控压钻井自动节流管汇压力调节特性研究

Pressure Regulation Characteristics of Automatic Choke Manifold in Managed Pressure Drilling

现代控压钻井作业中,依靠自动节流管汇施加和控制井口回压,从而间接控制井底压力。但由于阀门的压力调节特性与阀门开度存在较大的非线性,常规节流管汇很难通过单个节流阀实现全开度范围内的精确调节。为了提高控制精度,利用节流阀工作的3个状态,建立了压力调节特性与流量调节特性的对应关系,进而建立了节流管汇的压力调节特性模型,并对压力调节精度及流量对压力调节特性的影响进行了分析。研究分析表明,现有节流阀压力调节特性呈现一定非线性;通过优化阀芯可以增大节流阀的有效工作区间,但不能完全消除超调区间;钻井液排量对节流阀的压力调节特性影响较大,设计节流管汇时应考虑排量问题。

In modern managed pressure drilling operation ,automatic choke manifold is used to provide and control wellhead back pressure so as to control formation pressure .Due to the nonlinear relationship between regulating pressure and choke valve opening ,it is difficult to adjust the choke valve accurately by a single choke valve within the scope of full opening in conventional choke manifold .In order to enhance con-trolling precision ,the corresponding relation of pressure regulation performance and flow rate was estab-lished based on the three working states of choke valve ,the model of pressure regulation performance was also developed .By analyzing the pressure adjusting precision and the effect of flow rate on pressure regula-tion performance ,it is considered that pressure regulation performance of choke valve is somew hat non-lin-ear ,optimization of valve core can increase its effective working range ,but it can’t eliminate super-adjus-ting scope ,the flow rate of drilling fluids has a great effect on pressure regulation performance of choke valve ,the flow rate should be paid great attention w hen designing the choke manifold .