珠江口盆地深水区珠江组成岩作用对含气砂岩AVO特征的影响研究

The relationship between diagenesis and AVO anomaly of gas-bearing sandstone in the ZJ formation of the Pearl River Mouth Basin,China

珠江组深水扇含气砂岩在不同区域表现为不同的AVO响应特征,通过对影响含气砂岩地球物理参数的地质因素分析,认为成岩作用是决定珠江组含气砂岩AVO响应特征的主要因素。结合测井、岩心薄片、地震等资料,分析了各成岩作用对储层的影响,证明了压实作用、溶蚀作用、胶结作用分别在不同区域主导着珠江组含气砂岩的AVO响应特征。按成岩作用将研究区划分为3个成岩组合区,含气砂岩在强压实-中等溶蚀-弱胶结成岩组合区内为Ⅱ类AVO异常,在中等压实-强溶蚀-弱胶结成岩组合区为Ⅲ类AVO异常,在弱压实-弱溶蚀-强胶结成岩组合区为较弱的Ⅲ类AVO异常。分别在各区域内开展AVO分析并预测含气砂岩的分布,解决了研究区珠江组含气砂岩地震响应特征不一致的问题,取得了很好的应用效果,为其它类似地区的研究提供了借鉴。

A deep-water fan with gas-bearing sandstone in the ZJ formation presents different AVO response features in different deep-water areas of the Pearl River Mouth Basin. After a theoreticrl analysis of geophysical and geological factors, the complex diagenesis was considered the key factor affecting the AVO response of the gas-bearing sandstone. A composite analysis of well-logging data,core slice,and seismic data showed that different diagenesis processes,namely,compaction,dissolution,and cementation, predominate the AVO response in different areas of the gas-bearing sandstone in the ZJ formation. In accordance with the diagenesis of the ZJ formation,the study region was divided into the following three diagenetic zone：1） A strong conpaction-moderate dissolution-weak cementation zone,where the AVO anomaly of the gas-bearing sandstone is Class Ⅱ,2） a moderate compaction-strong dissolution-weak cementation zone, with a Class Ⅲ AVO anomaly, and 3） a weak compaction-weak dissolution-strong cementation zone,where the AVO anomaly is a relatively weaker Class Ⅲ.The AVO response was then analyzed for each of the three zones respectively, to predict the distribution of gas-bearing sandstone in ZJ formation As the proposed method solves the inconformity of seismic response in a study area, it could also be applied to other similar regions.