利用测井资料识别层序地层界面的几种方法

SOME METHODS FOR IDENTIFYING SEQUENCE BOUNDARIES AND CONDENSATION SECTIONS USING WELL LOGGING

以测井原理和层序地层学理论为基础 ,系统地分析了利用声波时差、电阻率、地层倾角等测井资料识别层序界面和生油岩密集段 (CS段 )的方法和原理。结果表明 ,层序界面对应于不整合面 ,它在声波时差对数与深度的关系图上常有回归线错开、斜率不同等响应特征。层序界面上、下地层产状常存在差异 ,导致在累积地层倾角图上出现异常转折点。CS段形成于最大湖泛面附近 ,常具有有机碳含量高、声波时差高的特点 ,在声波时差与电阻率的交汇图上 ,CS段对应于高幅度差。

On the basis of the principles of well logging and the theory of sequence stratigraphy, the methods and principles for identifying the sequence boundaries and condensation sections using the information of sonic logging, resistivity log and dipmeter were comprehensively analyzed. The result shows that the sequence boundary is correlative with unconformity surfaces which lead to the anomaly of the regression line of the logarithm of interval transit time versus its depth, such as the dislocation and different slopes on the regression line, different status of the above and below unconformity surfaces, which leads to the anomalous inflection points at the location of sequence boundary on the cumulative dip plot because of the different dip angles of the strata above and below the sequence boundary. The condensation section has the features of great amount of organic substances and big amplitude difference of interval transit time on the overlap map of interval transit time and resistivity curves.