欠平衡钻井直井段岩屑运移规律研究

欠平衡钻井技术由于具有提高钻速、及时发现和保护储层等优点,已被广泛应用。然而,地层气体进入井筒后,气液两相流型变化规律复杂。由于不同气液流型具有不同的携岩效果,因此井筒岩屑运移规律多变。首先分析单个岩屑的受力情况,建立岩屑运移数学模型。然后建立环空多相流流型判别模型及环空压力计算数学模型。最后以某井为例编制计算程序,分析相应的钻井参数及进行钻井参数优化。数值模拟结果与现场施工参数吻合。

Study on cuttings transport in vertical well with UBD

Underbanlanced drilling (UBD) technology is widely used in practice because it has many advantages such as improving drilling speed and discovering and protecting reservoir timeliness. However, after the formation gas enters into wellbore annulus, the rule of gas-liquid two-phase flow is complicate, because different gas-liquid flow pattern has different throughput capacity, as a result, the rule of cuttings transport is varied. Firstly, the essay introduces cuttings transport mathematical model; Secondly, it introduces the model of distinguishing different multiple phase flow patterns and the mathematical model of calculating annulus pressure; Finally, it takes some well for example and formulates calculator program, analyzes drilling parameters and optimizes drilling parameters. The results coincide with field parameters.