GEOPOLYMER CEMENTING FLUID WITH CONTROLLABLE THICKENING TIME

Abstract

A geopolymer cementing fluid with controllable thickening time includes the following components in parts by weight: 100 parts of a cementitious material, 10 parts-30 parts of an activator, 0.2 parts-5 parts of a retarder, 0.4 parts-4 parts of an anti-settling agent, and 30 parts-70 parts of water. The geopolymer cementing fluid of the present invention has the advantages of controllable thickening time, excellent compressive strength, good settlement stability, good rheological properties, green and eco-friendly, and the like. The geopolymer cementing fluid can be better suited for the operations of oil and gas well cementing and ensure cementing safety.

Claims

1. A geopolymer cementing fluid with a controllable thickening time, comprising the following components in parts by weight: a cementitious material: 100 parts, an activator: 5 parts-30 parts, a retarder: 0.2 parts-5 parts, an anti-settling agent: 0.4 parts-4 parts, and water: 30 parts-70 parts; wherein the cementitious material is a mixture of a fly ash, an ultra-fine fly ash, and a slag; the activator is a mixture of sodium sulfate, calcium hydroxide, and barium hydroxide; the retarder is a mixture of sodium tartrate and ethylenediamine tetra(methylene phosphonic acid) sodium; and the anti-settling agent is a mixture of diutan gum, a diatomite, and fumed silica; a weight ratio of the fly ash, the ultra-fine fly ash, and the slag is (20-60):(20-60):(10-30); the fly ash has a silica dioxide content greater than 40% and a specific surface area greater than 400 m.sup.2/kg; the ultra-fine fly ash has a silica dioxide content greater than 40% and a specific surface area greater than 1500 m.sup.2/kg; a weight ratio of the sodium sulfate, the calcium hydroxide, and the barium hydroxide is (40-80):(5-40):(5-60); a weight ratio of the sodium tartrate and the ethylenediamine tetra(methylene phosphonic acid) sodium is (0-100):(0-100); a weight ratio of the diutan gum, the diatomite, and the fumed silica is (0.1-1):(30-40):(30-40).

2. The geopolymer cementing fluid with the controllable thickening time according to claim 1, wherein the slag is a granulated blast furnace slag with a specific surface area greater than or equal to 400 m.sup.2/kg.

3. The geopolymer cementing fluid with the controllable thickening time according to claim 1, wherein the water is freshwater, seawater, or water of different salinities.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The contents and advantages described above and/or additional parts of the present invention will become evident from the description of embodiments in conjunction with the following drawings.

[0027] FIG. 1 is a thickening curve of the cement slurry prepared in Embodiment 2 of the present invention (120° C.), where the thickening curve of the cementing fluid shows that the cement slurry is stable and increases from 30 Bc to 100 Bc only needs a thickening time of 12 min, which is beneficial to the prevention of gas channeling and the guarantee of cementing quality.

[0028] FIG. 2 is a thickening curve of the cement slurry prepared in Embodiment 3 of the present invention (150° C.), where the thickening curve shows that the cement slurry is overall stable, which is beneficial to cementing safety.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the embodiments or the prior art will be briefly introduced below. The embodiments described below are only some embodiments of the present invention. For those of ordinary skill in the art, other embodiments can be obtained according to these embodiments without creative work.

Experimental Methods

[0030] The cementing fluid was prepared according to the cementing test standard API RP 10B, and the performance and compressive strength of the cementing fluid were determined.

Contrast Example 1

[0031] The cementing fluid was prepared with 80 parts of fly ash, 0 part of ultra-fine fly ash, 20 parts of slag, 1 part of anti-settling agent, 35 parts of water, 6 parts of sodium hydroxide, and 2 parts of ethylenediamine tetra(methylene phosphonic acid) sodium. The anti-settling agent is a mixture of diutan gum, diatomite, and fumed silica, and a weight ratio of the diutan gum, the diatomite, and the fumed silica is 1:32:32.

Contrast Example 2

[0032] The cementing fluid was prepared with 80 parts of fly ash, 0 part of ultra-fine fly ash, 20 parts of slag, 1 part of anti-settling agent, 35 parts of water, 6 parts of sodium hydroxide, and 4 parts of ethylenediamine tetra(methylene phosphonic acid) sodium. The anti-settling agent is a mixture of diutan gum, diatomite, and fumed silica, and a weight ratio of the diutan gum, the diatomite, and the fumed silica is 1:32:32.

Contrast Example 3

[0033] The cementing fluid was prepared with 80 parts of fly ash, 0 part of ultra-fine fly ash, 20 parts of slag, 1 part of anti-settling agent, 35 parts of water, 6 parts of sodium hydroxide, and 6 parts of ethylenediamine tetra(methylene phosphonic acid) sodium. The anti-settling agent is a mixture of diutan gum, diatomite, and fumed silica, and a weight ratio of the diutan gum, the diatomite, and the fumed silica is 1:32:32.

Embodiment 1

[0034] The cementing fluid was prepared with 40 parts of fly ash, 40 parts of ultra-fine fly ash, 20 parts of slag, 1 part of the anti-settling agent, 35 parts of water, 3.7 parts of calcium hydroxide, 10.6 parts of sodium sulfate, 4.3 parts of barium hydroxide, and 1 part of ethylenediamine tetra(methylene phosphonic acid) sodium. The anti-settling agent is a mixture of diutan gum, diatomite, and fumed silica, and a weight ratio of the diutan gum, the diatomite, and the fumed silica is 1:32:32.

Embodiment 2

[0035] The cementing fluid was prepared with 40 parts of fly ash, 40 parts of ultra-fine fly ash, 20 parts of slag, 1 part of anti-settling agent, 35 parts of water, 3.7 parts of calcium hydroxide, 10.6 parts of sodium sulfate, 4.3 parts of barium hydroxide, and 2 parts of ethylenediamine tetra(methylene phosphonic acid) sodium. The anti-settling agent is a mixture of diutan gum, diatomite, and fumed silica, and a weight ratio of the diutan gum, the diatomite, and the fumed silica is 1:32:32.

Embodiment 3

[0036] The cementing fluid was prepared with 40 parts of fly ash, 40 parts of ultra-fine fly ash, 20 parts of slag, 1 part of anti-settling agent, 35 parts of water, 3.7 parts of calcium hydroxide, 10.6 parts of sodium sulfate, 4.3 parts of barium hydroxide, and 3.5 parts of ethylenediamine tetra(methylene phosphonic acid) sodium. The anti-settling agent is a mixture of diutan gum, diatomite, and fumed silica, and a weight ratio of the diutan gum, the diatomite, and the fumed silica is 1:32:32.

Embodiment 4

[0037] The cementing fluid was prepared with 30 parts of fly ash, 40 parts of ultra-fine fly ash, 30 parts of slag, 1.5 parts of anti-settling agent, 40 parts of water, 3.7 parts of calcium hydroxide, 8.9 parts of sodium sulfate, 2.1 parts of barium hydroxide, and 3.5 parts of ethylenediamine tetra(methylene phosphonic acid) sodium. The anti-settling agent is a mixture of diutan gum, diatomite, and fumed silica, and a weight ratio of the diutan gum, the diatomite, and the fumed silica is 1:32:32.

Embodiment 5

[0038] The cementing fluid was prepared with 40 parts of fly ash, 40 parts of ultra-fine fly ash, 20 parts of slag, 1.5 parts of anti-settling agent, 40 parts of water, 3.7 parts of calcium hydroxide, 8.9 parts of sodium sulfate, 2.1 parts of barium hydroxide, and 3.5 parts of ethylenediamine tetra(methylene phosphonic acid) sodium. The anti-settling agent is a mixture of diutan gum, diatomite, and fumed silica, and a weight ratio of the diutan gum, the diatomite, and the fumed silica is 1:32:32.

Embodiment 6

[0039] The cementing fluid was prepared with 40 parts of fly ash, 40 parts of ultra-fine fly ash, 20 parts of slag, 0.7 parts of anti-settling agent, 40 parts of water, 4.0 parts of calcium hydroxide, 8.9 parts of sodium sulfate, 3.0 parts of barium hydroxide, 0.2 parts of sodium tartrate, and 0.2 parts of ethylenediamine tetra(methylene phosphonic acid) sodium. The anti-settling agent is a mixture of diutan gum, diatomite, and fumed silica, and a weight ratio of the diutan gum, the diatomite, and the fumed silica is 1:34:35.

Embodiment 7

[0040] The cementing fluid was prepared with 40 parts of fly ash, 40 parts of ultra-fine fly ash, 20 parts of slag, 2 parts of anti-settling agent, 40 parts of water, 4.0 parts of calcium hydroxide, 8.9 parts of sodium sulfate, 3.0 parts of barium hydroxide, 1.5 parts of sodium tartrate, and 3.5 parts of ethylenediamine tetra(methylene phosphonic acid) sodium. The anti-settling agent is a mixture of diutan gum, diatomite, and fumed silica, and a weight ratio of the diutan gum, the diatomite, and the fumed silica is 1:39:40.

TABLE-US-00001 TABLE 1 Table of experimental results Performance Embodiment Contrast Example testing 1 2 3 4 5 6 7 1 2 3 Thickening time 351 >500 >500 >500 >500 241 >500 <10 <30 65 at 70° C. (min) Thickening time 107 332 403 415 443 88 >500 — — — at 120° C. (min) Thickening time — 243 292 301 331 — >500 — — — at 150° C. (min) Compressive 24 h 24 6 1 1 1 27 0 5.2 5.6 5.6 strength at 72 h 41.2 42.3 40.6 36.2 34.1 41.8 26 11.3 10.9 11.4 70° C. (MPa) Note: — represents the geopolymer cementing fluid cannot be tested due to short thickening time.

[0041] According to Table 1, the thickening times in Contrast Example 1, Contrast Example 2, and Contrast Example 3 are relatively short, which is less than 65 min at 70° C., indicating that it is difficult to control the thickening time when sodium hydroxide is used as an activator. The thickening time at 120° C. in Embodiment 1 is 107 min, the thickening time at 120° C. in Embodiment 2 is 332 min, and the thickening time at 150° C. in Embodiment 3, Embodiment 4, and Embodiment 5 is 292 min, 301 min, and 331 min, respectively, which shows good time controllability, indicating that the thickening time can be easily regulated by using sodium sulfate and calcium hydroxide (barium hydroxide) instead of sodium hydroxide. In terms of compressive strength, due to the addition of ultra-fine fly ash in the embodiments, the geopolymer has a 72-hour strength much higher than that in the Contrast Examples since the ultra-fine fly ash has high activity. Since retarders are added at a large amount in Embodiment 2, Embodiment 3, Embodiment 4, and Embodiment 5, the thickening (settling) time of the geopolymer is longer, which results in a reduction of the 24-hour strength. Furthermore, the temperature differences of these embodiments are 50° C. and 80° C., respectively, which shows good adaptability to significant temperature differences.

[0042] Although embodiments of the present invention have been shown and described, those skilled in the art should understand that these embodiments can be varied, modified, replaced, and transformed without departing from the principle and purpose of the present invention. The scope of the present invention is defined by claims and their equivalents.