High temperature resistant Portland cement slurry and production method thereof

Abstract

The invention provides a high temperature resistant Portland cement slurry and a production method thereof. The high temperature resistant Portland cement slurry comprises the following components by weight: 100 parts of an oil well Portland cement, 60-85 parts of a high temperature reinforcing material, 68-80 parts of fresh water, 1-200 parts of a density adjuster, 0.1-1.5 parts of a suspension stabilizer, 0.8-1.5 parts of a dispersant, 3-4 parts of a fluid loss agent, 0-3 parts of a retarder and 0.2-0.8 part of a defoamer. The high temperature resistant Portland cement slurry has a good sedimentation stability at normal temperature, and develops strength rapidly at a low temperature. The compressive strength is up to 40 MPa or more at a high temperature of 350° C., and the long-term high-temperature compressive strength develops stably without degradation. Therefore, it can meet the requirements for field application in heavy oil thermal recovery wells, reaching the level of Grade G Portland cement for cementing oil and gas wells.

Claims

1. A high temperature resistant Portland cement slurry, characterized in that, the high temperature resistant Portland cement slurry comprises the following components by weight: 100 parts of an oil well Portland cement, 70 parts of a high temperature reinforcing material, 75 parts of fresh water, parts of a density adjuster, 0.1 parts of a suspension stabilizer, 1.2 parts of a dispersant, 3 parts of a fluid loss agent, 1.2 parts of a retarder and 0.3 part of a defoamer; the high temperature reinforcing material is formed by mixing a reinforcing material A, a reinforcing material B, a reinforcing material C, a reinforcing material D, a reinforcing material E and a reinforcing material F in a mass ratio of 60:2:3:2:2:1; wherein the reinforcing material A, the reinforcing material B, the reinforcing material C, the reinforcing material D, the reinforcing material E and the reinforcing material F comprise 6 reinforcing materials different from each other; the reinforcing material A comprises silica minerals; the reinforcing material B comprises aluminates; the reinforcing material C comprises mineral fibers; the reinforcing material D comprises phosphate minerals; the reinforcing material E comprises calcium hydroxide; the reinforcing material F comprises magnesium silicate minerals: the reinforcing materials have a particle diameter of 0.01 mm to 0.15 mm; the density adjuster comprises iron ore powder; the suspension stabilizer comprises attapulgite; the dispersant comprises sulfonated acetone-formaldehyde polymer; the fluid loss agent comprises 2-acrylamido-2-methylpropane sulfonic acid polymer; the retarder comprises 2-acrylamido-2-methylpropane sulfonic acid polymer; the defoamer comprises tributyl phosphate.

2. The high temperature resistant Portland cement slurry according to claim 1, characterized in that, the oil well Portland cement comprises one or more of Grade A, Grade G, and Grade H.

3. The high temperature resistant Portland cement slurry according to claim 1, characterized in that, the high temperature reinforcing material can withstand a temperature of 350° C. or higher, and can allow the Portland cement to withstand pressures of 40 MPa or more at the temperature of 350° C. or higher.

4. The high temperature resistant Portland cement slurry according to claim 1, characterized in that, the phosphate minerals comprise apatite.

5. A method for producing the high temperature resistant Portland cement slurry according to claim 1, comprising steps of: dry mixing the high temperature reinforcing material, the fluid loss agent, the suspension stabilizer, the dispersant and the Portland cement to be uniform, to obtain a dry blend; wet mixing the retarder, the defoamer and fresh water to be uniform, to obtain a wet blend; and adding the dry blend to the wet blend and stirring uniformly to obtain the high temperature resistant Portland cement slurry.

Description

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(1) In order to more clearly understand the technical features, objects, and advantages of the invention, the technical solutions of the invention will now be described in detail below, but it should not be construed as limiting the implementable scope of the invention.

EXAMPLE 1

(2) This example provides a high temperature resistant Portland cement slurry composed of the following components in ratio by weight: 100 parts of Grade A Portland cement, 69 parts of a high temperature reinforcing material, 73 parts of fresh water, 1 part of sulfonated acetone-formaldehyde polymer dispersant, 3 parts of 2-acrylamido-2-methylpropane sulfonic acid polymer fluid loss agent, 0.6 part of 2-acrylamido-2-methylpropane sulfonic acid polymer retarder, 0.3 part of tributyl phosphate, 0.1 part of attapulgite and 2 parts of iron ore powder.

(3) Among them, the high temperature reinforcing material is obtained by mixing silica minerals, plagioclase, whiskers, and sulfates in a mass ratio of 50:10:4:5; the obtained high temperature reinforcing material has a particle diameter of 0.01 mm to 0.15 mm.

(4) In this example, the high temperature resistant Portland cement slurry is produced by steps of:

(5) dry mixing the high temperature reinforcing material, the fluid loss agent, a suspension stabilizer, the dispersant and the Portland cement to be uniform, to obtain a dry blend;

(6) wet mixing the retarder, a defoamer and fresh water to be uniform, to obtain a wet blend; and

(7) subsequently, under agitation, adding the dry blend to the wet blend and stirring uniformly to obtain the high temperature resistant Portland cement slurry, and then adjusting the density of the obtained high temperature resistant Portland cement slurry to 1.90 g/cm.sup.3 using a density adjuster.

EXAMPLE 2

(8) This example provides a high temperature resistant Portland cement slurry composed of the following components in ratio by weight: 100 parts of Portland cement, 70 parts of a high temperature reinforcing material, 75 parts of fresh water, 1.2 parts of sulfonated acetone-formaldehyde polymer dispersant, 3 parts of 2-acrylamido-2-methylpropane sulfonic acid polymer fluid loss agent, 1.2 parts of 2-acrylamido-2-methylpropane sulfonic acid polymer retarder, 0.3 part of tributyl phosphate, 0.2 part of attapulgite and 4 parts of iron ore powder.

(9) Among them, the high temperature reinforcing material is obtained by mixing silica minerals, aluminates, mineral fibers, calcium hydroxide, phosphate minerals and magnesium silicate minerals in a mass ratio of 60:2:3:2:2:1; the obtained high temperature reinforcing material has a particle diameter of 0.01 mm to 0.15 mm Subsequently, the density of the obtained high temperature resistant Portland cement slurry is adjusted to 1.90 g/cm.sup.3 using a density adjuster.

EXAMPLE 3

(10) This example provides a high temperature resistant Portland cement slurry composed of the following components in ratio by weight: 100 parts of Portland cement, 78 parts of a high temperature reinforcing material, 77 parts of fresh water, 1.2 parts of sulfonated acetone-formaldehyde polymer dispersant, 3 parts of 2-acrylamido-2-methylpropane sulfonic acid polymer fluid loss agent, 1.2 parts of 2-acrylamido-2-methylpropane sulfonic acid polymer retarder, 0.3 part of tributyl phosphate, 0.1 part of attapulgite and 2 parts of iron ore powder.

(11) Among them, the high temperature reinforcing material is obtained by mixing silica minerals, metakaolin, mineral fibers, phosphate minerals and magnesium silicate minerals in a mass ratio of 60:10:4:3:1; the obtained high temperature reinforcing material has a particle diameter of 0.01 mm to 0.15 mm Subsequently, the density of the obtained high temperature resistant Portland cement slurry is adjusted to 1.90 g/cm.sup.3 using a density adjuster.

EXAMPLE 4

(12) This example provides a high temperature resistant Portland cement slurry composed of the following components in ratio by weight: 100 parts of Portland cement, 75 parts of a high temperature reinforcing material, 74 parts of fresh water, 1.1 parts of sulfonated acetone-formaldehyde polymer dispersant, 3 parts of 2-acrylamido-2-methylpropane sulfonic acid polymer fluid loss agent, 1.2 parts of 2-acrylamido-2-methylpropane sulfonic acid polymer retarder, 0.3 part of tributyl phosphate, 0.1 part of attapulgite and 0 part of iron ore powder.

(13) Among them, the high temperature reinforcing material is obtained by mixing silica minerals, metakaolin, mineral fibers, sulfates and mullite in a mass ratio of 60:8:4:1:2; the obtained high temperature reinforcing material has a particle diameter of 0.01 mm to 0.15 mm Subsequently, the density of the obtained high temperature resistant Portland cement slurry is adjusted to 1.90 g/cm.sup.3 using a density adjuster.

COMPARATIVE EXAMPLE 1

(14) This comparative example provides an oil well Portland cement slurry composed of the following components in ratio by weight: 100 parts of oil well Portland cement, 40 parts of sand, 3 parts of 2-acrylamido-2-methylpropane sulfonic acid polymer fluid loss agent, 0.2 part of 2-acrylamido-2-methylpropane sulfonic acid polymer, 0.4 part of sulfonated acetone-formaldehyde polymer dispersant and 46 parts of water. The density of the oil well Portland cement slurry is adjusted to 1.90 g/cm.sup.3.

COMPARATIVE EXAMPLE 2

(15) This comparative example provides an oil well aluminate cement slurry composed of the following components in ratio by weight: 100 parts of oil well aluminate cement, 30 parts of ultrafine slag, 3 parts of 2-acrylamido-2-methylpropane sulfonic acid polymer fluid loss agent, 0.2 part of 2-acrylamido-2-methylpropane sulfonic acid polymer, 0.4 part of sulfonated acetone-formaldehyde polymer dispersant, 0.39 part of phosphate retarder and 51 parts of water. Subsequently, the density of the oil well aluminate cement slurry is adjusted to 1.90 g/cm.sup.3 using barite.

TEST EXAMPLE 1

(16) This test example tested the performance of the high temperature resistant Portland cement slurries of Examples 1-4 and the cement slurries of Comparative Examples 1-2.

(17) Testing conditions: 70° C.×35 MPa×30 min

(18) Table 1 shows the test results of performance of the high temperature resistant Portland cement slurries of Examples 1-4 and the cement slurries of Comparative Examples 1-2. As known from the data in the table below, the cement slurries of Examples 1-4 and Comparative Examples 1-2 have similar performances, and all can meet the requirements of engineering applications.

(19) TABLE-US-00001 TABLE 1 Flow- API filter Free liquid Thickening Density ability loss amount time Test items (g/cm.sup.3) (cm) (mL) (%) (70 Bc/min) Example 1 1.90 21 24 0 164 Example 2 1.90 21 22 0 172 Example 3 1.90 20 20 0 158 Example 4 1.90 21 20 0 169 Comparative 1.90 22 38 0 177 Example 1 Comparative 1.90 21 36 0 192 Example 2

TEST EXAMPLE 2

(20) In this test example, each of the high temperature resistant Portland cement slurries of Examples 1-4 and the cement slurries of Comparative Examples 1-2 was filled into a strength mold to make a cement stone, and then cured at 70° C.×20.7 MPa for 3 days to form an initial state, and then cured at 350° C.×20.7 MPa for 7 days to form a first round, and then cured at 350° C.×20.7 MPa for every 10 days to form a round, and the compressive strength of the cement stone was tested after each curing round. Table 2 shows the strength test results of the high temperature resistant Portland cement stones of Examples 1-4 and the cement stones made by cement slurries of Comparative Examples 1-2 after different rounds of curing. As known from the data in the table below, the compressive strengths of the high temperature resistant Portland cement stones developed by the present application exceed 40 MPa, and the long-term strengths do not decline; while the cement stones of the Comparative Examples have compressive strengths of less than 10 MPa, and the long-term strengths are severely degraded. Therefore, the performance of the high temperature resistant Portland cement slurry system is superior to that of the cement slurry system of the Comparative Examples.

(21) TABLE-US-00002 TABLE 2 Notes Compressive strength (MPa) cement stone Test rounds structure Initial state state after Test items at 70° C. 1 2 3 4 curing Example 1 26.6 37.7 39.2 40.6 41.2 complete cement stone Example 2 23.3 42.3 43.5 45.7 51.1 complete cement stone Example 3 25.4 41.1 42.7 43.3 45.4 complete cement stone Example 4 27.9 39.6 41.3 41.9 42.7 complete cement stone Comparative 28.8 11.8 — — — cement stone Example 1 ruptured in the first round Comparative 18.2  4.8 — — — loose cement Example 2 stone structure in the first round

(22) It can be seen from Table 2 that the oil well Portland cement slurry produced in Comparative Example 1 has been ruptured after 10 days, one round of curing at 350° C.×20.7 MPa, and the oil well aluminate slurry produced in Comparative Example 2 has a loose structure after 10 days, one round of curing at 350° C.×20.7 MPa. The high temperature resistant Portland cement slurries produced in Examples 1-2 are more resistant to high temperatures and high pressures than the common oil well Portland cement slurries and oil well aluminate cement slurries in Comparative Examples 1-2, while keeping a complete cement stone structure after 40 days, four rounds of curing.

(23) In conclusion, the high temperature resistant Portland cement slurry provided by the invention has a good sedimentation stability, and the strength develops rapidly at low temperature, meeting the cementing demand in the early stage of the heavy oil steam injection thermal recovery. Moreover, the high temperature resistant Portland cement slurry provided by the invention has a compressive strength of up to 40 MPa or more at a high temperature of 350° C., and the long-term high-temperature compressive strength develops stably without degradation, reaching the level of Grade G Portland cement for cementing oil and gas well. As compared with Comparative Examples 1-2, the high temperature resistant Portland cement slurry provided by the invention has a cost reduced by about half than the price of aluminate cement or aluminophosphate cement, and does not need to separately develop the admixture and equipment for non-Portland cement, which greatly saves the cost for developing the cement slurry admixture and equipment. Most importantly, because the high temperature resistant Portland cement slurry provided by the invention has a similar system to the conventional Portland cement, the contact would not result in flocculation and thickening, and the compatibility is good, which improves the safety of cementing construction and greatly reduces the cost of cementing construction work.