摘要:
地震资料精细解释和储层预测需要对地质层位和砂体进行准确标定,合成地震记录的精度直接影响到地质层位的准确标定。在保证合理的时深关系、准确的反射系数前提下,利用测井资料得到确定性子波为提高合成地震记录精度的有效途径,理想化的雷克子波为判别地震资料品质的有效手段,二者结合提高了合成地震记录层位精细标定的精度。以南海北部珠江口盆地海域资料为例,根据理论子波合成地震记录与实际地震资料的对比分析,辨别了地震资料的有效性,地震资料1 225 ms强反射是受子波旁瓣影响在褶积过程中叠加了下面较强的正反射造成,非真实地层反射,不可做层序界面或标志对比层。通过标志层位的反射特征分析,标定了1个最大海泛面和4个三级层序界面,同时精确标定了2套砂体,识别了2套砂岩的顶底反射,确立了层位对比的基准面和标志层,为该区精细构造解释和岩性储层预测提供了依据。
Abstract:
The accurate calibration of stratigraphic boundaries and sand bodies, which are critical to fine interpretation of seismic data and reservoir prediction, depends on the precision of the synthetic seismogram. It is found that definite wavelet extracted from logging data is an effective way to enhance the precision of synthetic seismogram if rationale time-depth relation and accurate reflection coefficient are adopted, and the Ricker wavelet is an effective tool to judge the quality of seismic data. The combination of the definite wavelet and Ricker wavelet will provide a way to upgrade the precision of geological boundary calibration. In this paper, taking the Pearl River Mouth Basin of the Northern South China Sea as an example, through correlation of the synthetic seismogram and the acquired data, we evaluated the effectiveness of seismic data. The strong reflection of 1225 ms was not a real reflection of a geological boundary, but a superposition of a deeper strong normal reflection during convolution influenced by the side lobe of definite wavelet. Therefore, it does not represent a sequence boundary. Based on the careful study of reflection features of the sequence, a maximum flooding surface and four 3rd order sequence boundaries as well as two sets of sand bodies were identified as the markers for stratigraphic correlation, fine structural interpretation and reservoir prediction.
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