模型正演技术在鄂托克前旗地区的应用

Application of forward modeling technique in Otog Qianqi, Erdos basin

(东方地球物理公司研究院长庆分院，陕西西安710021)

Changqing Branch of Geophysical Research Institute, BGP, CNPC, Xian 710021, China

鄂托克前旗地区具备多套含气层系，勘探前景广阔。但该区横跨四大构造单元，构造条件复杂，各目的层储层均存在纵横向变化大、规律性不明显的问题，地震反射波组特征复杂多变。在分析区内井资料和地震资料的基础上，建立了奥陶系上覆煤系地层、奥陶系顶部古风化壳和上古生界主要目的层的地质模型，并通过模拟正演技术分别模拟了各地质模型的理论地震剖面，揭示了不同岩性组合、不同沉积环境和不同流体充填条件下的地震反射基本特征。在此基础上，对研究区主要目的层进行了地震解释和目标筛选，提供的3口建议井均获得了4×104 m3/d以上的工业气流。

Several gas-bearing formations with good exploration potential exist in Otog Qianqi area. However, the structure condition is complex for there are four structure units in the area. The reservoirs have problems of considerable lateral and vertical changes, non-obvious regularity, and complex characteristics of seismic reflection wave group. Based on the analysis of well data as well as seismic data, the geological models of overlying coal formation in Ordovician, paleoweathering curst on the top of Ordovician, and Neopaleozoic target formations. Then, the forward modeling technique was used to simulate the theoretical seismic sections of all geological models and to reveal the basic seismic reflection characteristics in the situation of different lithologic association, different sedimentary environment, and different fluid filling condition. On the basis of this, seismic interpretation and object filtering were carried out on the target formations, the three proposal wells all obtains more than 4×104 m3/d commercial gas flow.