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不同岩石多裂缝扩展规律研究

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为了研究不同岩石力学性能下多裂缝扩展规律,考虑流体流动对裂缝扩展以及岩石变形的影响,基于扩展有限元方法,建立水力压裂裂缝垂向扩展的数学模型,得到了多裂缝在不同力学性质岩石扩展过程中注入压力、注入点宽度、裂缝偏转度的变化规律,以及裂缝间距在不同岩石中的影响规律.结果表明,随着岩石弹性模量和抗拉强度的增强,相同压裂时间下的裂缝扩展长度增加,孔隙压力增加;岩石等效位移随着岩石弹性模量和抗拉强度的降低而增加,与裂缝数量呈正相关,并且随着裂缝数量的增加,岩石等效位移增加的趋势更明显;随着岩石弹性模量和抗拉强度的增强,裂缝间距对注入点孔隙压力的影响并不明显.当裂缝之间的间距增大到一定程度,裂缝间应力干扰作用减小,裂缝不发生偏转.该研究对不同岩性下水力压裂施工工艺簇间距的优选具有一定的借鉴意义.
Research on the Propagation Law of Multiple Cracks Under Different Lithology
In order to study the propagation law of multiple cracks under different rock mechanical properties,considering the influence of fluid flow on crack propagation and rock deformation,a mathematical model for vertical propagation of hydraulic fracturing cracks was established based on the extended finite element method.The effects of rocks with different mechanical properties on the injection pressure,injection point width,crack deflection,and crack spacing of multiple cracks were obtained.The results show that with the enhancement of elastic modulus and tensile strength,the crack propagation length and pore pressure increases under the same fracturing time.The equivalent displacement of rocks increases with the decrease of rock elastic modulus and tensile strength,and is positively correlated with the number of cracks.Moreover,as the number of cracks increases,the trend of the increase in equivalent displacement of rocks becomes more pronounced.With the enhancement of elastic modulus and tensile strength,the effect of crack spacing on pore pressure at the injection point is not significant.When the spacing between cracks increases to a certain extent,the stress interference between cracks decreases,and cracks do not deflect.This study has certain reference significance for optimizing the cluster spacing of hydraulic fracturing construction process under different lithology.

hydraulic fracturingpropagation finite elementmultiple crack propagationrock mechanics performance

杜林雅、王家航、李基伟、陈进程、张祯祥

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中国石油化工股份有限公司上海海洋油气分公司石油工程技术研究院,上海 200120

中石化石油工程技术研究院有限公司,北京 102200

水力压裂 扩展有限元 多裂缝扩展 岩石力学性能

"十三五"国家重大科技专项

2016ZX05027-003

2024

海洋石油
中国石油化工股份有限公司上海海洋油气分公司

海洋石油

影响因子:0.325
ISSN:1008-2336
年,卷(期):2024.44(3)