30～200 ℃水泥石强度演化及高温衰退机制

Strength Evolution and High Temperature Retrogression Mechanism of Setting Cement Temperature of 30—200 ℃

孙立君 郑冠一 李成龙 钱 钦 戴荣东 侯业贵 庞学玉 韩 超

SUN Lijun ZHENG Guanyi LI Chenglong QIAN Qin DAI Rongdong HOU Yegui PANG Xueyu HAN Chao

为了满足大温差井下环境井筒完整性的需要，需厘清更宽温度、压力范围影响下油井水泥力学性能演化规律。分别以水泥净浆、硅砂水泥体系为研究对象，系统研究了 30～200 ℃长温度区间内温度、压力、硅砂加量对油井水泥强度演化规律的影响，并探究了不同影响因素下水泥强度发展驱动机制及高温强度衰退机制。研究结果表明，30～110 ℃内，水泥净浆体系的抗压强度随温度、压力的升高而升高；温度由110 ℃升高至 150 ℃时，水泥石发生高温强度衰退。110～200 ℃内，硅砂水泥体系的超声波强度不是随着温度的变化单调变化，但增压可以加超速声波强度的发展；200 ℃时，硅砂水泥体系发生强度衰退和体积膨胀现象。增加硅砂量可在一定程度上减缓早期强度衰退速率。物相组成分析结果表明：水泥早期强度的发展主要与C-S-H 凝胶和氢氧化钙的生成有关；130 ℃下，造成水泥净浆高温强度衰退的主要原因是α-C2SH的生成；200 ℃下，造成硅砂水泥体系强度衰退的主要原因是非晶C-S-H向晶体逐渐转变。

To meet the requirements on well integrity of oil wells under large temperature difference environment，it is needed to clarify the evolution of mechanical properties of oil well setting cement under a wider range of temperature and pressure. Pure cement system and silica-cement system was selected as research targets，the influence of temperature，pressure and silica fume content on the evolution of cement strength under the temperature range of 30—200 ℃ was systematically studied and the driving mechanism of cement strength development and high temperature strength retrogression mechanism under each factor was investigated. The results showed that within 30—110 ℃，the compressive strength of pure cement system increased with the increase of temperature. As The temperature increased from 100 ℃ to 150 ℃，the strength retrogression of the pure cement system happened under high temperature. Within the temperature of 110—200 ℃，the ultrasonic intensity of silica-cement system changed not monotonically with the temperature；however，the ultrasonic intensity development could be accelerated by the increase of pressure. At the temperature of 200 ℃，the phenomena of strength retrogression and volume expansion of silica-cement system happened. By increasing the amount of silica sand，the early strength decline rate could alleviated to a certain extent. Phase composition analysis showed that the development of the early strength of cement was mainly related to the formation of C-S-H gel and Ca（OH）2；at the temperature of 130 ℃，the main reason causing the high temperature strength retrogression of pure cement system was the formation of α-C2SH；at the temperature of 200 ℃，the main reason causing the strength retrogression of silica-cement system was that the C-S-H gel was gradual transited from amorphous to other crystalline.

10.19346/j.cnki.1000-4092.2025.01.004