层状盐岩储气库腔体偏溶影响因素及技术对策

中国石油大学(华东)储运与建筑工程学院

层状盐岩;储气库;偏溶;地层倾角;造腔工艺

Influencing factors of eccentric dissolution in gas storage cavities within layered salt rock and technical countermeasures
LENG Xiaoman

College of Pipeline and Civil Engineering, China University of Petroleum (East China)

layered salt rock, gas storage, eccentric dissolution, formation dip, cavity-building process

DOI: 10.6047/j.issn.1000-8241.2025.02.010

备注

【目的】为提高中国层状盐岩成腔效率,控制盐穴腔体规则度,扩大有限厚度盐层可形成的储气空间,保障造腔及注气排卤过程中管柱安全,针对金坛储气库勘探与钻井成果进行精细地质模型描述,统计分析了区域内腔体的形状溶蚀演变趋势与对应的造腔工艺措施,系统研究了腔体偏溶的影响因素与作用机理。【方法】金坛盐矿为典型的多夹层盐岩,应用三维地震勘探成果结合滚动实施的单井测井数据建立了区域盐岩及隔夹层发育地质模型,精细表征盐岩及隔夹层构造起伏,并对井筒周围隔夹层倾角趋势进行针对性研究。结合金坛储气库腔体实测声呐数据成果分析形状溶蚀扩展趋势及偏溶出现时机与地质特征关系,通过对比不同井隔夹层段溶蚀时注水动态与管柱控制策略研究了相关造腔工艺对腔体形状发展及控制的具体影响。【结果】井筒周围地层构造中的盐岩与隔夹层的垮塌时间不同、隔夹层倾角对腔体内流场干扰是导致腔体形状发生偏溶的基础地质因素,造腔管柱与隔夹层深度位置关系、注水排量等是导致腔体形状发生偏溶的关键工艺因素,应基于精细地质认识有针对性地提出合理的造腔工艺措施。【结论】中国盐矿普遍存在夹层多、倾角大的地质特征,应用新钻井测井数据结合勘探成果滚动加强地质认识,对存在偏溶风险的腔体进行针对性设计与控制,提高腔体体积、形状规则度,降低盐穴储气库投资成本,有助于高效推进复杂层状盐层储气库建设。(图 13,参[26]
[Objective] This paper aims to enhance practices in the gas storage sector of China, specifically by improving the efficiency of cavity formation in layered salt rock, controlling the cavity regularity of salt caverns, expanding potential gas storage space within salt beds of limited thickness, and ensuring the safety of tubing strings during cavity building, gas injection, and brine displacement. To achieve these objectives, detailed geological modeling was conducted to reflect the exploration and drilling results from Jintan gas storage. The evolution trends of cavity shapes due to dissolution in this gas storage area were statistically analyzed, along with relevant cavity-building process measures. Furthermore, the influencing factors and action mechanisms of eccentric dissolution in the cavities were systematically investigated. [Methods] The Jintan salt mine is situated within a typical multi-interbedded salt rock formation. A geological model for the regional development of salt rock and interlayers was established using three-dimensional seismic exploration results, along with data from single well logging conducted on a progressive basis. This approach allowed for a detailed characterization of the tectonic fluctuations of salt rock and interlayers. A subsequent study focused on the dip trends of interlayers close to the wellbores. Utilizing sonar data from cavity measurements at Jintan gas storage, the relationships of trends in shape expansion due to dissolution were analyzed in relation to the timing of eccentric dissolution and geological characteristics. By comparing the water injection dynamics and tubing string control strategies during the dissolution process in interlayer intervals across wells, the study explored the specific influences of relevant cavity-building processes on the development and control of cavity shapes. [Results] The collapse of salt rock and interlayers within the stratigraphic structure around the wellbores at different times, along with disturbances caused by interlayer dips to the flow field within the cavities, were identified as fundamental geological factors leading to eccentric dissolution that affects cavity shapes. The vertical positional relationships of tubing strings used for cavity construction in relation to interlayers and water injection displacements were revealed to be key process factors contributing to the eccentric dissolution. Therefore, it is recommended to propose targeted and rational cavity-building process measures based on a detailed geological understanding. [Conclusion] Salt mines in China are generally characterized by numerous interlayers and steep dips. It is recommended to progressively enhance geological understanding through the application of updated drilling and logging data in conjunction with exploration results. This strategy enables targeted design and control of cavities at risk of eccentric dissolution, improves cavity volumes and shape regularity, and reduces the investment cost of salt cavern gas storage. Consequently, it supports the efficient promotion of gas storage construction in complex stratified salt beds. (13 Figures, 26 References)
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