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CN-121990790-A - High-temperature-resistant thixotropic cement paste and application thereof

CN121990790ACN 121990790 ACN121990790 ACN 121990790ACN-121990790-A

Abstract

The invention provides high-temperature-resistant thixotropic cement paste and application thereof. The cement slurry comprises cement, first fly ash, slag, silica sand, thixotropic agent, fluid loss agent, retarder and water.

Inventors

  • LIU XIANGHUA
  • WU JIARONG
  • HE YINGZHUANG
  • LU FEIFEI
  • LI WENXIA
  • LV PING

Assignees

  • 中国石油化工股份有限公司
  • 中国石油化工股份有限公司西北油田分公司

Dates

Publication Date
20260508
Application Date
20241108

Claims (10)

  1. 1. A cement paste comprises cement, first fly ash, slag, silica sand, thixotropic agent, fluid loss agent, retarder and water.
  2. 2. The cement slurry of claim 1, wherein the cement is a class G oil well cement.
  3. 3. The cement slurry of claim 1, wherein the first fly ash has a particle size of 1000 to 1250 mesh, and/or The slag having a particle size of 1000 to 1250 mesh, and/or The grain size of the silica sand is 120 to 200 meshes.
  4. 4. Cement slurry according to claim 1, characterized in that the slag is S95 grade slag and/or S105 grade slag.
  5. 5. The cement paste according to claim 1, wherein the thixotropic agent is formed by combining a second fly ash with a synthetic polymer-based thixotropic agent, wherein the synthetic polymer-based thixotropic agent is formed by polymerizing 2-acrylamide-2-methylpropanesulfonic acid and acrylamide, the mass ratio of the 2-acrylamide-2-methylpropanesulfonic acid to the acrylamide is (3-4): (7-6), the synthetic polymer-based thixotropic agent uses a cross-linking agent of N, N-Methylenebisacrylamide (MBA) in an amount of 0.5% to 3% of the total monomer mass, the initiator used is ammonium persulfate in an amount of 1% to 4% of the total monomer mass, and the second fly ash has a particle size of 200 to 500 mesh in an amount of 800% to 900% of the total monomer mass.
  6. 6. The cement slurry of claim 1, wherein the fluid loss additive is SCF180 and/or BXF-200L.
  7. 7. The cement slurry of claim 1, wherein the retarder is DHZ-3.
  8. 8. The cement slurry according to claim 1, wherein the cement is used in an amount of 40% to 50%, the first fly ash is used in an amount of 15% to 25%, the slag is used in an amount of 10% to 20%, the silica sand is used in an amount of 15% to 25%, the thixotropic agent is used in an amount of 4% to 6%, the fluid loss additive is used in an amount of 5% to 8%, and the retarder is used in an amount of 5% to 6% based on 100% by mass of the total of cement, the first fly ash, the slag and the silica sand.
  9. 9. The cement slurry of claim 1, wherein the cement slurry has a water to solids ratio of 0.44.
  10. 10. Use of a cement slurry according to any one of claims 1 to 9 in high temperature gas well cementing.

Description

High-temperature-resistant thixotropic cement paste and application thereof Technical Field The invention relates to the field of oilfield chemistry and oil and gas well cementing materials, in particular to thixotropic cement paste suitable for gas channeling prevention well cementation. Background The gas layer of the high-temperature high-pressure gas well in the north direction is active, is difficult to press stably, has poor sealing quality, and can not ensure safe production because of the two sets of pressure rising of the multiple wells. Although the sealing of the high-pressure gas layer is avoided through the well structure at present, along with the development of oil fields, the drilling and development of the northbound high-pressure gas well is restricted by the gas channeling prevention well cementation short plate, and the bottleneck is overcome, so that the technical innovation is brought. The pressure stabilizing layer directly relates to success and failure of high-pressure gas layer well cementation, and 7 cement slurry systems such as high-temperature gas generation resistance, elastic latex, salt water colloidal particles, latex silicon, emulsion silicon and the like which are used can not effectively stabilize the stratum. Through investigation, thixotropic cement paste has the characteristics of breaking a gel structure under the shearing action and quickly recovering the gel structure after standing, can quickly form high gel strength after stopping pumping to be a main cause of preventing gas channeling, and simultaneously prevents mechanical deformation and bubble generation of a liquid column to a certain extent due to further development of the gel strength after entering a transitional state, thereby achieving the purpose of preventing gas channeling. However, no mature thixotropic cement paste system exists at present, the temperature of the northbound gas layer is high and exceeds 170 ℃, and higher requirements are put on the research of the thixotropic cement paste system. Disclosure of Invention One of the present invention provides a cement slurry comprising cement, a first fly ash, slag, silica sand, a thixotropic agent, a fluid loss agent, a retarder and water. In one embodiment, the cement is a class G oil well cement. In one embodiment, the first fly ash has a particle size of 1000 to 1250 mesh. In a specific embodiment, the slag has a particle size of 1000 to 1250 mesh. In one embodiment, the silica sand has a particle size of 120 to 200 mesh. In one embodiment, the slag is S95 grade slag and/or S105 grade slag. In one embodiment, the thixotropic agent is formed by combining a second fly ash with a synthetic polymer-based thixotropic agent, wherein the synthetic polymer-based thixotropic agent is formed by polymerizing 2-acrylamide-2-methylpropanesulfonic acid and acrylamide, the mass ratio of 2-acrylamide-2-methylpropanesulfonic acid to acrylamide is (3-4): (7-6), the synthetic polymer-based thixotropic agent uses a cross-linking agent of N, N-Methylenebisacrylamide (MBA) in an amount of 0.5% to 3% of the total monomer mass, uses ammonium persulfate as an initiator in an amount of 1% to 4% of the total monomer mass, and the second fly ash has a particle size of 200 to 500 mesh in an amount of 800% to 900% of the total monomer mass. In one specific embodiment, the fluid loss additive is SCF180 and/or BXF-200L. In one embodiment, the retarder is DHZ-3. In one embodiment, the cement is used in an amount of 40% to 50%, the first fly ash is used in an amount of 15% to 25%, the slag is used in an amount of 10% to 20%, the silica sand is used in an amount of 15% to 25%, the thixotropic agent is used in an amount of 4% to 6%, the fluid loss additive is used in an amount of 5% to 8%, and the retarder is used in an amount of 5% to 6% based on 100% of the total mass of cement, the first fly ash, the slag and the silica sand. In one embodiment, the cement slurry has a water to solids ratio of 0.44. Use of the cement paste according to any one of the invention in high temperature gas well cementing In one embodiment, the elevated temperature may be up to 180 ℃. The invention has the beneficial effects that: the high-temperature-resistant thixotropic cement paste system can achieve the aim of good gas channeling prevention performance under the condition of 180 ℃ of cement paste, can be used for gas channeling prevention well cementation of high-temperature high-pressure wells in the north, and obviously has better application and popularization prospects. Drawings Fig. 1 shows thixotropic property testing at 130 ℃ for cement paste prepared based on the formulation of example 1. Fig. 2 shows thixotropic property testing at 170 ℃ for cement slurries prepared based on the formulation of example 2. Fig. 3 shows thixotropic property testing at 180 ℃ for cement paste prepared based on the formulation of example 3. Fig. 4 shows thixotropic property tests at 140 ℃ for cement slurries pr