井下微流量测量实时传输系统研究及应用

Real-time Transmission System of Downhole Micro-flow Measurement

微流量控制的钻井技术主要通过实时监测钻井液进出口流量变化来判断井下复杂情况,并通过调节井口节流装置的开度来控制井口回压。井下微流量工具可实现实时传输功能,这为微流量高效准确控制提供了有利保证,从而,设计了井下微流量测量实时传输系统,本系统可以将井下测试仪器的信号通过MWD传输至地面,为地面回压、流量的控制提供参数。本装置的优点主要体现在对井下发生的溢流和井漏事故的快速处理上,如果没有发生相应事故,则只需保持井底环空流量和压力的稳定;一旦井下发生压力相关事故,控压机制就会启动,通过判断井下环空流量的变化及侵入流体的含气率,结合井口参数,采取合理措施对井底流量、压力进行控制。

In micro-flow controlled drilling technology, downhole complicated conditions are mainly estimated by real- time monitoring of inlet and outlet flowing variation of drilling fluid, and wellhead back pressure is adjusted through the opening control of throttling devices. However, by downhole micro-flow tool, the function of real-time transmission can be achieved to provide a guarantee for controlling micro-flow rate efficiently and accurately. Thus,a real-time transmission system of downhole micro-flow measurement is designed. With the system, the signal of downhole tester can be transferred to the ground through MWD, providing some parameters about back pressure and flow control. Its main advantage is the fast processing for accidents of downhole overflow and lost circulation. If there is no accident, it just needs to maintain the stability of annular flow rate and annular pressure; but if many accidents related to pressure occur, the mechanism of pressure control will start to adjust downhole flow and pressure through estimating the annular flow variation and the gas content of invading fluids combining with wellhead parameters.