缝洞型隐蔽油气藏的井孔弹性波散射机理及成像方法研究

It’s extremely important to detect fractured-vuggy subtle reservoirs information for the exploration and development (acid fracturing, well location optimization) and increasing the rate of exploitation in (ultra-)deep formation. When the scale of fractured-vuggy surrounding a wellboreis equal to the wavelength of acoustic wave, small-scale heterogeneities in the rock formation could excite strong scattering wave which creates great uncertainty for logging data imaging processing and interpretation. To guide the exploration and development of the.ractured-vuggy subtle reservoirs, a scattered wave imaging method, which is based on the elastic waves scattering mechanism in the borehole environment, is proposed. According to the borehole scattering theory, we investigate scattered wave and direct wave and reflected wave field difference, and study the relationship between scattering wave amplitude and attenuation, which act as a constraint condition for the compensation of scattered wave field. Based on sound field characteristics and attenuation laws, the orgin logging data would be processed to suppress random noise from logging ,direct borehole waves and reflected wave from horizontal layer, and extract scattered wave fields from.outside the well. The migration imaging will be done with the scattered wave data by the method of Kirchhoff integration reverse propagation. Take account of timeliness and imaging accuracy, the migration imaging will be done with the scattered wave data by the method of Gaussian beam inverse time migration.The imaging results outside the borehole will be used for the guidance of the exploration and development in subtle reservoirs. Based on the theory study and field applications, the evaluation standard for fractured-vuggy subtle reservoirs will be established. The theory and method will form an application technique.

深层、超深层缝洞型隐蔽油气藏单井成像对于指导油气开发（酸化压裂、井位优化等）、提高油气钻遇率至关重要。当井孔周围缝洞非均匀体的尺度与声波的波长相当时，会产生很强的散射波，反射波成像数据处理往往视其为噪声而加以压制，给缝洞共存储层测井解释造成较大不确定性。本项目针对缝洞型油气藏的声学复杂性及特殊性，提出一种基于井孔弹性波散射机理的成像探测方法。根据井孔散射声场理论考察散射波与直达波和反射波波场差异，研究散射波幅度与频率、衰减之间的函数关系，以此为约束条件反演散射衰减品质因子；基于声场特征及衰减规律，压制测井随机噪声、井孔直达波和来自水平层界面的反射波，提取来自井外的散射波场；进一步利用兼具时效性和成像精度的高斯束逆时偏移对散射波数据进行处理，实现井外数十米缝洞储集体的声学成像，用于指导深层、超深层隐蔽油气藏的勘探开发。形成缝洞型隐蔽油气藏远探测成像理论及方法，将理论和方法形成应用技术。

碳酸盐岩油气藏在我国储量大、分布广泛，深层、超深层缝洞型碳酸盐岩是未来勘探开发的重要领域，由于勘探难度大，是否发育储集体是制约深层、超深层资源勘探的关键因素。碳酸盐岩具有极强的非均质性和各向异性，探测井外数十米范围内缝洞发育带信息(尺度、方位、发育度等)对于缝洞型隐蔽油气藏生产开发、酸化压裂、井位优化等至关重要。本项目针对缝洞型油气藏的声学复杂性及特殊性，提出一种基于井孔弹性波散射机理的成像探测方法。根据井孔散射声场理论考察散射波与直达波和反射波波场差异，研究散射波幅度与衰减之间的函数关系，以此为约束条件反演散射衰减品质因子；基于声场特征及衰减规律，压制测井随机噪声、井孔直达波和水平层界面的反射波，提取来自井外的散射波场；进一步利用兼具时效性和成像精度的高斯束逆时偏移对散射波数据进行处理，实现井外数十米缝洞储集体的声学成像。数值模拟和现场实例表明，基于散射波的远探测成像可以实现井周数十米范围内的非均质体评价。本项目的研究成果作为地震成像的有益补充，对深层、超深层碳酸盐岩精细勘探具有重要意义，为碳酸盐岩油气藏的数据处理及解释提供理论支撑。

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