断层相关裂缝定性识别:原理与应用

Qualitative Identification of Fault-Related Fracture (FRF): Principle and Its Application

介绍一种定性识别和预测断层相关裂缝的新方法——断面脱空法。该方法以断面脱空理论为基础,通过建立断面脱空空间与断层相关裂缝之间的置换模型,从而实现通过观察断层形迹开展地下断层相关裂缝的定性识别。以塔中Ⅰ号断裂带西侧中古3、塔中72两个井区下奥陶统良里塔格组(O3l)为例,基于地震资料分别开展剖面和平面上的断层相关裂缝识别,并将预测结果与钻井、测井及地震属性分析获得的裂缝发育特征进行对比研究。结果表明:利用断面脱空原理预测结果与钻测井揭示结果基本一致,与根据均方根检测的裂缝平面分布对比,细节上有差异,但总体特征基本一致,表明利用断面脱空原理可以定性地对断层相关裂缝做出预测。断面脱空理论的提出不仅为定性评价地表、地下断层相关裂缝发育分布规律提供一种新思路,更为定量表征断层相关裂缝提供重要的理论依据。

In broad gentle structure regions of both compact carbonates and sandstones, some fault- related fracture （FRF） traps are important domains for hydrocarbon exploration. However, the qualitative and quantitative identification of FRF is still difficult in structural geology. In this paper, a new method for qualitative identification and prediction of FRF, based on fault detachment theory, was introduced. With the establishment of replacement model between fault plane void space and FRF, qualitative identification and prediction of FRF can be carried out through observing the combination structural features among top and bottom surfaces of the fault and its fault surface. Taking Zhonggu 3 and Tazhong 72 wellblocks as examples, qualitative identification of FRF was firstly conducted for the Upper Ordovician Lianglitage Formation in both vertical seismic profiles and in plane. The predicted result based on fault detachment theory was compared with those results from logging and seismic attribute analysis, respectively. The results show that the predicted results are basically consistent with those revealed from logging data, and the plane distribution results are almost consistent with the overall characteristics obtained from RMS, with difference in details. It indicates that the fault detachment theory can be effectively used to qualitatively predict the FRF. The fault detachment theory, not only provides a new qualitative evaluation idea and method for the development distribution of FRF both ground and underground, but also provides an important theoretical basis for quantitative characterization of FRF.