塔中Ⅰ号断裂带奥陶系灰岩裂缝特征探讨

塔里木盆地塔中Ⅰ号断裂带奥陶系灰岩储层发育不规则的、复杂的裂缝系统,并以发育高角度的张剪性微-小缝为特征,非构造成因缝包括溶蚀缝和成岩缝,构造缝可分为方解石充填的高角度大-中缝、“X”型剪切缝和水平缝.根据裂缝的充填特征与切割关系可划分为具有不同特征的四期成因裂缝,结合测井新技术分析发现有效缝的走向多与塔中Ⅰ号断裂带近于垂直,而被方解石充填的无效缝多与之呈低角度相交.综合分析表明裂缝的有效性受控于现代区域应力场以及长期继承性的古构造应力格局等,而裂缝的发育程度与局部构造曲率的关系不明显,沿塔中Ⅰ号断裂带奥陶系碳酸盐岩寻找裂缝型油气藏是一重要勘探领域.

THE FRACTURE CHARACTERISTICS OF ORDOVICIAN LIMESTONE IN TAZHONG NO.1 FAULT BELT

The fracture system of the Ordovician limestone reservoir is irregular and complicated which has the characteristics of welldeveloped highangle tensoshear microsmall fractures in the Tazhong No.1 fault belt of Tarim Basin. Nonstructure genetic fractures include solutionfracture and diageneticfracture. The structure genetic fractures consist of calcitefilled highangle bigmiddle fractures, X type shearfractures and horizontal fracture. On the basis of its cutandfill features, the fracture system can be further divided into fourstage genetic fractures with different features. With the new logging interpretation technology, the strike of the effective fractures are nearly perpendicular to Tazhong No.1 fault belt, but the calcitefilled fractures are subparallal to it. The comprehensive analyses and studies indicating that the effective of the fracture is mainly controlled by present regional stress field and longterm compressional stress field of paleostructure, ect. But the fracture density has less relation with the local structure curvature. Fracture pool is an important exploration object for the Ordovician limestone along Tazhong No.1 fault belt.