8月20日清晨，长庆油田采油五厂黄3区一口二氧化碳注入井旁，巡检人员打开井口数据界面，注入压力、套压、温度等参数实时刷新。

On the early morning of August 20th, beside a carbon dioxide injection well in the Huang3 area of the Fifth Oil Production Plant of Changqing Oilfield, the inspection personnel opened the data interface of the wellhead. The parameters such as injection pressure, casing pressure and temperature were updated in real time.

地面上，井口装置安静运行；地下深处，二氧化碳正沿着井筒进入油藏，在微小孔隙间驱动原油，也在地层中逐渐实现封存。

On the surface, the wellhead equipment is operating quietly; deep underground, carbon dioxide is flowing along the wellbore into the oil reservoir, driving crude oil through tiny pores and gradually achieving sequestration within the rock formations.

在CCUS工程中，二氧化碳要经历捕集、输送、注入、驱油、循环利用和地质封存等多个环节。对于油田现场来说，注入井既是二氧化碳进入地下的“通道”，也是防止其异常窜流和泄漏的第一道关口。

In the CCUS project, carbon dioxide needs to go through multiple stages such as capture, transportation, injection, oil displacement, recycling and geological storage. For the on-site oilfield, the injection well serves as both the "channel" for carbon dioxide to enter the ground and the first line of defense against abnormal seepage and leakage.

注入井有了“体检表”

The injection wells now have "checklists"

截至目前，长庆油田已在14个区块推进CCUS试验与工业化应用，建成年注入能力70万吨的工程体系，累计注入二氧化碳120万吨以上。其中，黄3区CCUS国家级示范工程累计注入二氧化碳39万吨以上，成为长庆油田探索低渗透油藏二氧化碳驱油与封存的重要阵地。

As of now, the Changqing Oilfield has carried out CCUS trials and industrial applications in 14 blocks, establishing an engineering system with an annual injection capacity of 700,000 tons. A total of over 1.2 million tons of carbon dioxide have been injected. Among them, the national-level demonstration project of CCUS in the Huang3 area has injected over 3.9 million tons of carbon dioxide, becoming an important base for the Changqing Oilfield to explore carbon dioxide flooding and storage in low-permeability oil reservoirs.

随着注入规模的扩大，一个问题越来越清晰地摆在技术人员面前：二氧化碳注下去以后，怎么确保它按照设计路径进入油藏，而不是沿着井筒、水泥环微缝或环空异常通道上窜？

As the injection scale expands, a problem becomes increasingly clear to the technicians: After the carbon dioxide is injected, how can we ensure that it enters the oil reservoir along the designed path, rather than flowing up through the wellbore, the cement ring micro-fissures, or the abnormal channels in the annulus?

二氧化碳有自己的“脾气”。在一定温压条件下，它易与水形成碳酸环境，对金属管柱、水泥石和密封材料进行腐蚀。对于低渗透油藏，注入压力波动、地层应力变化、长期交变载荷，也会考验水泥环和地层界面的密封能力。

Carbon dioxide has its own "temperament". Under certain temperature and pressure conditions, it readily reacts with water to form a carbonic acid environment, which can cause corrosion to metal pipe columns, cement rocks and sealing materials. For low-permeability oil reservoirs, fluctuations in injection pressure, changes in formation stress, and long-term alternating loads will also test the sealing ability of the cement ring and the formation interface.

一口注入井的风险，往往藏在看不见的地方：油管螺纹是否长期气密封，封隔器胶筒是否耐受二氧化碳腐蚀和压力波动，水泥环是否存在微裂缝，套管外壁是否受到环空介质腐蚀，环空压力变化背后是否暗示着微渗通道。

The risks of a single injection well often lie in areas that are not visible: whether the pipe threads have maintained a long-term gas seal, whether the packer rubber sleeve can withstand carbon dioxide corrosion and pressure fluctuations, whether there are micro-cracks in the cement ring, whether the outer wall of the casing is corroded by the medium in the annulus, and whether the changes in annular pressure imply the existence of micro-permeable channels.

长庆油田将这些问题纳入一套完整的“井筒体检表”。从井口装置到井下管柱，从固井质量到环空保护液，从材料防腐到压力监测，每一个部件、每一道屏障都有对应的评价指标和管控要求。

The Changqing Oilfield has incorporated these issues into a comprehensive "wellbore health check list". From the surface equipment to the downhole tubing, from the cementing quality to the wellbore protection fluid, from material corrosion prevention to pressure monitoring, each component and each barrier has corresponding eva luation indicators and control requirements.

“过去是发现异常再处理，现在要把风险识别前移。”长庆油田油气工艺研究院井下作业与工具研究所王在强形象地说，CCUS井筒完整性管理，就是给地下“碳流”装上多道安全门，让二氧化碳进得去、留得住、查得清、控得稳。

"In the past, abnormalities were detected and then dealt with. Now, the risk identification process needs to be moved forward." Wang Zaiqiang, from the Downhole Operations and Tools Research Institute of the Oil and Gas Process Technology Research Institute of Changqing Oilfield, vividly said. "CCUS wellbore integrity management is like installing multiple safety gates for the underground 'carbon flow', allowing carbon dioxide to enter, remain, be inspected and controlled stably."

创新整套技术锻造“密封锁”

Innovatively developing a complete set of technologies to create the "Sealing Lock"

水泥环与套管之间、水泥环与地层之间，一旦出现胶结不良或微环隙，二氧化碳就可能沿着薄弱界面运移。封隔器密封性能下降，可能造成油套连通；管柱腐蚀穿孔，可能引发套压异常；环空保护液性能不足，也会削弱对套管和油管外壁的防护。

In the case of poor cement bonding or micro-porosity between the cement ring and the casing, or between the cement ring and the formation, carbon dioxide may migrate along the weak interface. The sealing performance of the packer deteriorates, which may lead to oil-tube communication; corrosion and perforation of the pipe string may cause abnormal wellbore pressure; and insufficient performance of the fluid in the annulus will also weaken the protection of the outer walls of the casing and tubing.

面对这些隐蔽风险，长庆油田没有把井筒完整性当作单一设备问题，而是以系统思维推进管柱、工具、材料、监测、施工组织协同攻关。

Facing these hidden risks, the Changqing Oilfield did not view wellbore integrity as a single equipment issue. Instead, it adopted a systematic approach to jointly tackle the issues of pipe strings, tools, materials, monitoring, and construction organization.

在盐309区块，长庆油田部署盐气1井、盐气3井、盐气4井、盐气6井4口注气井，采用大通径连续油管注气完井工艺，建成长庆油田首个连续油管注气完井平台。该平台采用规格为60.3毫米的耐蚀合金连续油管作为注气核心管柱，一体化、无接箍的管柱结构，消除了传统螺纹连接带来的泄漏隐患，也为分布式光纤监测、精准吸气剖面测试等后续动态监测预留了空间。

In the Salt 309 block, Changqing Oilfield has deployed 4 injection wells, namely Salt Gas Well 1, Salt Gas Well 3, Salt Gas Well 4, and Salt Gas Well 6. These wells adopt the large-diameter continuous tubing gas injection completion technology. A continuous tubing gas injection completion platform for Changqing Oilfield has been established. This platform uses a corrosion-resistant alloy continuous tubing with a specification of 60.3 millimeters as the core tubing column. The integrated and without-spigot structure eliminates the leakage risks caused by traditional threaded connections and also reserves space for subsequent dynamic monitoring such as distributed optical fiber monitoring and precise gas absorption profile testing.

与管柱配套的，是自主研制的新型高效气密封封隔器和连续油管专用坐封球座。通过优化材料与结构设计，井下工具的可靠性和长期密封稳定性进一步提升，相当于为地下“碳仓库”加装了一道更加可靠的“密封锁”。

Complementary to the pipe string are the newly-developed, highly efficient gas seal isolation devices and the special seating balls specifically designed for continuous tubing. Through optimizing the material and structural design, the reliability and long-term sealing stability of the downhole tools have been further enhanced. This is equivalent to installing a more reliable "sealing lock" for the underground "carbon warehouse".

“首个CCUS连油注气完井平台的建成投运，提升了注采工艺的技术水平，为连续油管注气完井扩大试验积累了丰富的施工经验，对长庆油田实现注入井全生命周期安全注气、打造CCUS特色技术及品牌工程具有里程碑的意义。”长庆油田油气工艺研究院技术负责人吕伟说。

The completion and operation of the first CCUS continuous oil injection and gas injection well completion platform have enhanced the technical level of the injection and production process, accumulated rich construction experience for the expansion of continuous tubing gas injection well completions, and have significant milestone significance for the Longqing Oilfield to achieve safe gas injection throughout the entire life cycle of injection wells, to develop CCUS characteristic technologies and brand projects. This was said by Lv Wei, the technical director of the Oil and Gas Technology Research Institute of Longqing Oilfield.

围绕连续油管注气完井技术，长庆油田已申报国家发明专利4项、实用新型专利1项、发布技术标准1项，为CCUS注入井井筒完整性控制提供了可复制、可推广的“长庆方案”。

Regarding the continuous tubing gas injection well completion technology, the Changqing Oilfield has applied for 4 national invention patents, 1 utility model patent, and released 1 technical standard. This has provided a replicable and scalable "Changqing solution" for the wellbore integrity control of CCUS injection wells.

每口井都有一本“安全账”

Each well has its own "safety ledger"

对于CCUS工程来说，新井要建得稳，老井转注更要看得准。

For the CCUS project, the construction of new wells must be stable, and the operation of old wells for injection must be precisely controlled.

长庆油田部分CCUS注入井由老井转注而来。过去这些井用于采油、注水或其他生产任务，井史长、作业次数多、井况差异大。它们在原有生产条件下可能运行正常，但并不意味着一定适合二氧化碳注入。一旦固井质量、套管状况、封隔器密封、防腐能力等基础条件没有评价清楚，就可能把原本隐蔽的井筒风险带入CCUS注入阶段。

Some of the CCUS injection wells in the Changqing Oilfield were originally oil production wells or water injection wells. In the past, these wells were used for oil extraction, water injection, or other production tasks. They had long histories, numerous operations, and significant differences in well conditions. They might operate normally under the original production conditions, but this does not necessarily mean they are suitable for carbon dioxide injection. If the basic conditions such as cementing quality, casing condition, packer sealing, and anti-corrosion capability are not eva luated clearly, the previously hidden wellbore risks may be brought into the CCUS injection stage.

为解决这一问题，长庆油田把老井井筒的完整性评价前移到方案设计和转注决策阶段——

To address this issue, the Changqing Oilfield has moved the integrity assessment of the old well shafts to the stage of scheme design and transfer-in decision-making.

在设计端，针对二氧化碳注入井工况，优选气密封管柱、耐腐蚀材质、防腐水泥体系和可靠封隔器组合，把防腐、防窜、防压失效要求前置到方案设计阶段。

In the design stage, for the operation conditions of carbon dioxide injection wells, the preferred options include gas-sealing pipe strings, corrosion-resistant materials, anti-corrosion cement systems, and reliable packers. The requirements for anti-corrosion, anti-squeezing, and anti-pressure failure are incorporated at the design stage.

在施工端，严控固井质量、管柱连接、封隔器坐封、井口试压等关键工序，确保每一道井筒屏障在入井之初就达到设计要求。

At the construction site, strict control is exercised over key processes such as cementing quality, pipe string connection, packer setting, and wellhead pressure testing, to ensure that each barrier in the wellbore meets the design requirements from the very beginning of the well entry.

在运行端，重点监测注入压力、油套压、环空压力、温度变化和注入量变化，一旦出现套压持续恢复、压力异常波动等苗头，技术人员就可以通过泄压恢复测试、环空液面测试、气体组分分析等方式，判断出异常是来自管柱、封隔器、套管，还是水泥环和地层界面。

At the operation site, the key monitoring items include injection pressure, oil-tubing pressure, annular pressure, temperature changes, and injection volume changes. If there are signs such as continuous recovery of tubing pressure or abnormal pressure fluctuations, technicians can use methods like pressure relief recovery tests, annular liquid level tests, and gas component analysis to determine whether the anomaly is caused by the pipe string, packer, casing, cement ring, or the interface between the formation.

这套体系让每一口井都有风险画像、运行边界和处置预案。从“出了问题再处理”到“发现苗头就预警”，长庆油田正在把井筒完整性管理从事后治理推向事前预防、事中监测和闭环处置。

This system provides each well with a risk profile, operational boundaries and response plans. From "addressing problems after they occur" to "warning when problems are detected early", the Changqing Oilfield is shifting wellbore integrity management from post-event remediation to proactive prevention, real-time monitoring and closed-loop handling.

井筒完整性不仅是“防得牢”的安全问题，也是CCUS工程的效益问题。井筒稳，注入制度才能稳；封隔可靠，二氧化碳才能更多地进入目标油层；环空受控，现场才能减少非计划停注和维护作业。安全屏障越可靠，绿色低碳工程的经济账才越算得清。

Well integrity is not only a safety issue of "being well secured", but also a cost-effectiveness issue for CCUS projects. A stable well can ensure a stable injection system; reliable isolation can allow more carbon dioxide to enter the target oil layer; and controlled annular space can reduce unplanned shutdowns and maintenance operations on-site. The more reliable the safety barrier is, the clearer the economic calculation of the green and low-carbon project will be.

随着长庆油田CCUS从先导试验走向扩大应用，单靠经验盯井已经难以适应规模化发展需要。注入井不再只是井号和报表上的一串数据，而是拥有完整生命周期档案的“数字对象”。设计参数、完井结构、固井质量、管柱材质、封隔器型号、试压结果、腐蚀监测、环空压力、历次作业记录等信息逐步汇集，成为判断井筒状态的基础资料。

As the CCUS technology in the Changqing Oilfield progresses from pilot trials to large-scale application, relying solely on experience to monitor individual wells is no longer sufficient to meet the requirements of large-scale development. Injection wells are no longer just a series of numbers and data on a report sheet; instead, they are "digital objects" with complete lifecycle archives. Design parameters, well completion structure, cementing quality, pipe material, packer model, test pressure results, corrosion monitoring, annular pressure, and records of previous operations are gradually collected, becoming the basic data for assessing the condition of the wellbore.

如今，长庆油田CCUS技术已从单点试验迈向规模化布局。二氧化碳在地下驱动原油，也在推动油田开发方式向绿色低碳转变。而井筒完整性体系，就像这项工程的地下安全证书，证明每一吨被注入的二氧化碳，不只是进入地层，更是在可监测、可评价、可管理的体系中安全运行。

Currently, the CCUS technology of Changqing Oilfield has advanced from single-point experiments to large-scale deployment. Carbon dioxide is used to drive crude oil underground, and it is also promoting the transformation of oilfield development methods towards green and low-carbon. The well integrity system, like the underground safety certificate for this project, proves that every ton of injected carbon dioxide not only enters the formation, but also operates safely within a monitored, eva luated and manageable system.