石油与天然气地质 ›› 2023, Vol. 44 ›› Issue (5): 1321-1332.doi: 10.11743/ogg20230520

• 方法技术 • 上一篇    

温-压耦合作用下深层盐岩盖层封闭能力演化特征

赵珊1,2(), 刘华1,2, 杨宪章3, 朱永峰3, 王伸1,2, 张科3, 魏鑫1,2   

  1. 1.深层油气全国重点实验室,中国石油大学(华东) 地球科学与技术学院,山东 青岛 266580
    2.海洋国家实验室 海洋矿产资源 评价与探测技术功能实验室,山东 青岛 266071
    3.中国石油 塔里木油田分公司,新疆 库尔勒 841001
  • 收稿日期:2023-03-13 修回日期:2023-06-30 出版日期:2023-10-01 发布日期:2023-10-19
  • 第一作者简介:赵珊(1993—),女,博士,油气成藏机理与分布规律。E-mail: 924208649@qq.com
  • 基金项目:
    国家自然科学基金项目(42172147);国家重点研发计划专项(2019YFC0605502);中国石油重大科技专项(ZD2019-183-002)

Evolutionary characteristics of sealing capacity of deep salt caprocks under temperature-pressure coupling

Shan ZHAO1,2(), Hua LIU1,2, Xianzhang YANG3, Yongfeng ZHU3, Shen WANG1,2, Ke ZHANG3, Xin WEI1,2   

  1. 1.School of Geosciences,China University of Petroleum (East China),Qingdao,Shandong 266580,China
    2.Laboratory for Marine Mineral Resources,National Laboratory for Marine Science and Technology,Qingdao,Shandong 266071,China
    3.PetroChina Tarim Oil Field Company,Korla,Xinjiang 841001,China
  • Received:2023-03-13 Revised:2023-06-30 Online:2023-10-01 Published:2023-10-19

摘要:

为了研究温-压耦合作用对盐岩盖层封闭能力演化的影响,选择中国金坛盐洞的盐岩样品,利用高温-高压三轴岩石力学测试系统实验装置,设计开展恒温变压、恒压变温以及温-压耦合3组实验,模拟温度、压力条件对盐岩盖层封闭能力演化的影响。研究结果表明:①温-压耦合作用导致盐岩短期强度大幅减弱,塑性大幅增强,缩短了脆-塑性转化时间,其中,由温度引起的盐岩短期强度降低百分比(Ti )大于35.06 %;压力引起的盐岩短期强度降低百分比(pi )最大只有38.25 %,表明埋藏过程中,盐岩力学性质主要受控于温度。②单一压力作用下,盐岩裂缝具有逐渐减少、愈合的趋势;而温-压耦合作用下,盐岩会出现“裂缝再次发育”现象,其中,低温阶段(温度<90 ℃),压力占主导地位,高温阶段(温度≥90 ℃),温度占主导地位,盐岩出现蠕变损伤。③建立“深层盐岩”脆性—脆-塑性—塑性—蠕变损伤—损伤愈合”演化模式,其中,蠕变损伤阶段对于盐下油气藏的保存极为不利。因此,准确厘定盐岩封闭能力的演化特征可为深层盐下油气藏的富集规律分析提供理论依据。

关键词: 温-压耦合, 三轴应力-应变实验, 脆-塑性转化, 热损伤, 封闭能力演化, 深层盐岩盖层

Abstract:

Three sets of experiments, including constant temperature-variable-pressure, variable temperature-constant pressure, and temperature-pressure coupling, were executed to simulate the influence of temperature and pressure conditions on the evolution of salt rock cap sealing ability using the experimental device of high temperature and high pressure triaxial rock mechanics testing system on salt rock samples from Jintan Salt Cave, China. The results indicate that: ① The coupling effect of temperature and pressure leads to a significant reduction in short-term strength, significant enhancement of plasticity of salt rock, and shortening of brittle-to-plastic transition time. The percentage (Ti ) of short-term strength reduction of salt rock caused by temperature is greater than 35.06 % while the maximum short-term strength reduction percentage (Pi ) of salt rock caused by pressure is only 38.25 %, indicating that the mechanical properties of salt rock are mainly controlled by temperature during the burial process. ② Under a single pressure, salt rock fractures have a trend of gradually decreasing and healing; while under the coupling of temperature and pressure, the salt rock will experience a phenomenon of “re-cracking”, with pressure dominating the low temperature stage (temperature < 90 ℃) and temperature dominating the high temperature stage (temperature ≥ 90 ℃), resulting in creep damage to the salt rock. ③ An evolutionary model of “brittleness—brittleness-plasticity—plasticity—creep damage—damage healing” was established for deep salt rocks. Under the coupling of temperature and pressure, the creep damage stage is extremely unfavorable for the preservation of oil and gas reservoirs under high temperature conditions. Therefore, accurately determining the evolution characteristics of salt rock sealing ability can provide a theoretical basis for analyzing the enrichment patterns of deep pre-salt oil and gas reservoirs.

Key words: temperature-pressure coupling, triaxial stress-strain experiment, brittle-plastic transition, thermal damage, sealing capacity evolution, deep salt caprock

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