# US 2020/0399525 A1 · Well Cementing Method for Improving Well Cementing Quality by Controlling Hydration Heat of Cement Slurry > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0399525 A1 - Document ID: US20200399525A1 - Status: Published application - Kind: A1 - Application number: 16/854,376 - Filed: 2020-04-21 - Published: 2020-12-24 - Earliest claimed: 2019-06-24 - Assignees: PetroChina Company Limited; CNPC Engineering Technology R&D Company Limited - Applicants: PetroChina Company Limited; CNPC Engineering Technology R&D Company Limited - Inventors: Shuoqiong Liu; Hua Zhang; Jianzhou Jin; Ming Xu; Yongjin Yu; Fengzhong Qi; Congfeng Qu; Hong Yue; Youcheng Zheng; Wei Li; Yong Ma; Youzhi Zheng; Zhao Huang; Jinping Yuan; Zhiwei Ding; Chongfeng Zhou; Chi Zhang; Zishuai Liu; Hongfei Ji; Yuchao Guo; Xiujian Xia; Yong Li; Jiyun Shen; Huiting Liu; Yusi Feng; Bin Lyu - Web page: https://patentgrep.com/patent/US20200399525A1 ## CPC - C09K 8/467: containing additives for specific purposes - C04B 28/02: containing hydraulic cements other than calcium sulfates - E21B 33/14: for cementing casings into boreholes - Y02W 30/91: Use of waste materials as fillers for mortars or concrete - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT ## Abstract A well cementing method is described for improving cementing quality by controlling the hydration heat of cement slurry. By controlling the degree and/or rate of hydration heat release from cement slurry, the method improves the hydration heat release during formation of cement with curing of cement slurry, improves the binding quality between the cement and the interfaces, and in turn improves the cementing quality at the open hole section and/or the overlap section. The cementing method improves cementing quality of oil and gas wells and reduces the risk of annular pressure. ## Claims ### Claim 1 A well cementing method for improving cementing quality by controlling the hydration heat of cement slurry, wherein by controlling the degree and/or rate of hydration heat release from cement slurry, the method improves the hydration heat release during formation of cement with curing of cement slurry, improves the binding quality between the cement and the interfaces, and in turn improves the cementing quality at the open hole section and/or the overlap section; wherein the cementing quality at the open hole section is improved by increasing the degree and/or rate of hydration heat release from cement slurry; and the cementing quality at the overlap section is improved by lowering the degree and/or rate of hydration heat release from cement slurry. ### Claim 2 (depends on 1) The well cementing method according to claim 1, wherein increasing the degree of hydration heat release from cement slurry is achieved by adding a material generating a high hydration heat to cement slurry. ### Claim 3 (depends on 2) The well cementing method according the claim 2, wherein the material generating a high hydration heat includes an accelerating early strength agent. ### Claim 4 (depends on 1) The well cementing method according to claim 1, wherein increasing the rate of hydration heat release from cement slurry is achieved by either or both of adding an accelerating early strength agent, and shortening the additional safety time for thickening of cement slurry. ### Claim 5 (depends on 4) The well cementing method according to claim 4, wherein the accelerating early strength agent includes one of, or a combination of two or more of: sodium chloride, sodium carbonate, sodium formate, sodium nitrite, calcium chloride, calcium formate, calcium sulfate, calcium metasilicate, sodium aluminate, metakaolin, magnesium trisilicate, magnesium oxide, strontium sulfate, strontium carbonate, strontium nitrate, lithium carbonate, gypsum, hemihydrate gypsum, dihydrate gypsum, magnesium oxide, calcium oxide, activated slag, and ultra-fine cement. ### Claim 6 (depends on 1) The well cementing method according to claim 1, wherein lowering the degree of hydration heat release from cement slurry is achieved by adding an inert material to cement slurry, reducing the addition amount of a material generating a high hydration heat, and/or prolonging the additional safety time for thickening of cement slurry. ### Claim 7 (depends on 6) The well cementing method according to claim 6, wherein the inert material includes one of, or a combination of two or more of: iron ore powder, barite, hollow glass beads, and quartz sand. ### Claim 8 (depends on 1) The well cementing method according to claim 1, wherein lowering the rate of hydration heat release from cement slurry is achieved by adding a retarder and/or prolonging the additional safety time for thickening of cement slurry. ### Claim 9 (depends on 8) The well cementing method according to claim 8, wherein the retarder includes one of, or a combination of two or more of: an organic phosphonate-based retarder, an AMPS-based retarder, a phosphate-based retarder, glucose, and sodium borate. ### Claim 10 (depends on 1) The well cementing method according claim 1, wherein the cement component in the cement slurry is one of or a combination of two or more of: class A oil well cement, class B oil well cement, class C oil well cement, class D oil well cement, class E oil well cement, class F oil well cement, class G oil well cement, class H oil well cement, and class J oil well cement. ### Claim 11 (depends on 10) The well cementing method according to claim 10, wherein the cement slurry further contains one of or a combination of two or more of: a toughening agent, a fluid loss additive, a dispersant, a defoaming agent, a fleeing-proof agent, silica, and water. ### Claim 12 (depends on 1) The well cementing method according to claim 1, further comprising controlling the strength and/or elastic modulus of the cement formed from the cement slurry. ### Claim 13 (depends on 1) The well cementing method according to claim 1, wherein for well cementing of a well of a pure overlap section, hydration heat is controlled by lowering the degree and/or rate of hydration heat release from cement slurry; wherein the cement slurry is cement slurry with high strength and low elastic modulus, the additional safety time is 60-300 minutes for thickening of the lead slurry and 30-200 minutes for thickening of the tail slurry. ### Claim 14 (depends on 1) The well cementing method according to claim 1, wherein the well cementing is performed on a long-overlap-section well having a length of overlap section greater than 150 m; wherein for well cementing with single setting cement slurry, controlling of hydration heat is achieved by lowering the degree and/or rate of hydration heat release from the cement slurry; wherein the cement slurry is cement slurry with high strength and low elastic modulus, and its additional safety time for thickening is 60-300 minutes; for well cementing with separable setting cement slurry, for the lead slurry, controlling of hydration heat is achieved by lowering the degree and/or rate of hydration heat release from the slurry, wherein the lead slurry is cement slurry with high strength and low elastic modulus, and its additional safety time for thickening is 60-300 minutes; and for the tail slurry, controlling of hydration heat is achieved by increasing the degree and/or rate of hydration heat release from the slurry, wherein the tail slurry is cement slurry with high strength, and its additional safety time for thickening is 30-60 minutes; for well cementing with multi-setting cement slurry, for the lead slurry, controlling of hydration heat is achieved by lowering the degree and/or rate of hydration heat release from the slurry, wherein the lead slurry is cement slurry with high strength and low elastic modulus, and its additional safety time for thickening is 60-300 minutes; for intermediate slurry, controlling of hydration heat is achieved by lowering the degree and/or rate of hydration heat release from the slurry, wherein the intermediate slurry is cement slurry with high strength and low elastic modulus, and its additional safety time for thickening is 60-200 minutes; and for the tail slurry, controlling of hydration heat is achieved by increasing the degree and/or rate of hydration heat release from the slurry, wherein the tail slurry is cement slurry with high strength, and its additional safety time for thickening is 30-60 minutes. ### Claim 15 (depends on 14) The well cementing method according to claim 14, wherein for well cementing with separable setting cement slurry or multi-setting cement slurry, the tail slurry enters the overlap section by 100 m or more. ### Claim 16 (depends on 15) The well cementing method according to claim 15, wherein for well cementing with separable setting cement slurry or multi-setting cement slurry, the tail slurry enters the overlap section by 100 m to 300 m. ### Claim 17 (depends on 1) The well cementing method according to claim 1, wherein the well cementing is performed on a short-overlap-section well having a length of the overlap section not greater than 150 m; wherein for well cementing with single setting cement slurry, controlling of hydration heat is achieved by lowering the degree and/or rate of hydration heat release from the cement slurry; wherein the cement slurry is cement slurry with high strength and low elastic modulus, and its additional safety time for thickening is 60-300 minutes; for well cementing with separable setting cement slurry, for the lead slurry, controlling of hydration heat is achieved by lowering the degree and/or rate of hydration heat release from the slurry, wherein the lead slurry is cement slurry with high strength and low elastic modulus, and its additional safety time for thickening is 60-300 minutes; and for the tail slurry, controlling of hydration heat is achieved by increasing the degree and/or rate of hydration heat release from the slurry, wherein the tail slurry is cement slurry with high strength, and its additional safety time for thickening is 30-60 minutes; for well cementing with multi-setting cement slurry, for the lead slurry, controlling of hydration heat is achieved by lowering the degree and/or rate of hydration heat release from the slurry, wherein the lead slurry is cement slurry with high strength and low elastic modulus, and its additional safety time for thickening is 60-300 minutes; for intermediate slurry, controlling of hydration heat is achieved by increasing the degree and/or rate of hydration heat release from the slurry, wherein the intermediate slurry is cement slurry with high strength, and its additional safety time for thickening is 60-200 minutes; and for the tail slurry, controlling of hydration heat is achieved by increasing the degree and/or rate of hydration heat release from the slurry, wherein the tail slurry is cement slurry with high strength, and its additional safety time for thickening is 30-60 minutes. ### Claim 18 (depends on 13) The well cementing method according to claim 13, wherein the high strength occurs when the strength of the cement formed from the cement slurry is not lower than the compression strength of pure cement under the same conditions. ### Claim 19 (depends on 18) The well cementing method according to claim 18, wherein the high strength occurs when the 7-day strength is greater than 28 MPa. ### Claim 20 (depends on 13) The well cementing method according to claim 13, wherein the low elastic modulus occurs when the elastic modulus of the cement formed from the cement slurry is smaller than that of pure cement under the same conditions; wherein the low elastic modulus occurs when the elastic modulus is less than 10 GPa.