珠江口盆地白云深水区含气储层AVO模板的建立及应用

AVO template and its application for a gas-bearing reservoir in the deep water of the Baiyun area,the Pearl River Mouth Basin

白云深水区多口油气钻探揭示砂质储层含气和含水都有可能表现为Ⅲ类或Ⅳ类的AVO及亮点异常,单纯依靠亮点+Ⅲ类AVO异常进行烃类气体预测具有多解性,是钻前储层的流体预测面临的新挑战和难点。本文利用珠江口盆地白云深水区测井数据,根据储层特征与含气性差异性优选了多口测井数据齐全井,利用测井数据对不同井位储层段的AVO特征进行分析。通过Aki-Richards公式计算了不同井的截距和梯度属性,建立了白云深水区P和G属性图版。对比分析发现不同含气储层,随着岩性、含气性差异及其岩性组合不同,呈现不同AVO异常特征,岩心分析表明该异常不仅与储层含气性有关,也与盖层岩性密切相关,尤其是当盖层或者储层含有灰岩时,对AVO异常影响较大。利用M矿区目标储层的叠前反演弹性参数,再结合本文建立的P和G属性图版和流体识别因子方法,对目标储层含气性进行了预测,发现了该储层在横向上含气性不同,钻探结果证实预测结果有效与可靠,表明该AVO模板具有较好的实用性。

Several drilled sites in the Baiyun deep-water area revealed that sandstone reservoirs of gas-bearing and water-bearing sediments may manifest as AVO of type Ⅲ or type Ⅳ and bright spot anomalies. The prediction of hydrocarbon gas relying on the bright spot and AVO anomaly of type Ⅲ has uncertainty, which causes difficulties in the prediction of reservoir fluid before drilling. Based on the well logging data in the Baiyun deep-water area, the Pearl River Mouth basin, the characteristics of the AVO reservoir were analyzed, and obvious differences between the reservoir characteristics and gas-bearing were identified. The intercept and gradient properties of the different wells were calculated using the Aki–Richards formula to establish the crossplot between P and G attributes in the study area. The anomalies of AVO influenced by lithology, gas-bearing, and lithological combination showed different characteristics. The core analysis indicated that the AVO anomalies were not only related to the gas-bearing property of the reservoir, but also closely related to the lithology of the overlying strata, especially when the overlying strata or the reservoir contained limestone. The prestack inversion elastic properties of the target reservoir in the M area, combined with the P and G attribute and fluid factor established in this paper, were used to predict the reservoir properties of the gas saturation. The drilling results proved that the gas saturation is variable in the later and the AVO template can predict reservoir properties better, which indicates the AVO template is effective and reliable.