硅酸盐学报

高温油气井不同工况下低密度固井水泥长期性能演变规律

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李扬 ¹^,² , 庞学玉 ¹^,² , 于永金 ³ , 刘慧婷 ³ , 郭胜来 ¹^,² , 汪海阁 ³ , 吕开河 ¹^,² , 孙金声 ¹^,²

硅酸盐学报 | 研究论文 2026,54(8): 2843-2856

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硅酸盐学报 |研究论文 2026 , 54 (8) : 2843 -2856

高温油气井不同工况下低密度固井水泥长期性能演变规律

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李扬¹^,², 庞学玉¹^,², 于永金³, 刘慧婷³, 郭胜来¹^,², 汪海阁³, 吕开河¹^,², 孙金声¹^,²

作者信息

^1．深层油气全国重点实验室，中国石油大学（华东），山东青岛 266580

^2．中国石油大学（华东）石油工程学院，山东青岛 266580

^3．中国石油工程技术研究院有限公司，北京 102206

通讯作者:

庞学玉（1982—），男，博士，教授。

作者简介:

李扬（1997—），男，博士研究生。

Long-Term Property Evolution of Low-Density Well Cement Under Different Working Conditions in High-Temperature Oil and Gas Wells

Yang LI¹^,², Xueyu PANG¹^,², Yongjin YU³, Huiting LIU³, Shenglai GUO¹^,², Haige WANG³, Kaihe LV¹^,², Jinsheng SUN¹^,²

Affiliations

^1.State Key Laboratory of Deep Oil and Gas, China University of Petroleum (East China), Qingdao 266580, Shandong, China

^2.School of Petroleum Engineering. China University of Petroleum (East China), Qingdao 266580, Shandong, China

^3.CNPC Engineering Technology R & D Company Limited, Beijing 102206, China

Corresponding Author:

{PANG} Xueyu (1982-), male, Ph.D., Professor. E-mail: x.pang@upc.edu.cn

LI Yang (1997-), male, Doctoral candidate. E-mail: lyangupc@163.com

出版时间: 2026-05-11 doi: 10.14062/j.issn.0454-5648.20250842

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摘要

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井下高温高压环境会造成固井水泥的长期强度衰退，对井筒完整性构成重大风险。本工作探讨了不同高温工况下，低密度加砂固井水泥在180 ℃长期养护下的性能（抗压强度、杨氏模量、渗透率和孔隙结构）的演变。结果表明，常规高水灰比的低密度水泥在高温条件下（180 ℃）直接成型，并在养护时出现非常明显的力学性能衰退及孔隙粗化，而在80 ℃低温预养护成型180 ℃长期养护过程中力学性能非常稳定。通过加入空心玻璃微珠降低水灰比，可以显著提升低密度水泥石早期强度；然而2种养护方式下含有空心玻璃微珠的配方均出现较为明显的强度衰退，且高温直接成型条件下衰退更为严重。热重和X射线衍射分析表明，180 ℃高温成型的养护条件下，随养护时间增加，无定型水化产物与雪硅钙石向其他晶体相的转化，且水化产物热重分解峰变化比较明显，此为水泥石强度衰退的主要原因。相比之下，在80 ℃成型后再经过180 ℃长期养护，无定型水化产物与雪硅钙石含量随养护时间增加均十分稳定，此为水泥石强度稳定的主要原因。

关键词

高温高压 / 强度衰退 / 玻璃微珠 / 硅砂 / 低密度

Abstract

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Introduction

With the increasing depth of oil and gas exploration, high-temperature and high-pressure conditions become common in deep and ultra-deep wells. Under such harsh environments, the long-term integrity of wellbore cement is frequently compromised due to the strength retrogression, posing serious risks to zonal isolation and production safety. Although silica sand is widely used to mitigate strength degradation via modifying the Ca/Si ratio of hydration products, recent studies show that significant strength loss still occurs at ultra-high temperatures.

Previous studies focused on curing regimes involving low-temperature pre-curing followed by high-temperature exposure, which mainly represent upper wellbore conditions. However, in deeper sections of high-temperature wells, cement typically sets and cures directly at elevated temperatures, resulting in more severe degradation. In addition, low-density cement is widely applied in cementing operations, its long-term performance under such conditions remains insufficiently understood, particularly beyond short-term curing periods. This study was to investigate the long-term performance evolution and underlying mechanisms of low-density sand-added oil well cement under different high-temperature conditions, providing a guidance for the design of durable cement systems for deep well applications.

Methods

Six low-density cement slurry formulations with a target density of 1.6 g/cm³ were designed, incorporating silica sand, silica fume, and hollow glass microspheres. Two curing regimes were adopted to simulate different downhole environments, i.e., (1) direct curing at 180 ℃ to represent high-temperature deep well conditions, and (2) curing at 80 ℃ for 2 d and then long-term curing at 180 ℃ to simulate upper wellbore conditions. The long-term performance of cement samples was evaluated after curing at 180 ℃ for 2, 30 d, and 90 d, respectively. The compressive strength, Young's modulus, and permeability were measured to assess macroscopic properties. The microstructural and mineralogical evolution was characterized by mercury intrusion porosimetry (MIP), X-ray diffraction (XRD), thermogravimetric analysis (TG), and scanning electron microscopy (SEM), enabling a comprehensive analysis of pore structure development and hydration product transformation.

Results and discussion

The results indicate that curing conditions have a decisive influence on the long-term performance of low-density cement systems. Under direct high-temperature curing at 180 ℃, all formulations exhibit severe strength retrogression. The compressive strength of silica sand-based systems remains approximately 28 MPa within 30 d, but decreased to below 10 MPa after 90 d. The incorporation of hollow glass microspheres significantly enhances the early strength (i.e., up to 45 MPa at 2 d). However, these systems experience a rapid deterioration, with strength nearly disappearing after 30 d. In contrast, the samples subjected to low-temperature pre-curing and followed by high-temperature exposure show significantly improved stability. For formulations without hollow glass microspheres, the compressive strength remains stable or slightly increases for 90 d. However, the systems containing hollow glass microspheres still exhibit a noticeable strength reduction, indicating their limited suitability for high-temperature applications. The evolution of Young's modulus and permeability is consistent with the strength results. Under direct high-temperature curing, Young's modulus decreases markedly, while permeability increases in orders of magnitude, indicating severe degradation of structural integrity. Conversely, under low-temperature pre-curing conditions, the parameters both remain relatively stable, reflecting an improved durability. The microstructural analysis reveals that pore structure coarsening plays a key role in the performance degradation. Under direct high-temperature curing, the median pore size increases significantly from tens to hundreds of nanometers, accompanied by a transformation from harmless pores to harmful large pores. In contrast, the samples subjected to low-temperature pre-curing exhibit slower pore coarsening and more stable pore size distributions. The mineralogical evolution further explains the observed macroscopic behavior. Under direct high-temperature curing, beneficial amorphous hydration products and tobermorite gradually transform into more crystalline phases such as xonotlite, leading to the strength loss. The thermogravimetric analysis confirms significant changes in decomposition peaks, indicating alterations in hydration product composition. In contrast, under low-temperature pre-curing conditions, the content of amorphous phases and tobermorite remains relatively stable, contributing to sustained mechanical performance. The SEM images show that hollow glass microspheres progressively react and disappear under prolonged high-temperature exposure, leaving large voids that significantly deteriorate the microstructure. Although these microspheres enhance the early strength, their long-term effect is detrimental due to the pore enlargement and structural weakening.

Conclusions

This study demonstrated that curing conditions critically affected the long-term performance of low-density sand-added oil well cement. Direct high-temperature curing led to severe strength retrogression, pore structure coarsening, and unfavorable phase transformations, whereas low-temperature pre-curing significantly improved long-term stability. Hollow glass microspheres were effective in enhancing early strength but are not suitable for high-temperature applications due to their negative impact on long-term durability. The stability of hydration products, particularly amorphous phases and tobermorite, could be identified as a key factor governing strength retention. These findings could provide important insights into the design of durable cement systems for high-temperature oil and gas wells and highlight the necessity of considering both curing conditions and material composition in practical applications.

Key words

high temperature / strength retrogression / hollow glass microspheres / silica sand / low-density cement

引用本文

李扬, 庞学玉, 于永金, 刘慧婷, 郭胜来, 汪海阁, 吕开河, 孙金声. 高温油气井不同工况下低密度固井水泥长期性能演变规律. 硅酸盐学报, 2026 , 54 (8) : 2843 -2856 . DOI: 10.14062/j.issn.0454-5648.20250842

Yang LI, Xueyu PANG, Yongjin YU, Huiting LIU, Shenglai GUO, Haige WANG, Kaihe LV, Jinsheng SUN. Long-Term Property Evolution of Low-Density Well Cement Under Different Working Conditions in High-Temperature Oil and Gas Wells[J]. Journal of the Chinese Ceramic Society, 2026 , 54 (8) : 2843 -2856 . DOI: 10.14062/j.issn.0454-5648.20250842

基金

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国家自然科学基金(52288101)
中国石油大学（华东）深层油气全国重点实验室自主研究课题(SKLDOG2024-ZYTS-11)

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2026年第54卷第8期

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文章信息

doi: 10.14062/j.issn.0454-5648.20250842

接收时间：2025-11-14
首发时间：2026-10-22
出版时间：2026-05-11

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收稿日期：2025-11-14
修回日期：2025-12-02

基金

国家自然科学基金(52288101)

中国石油大学（华东）深层油气全国重点实验室自主研究课题(SKLDOG2024-ZYTS-11)

作者信息

^1．深层油气全国重点实验室，中国石油大学（华东），山东青岛 266580

^2．中国石油大学（华东）石油工程学院，山东青岛 266580

^3．中国石油工程技术研究院有限公司，北京 102206

通讯作者:

庞学玉（1982—），男，博士，教授。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20250842

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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