利用叠后提频及多属性分析预测砂泥岩薄互层——以轮南石炭系砂泥岩段为例

Thin inter-bed prediction with poststack frequency improvement and multi-attribute analysis:an example of Carboniferous sand-mudstone member in Lunnan Area

轮南地区石炭系砂泥岩段发育薄互层储层,油气显示丰富,勘探开发潜力大。由于埋深大(大于5300m)、储层物性变化快、砂泥组合复杂、单层厚度小(1～3m)等原因,常规的分频、反演等薄互层预测方法难以奏效。在精细地质研究基础上,基于GeoEast系统开展正演模拟、叠后提频处理、多属性综合预测等研究,预测了有效储层的平面分布,获得以下认识:①振幅主要是储层厚度和物性的综合响应,砂体的组合样式和流体性质对振幅的影响较小,因此可以利用振幅及波形特征有效地预测储层;②研究区频谱波形分为6类,频谱波形分类属性可实现薄砂岩富集区与泥岩富集区的区分;③高亮体属性对薄互层型储层预测效果较好,高值区多层砂体累加的有效厚度较大(一般大于10m),储层物性较好(孔隙度一般大于12%),低值区砂体累加有效厚度较小(一般小于6m),且物性较差。

Thin inter-bedded reservoirs are well developed in the Carboniferous sand-mudstone member in Lunnan Area,which shows great hydrocarbon potential.However it is very difficult to predict the distribution of this kind of reservoirs with conventional methods due to deep burial(great than5300 m),physical-property rapid changes,and small bed thickness(1~3 m).Forward modeling,post stack resolution processing,and multi-attribute analysis provided by GeoEast System are used for in-depth geological analysis.The plane distribution of reservoirs is well characterized.The following understandings are obtained:(1)Amplitude characteristics are mainly responses of reservoir thickness and physical properties,while sand combination and the fluid property have less influence on the amplitude characteristics.Therefore,the reservoir prediction can be achieved with amplitude and waveform characteristics;(2)Six seismic facies in the study area are classified.Spectrum and waveform classification attributes can relatively distinguish thin sandstone and mudstone areas;(3)Highlight volume attribute can accurately predict thin inter-bedded reservoirs.The sand inter-bed thickness with high value is usually more than 10 mwith good physical properties(porosity bigger than12%);while low value is small thickness(generally less than 6 m)with poor physical properties.