中文摘要：

页岩气是非常规天然气的一种,具有极低的孔隙度和基质渗透率,在勘探开发过程中势必要进行天然裂缝研究和评价。通过对长宁地区大量野外露头及岩心的观测统计,采用了页岩天然裂缝的地质成因、力学性质和形态特征相结合的页岩裂缝分类方案,将该区天然裂缝划分为构造裂缝、成岩裂缝和异常高压裂缝三类,其中构造裂缝进一步依据形态及力学性质划分为穿层剪切缝、层内扩张缝和顺层滑脱缝;成岩裂缝进一步依据形态特征划分为层理缝和收缩缝。本文论述了分类方案的合理性,并分别阐述了页岩中各天然裂缝类型的特征。在此基础上,总结了页岩天然裂缝研究对页岩气勘探开发的作用及意义。层内扩张缝和页理缝影响页岩气的富集,而穿层剪切缝和顺层滑脱缝则在不同地质背景中影响页岩气的保存。

英文摘要：

A large number of outcrop and core observation statistics show that the natural fracture of shale gas of an overall consideration as geological causes mechanics properties and morphological characteristics are the most reasonable method for fracture classification. The natural fractures of the Shale in this area can be divided into three categories tectonic fractures, diagenetic fractures and abnormal high- pressure- related fractures. Tectonic fractures can be further divided into transformational shear fractures, intraformational open fractures and bedparallel shear fractures, whereas diagenetic fractures can be divided into bed- parallel lamellated fractures and shrinkage fractures.On the basis of this elaborate the geological characteristics of each fracture types in shale, we sum up the important of shale gas fracture to the exploration and development of shale gas. Transformational shear fractures, intraformational open fractures, bed- parallel shear fractures and lamellated fractures are significant to shale gas. Intraformational open fractures and lamellation fractures can enrich the degree of shale gas. Transformational shear fractures and bed-parallel shear fractures determine the gas preservation in different areas.