油藏模型含油饱和度变化的地震振幅响应特征

Seismic amplitude response characteristics of oil-bearing saturability variation of the oil pool model

针对储层流体地震检测技术不容易识别油层(不含气)的现状,深入研究油、水弱弹性参数差异条件下的地震响应同油水饱和度变化之间的关系,对提升油层地震检测成功率有重要意义。因此,利用矢量波场数值模拟技术,对不同含油饱和度条件下的油藏模型进行波场正演,利用正演结果探索性地研究仅含油—水混合流体油藏的含油饱和度变化引起的地震响应特征,为油层地震检测和定量解释提供参考。研究结果显示:仅含油—水混合流体的油藏在不同含油饱和度时的AVO响应特征基本一致,利用常规手段较难有效区分含油与含水,但通过压制储层反射中的非油气响应,突出油气响应的振幅校正处理后,可以明显看到储层含油饱和度变化引起的地震响应,且不同含油饱和度范围的地震响应特征不同,呈明显的非线性特征,因此,地震资料携带了储层流体信息,利用地震资料检测储层含油性及含油量是可行的,但对储层含油性和饱和度的合理解释需要以正确认识储层含油饱和度变化同地震响应之间的非线性规律为前提基础。

To tackle the status that the reservoir fluid seismic detection technique cannot easily recognize oil bed（ containing no gas）,it is of great significance to study the relationship between the seismic response and the oil-water saturability under the condition of the difference in oil and water weak elastic parameters so as to improve the success rate of the oil bed seismic detection.Utilizing the vector wave field digital simulation technique,the author performed wave field forward processing of the oil pool under the condition of different oil-bearing saturabilities and,using the inversion results,tentatively studied the seismic response characteristics caused by the oil-bearing saturability variation in the oil pool that contains only oil-water mixed fluid,so as to provide reference for the seismic detection and quantitative interpretation of the oil bed.According to the results obtained,the AVO response characteristics of the oil reservoir that contains only oil-water mixed fluid are basically consistent under the condition of different oil-bearing saturabilities,and hence it is difficult to use routine means to distinguish oil from water.Nevertheless,through suppressing non-oil and gas response in the reflection of the oil reservoir and making prominent the oil and gas response by amplitude correction,the seismic response resulting from the oil-bearing saturability of the oil reservoir can be clearly observed,and the seismic response characteristics in different oil-bearing saturability ranges are different and exhibit evident nonlinear features.In this way,the seismic data carry fluid information of the oil reservoir,and the utilization of the seismic data to detect the oil-bearing potential and oil-bearing quantity is feasible.However,the reasonable interpretation of the oil-bearing potential and saturability should be based on the prerequisite of the correct understanding of the nonlinear relationship between the oil-bearing saturability variation of the oil reservoir and the seismic response.