川西深井协同控制立压与套压循环排气研究

考虑压力波速、井底压力响应时间、气体滑脱等因素,结合立管压力与套管压力对U形管的共同作用原理,通过协同控制立管压力与套管压力,建立了抑制井底气侵的控制方程。提出了协同控制套管压力-补偿环空压降模型,利用计算机编程对其求解。以某深井钻井为例,结果表明,气侵量增大、气侵发现延迟,套管压力呈现增大趋势; 气侵从井底循环出井口的过程中,套管压力呈现先增大后减小的控制趋势; 当井底出现气体时,立管压力首控同套管压力首控比较,4 000 m井深的首控时间可节约75.4%,这是由于立管中未遭受气侵,几秒内可将立管压力作用于井底,而套管中遭受气侵,呈现多相流动形式,井底接受套管压力的响应时间滞后数十秒; 发现气侵后,首控立管压力,抑制气侵发生,同时微调套管压力,可达到快速抑制气侵的目的。

Research of Cooperative Control Standing Pressure and Casing PressureFast Suppression Gas Influx in Depth Well in Chuanxi

Considering the pressure wave velocity,pressure response time,gas slippage and other some factors,combined with standing pressure and casing pressure in the U-tube,a cooperative control model is established based on standing pressure and casing pressure while gas influx occurs.Computer programming is adopted to solve the model.Results show that with the increases of gas influx rate and the delay time to found,casing pressure are significantly increased; in the process of gas moves from wellbottom to wellhead,the trend of casing pressure control is that at first increases and then decreases; the standpipe will not be impacted by gas invasion.Compared the control of casing pressure,the time control of standing pressure can save 75.4% in the well depth of 4000 m.Therefore,the wellbottom can be acted by standing pressure within a few seconds,casing pipe will be impacted by gas invasion,and the response time lag at tens of seconds in wellbottom.If gas invasion is discovered,the standing pressure is controlled in a directly,and then trimming casing pressure which can compensate the pressure drop due to gas move,which can ensure the rapid implementation of balanced pressure drilling.