盐岩岩芯制备方法及蠕变特性  

Artificial Preparation Method and Creep Characteristics of Salt Rock Core

作　　者：项明 张喆 李梦博 王名春 闫传梁 XIANG Ming;ZHANG Zhe;LI Meng-bo;WANG Ming-chun;YAN Chuan-liang(CNOOC International Corporation,Beijing 100000,China;School of Petroleum Engineering,China University of Petroleum(East China),Qingdao 266000,China;CNOOC Research Institute Co.,Ltd.,Beijing 100029,China)

机构地区：[1]中国海洋石油国际有限公司,北京100000 [2]中国石油大学(华东)石油工程学院,青岛266000 [3]中海油研究总院有限责任公司,北京100029

出　　处：《科学技术与工程》2025年第3期1018-1027,共10页Science Technology and Engineering

基　　金：国家自然科学基金基础科学中心项目(52288101);山东省高等学校青年创新团队项目(2022KJ072)。

摘　　要：世界范围内分布着大量的盐下油气田,由于盐层取芯作业造价昂贵,因此难以针对具体区块的盐岩岩芯进行蠕变实验。针对以上难题,创建了一种人造盐岩岩芯压制方法,通过调整制备温度和压力来控制重结晶程度。通过测试在不同制备条件下的盐岩岩芯的声波速度、密度、单轴峰值强度,优选出了最佳的制备条件,并通过蠕变实验验证了人造盐岩岩芯与天然盐岩岩芯具有相似的蠕变特性,通过人造盐岩岩芯代替天然岩芯的方案是可行的;基于室内蠕变实验构建了盐岩的黏弹性本构模型,研究发现,盐岩的减速蠕变阶段的流变特征符合Kelvin模型,稳态蠕变阶段符合Heard模型,编译UMAT子程序描述其减速、稳态阶段蠕变特征,具有较好的拟合度,表明本研究中构建的黏弹性模型的适用性;对不同含量硬石膏的复合盐岩进行了蠕变实验,结果表明硬石膏的存在对盐岩的蠕变具有一定的抑制作用,盐岩中硬石膏含量越高,岩石的蠕变速率越低,因此在含有硬石膏的盐膏层中,可适当降低钻井时所使用的钻井液的密度。A significant number of subsalt oil and gas fields are distributed worldwide.Due to the high costs associated with coring operations in salt formations,conducting creep experiments on specific salt rock cores is challenging.To address this issue,a method for creating artificial salt rock cores was developed wherein the degree of recrystallization was controlled by adjusting the preparation temperature and pressure.By testing the acoustic velocity,density,and uniaxial peak strength of salt rock cores under different prepa-ration conditions,the optimal preparation conditions were identified.Creep experiments verified that the artificial salt rock cores exhibit similar creep characteristics to natural salt rock cores,indicating the feasibility of using artificial cores as substitutes for natural ones.Based on indoor creep experiments,a viscoelastic constitutive model of salt rock was constructed.The result showed that the rheological characteristics of the decelerating creep stage conform to the Kelvin model,while the steady-state creep stage aligns with the Heard model.A UMAT subroutine was compiled to describe the creep characteristics of the decelerating and steady-state stages,demonstra-ting a good fit and indicating the applicability of the viscoelastic model constructed in this study.Creep experiments on composite salt rocks with different contents of anhydrite showed that the presence of anhydrite inhibits the creep of salt rock.The higher the anhydrite content in the salt rock,the lower the creep rate of the rock.Therefore,in salt layers containing anhydrite,the density of drilling fluid used during drilling can be appropriately reduced.

关 键 词：人造岩芯 盐岩 蠕变 岩石力学 

分 类 号：TE142[石油与天然气工程—油气勘探] O345[理学—固体力学]