欠平衡钻井井底压力自动控制技术

Automatic Control of Bottom Hole Pressure while Underbal anced Drilling

在建立井底压力模型的基础上,研制开发了欠平衡钻井井底压力自动控制系统,其井底或井口压力计算模块根据数据采集模块提供的实时数据结合其它井身结构、钻具组合、钻井液性能等静态数据把计算结果传给电控节流阀控制模块,由其调节电控节流阀的开度,从而达到调节井口压力、特别是井底压力的目的。该系统有两种模式:井底压力的自动控制和井口压力的自动控制,分别可以满足欠平衡钻井施工和压井施工的要求。该系统由上位机和下位机组成,上位机负责采集、计算与控制,下位机负责显示、数据录入及数据管理。

Based on the bottomhole pressure model, the automatic control system of bottomhole pressure is developed in an underbalanced pressure situation. Computation modules including bottomhole and surface pressures can d eal with real time data provided by acquisition units and other static data, inc luding casing schematics, bottomhole assemblies and mud properties. In addition, the computational results can also be transmitted to the electric control unit which can adjust orifices of choke valves and thus control well head pressure, e specially the bottomhole pressure. The system has two different functions: autom atic controls of well head pressure and bottomhole pressure, which can meet sepa rately requirements for underbalanced drilling and killing operations. It consis ts of upper unit and bottom unit. The upper one is responsible for acquisition, computation and control; and the bottom one for display, data input and data adm inistration.