固定节流阀特性研究

STUDY ON FEATURES OF FIXED THROTTLE VALVE

钻井过程中为了平衡地层压力,需要井控节流阀向井底提供回压。但对于高压地层,靠一级节流阀不可能提供足够的回压来平衡地层压力,这就需要采用二级节流甚至多级节流来提供足够大的回压。在实际应用中可采用一级固定节流阀和一级可调节流阀相结合的方式来提供回压。固定节流阀主要是采用细长孔来实现降压,使得流入可调节流阀的液体压力低于50MPa来保证可调节流阀在安全可靠的情况下调节对井底回压,实现成功压井。为此,应用流体力学理论和先进的流体分析软件ANSYS,对井控装置中用于多级节流的固定节流阀的孔径以及长度大小对压降的影响进行了数值计算分析。结果表明,理论上得到的结论与数值计算结果基本一致。

In order to balance formation pressure during drilling, throttle valve is required to provide back pressure towards hole bottom. And it is impossible to provide sufficient back pressure to balance the formation pressure by only one throttle valve when drilling through high pressure formation. During the actual field work one fixed throttle valve and one adjustable throttle valve are often combined together to exert enough back pressure. The fixed throttle valve adopts an elongated bore to realize pressure reduction, which can reduce the pressure of the incoming liquid down to below 50 MPa so as to adjust the back pressure exerted on the hole bottom safely and reliably to kill the well successfully. Therefore the fluid dynamics theories and the advanced flow analysis software ANSYS are used to conduct numerical calculation and analysis regards the effects of bore diameter and length of the fixed throttle on pressure reduction. The study results show the numerical calculation results are similar to the theoretical values, which has provided theoretic basis for proper selection of fixed throttle at the well site.