基于超声波实验研究压力及流体对致密岩石横波衰减特征的影响  

Effects of pressure and fl uid properties on S-wave attenuation of tight rocks based on ultrasonic experiments

作　　者：潘旭铭 巴晶[1] 马汝鹏 刘卫华 程卫 JoséM.Carcione Xuming Pan;Jing Ba;Rupeng Ma;Weihua Liu;Wei Cheng;JoséM.Carcione(School of Earth Sciences and Engineering,Hohai University,Nanjing,211100,China;Sanya Off shore Oil and Gas Research Institute,Northeast Petroleum University,Sanya,572000,China;SINOPEC Geophysical Research Institute Co.,Ltd.,Nanjing,211100,China;National Institute of Oceanography and Applied Geophysics(OGS),Trieste,Italy)

机构地区：[1]河海大学地球科学与工程学院,南京211100 [2]东北石油大学三亚海洋油气研究院,三亚572000 [3]中石化石油物探技术研究院有限公司,南京211100 [4]National Institute of Oceanography and Applied Geophysics(OGS),Trieste,Italy

出　　处：《Applied Geophysics》2024年第2期246-264,419,共20页应用地球物理（英文版）

基　　金：supported by the Natural Science Foundation of Jiangsu Province(Grant No.BK20200021);the National Natural Science Foundation of China(Grant No.42174161 and 41974123);the Natural Science Foundation of Heilongjiang Province of China(YQ2023D005).

摘　　要：我国致密油气储层勘探前景广阔,开采价值高,但其储层岩石具有低孔、低渗、强非均质性等特征,建立储层波响应与岩石物性参数之间的联系仍面临挑战,针对致密储层波响应规律的研究有待深入开展。孔隙流体性质及围压会影响岩石的剪切模量及横波衰减,本文对部分饱和的8块致密岩石在不同围压条件下开展了超声波实验观测,采用谱比法估算岩石的横波衰减。结果显示,横波衰减随围压上升而下降,且饱水岩石的横波衰减大于饱油,饱气状态衰减最弱。气、水部分饱和岩石的测量结果中,岩石样本的横波衰减在中间含水饱和度达到峰值,此外,横波衰减随孔隙度、渗透率上升均有增大的趋势。基于实验测量的岩石物性参数,结合Voigt-Reuss-Hill(VRH)平均、微分等效介质模型和喷射流模型构建了致密岩石衰减模型,分析了不同围压条件下含流体岩石的衰减特征,结果显示,该模型可合理描述横波衰减特征。在完全饱和与部分饱和条件下,模型预测的横波衰减显示出明显的压力及流体敏感性。以样本TS1-19为例,在完全饱和、变围压条件下,模型预测的横波衰减峰值在11.6~69.5范围内,衰减峰值随着围压增大而降低,且峰值频率有向高频端移动的趋势。在部分饱和、围压30MPa条件下,模型预测的横波衰减峰值在15.5~39.8范围内,衰减峰值随着含水饱和度增大而增大,且峰值频率向低频端移动。对于所有样本,以30MPa围压为例,所预测的横波衰减在5.6~38.6范围内,其中在饱和条件下,模型预测横波衰减随着孔隙度增大而增大,随着围压增大而减小;在气水部分饱和条件下,随着含水饱和度的增大,基于模型及Voigt和Reuss边界法预测的横波衰减整体呈增大的趋势,而实验观测到的横波衰减在中间饱和度达到极大值。The tight oil/gas reservoirs in China have showed the great exploration prospects and high production potential,with the characteristics of low porosity,low permeability,and signifi cant heterogeneity in formation rocks.It remains a challenge to sort out the relations between reservoir wave responses and rock physical properties,and the further studies on the wave response patterns of tight reservoirs are in an urgent demand.The shear modulus and S-(shear)wave attenuation of rocks are aff ected by the properties of pore fl uid and confi ning pressure.The ultrasonic wave experiments are performed on eight partially-saturated tight sandstone samples at diff erent confi ning pressures,and we estimate S-wave attenuation with the spectral-ratio method.Results show that S-wave attenuation decreases with increasing confining pressure,and the water saturation case shows more loss compared to the oil saturation case,while the gas saturation case gives the lowest attenuation.We observe the S-wave relaxation peak at an intermediate water saturation for the gas-water partial-saturation case in general.S-wave attenuation increases with increasing porosity or permeability.Based on the measured rock physical properties,and combined with the Voigt–Reuss–Hill(VRH)average,diff erential eff ective medium(DEM)model and squirt-fl ow model,a tight rock attenuation model is proposed for analyzing the attenuation characteristics of fl uid-saturated rocks at diff erent confi ning pressures.The model reasonably describes the S-wave attenuation characteristics.The model predictions of S-wave attenuation show apparent pressure-and fl uid-sensitivity at full saturation and partial saturation conditions.For sample TS1-19 at full saturation with diff erent confi ning pressures,the S-wave peak attenuation predicted by the model ranges from 11.6 to 69.5,and decreases with confi ning pressure,while the relaxation frequency shifts to high frequency end.For the partial saturation condition of the sample,the predicted S-wave peak attenuation ran

关 键 词：致密岩石 横波衰减 岩石物理实验 围压 流体饱和度 喷射流模型 

分 类 号：P618.13[天文地球—矿床学] P631.4[天文地球—地质学]