一种气体钻井井底流体侵入量的简易算法

A new simple algorithm for calculating the bottom-hole fluid invasive amount of gas drilling

在气体钻井过程中,地层出水、出气易引起卡钻、井壁失稳等事故.为计算气体钻井流体侵入量,根据质量守恒原理,建立流体侵入量计算模型,推导井底流体侵入量表达式,利用井筒内平均流速计算流体滞后时间,并根据流体侵入量的计算结果给出相应的钻井方式.计算实例表明,流体侵入量模型简单、直观性强,可为气体钻井方式转换、减少钻井事故提供指导.

During the gas drilling process,formation water and gas will results in drilling accidents such as sticking of tool and wellbore instability etc,so to accurately calculate the fluid invasion amount plays a very important role in gas drilling.This paper presents a new method using quality conservation principle to calculate fluid invasive amount,which knew the fluid amount of the outflow to derive the bottom fluid invasion amount.The calculated examples show that the established fluid invasion calculating model is simple and intuitive.The model can also judge the type of the invasive fluid.So it provides a theoretical basis for transforming patterns of gas drilling and reducing drilling failures.