常规AVO分析是以单一界面为前提,用来分析薄层的AVO响应特征存在误差。Brekhovski给出的层状传播矩阵方程考虑了层内波的反射和透射以及层厚等影响因素,更适合用于讨论薄互层的地震响应特征。对薄层进行Brekhovski正演,发现不同入射角下振幅与厚度关系不同,与叠后全叠加振幅相比,截距P属性和薄层厚度之间的线性关系更强,说明P属性比全叠加振幅更有利于薄层厚度预测。不同薄互层模型的Brekhovski正演结果表明:净厚度和泊松比是影响AVO曲线特征的两个主要因素,净厚度越小,泊松比对截距P和梯度G属性的影响越小;当泊松比一定时,净厚度和P、G属性呈近似线性关系,P属性与净厚度关系更敏感,可用于薄互层净厚度预测。应用实例证明在薄互层区P属性用于砂地比预测效果比较好,叠后振幅和叠前反演的弹性阻抗预测的净砂岩厚度精度较差。

Conventional AVO analysis method based on single interface can result in errors in thin layer AVO response characteristics. The Brekhovski layered propagation matrix equation takes into account reflection and transmission of layer wave and thickness, therefore it is more suitable for discussing the seismic response characteristics of thin interbeds. We conducted Brekhovski forward modeling on thin layer and found different relationship between amplitude and thickness using different offsets. The results indicate that pitch attribute has stronger linear relationship with thickness comparing with post stack, full stack amplitude, and can be a good indicator for thin interbed thickness. In different thin interbed model tests by Brekhovski forward modeling, net thickness and Poisson's ratio are two main factors affecting AVO curve characters. Poisson's ratio has less influence on pitch and gradient attributes for small net thickness. While Poisson's ratio is constant, net thickness shows near linear relationship with pitch and gradient attributes, with pitch attribute more sensitive to net thickness, which means pitch attribute could be used for net thickness prediction. Testing results demonstrated that in thin interbed area, pitch attribute is promising for sandstone percentage prediction, whereas accuracy of net thickness prediction by poststack amplitude or prestack elastic impedance inversion is poor.

松辽盆地苏家屯区块沙河子组发育河流相致密砂岩储层，具有低孔、低渗、单砂体薄（3~5 m）、非均质性强及弹性参数差异小等特点，储层识别和预测难度大。在Xu?White理论模型基础上，通过引入虚拟岩性和误差融合方法，优化了横波速度预测过程，提高测井横波速度预测精度，并结合实测岩心样本分析结果，构建了适合研究区致密含气砂岩敏感的流体因子参数，通过叠前地质统计反演获取高分辨率的敏感弹性参数体，对目的层含气砂体的分布范围进行预测。预测结果与实钻井吻合度较高，取得了较好的实际应用效果。

在西湖凹陷B构造,高孔渗的储层“甜点”是该区花港组成藏的主控因素之一,利用地震资料开展致密砂岩背景下的储层“甜点”预测是该区增产增效的重要措施。研究区内4口井的弹性参数全面筛选分析结果表明,对花港组砂岩最敏感的弹性参数是泊松比,对储层“甜点”最敏感的弹性参数是密度。在叠前道集优化处理的基础上,由叠前AVO三参数反演得到最敏感的弹性参数数据体(泊松比和密度数据),以此为基础开展定量解释并预测砂体及储层“甜点”的分布。通过与沉积相对比分析,预测的花港组砂体平面展布特征与沉积相相吻合,储层“甜点”的分布受沉积相带的控制作用明显。基于砂体及储层“甜点”预测结果,在花港组新增落实一系列构造岩性圈闭,累计面积为102.6km2,为该区提高储层“甜点”钻遇率、扩展隐蔽油气藏勘探提供了有力的生产支撑。

In structure B of the Xihu depression,the search for sweet spots in high porosity-permeability reservoirs in the Huagang Formation is a critical task.The prediction of sweet spots by seismic exploration can increase the production and efficiency of the exploitation significantly.Through a comprehensive analysis of the elastic parameters of four wells in the target area,it was found that Poissons ratio and density are the most sensitive parameters for the identification of the Huagang Formation and the sweet spots,respectively.Through an optimized processing of prestack gathers based on a prestack amplitude versus offset three-parameter inversion,information on the aforementioned parameters was obtained.Then,quantitative interpretation and prediction of the distribution of sand bodies and sweet spots were carried out.It was found that the planar distribution patters of the sandstone in the Huagang Formation is consistent with that of sedimentary facies,which strongly controls the distribution of sweet spots.Based on this result,a series of structural lithologic traps were identified in the formation,which cover a total area of 102.6km2.It is concluded that the proposed method provides a base for improving the sweet-spot drilling rate and expanding the exploration of the subtle oil and gas reservoirs in this area.

松辽盆地龙凤山气田营城组发育河流相致密砂岩储层,主力气层营Ⅳ砂组具有孔渗低、单砂体薄(3～5m)、非均质性强、弹性参数差异小等特点,优质储层识别和预测难度大。基于研究区岩样测试和岩石物理分析,优选致密含气砂岩的敏感弹性参数组合;通过叠前道集振幅恢复处理和叠前地质统计反演获取高分辨率的敏感弹性参数体,并利用贝叶斯分类方法识别致密含气砂岩。识别结果与实钻井结果吻合度较高,提高了薄层致密含气砂岩的预测精度,为后期开发井位部署提供了有效的技术支撑。

The Yingcheng Formation of the Longfeng Mountain gas field in Songliao Basin,China,has a fluvial facies tight sandstone reservoir.However,it is difficult to predict the effective reservoir of the gas field,because its main gas formation,the Ying IV sandstone formation,has inferior reservoir properties,namely,low porosity and permeability,a thin single-body thickness of only 3~5〖KG*9〗m,strong heterogeneity,and a small elastic parameter difference.According to rock sample tests and rock physics analyses of nine cores from the research area,we optimally selected the elastic parameter combination of tight sandstone,and obtained the elastic parameters sensitive to gas sandstone by means of pre-stack gather optimal amplitude recovery processing and pre-stack geological statistical inversion.Then,we adopted the Bayesian classification method to predict tight gas sandstone.The predicted result was highly consistent with the field drilling data,which means its high accuracy of tight sandstone gas prediction.The proposed method could provide support for well deployment.

层序地层学是地层沉积解释的重要基础理论与方法。然而,在满足被动大陆边缘条件下,海相层序地层学在层序界面划分和解释方法上仍存在许多不同。尤其是对于不满足被动大陆边缘条件的陆相沉积,其陆相层序地层学理论在应用中更面临诸多挑战。此外,在局域三维地震资料解释时,如何正确理解和应用层序地层学理论与方法也存在很多值得探讨的问题。针对松辽盆地薄储层勘探、开发中的技术需求,特别是在地震资料的分辨率难以完全满足薄储层解释的情况下,充分利用三维地震数据和测井资料,聚焦薄储层研究目标构建储层相对等时面,并使之满足拟被动大陆边缘条件,从而建立其与层序界面的联系,为应用局域三维地震资料开展层序地层学解释创造必要条件。通过对沿顶部层序界面拉平的地震剖面和测井资料的解释,可获得局域古地貌、局域沉积中心、局域沉积物源等沉积信息。在此基础上,当两个相邻层序界面间的地层沉积环境满足拟被动大陆边缘条件时,应用空间相对分辨率理念,依据地震属性切片开展储层沉积演化解释,进而获得薄储层的沉积相和空间展布规律的认识。

Sequence stratigraphy provides an important theoretical framework for interpreting stratigraphic deposition.However,even in a passive continental margin in marine environment,many ambiguities in the division and interpretation of sequence boundaries are possible.When the passive continental margin condition is not met in a continental environment,the interpretation is even more problematic.In the interpretation of local three-dimensional (3D) seismic data,the correct application of sequence stratigraphy is also very challenging.To meet the needs of exploration and development of thin reservoirs in the Songliao Basin even with seismic data with insufficient resolution,3D seismic and logging data were fully exploited to construct the relative isochronal surface of the reservoir and identify a quasi-passive continental margin condition.In this manner,a relationship with the sequence boundary could be established,and a reference for the application of local 3D seismic data for sequence stratigraphy interpretation could be provided.By interpreting the seismic profile and logging data flattening along the top sequence boundary,sedimentary information such as local paleogeomorphology,local sedimentary centers,and local sediment sources could be obtained.Then,the concept of spatial relative resolution was applied to interpret the sedimentary evolution of the reservoir according to seismic attribute slices,and the sedimentary facies and spatial distribution patterns of the thin reservoir could also be obtained.

对楔形砂体正演模型的谱分解响应特征(峰值频率、谱比)的分析表明,反射波的谱分解特征主要受控于地层反射系数序列、层厚以及孔隙流体特征.与含气储层相关的谱分解异常所出现的频率范围并无统一规律,既可以出现与含气相关的低频谱分解异常,也可出现与含气相关的高频谱分解异常.根据所研究储层的特性建立了系统正演模型,利用该模型得到了特定储层谱属性的变化特征,为运用谱分解技术进行储层流体检测时选择最佳频率范围提供了依据.

The spectral attributes from synthetic forward model were analyzed.The analysis result reveals that the reservoir thickness and reflectivity series are the first-order factors to control the spectral decomposition response.The spectral anomalies of the gas-associated reservoirs can occur at low-frequency sections or high-frequency sections.The systematic synthetic model was developed on the basis of reservoir properties.This model can provide information about the properties of spectral attributes for the special reservoirs and is helpful in selection of the optimal frequency range in the reservoir fluid detection.