莺歌海盆地东方区纵横波速度变化对AVO类型的影响

莺歌海盆地东方区由于特殊的温压环境和形成机制，导致低速泥岩特别发育，而低速泥岩和含气砂岩表现为较相近地震相和AVO特征，致使应用AVO技术识别砂岩效果并不理想。为了有效分析该区砂泥岩AVO特征，从Zoeppritz方程简化式出发，剖析不同弹性参数相对变化对AVO反射系数的影响，在此基础上明晰东方区上中新统黄流组含气砂岩随深度的变化规律，明确了横波速度是影响该区含气砂岩III类、IV类AVO响应特征的主要因素。最后对相同的IV类含气砂岩和低速泥岩进行分析，低速泥岩的IV类AVO异常更为明显，为有效区分低速泥岩和含气砂岩，结合岩石物理分析和叠前同时反演结果可以有效剔除低速泥岩陷阱的影响，为东方区储层预测和烃类检测提供重要技术支撑。

Analysis of the influence of P-S wave velocity variation on AVO type in the Dongfang area,Yinggehai Basin

Because of the special temperature and pressure environment and formation mechanism in Dongfang area, low-speed mudstone develops especially, while low-speed mudstone and gas-bearing sandstone show relatively similar seismic facies and AVO characteristics, so the effect of identifying sandstone by AVO technique is not ideal. In order to effectively analyze the AVO characteristics of sandstone and mudstone in this area, this paper analyzes the influence of the relative variation of elastic parameters on AVO reflection coefficient based on the simplified formula of Zoeppritz equation. On this basis, the variation rule of gas-bearing sandstone of Huangliu Formation in Dongfang area with depth is clarified. It is clear that the shear wave velocity is the main factor affecting the response characteristics of III and IV types of gas-bearing sandstone in this area. Finally, the same IV type gas-bearing sandstone and low-speed mudstone are analyzed, and the IV type AVO anomaly of low-speed mudstone is more obvious. In order to distinguish the low-speed mudstone and gas-bearing sandstone effectively, the combination of petrophysics and prestack simultaneous inversion can effectively eliminate the impact of low-speed mudstone traps and provide important technical support for reservoir prediction and hydrocarbon detection in the Dongfang area.