Natural opening-mode fractures existing in the subsurface can be partially or completely sealed by diagenetic cements (e.g., joints and veins), and these cemented fractures may reopen during core recovery to the ground surface. Depending on the cement/host-rock material properties, debonding or re-fracturing may happen within the cement or at the cement/rock interface. We demonstrate the role of induced stresses in opening cemented fractures (veins) during cores recovery to the surface and to determine whether cracks form along the vein interface or through the core and why. We consider vein as a thin layer sandwiched inside the rock mass, and use the theory of eigenstrain to calculate stress disturbances at the core surface due to the release of in-situ stresses and the difference between surface and downhole temperatures. Then, we employ the theory of elasticity to calculate the maximum tensile stress at the edge of the vein. This tensile stress can be used to estimate the tensile strength of the diagenetic cements inside natural fractures. Using the developed technique, we solve practical examples to determine whether debonding is more likely within the natural cement or at cement/host-rock bonding. For the case of core recovery in Marcellus Shale with a calcite vein, we find that the maximum tensile stress normal to the vein plane happens at the center of the vein. We observe this phenomenon for both alignment of c-axis orientation with the layering, perpendicular to the fracture wall ($\perp \text{c}$-axis) and parallel to the fracture wall ($\text{∥c}$-axis). Therefore, theoretically, cracks likely form at the center of the calcite vein rather than the Marcellus Shale/calcite interface. Laboratory tests to date have shown that re-fracturing of calcite veins in Marcellus Shales can occur either within the calcite or at the calcite/Shale interface. For the case of core recovery in sandstone with fractures cemented with continuous crystallized quartz grains, the proposed solution predicts re-breaking at the center of the vein. For this case, we investigate two crystallographic orientations of quartz, $\text{c}$-axis orientation perpendicular to the fracture wall and $\text{a}$-axis orientation perpendicular to the fracture wall. Based on the current calculations for both crystallography of quartz, the tensile stress normal to the quartz plane is maximum at the center of the vein. Petrographic evidence, using secondary electron (SE) and cathodoluminescence (CL) images, supports our model predicting breakage within quartz veins as opposed to at the cement/sandstone host-rock interface. However, in a hypothetical case in which the calcite c-axis forms parallel to fracture walls in sandstone host-rock, debonding is predicted at the interface rather than within the vein cement.

存在于地下的自然开放型裂缝可以用成岩胶结剂（例如，关节和静脉）部分或完全封闭，这些胶结裂缝可能在岩心恢复至地面时重新开放。取决于水泥/基岩材料的特性，在水泥内或在水泥/岩界面处可能发生脱粘或再破裂。我们证明了诱导应力在岩心恢复至表面的过程中在打开胶合裂缝（静脉）中的作用，并确定了裂纹是沿静脉界面形成还是贯穿岩心形成以及为什么产生。我们将静脉视为夹在岩体内部的薄层，并使用本征理论来计算由于地应力释放以及地表温度与井下温度之间的差异而引起的岩心表面应力扰动。然后，我们采用弹性理论来计算静脉边缘的最大拉应力。该拉伸应力可用于估计天然裂缝内成岩水泥的拉伸强度。使用开发的技术，我们解决了一些实际示例，以确定在天然水泥中还是水泥/主体-岩石粘结中更可能发生脱胶。对于具有方解石矿脉的Marcellus页岩岩心恢复的情况，我们发现垂直于矿脉平面的最大拉应力发生在矿脉的中心。我们观察到这种现象，即c轴方向与分层都垂直于裂缝壁对齐（该拉伸应力可用于估计天然裂缝内成岩水泥的拉伸强度。使用开发的技术，我们解决了一些实际示例，以确定在天然水泥中还是水泥/主体-岩石粘结中更可能发生脱胶。对于具有方解石矿脉的Marcellus页岩岩心恢复的情况，我们发现垂直于矿脉平面的最大拉应力发生在矿脉的中心。我们观察到这种现象，即c轴方向与分层都垂直于裂缝壁对齐（该拉伸应力可用于估计天然裂缝内成岩水泥的拉伸强度。使用开发的技术，我们解决了一些实际示例，以确定在天然水泥中还是水泥/主体-岩石粘结中更可能发生脱胶。对于具有方解石矿脉的Marcellus页岩岩心恢复的情况，我们发现垂直于矿脉平面的最大拉应力发生在矿脉的中心。我们观察到这种现象，即c轴方向与分层都垂直于裂缝壁对齐（我们发现垂直于静脉平面的最大拉应力发生在静脉的中心。我们观察到这种现象，即c轴方向与分层都垂直于裂缝壁对齐（我们发现垂直于静脉平面的最大拉应力发生在静脉的中心。我们观察到这种现象，即c轴方向与分层都垂直于裂缝壁对齐（$\perp \text{C}$轴）并平行于断口壁（$\text{∥c}$-轴）。因此，从理论上讲，裂纹可能在方解石脉的中心而不是马塞勒斯页岩/方解石界面形成。迄今为止的实验室测试表明，马塞勒斯页岩中的方解石脉再破裂可能发生在方解石内部或方解石/页岩界面。对于砂岩中具有连续结晶石英晶粒胶结的裂缝的岩心恢复的情况，建议的解决方案预测在静脉中心会再次破裂。对于这种情况，我们研究了石英的两个晶体学取向，$\text{C}$垂直于骨折壁的轴向 $\text{一种}$轴方向垂直于裂缝壁。根据当前两种石英晶体学的计算结果，垂直于石英平面的拉伸应力在静脉中心处最大。使用二次电子（SE）和阴极发光（CL）图像的岩石学证据支持了我们的模型，该模型预测了石英脉内的破裂，而不是水泥/砂岩基质-岩石界面的破裂。但是，在假设方解石c轴平行于砂岩基质岩石中的裂缝壁的情况下，预计在界面处而不是在脉状胶结物中会发生脱胶。