Production-induced three-dimensional surface displacement over oil/gas fields measured by InSAR and its induced environmental impacts

Oil and gas production can cause a drop in pore pressure within the reservoir, increasing effective stress and resulting in reservoir compaction. Subsurface reservoir compaction propagates to the Earth’s surface, manifesting as land subsidence, which can damage oil/gas production facilities and surface infrastructure. When oil and gas fields are situated in low-lying delta regions, land subsidence exacerbates the impact of flooding and inundation. A three-dimensional (3D) displacement field is expected over an oil/gas-producing field due to oil reservoirs’ typically significant burial depth relative to their horizontal extent. In this study, we proposed a novel method to retrieve the complete 3D displacement field over producing oil/gas fields. By integrating multi-geometry InSAR line-of-sight (LOS) observations, we derived the vertical and east-west displacement components, while the north-south component was estimated based on an assumed physical relationship between horizontal and vertical displacements. We applied this method to the oil fields in Liaohe River Delta in Northeastern China and the Sebei gas fields in Northwestern China. The derived 3D displacement field reveals a circular subsidence bowl with a maximum subsidence rate of ~20 cm/year at the center, accompanied by a centripetal pattern of horizontal displacements with maximum rates of ~5 cm/year directed toward the subsidence center. The retrieved 3D displacements align well with predictions from geomechanical modeling, which assumes a disk-shaped reservoir undergoing a uniform reduction in pore fluid pressure. Finally, we highlight infrastructure damage caused by oil production-induced land subsidence and its impact on flood inundation in the low-lying Liaohe River Delta.

石油和天然气的生产会导致储层内孔隙压力下降，增加有效应力，从而导致储层压实。地下储层压实会向地表传播，表现为地面沉降，这可能会损坏石油/天然气生产设施和地面基础设施。当石油和天然气田位于低洼的三角洲地区时，地面沉降会加剧洪水和淹没的影响。由于油藏通常具有相对于其水平扩展而言显著的埋藏深度，因此预计油气生产场地上会出现三维（3D）位移场。本研究提出了一种新方法，用于提取生产油气田上的完整三维位移场。通过结合多几何InSAR视线（LOS）观测，我们推导出了垂直位移和东西方向的位移分量，而南北方向的分量则基于水平位移和垂直位移之间的假定物理关系进行估算。我们将该方法应用于位于中国东北的辽河三角洲油田和位于中国西北的塞北气田。提取的三维位移场揭示了一个圆形沉降盆地，沉降速率最大约为20 cm/yr，位于中心区域，伴随着向沉降中心指向的以圆心为中心的水平方向位移模式，最大水平方向位移速率约为5 cm/yr。提取的三维位移与地质力学建模的预测结果很好地对齐，后者假定储层呈盘状，并经历孔隙流体压力的均匀降低。最后，我们突出了石油生产引起的地面沉降对基础设施造成的损害及其在低洼辽河三角洲地区对洪水淹没的影响。