Well cementation working solution prepared from red mud, slag and waste drilling fluids

Abstract

A well cementation working solution prepared from red mud, slag and waste drilling fluids. The working solution is prepared from the following components in parts by weight: 100 parts of waste drilling fluids, 50-100 parts of slag, 5-50 parts of red mud, 4-7 parts of a suspension stabilizer, 1-7 parts of an activating aid, 0.5-5 parts of an anti-pollution agent and 0.4-3.5 parts of a diluent. The waste drilling fluids are waste waterborne drilling fluids. The slag is blast furnace slag or vanadium-titanium slag. The suspension stabilizer is sodium bentonite, carboxymethyl cellulose or a mixture of sodium bentonite and carboxymethyl cellulose. The activating aid is sodium metasilicate nonahydrate, sodium carbonate or a mixture of sodium metasilicate nonahydrate and sodium carbonate. The anti-pollution agent is sodium salicylate, potassium citrate or a mixture of sodium salicylate and potassium citrate. The diluent is sodium lignin sulfonate.

Claims

1. A well cementation working solution, comprising the following components in parts by weight: 100 parts of waste drilling fluids; 50-100 parts of a slag; 5-50 parts of an alkaline activator, wherein the alkaline activator consists of a non-dealkalized Bayer red mud; 4-7 parts of a suspension stabilizer; 1-7 parts of an activating aid; 0.5-5 parts of an anti-pollution agent; and 0.4-3.5 parts of a diluent; wherein the well cementation working solution does not comprise sodium hydroxide and potassium hydroxide.

2. The well cementation working solution of claim 1, wherein the waste drilling fluids are waste waterborne drilling fluids and the waste waterborne drilling fluids comprise a waterborne drilling fluid suitable for high temperature and high pressure drilling, wherein, the waterborne drilling fluid has a density ranging from 1.10 g/cm.sup.3 to 2.05 g/cm.sup.3.

3. The well cementation working solution of claim 1, wherein the slag is a blast furnace slag or a vanadium-titanium ore slag, the blast furnace slag is a S105 pulverized and water quenched blast furnace slag, and the vanadium-titanium slag has a particle diameter of 10-50 μm.

4. The well cementation working solution of claim 1, wherein the suspension stabilizer is one item selected from the group consisting of sodium bentonite, carboxymethyl cellulose or a mixture of sodium bentonite and carboxymethyl cellulose.

5. The well cementation working solution of claim 1, wherein the activating aid is one item selected from the group consisting of sodium metasilicate nonahydrate, sodium carbonate or a mixture of sodium metasilicate nonahydrate and sodium carbonate.

6. The well cementation working solution of claim 1, wherein the anti-pollution agent is one item selected from the group consisting of sodium salicylate, potassium citrate or a mixture of sodium salicylate and potassium citrate.

7. The well cementation working solution of claim 1, wherein the diluent is sodium lignosulfonate.

8. A method for using the well cementation working solution of claim 1, comprising the step of applying the well cementation working solution to a well cementation of oil and gas wells.

9. The method according to claim 8, wherein the waste drilling fluids are waste waterborne drilling fluids, and the waste waterborne drilling fluids comprises a waterborne drilling fluid suitable for high temperature and high pressure drilling, wherein, the waterborne drilling fluid has a density ranging from 1.10 g/cm.sup.3 to 2.05 g/cm.sup.3.

10. The method according to claim 8, wherein the slag is a blast furnace slag or a vanadium-titanium ore slag, the blast furnace slag is a S105 pulverized and water quenched blast furnace slag, and the vanadium-titanium slag has a particle diameter of 10-50 μm.

11. The method according to claim 8, wherein the suspension stabilizer is one item selected from the group consisting of sodium bentonite, carboxymethyl cellulose or a mixture of sodium bentonite and carboxymethyl cellulose.

12. The method according to claim 8, wherein the activating aid is one item selected from the group consisting of sodium metasilicate nonahydrate, sodium carbonate or a mixture of sodium metasilicate nonahydrate and sodium carbonate.

13. The method according to claim 8, wherein the anti-pollution agent is one item selected from the group consisting of sodium salicylate, potassium citrate or a mixture of sodium salicylate and potassium citrate.

14. The method according to claim 8, wherein the diluent is sodium lignosulfonate.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) I. Preparation of Well Cementation Working Solution Prepared from Red Mud, Slag and Waste Drilling Fluids

(2) The present invention will now be described in detail in connection with specific embodiments.

Embodiment 1

(3) Formula: 100 parts of waste drilling fluids (1.12 g/cm.sup.3), 90 parts of finely-ground and water-quenched blast furnace slag, 10 parts of red mud, 5 parts of sodium bentonite, 6 parts of sodium metasilicate nonahydrate, 1 part of sodium salicylate, and 0.5 part of sodium lignosulfonate.

Embodiment 2

(4) Formula: 100 parts of waste drilling fluids (1.12 g/cm.sup.3), 80 parts of finely-ground and water-quenched blast furnace slag, 20 parts of red mud, 5.5 parts of carboxymethyl cellulose, 5.5 parts of sodium carbonate, 1.5 parts of potassium citrate, and 0.8 part of sodium lignosulfonate.

Embodiment 3

(5) Formula: 100 parts of waste drilling fluids (1.12 g/cm.sup.3), 70 parts of finely-ground and water-quenched blast furnace slag, 30 parts of red mud, 5 parts of carboxymethyl cellulose, 2 parts of sodium metasilicate nonahydrate, 3.8 parts of sodium carbonate, 0.8 part of sodium salicylate, 1 part of potassium citrate and 1.2 parts of sodium lignosulfonate.

Embodiment 4

(6) Formula: 100 parts of waste drilling fluids (1.12 g/cm.sup.3), 90 parts of vanadium-titanium slag, 10 parts of red mud, 5 parts of sodium bentonite, 5 parts of sodium metasilicate nonahydrate, 0.8 part of sodium salicylate, and 0.9 part of sodium lignosulfonate.

Embodiment 5

(7) Formula: 100 parts of waste drilling fluids (1.12 g/cm.sup.3), 80 parts of vanadium-titanium slag, 20 parts of red mud, 5.5 parts of carboxymethyl cellulose, 5.5 parts of sodium metasilicate nonahydrate, 1 part of sodium salicylate, 0.6 part of potassium citrate, and 0.5 part of sodium lignosulfonate.

(8) Ii. Performance Testing of Well Cementation Working Solution Prepared from Red Mud, Slag and Waste Drilling Fluids

(9) In Embodiment 1, Embodiment 2, Embodiment 3, Embodiment 4, and Embodiment 5, cured slurry is respectively prepared according to the national standard GB/T19139-2012, and basic performances, such as the density, fluidity and thickening time of this cured slurry system are measured. The slurry is poured into a grinding apparatus, and after curing under standard conditions for different periods (3 days, 7 days, 14 days, and 28 days), the compressive strength of the cured slurry and the ion content in leachate are measured (referring to standard HJ/T299-2007).

(10) The engineering performance results of the well cementation working solution prepared from red mud, slag and waste drilling fluids are shown in Table 1. The compressive strength evaluation results of the cured slurry samples under standard conditions in different periods and the ion content of leachate are shown in Table 2 and Table 3 respectively.

(11) TABLE-US-00001 TABLE 1 Engineering Performance of Well Cementation Working Solution Prepared from Red Mud, Slag and Waste Drilling Fluids Embodi- Density Flow Filter loss Thickening time ment (g/cm.sup.3) (cm) (ml) (min) 1 1.52 23 66 290 2 1.64 20.5 56 328 3 1.49 19 44 390 4 1.54 22.5 60 270 5 1.66 21 49 311

(12) The test evaluation results in Table 1 show that the present invention has good engineering performance and can well meet the requirements of on-site well cementation construction.

(13) TABLE-US-00002 TABLE 2 Compressive Strength of Well Cementation Working Solution Prepared from Red Mud, Slag and Waste Drilling Fluids Embodi- Curing temperature Compressive Strength (MPa) ment (° C.) 3 days 7 days 14 days 28 days 1 25 4.16 7.16 9.88 11.53 2 25 3.77 6.58 9.12 10.04 3 25 3.14 5.89 8.86 9.00 4 25 4.28 7.56 10.14 12.18 5 25 4.00 7.12 9.43 10.62

(14) By analyzing the compressive strength test results in different embodiments after curing under standard conditions for different periods (as shown in Table 2), it can be seen that for the same embodiment, as the curing period increases, the compressive strength after the curing of the slurry is increasing continuously. Although the addition of red mud has certain damage to the compressive strength of the well cementation working solution, the overall strength is still relatively high, which can meet the strength requirements for a filling section in the field well cementation operation.

(15) TABLE-US-00003 TABLE 3 Heavy Metal Leaching Concentration of Well Cementation Working Solution Prepared from Red Mud, Slag and Waste Drilling Fluids Embodi- Heavy Ion Concentration (mg/L) ment Category 3 days 7 days 14 days 28 days 1 As 0.23 0.17 0.12 0.10 Pb 0.02 0.01 0.01 ≤0.01 Zn 0.12 0.07 0.05 0.04 2 As 0.25 0.18 0.14 0.11 Pb 0.03 0.02 0.01 ≤0.01 Zn 0.13 0.09 0.07 0.06 3 As 0.25 0.19 0.14 0.12 Pb 0.03 0.02 0.01 0.01 Zn 0.13 0.10 0.08 0.07 4 As 0.20 0.12 0.07 0.06 Pb 0.02 ≤0.01 ≤0.01 ≤0.01 Zn 0.11 0.06 0.04 0.04 5 As 0.22 0.13 0.08 0.07 Pb 0.02 0.01 ≤0.01 ≤0.01 Zn 0.12 0.08 0.06 0.06 Note: ≤refers to testing limit

(16) By analyzing the heavy metal leaching concentration in Table 3, it is known that as the curing period increases, the heavy metal contents of As, Pb, and Zn leached in the sample gradually decrease, thereby indicating that the cured working solution has good sealing ability for heavy metals such as As, Pb and Zn contained in red mud.

(17) From the above, the present invention meets the performance requirements of ordinary well cementation working solutions, and has lower cost and better economical applicability than the conventional cured fluid system of cement slurry. The working solution system consumes a huge amount of industrial wastes (slag, red mud and waste drilling fluids) by replacing cement with slag, replacing an activator with red mud and partially replacing water with drilling fluid, thereby greatly reducing the environmental pollution caused by the stacking (or discharge) of industrial wastes, and providing a new idea for the recycling of industrial wastes. Meanwhile, the working solution preparation process is the same as the traditional well cementation construction process, and is simple in operation and has good engineering applicability.