陆梁油田侏罗系油藏薄储层预测方法及应用

Prediction Method and Application of Thin Reservoir in Jurassic Reservoir of Luliang Oilfield

陆梁油田侏罗系油藏具有一定开发潜力。侏罗系西山窑组自上而下为3段,含油层为西山窑一段,据段内多个泥岩隔层分布进一步将西一段划分为2个油层组5个小层,具“一砂一藏”特点。由于5~10 m薄砂层很难直接在地震剖面上成像,为侏罗系西山窑组油藏的薄储层精准预测带来了一定困难。为了解油层及薄储层的平面及空间展布特征,本次研究基于钻井、测井、试油等资料,以三维叠后地震数据的子波主频,建立研究区地震记录波形与合成记录波形两个信号的互相关函数计算衰减系数Qf,并完成时-频衰减高精度合成记录标定。通过确定地震波阻抗识别门槛值,结合薄储层地震振幅属性数据体与岩性解释的储层特征分析资料,输出西山窑组西一段地震波阻抗反演剖面及油层厚度图。预测结果表明,开发井油层厚度为5~8 m薄砂体,与实际资料准确率达90%,为油藏开发扩边提供了理论依据。

The Jurassic oil reservoir in Luliang Oilfield has certain development potential.The Jurassic Xishanyao Formation consists of three sections from top to bottom,with the oil bearing layer being Xishanyao Section 1.Based on the distribution of multiple mudstone interlayers within the section,the Xishanyao Section is further divided into two oil layer groups and five small layers,with the characteristic of“one sand and one reservoir”.Due to the difficulty in directly imaging the 5 m-10 m thin sand layer on seismic profiles,it poses certain difficulties in accurately predicting the thin reservoir of the Jurassic Xishanyao Formation oil reservoir.To determine the planar and spatial distribution characteristics of oil layers and thin reservoirs,this study is based on drilling,logging,and oil testing data;Establish a cross-correlation function between the seismic record waveform and the synthesized record waveform in the study area using the main frequency of the wavelet of the 3D stacked seismic data to calculate the attenuation coefficient Qf;And complete high-precision synthesis record calibration for time-frequency attenuation.By determining the threshold value for seismic impedance identification and combining the seismic amplitude attribute data of thin reservoirs with the reservoir characteristic analysis data of lithology interpretation,the seismic impedance inversion profile and oil layer thickness map of the western section of the Xishanyao Formation are output.The prediction results show that the accuracy of the thin sand body with a thickness of 5 m-8 m in the development well oil layer is 90%compared to the actual data.This provides a theoretical basis for the expansion of oil reservoir development.