不整合背景下砂岩边界识别——以SH地区戴一段为例

Sandstone boundary recognition under unconformity background——by taking Dai 1 section in SH area as an example

SH地区戴一段以岩性油气藏为主,单砂体厚度不超过10 m,由于戴一段底部不整合面的影响,不整合强反射背景屏蔽了附近砂岩的有效信息,因此准确预测砂体边界是寻找油气藏的关键。为了准确识别不整合背景下的薄砂体,对比强反射分离算法,确定强反射分离流程,讨论强分离过程中去强参数的选取,建立正演模型检验处理后地震数据的可靠性。研究证实,基于层约束的动态快速匹配追踪方法能够消除断层等因素引起的异常值、加强运算稳定性和提高运算速度。根据研究区井旁道地震数据、测井数据、属性分析结果等,确定分离系数为0.7时的强反射分离处理的地震数据相对合理,能显示有效储层信息。利用强反射分离后的地震数据提取三相属性,认为振幅属性与有效储层厚度具有正相关性,振幅属性结果能反映储层展布特征,可提高砂岩尖灭线识别的精度。所部署的井位钻遇油层,证实了强反射分离方法的可靠性。

Dai 1 section of SH area is mainly focused on finding lithologic oil and gas reservoirs,and the single sand body thickness of E_(2)d_(1) section shall not exceed 10 m.The bottom interface of E_(2)d_(1) in SH area is an unconformity,which displays refection characteristic of strong energy on seismic profile.This strong reflection could conceal information of sandstone nearby the unconformity surface.Therefore,accurate prediction of sand body boundary is the key to find oil and gas reservoirs.In order to accurately identify thin sand bodies under unconformable background,the strong reflection separation algorithm is studied,the strong reflection separation process is determined,the selection of strong parameters during the strong separation is discussed,and the forward model is established to verify the reliability of the processed seismic data.It is proved that the matching tracking algorithm of layer constraints can avoid outliers caused by fault factors,strengthen the stability of operation and improve the operation speed.According to the well sideway seismic data,well logging data and attribute analysis results,the seismic data with strong reflection separation processing obtained by determining the separation coefficient of 0.7 is relatively reasonable and can display effective reservoir information.The three phase attributes were extracted from the seismic data after strong reflection separation,and it was considered that the amplitude attribute was positively correlated with the effective reservoir thickness,and the attribute results reflected the reservoir distribution characteristics and improved the accuracy of pinch-out line identification of sandstone.The deployed well sites are drilled into the reservoir,confirming the reliability of the strong reflection separation method.