Natural fractures are widespread in shales in sedimentary basins and can significantly increase the bulk permeability and enhance fluid flow, which are thereby considered to be a key factor in shale gas development, seal integrity analysis, site selection for CO₂ sequestration and nuclear waste disposal. Although many fractures in shale owe their origin to tectonism, a substantial proportion of fractures are induced by shale diagenesis, hydrocarbon generation and expulsion during different stages of burial. The conditions under which non-tectonic fractures are generated during shale diagenesis generally include (1) fluid overpressure due to clay mineral dehydration (e.g., smectite to illite transition); (2) differential compaction caused by abrupt porosity reduction during silica diagenesis (e.g., opal-A dissolution); and (3) pressure solution in the rock matrix and neomorphic calcite. With an increasing thermal maturity of organic matter, natural hydraulic fractures can be produced in organic-rich shale during (1) early generation of biogenic gas; (2) oil generation and primary migration; and (3) cracking of oil to gas. At the early stage of the oil window, contraction fractures may also be formed in organic matter due to thermal shrinkage. A better understanding of the origins of non-tectonic fractures induced during shale burial may yield important implications for the interplay between fracture mechanics, inorganic/organic matter evolution and fluid flow in shale.

沉积盆地页岩中天然裂缝普遍存在，可显着提高体渗透率，增强流体流动，被认为是页岩气开发、密封完整性分析、CO ₂选址的关键因素封存和核废料处理。尽管页岩中的许多裂缝起源于构造作用，但很大一部分裂缝是由页岩成岩作用、不同埋藏阶段的生烃和排烃作用诱发的。页岩成岩作用产生非构造裂缝的条件一般包括（1）粘土矿物脱水（如蒙脱石向伊利石转变）引起的流体超压；(2) 二氧化硅成岩作用（如蛋白石-A溶解）孔隙度突然降低引起的压实差异；(3) 岩石基质和新质方解石中的压力解。随着有机质热成熟度的提高，富含有机质页岩可在（1）生物气早期生成过程中产生天然水力裂缝；(2) 生油和初级运移；(3)石油裂解制气。在油窗初期，有机质也可能因热收缩而形成收缩裂缝。更好地了解页岩埋藏期间诱发的非构造裂缝的起源可能会对页岩中的裂缝力学、无机/有机物质演化和流体流动之间的相互作用产生重要影响。