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地质力学学报:2021,27(1):1-9
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川西须家河组致密砂岩高温后的物理力学特征参数试验研究
(1.西南石油大学油气藏地质及开发工程国家重点试验室, 四川 成都 610500;2.中海石油 (中国) 有限公司湛江分公司, 广东 湛江 524057)
Experimental study on physical and mechanical characteristics of tight sandstones in the Xujiahe Formation in western Sichuan after high-temperature exposure
(1.State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation, Chengdu 610500, Sichuan, China;2.Zhanjiang Branch of China National Offshore Oil Corporation Limited, Zhanjiang 524057, Guangdong, China)
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投稿时间:2019-11-01    修订日期:2020-04-21
中文摘要: 为了在井下加热改善近井区域渗流能力以提高低渗透油气藏开采效率的同时保证井壁稳定,研究了高温对四川隆昌须家河组须二段致密砂岩微观结构、力学性质及渗透性的影响,对26~1000℃高温处理后的试样进行了热重分析、电镜扫描分析(SEM)、声波测试、物理参数测定、单轴压缩试验及渗透率测试,分析高温后试样的组分、微观结构、力学参数及渗透率与温度的相关性。结果表明:在26~1000℃范围内,致密砂岩试样随温度升高不断脱去内部水分,粘土矿物含量分阶段减少,进而造成试样质量减小、视密度降低;致密砂岩岩石性能在400℃左右存在一个阈值温度,当致密砂岩高于400℃时,其抗压强度及抗变形能力急剧降低;内部裂缝网络随着温度的增高,裂缝数量不断增多,裂缝网络规模不断增大,导致高温后岩样渗透率不断增加,且增速随温度不断增大,表明将油气井加热温度控制在400℃以上并增大加热范围有利于提高单井产能。研究结果可为致密砂岩气藏中实施电加热增产技术时判断井筒安全性及单井产能增产效果提供一定参考。
中文关键词: 高温加热  致密砂岩  波速  渗透率  力学性质
Abstract:This study aims to boost the seepage capacity in the near-well area by the downhole heating so as to improve the production efficiency of low-permeability reservoir while ensuring the sidewall stability. Taking the second member of the Xujiahe Formation in Longchang as the subject, the effect of high temperature on the microstructure, mechanical property and permeability of tight sandstones were studied. The samples underwent thermogravimetric analysis, scanning electron microscopy (SEM), acoustic wave test, physical parameter measurement, uniaxial compression test and permeability test after high-temperature exposure in the range of 26 ℃ to 1000 ℃, and temperature's relevance to the composition, microstructure, mechanical parameter and permeability were analyzed. The test results showed that the internal moisture of the samples was removed continuously with the increase of temperature, and the content of clay minerals decreased by stages in the range of 26 ℃ to 1000 ℃, which led to the decrease of sample mass and apparent density. There was a threshold temperature at about 400 ℃ for the performance of tight sandstone. When the temperature was higher than 400 ℃, the compressive strength and deformation resistance of the samples decreased sharply. With the increase of temperature, more internal fractures emerged and the network size was enlarged, leading to the continuous growing increase of permeability. Therefore, it is considered that keeping the downhole heating temperature above 400 ℃ and expanding the heating range as well are conducive to improving the productivity of single well. The findings of this study are of value for evaluating the wellbore stability and stimulation effect of single well while applying the electric heating technology in tight sandstone reservoirs.
文章编号:     中图分类号:TU45;TE31    文献标志码:
基金项目:国家自然科学基金项目(51674217)
引用文本:
于鑫,李皋,陈泽,等,2021.川西须家河组致密砂岩高温后的物理力学特征参数试验研究[J].地质力学学报,27(1):1-9.DOI:10.12090/j.issn.1006-6616.2021.27.01.001
YU Xin,LI Gao,CHEN Ze,et al,2021.Experimental study on physical and mechanical characteristics of tight sandstones in the Xujiahe Formation in western Sichuan after high-temperature exposure[J].Journal of Geomechanics,27(1):1-9.DOI:10.12090/j.issn.1006-6616.2021.27.01.001

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