砾石充填服务管柱防窜力学分析及解决方案

摘要

During sand control for offshore gravel-packing completion, the performance of downhole tools is predominantly affected by their relative positions. In order to maintain accurate positions of inner string & outer string, and select proper downhole load positioning tool & optimal loading tonnage, forces on the completion string during and after gravel-packing operation were analyzed. Then, a mechanical model of interaction of packing fluids on the completion string was established and used to derive the optimal loading tonnage of donwhole load positioning tool. The model assumes the downhole load positioning tool as loading point and the axial channeling load of the string to be subject to circulating pressure differential of fluid, thermal expansion of string, bending of string, and other factors. Simulation tests of wells and studies of field applications indicate that the mechanical model basically tallies actual operation conditions and proves the necessity that appropriate downhole load positioning tool should be used in gravel-packing operation. This model can be used to provide supporting data for field operations and anticipate any abnormal condition, thus effectively contributing to the higher success of operations.%海上砾石充填完井防砂作业中，井下工具的相对位置是影响其功能实现的关键因素。为了保证内层服务管柱与外层管柱的位置准确性、选择合适的井下负荷定位工具及最佳压载吨位，对充填作业中及作业后的服务管柱进行了受力分析，建立了充填流体作用于完井管柱的力学模型，并推导出井下负荷定位工具的最佳压载吨位，模型假设井下负荷定位工具为承载点，管柱轴向窜动负载受流体循环压差、管柱热胀冷缩以及管柱弯曲等因素的影响。试验井模拟试验和现场实例分析表明，管柱力学模型与实际作业情况基本吻合，验证了在砾石充填作业过程中使用配套井下负荷定位工具的必要性，为现场作业提供数据支持，并对异常情况进行预判。