波形分类技术在缝洞型储层流体识别中的应用

塔里木盆地塔河地区奥陶系碳酸盐岩缝洞型储层的缝洞空间分布散乱,缝洞的规模、形态和内部结构等特征差异明显,导致缝洞型储层的流体难以识别。缝洞型储层内部地震波形的微弱差异在一定程度上能够表征其内部流体特征。传统上沿层段提取地震波形的波形分类技术无法准确地定位缝洞型储层。应用波形分类与三维缝洞体雕刻相结合的新技术识别缝洞流体,可为降低勘探风险、提高钻井成功率提供一种新的思路。首先利用瞬时振幅属性建立缝洞体三维空间模型,确定缝洞储层的空间位置,从而获得缝洞储层内部的地震波形;使用特征加权K近邻法,结合油气井资料,对缝洞型储层进行波形分类,建立储层内流体类型与地震波形之间的网络关系,并将其应用于未知区域的储层流体识别;最终得到缝洞型储层的流体类型。理论模型和实际地震资料测试结果表明该方法具有一定的实用价值。

Application of waveform classification technology for fluid identification in fractured-vuggy reservoir

The fractured-vuggy reservoir of Ordovician carbonates in Tahe area, Tarim Basin is scattered in space, characterized by great differences in the size, shape and internal structure, leading to a difficulty in identifying the reservoir fluid. The weak difference of seismic waveforms in fractured-vuggy reservoir can characterize its internal fluid characteristics to some extent. The traditional waveform classification technology extracting seismic waves along the layer is unable to locate the fractured-vuggy reservoir accurately. A new method combining waveform classification technology with 3D fractured-vuggy body engraving technology is put forward to identify the fluid of fractured-vuggy reservoirs, which provides a new idea for reducing exploration risk and improving drilling success rate. Firstly, the instantaneous amplitude attribute is used to establish a 3D space model of the fractured-vuggy bodies. The spatial location of fractured-vuggy reservoirs will be determined to obtain the seismic waveform inside fractured-vuggy reservoirs. Then, the feature weighted K-nearest neighbor method in combination with oil and gas well data is applied to classify the waveforms of fracture-cavity reservoirs, so as to create the network relationship between fluid types and seismic waveforms in the reservoir and further apply it to reservoir fluids in unknown regions. Finally, the fluid type of the fractured-vuggy reservoir is obtained. The testing results of theoretical model and practical seismic data show that this method has a certain practical value.