【摘要】 我国深层海相碳酸盐岩地层蕴藏有丰富的天然气资源,但因演化历史长、埋深大等因素影响,储层含气性评价困难。评述了现有储层含气性地震检测技术(包括亮点、AVO异常、低频阴影等)在深层天然气储层识别中的适用性,认为亮点和AVO异常反映的是界面响应,而低频阴影反映的是储层的"体"响应。储层含气性检测不仅要确定储层是否含气,还要确定储层含气量。为此,介绍了一种新的基于地震纹倒谱分析的储层含气性检测方法,指出(1)雷克子波的地震纹倒谱参数随子波频率呈非线性变化;(2)地震纹倒谱参数对储层参数变化反应灵敏;(3)含气储层地震响应的1阶倒谱系数呈高值异常,而2阶倒谱系数呈低值异常,且二者呈镜像对称。地震纹倒谱对弱反射的敏感性使得该方法能够发现"暗点"型气藏,同时因与模型无关而克服了诸多建模带来的弊端,能够对深层超深层储层含气性进行较为可靠的检测。探讨了基于地震的深层碳酸盐岩储层产能评价问题,认为地震纹分析与频散分析相结合有望能确定储层的含气性并估算其可采储量。更多还原

【Abstract】 There are abundant natural gas resources in deep marine carbonate strata onshore China.It is necessary but difficult to discover gas-bearing reservoirs and evaluate their gas content,due to their long evolutionary history and large buried depth.This paper reviews existing hydrocarbon detection techniques,such as bright spot,AVO,and low-frequency shadow,in the identification of deep gas carbonate reservoir.Bright spots and AVO anomalies reflect the interface response,while low-frequency shadows reflect the response of the"body"of the reservoir.In this paper a hydrocarbon detection technique is proposed based on seismic cepstrum analysis.The cepstrum of the Ricker wavelet varies nonlinearly with frequency and the seismic cepstrum is sensitive to reservoir parameters.In addition,the first-order cepstral coefficient of the seismic cepstrum of gas-bearing reservoirs is of a high-value anomaly,while the second-order cepstral coefficient represents a low-value anomaly,and the two anomalies are mirror-symmetric.The sensitivity of the seismic cepstrum to weak reflection enables the method to detect"dim spot"gas reservoirs.In addition,the method is independent of reservoir modeling.Discussion on capacity evaluation based on seismic data analysis suggested that combined analysis of seismic print and dispersion could effectively detect gas-bearing reservoir and estimate the recoverable reserves for a deep carbonate reservoir.更多还原