While underbalance drilling spreads greatly, rotating blowout preventer, as a kind of high technical product, is the crucial equipment to control well pressure.

国内欠平衡钻井普遍实施,要用到的旋转是关键设备,技术含量高。

The minimum underbalance is independent of viscosity and compressibility and of reservoir fluids.It is a function of the formation porosity, permeability and radius of perforation channels.

最测试压差不是依赖于地层度和压缩性，而是为地层孔隙度、渗透率和射孔孔眼半径的函数。