

[0047] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A large-temperature-difference cementing slurry, characterized in that, the cementing slurry comprises the following components in parts by weight: oil well cement 95-105 parts, gypsum 5-15 parts, red mud 15-35 parts, sulphoaluminate cement 8-25 parts, silicon powder 30-50 parts, water 70-95 parts, and additives 1-15 parts; the additives comprise at least one of the following components in parts by weight: a fluid loss additive 1-5 parts, a retarder 1-2 parts, an expansive agent 1-4 parts, and a defoaming agent 1-4 parts. 2.The large-temperature-difference cementing slurry according to claim 1, wherein, the cementing slurry comprises the following components in parts by weight: oil well cement 98-102 parts, gypsum 6-10 parts, red mud 20-35 parts, sulphoaluminate cement 10-20 parts, silicon powder 30-50 parts, water 73-95 parts, and additives 1-15 parts.

3. The large temperature range cementing slurry of claims 1 or 2, wherein, the oil well cement is oil well G-class cement.

4. The large temperature range cementing slurry of claims 1 or 2, wherein, the gypsum is semi-hydrated gypsum.

5. The large temperature range cementing slurry of claims 1 or 2, wherein, the red mud is Bayer-process red mud.

6. The large temperature range cementing slurry of claims 1 or 2, wherein, the silicon powder has a mesh number of 200-400 mesh and a SiO2 content of more than 99%.

7. The large temperature range cementing slurry of claims 1 or 2, wherein, the water is at least one of fresh water, slightly salty water, salty water, brine, and brackish water. 8.The large-temperature-difference cementing slurry according to claim 1, wherein, the fluid loss additive is an acrylamide fluid loss additive and / or a polyvinyl alcohol fluid loss additive; the retarder is a copolymer of 2-acrylamido-2-methylpropane sulfonic acid and itaconic acid; the expansive agent is a calcium oxide expansive agent and / or a magnesium oxide expansive agent; the defoaming agent is a silicone defoaming agent and / or a polyether defoaming agent.

9. The method of preparing a large temperature range cementing slurry according to any of claims 1 to 8, characterized in that, The preparation method comprises mixing and stirring the oil well cement, gypsum, red mud, sulphoaluminate cement, silicon powder, water, and additives uniformly to obtain the large-temperature-difference cementing slurry. 10.Use of the large-temperature-difference cementing slurry according to any one of claims 1-8 in large-temperature-difference cementing.

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