Well integrity is crucially dependent on the bonding quality between cement and rock. Several studies have been made of this in the past, but none have taken into account that the drilled rock can be fractured and damaged during drilling. Especially a caprock fractured in the near-well zone can jeopardize well integrity. In this paper we have investigated the effect of shale caprock damage on the quality of well cement bonding to shale. Both intact and fractured rock has been cemented under realistic conditions, and the degree of the bonding (e.g. contact surface between the shale and cement) has been studied by X-ray computed tomography (CT) scanning. It was found that in the shale samples with fractured borehole, partial cement slurry penetration into the fracture network resulted in larger volume of leakage pathways than in the intact shale samples. The leakage potential through each of the samples was estimated based on connected cracks found by numerical calculations from three-dimensional (3D) reconstruction of CT data.

井的完整性关键取决于水泥和岩石之间的粘结质量。过去已经对此进行了几项研究，但是没有考虑到钻凿的岩石在钻探过程中会破裂和损坏。特别是在近井带破裂的盖层会危害井的完整性。在本文中，我们研究了页岩盖岩破坏对水泥与页岩粘结质量的影响。完整的岩石和破裂的岩石都已在实际条件下进行了胶结，并且已通过X射线计算机断层扫描（CT）扫描研究了粘结程度（例如，页岩与水泥之间的接触面）。研究发现，在钻孔破裂的页岩样品中，与完整的页岩样品相比，部分水泥浆渗透到裂缝网络中会导致更大的泄漏路径。通过连接的裂缝，估计通过每个样品的漏电势，这些裂缝是通过对CT数据的三维（3D）重建进行数值计算得出的。