泡沫固井水泥浆密度与环空液柱压力变化规律研究

Study on Change Rules of Foam Cementing Slurry Density and Annular Static Liquid Column Pressure

摘要:

超低密度泡沫水泥浆是解决低漏失压力井固井漏失，提高固井质量的有效措施。除泡沫水泥浆体系的开发与性能优化外，掌握泡沫水泥浆在环空内产生的静液柱压力随井深的变化规律，是成功实施该工艺技术的前提。借助实际气体状态方程，考虑温度、压力变化对充入氮气的影响，建立了静液柱压力和水泥浆密度与井深之间的数学模型，以迭代法编程求解该隐函数方程，并借助VB语言实现程序运算。分析了含气量变化、井深等因素对泡沫水泥浆密度及静液柱压力的影响规律，并提出了泡沫水泥浆“防漏”与“压稳”固井浆柱结构设计思路，为该工艺平衡压力固井设计提供了一定的参考和理论依据。该设计方法经现场应用，证实其运算结果的可靠性。

Abstract:

Ultra-low density foam cement slurry is an effective technical measure to solve cementing leakage and improve cementing quality for low leakage pressure well. In addition to the foam cementing slurry development and the performance optimization, confirming static liquid column pressure (SLCP) at different annulus depth is necessary for foam cementing slurry application. With the help of real gas state equation, taking the influence on N2 filling volume by the variation of temperature and pressure into account, a mathematical model of SLCP and density of foam cement slurry together with the well depth was established, the implicit function is solved by iterative method and the program operation is realized by using VB language. The influence rules of gas content variation and well depth on foam cementing slurry density and SLCP are analyzed; the cementing slurry column structure design ideas for foam cement slurry are given for cementing leakage prevention and pressure stability which can be reference and theoretical basis for balanced pressure cementing design. This design method has been proved to be reliable by field application.