海上油田负压作业有效负压值分析与管柱优化探讨

中国海上油田常采用负压射孔或平衡射孔负压返涌技术，以降低射孔作业对储层的污染问题，但当前作业并未考虑管柱结构对实际有效负压值的影响，且作业中有时会因井下工具原因导致复杂事故。在常用负压作业管柱结构的基础上，计算分析了RTTS封隔器位置、负压阀下入深度、钻杆套管尺寸等因素对有效负压值的影响，结果表明：若将RTTS封隔器置于井口位置，有效负压值不低于预设值的98%；在满足造负压的前提下适当提高负压阀的位置，由此对有效负压值的影响可以忽略。探究了采用环形防喷器替代RTTS封隔器、减小负压阀下深等优化方案的可行性，并针对该方案中存在的潜在风险进行了分析并提出相应解决对策。相比传统方案，改进后的负压作业管柱无RTTS封隔器，负压阀位置处井斜小，作业过程简化，有利于提高现场作业效率。

Analysis of Effective Negative Pressure and Discussion of String Optimization in Offshore Oilfield

In offshore oil field in China, negative pressure perforating or balanced perforating with negative pressure flowback technology is often adopted to reduce the pollution of reservoir during perforating operations. However, the influence of string structure on actual effective negative pressure value is not considered in current operations, and sometimes complicated accidents may be caused by downhole tools during operations. Based on the commonly used negative pressure string structure, this paper calculated and analyzed the influence of RTTS packer position, negative pressure valve depth, drill pipe casing size and other factors on effective negative pressure value. On the premise of meeting the requirements of negative pressure, raising the position of the negative pressure valve moderately has little effect on the effective negative pressure value. The feasibility of using annular blowout preventer instead of RTTS packer and reducing the depth of negative pressure valve was researched. Compared with the traditional scheme, the improved negative pressure operating string has no RTTS packer, and the well deviation is low in negative pressure valve position, which simplifies the operation process and is conducive to improving the field operation efficiency.