基于井下流量测量的微流量控制系统

Micro-Flow Control System Based on Downhole Flow Measurement

为了能够快速有效地监测井下复杂情况并控制井底压力,开发了一种基于微流量测量的控制系统,根据实时监测钻井液进出口流量的变化来判断井下复杂情况,通过调节井口节流装置的开度来控制井口回压,从而实现对井底压力的精确调节和控制。设计了一套井下压差式环空微流量测量装置,该装置能够快速监测由于早期井涌、井漏等井下复杂情况而引起的井底流量的微小变化,并将井下测得的数据通过MWD传送至地面,与井口数据相结合进行分析,从而能够更加有效地提高微流量控制系统对井底复杂情况的判断能力和系统控制精度。介绍了井下微流量控制流程,进行了压差式井下环空流量测量装置的入井试验,分析了试验结果。入井试验表明,该装置可成功监测环空井底微流量变化,及时反映井底工况,且测量精度较高。

In order to monitor down-hole complex conditions and control bottom-hole pressure,a new drilling method based on micro-flow control has been developed in recent years. As a type of MPD, this technique can identify downhole complex conditions and control the backpressure by adjusting the opening of choke. This technique controls the down-hole pressure accurately by monitoring real time change of drill- ing fluid＇s flow rate in the surface. A Differential Pressure Meter has been developed based on problems of current MFC methods,which can detect the micro-change of downhole flow induced by early kick,lost cir- culation and other complicated conditions and the information is transmitted to the surface by MWD. Through the borehole experiments for Differential Pressure Meter of the micro-flow, the micro-change of downhole flow can be measured successfully, downhole conditions can be identified in a timely manner with high accuracy.