基于无预制裂纹3排平行孔平板的疲劳试验,对含相似应力水平的多细节结构产生多处损伤(Multiple Site Damage,MSD)的规律进行了研究。为了研究产生MSD结构中裂纹之间的干涉影响,利用Franc2D/L对主裂纹、等长双侧裂纹,等长单双裂纹、单孔...基于无预制裂纹3排平行孔平板的疲劳试验,对含相似应力水平的多细节结构产生多处损伤(Multiple Site Damage,MSD)的规律进行了研究。为了研究产生MSD结构中裂纹之间的干涉影响,利用Franc2D/L对主裂纹、等长双侧裂纹,等长单双裂纹、单孔等长双裂纹四种开裂模式的裂纹应力强度因子进行了计算分析。计算结果表明:裂纹扩展初期,裂纹主要受到自身开裂孔的干涉影响,四种模式下裂纹的无量纲应力强度因子比较相近;随着裂纹长度的增加,试验和有限元结果都表明了裂纹间的干涉影响显著加快了裂纹的扩展速度。展开更多
In recent years,the Yanchang shale-oil formations of the Ordos Basin are rich in reserves with complex lithology and structure characteristics,low porosity and low permeability,and weak anomalies for oil and water dis...In recent years,the Yanchang shale-oil formations of the Ordos Basin are rich in reserves with complex lithology and structure characteristics,low porosity and low permeability,and weak anomalies for oil and water discriminations,have been the key targets of unconventional oil/gas resource exploration and development in the relevant areas.The joint acoustic-electrical(AE)properties can be used to interpret reservoir lithology,mineralogy,pore structure,and fluid saturation.To conduct tests of thin section analysis,X-ray diff raction,and ultrasonic and electrical experiments at diff erent pressures and saturation degrees,cores from the shale-oil formations in the Q area of the basin are collected.The variations in AE properties with respect to clay content,porosity,pressure(microfracture),and saturation are analyzed.The experimental results indicate that the rock physics behaviors of sandstones with diff erent clay contents vary significantly.The AE properties of clean sandstones are basically dependent on the microfractures(pressure),while for muddy sandstones,the clay content is an important factor affecting the responses.The target reservoir consists of interbedded sandstone and shale layers.The AE equivalent medium equations and the Gurevich theory are applied to establish the joint models for the diff erent lithologies and simulate the variations in AE properties with respect to fluid type,pore structure,and mineral components.The three-dimensional joint templates of clean and muddy sandstones,as well as shale,are developed based on the elastic and electrical attributes and then calibrated using the experimental and well-log data.The reservoir properties are estimated with the templates and validated by the log data.The results indicate that the joint templates based on lithology characteristics can eff ectively characterize the properties of interbedded sandstone and shale layers.Furthermore,the combined application of AE data provides more beneficial information for the assessment of rock properties,leading to precise estimates that conform with the actual formation conditions.展开更多
文摘基于无预制裂纹3排平行孔平板的疲劳试验,对含相似应力水平的多细节结构产生多处损伤(Multiple Site Damage,MSD)的规律进行了研究。为了研究产生MSD结构中裂纹之间的干涉影响,利用Franc2D/L对主裂纹、等长双侧裂纹,等长单双裂纹、单孔等长双裂纹四种开裂模式的裂纹应力强度因子进行了计算分析。计算结果表明:裂纹扩展初期,裂纹主要受到自身开裂孔的干涉影响,四种模式下裂纹的无量纲应力强度因子比较相近;随着裂纹长度的增加,试验和有限元结果都表明了裂纹间的干涉影响显著加快了裂纹的扩展速度。
基金supported by the National Natural Science Foundation of China (Nos.41974123,42174161)the Jiangsu Innovation and Entrepreneurship Plan and the Jiangsu Province Science Fund for Distinguished Young Scholars (grant no.BK20200021).
文摘In recent years,the Yanchang shale-oil formations of the Ordos Basin are rich in reserves with complex lithology and structure characteristics,low porosity and low permeability,and weak anomalies for oil and water discriminations,have been the key targets of unconventional oil/gas resource exploration and development in the relevant areas.The joint acoustic-electrical(AE)properties can be used to interpret reservoir lithology,mineralogy,pore structure,and fluid saturation.To conduct tests of thin section analysis,X-ray diff raction,and ultrasonic and electrical experiments at diff erent pressures and saturation degrees,cores from the shale-oil formations in the Q area of the basin are collected.The variations in AE properties with respect to clay content,porosity,pressure(microfracture),and saturation are analyzed.The experimental results indicate that the rock physics behaviors of sandstones with diff erent clay contents vary significantly.The AE properties of clean sandstones are basically dependent on the microfractures(pressure),while for muddy sandstones,the clay content is an important factor affecting the responses.The target reservoir consists of interbedded sandstone and shale layers.The AE equivalent medium equations and the Gurevich theory are applied to establish the joint models for the diff erent lithologies and simulate the variations in AE properties with respect to fluid type,pore structure,and mineral components.The three-dimensional joint templates of clean and muddy sandstones,as well as shale,are developed based on the elastic and electrical attributes and then calibrated using the experimental and well-log data.The reservoir properties are estimated with the templates and validated by the log data.The results indicate that the joint templates based on lithology characteristics can eff ectively characterize the properties of interbedded sandstone and shale layers.Furthermore,the combined application of AE data provides more beneficial information for the assessment of rock properties,leading to precise estimates that conform with the actual formation conditions.