Flow regulation and bottom hole pressure control under gas influx condition based on RMR system

Abstract

During the drilling process of RMR system, when the gas reservoir is drilled, the bottom hole pressure and formation pressure are in an unbalanced state, and the formation fluid invades the bottom hole under the action of pressure difference, further causing complex situation such as overflow and kick. In order to effectively control the bottom hole pressure during drilling and ensure drilling safety, a bottom hole pressure calculation model of RMR system under gas influx condition is established based on the gas-liquid two-phase flow theory. Three flow regulation methods of increasing the outlet flow of drilling pump and subsea pump at the same time, reducing the outlet flow of subsea pump while the outlet flow of drilling pump remains unchanged, and increasing the outlet flow of drilling pump while reducing the outlet flow of subsea pump are selected to dynamically simulate the change process of bottom hole pressure after flow regulation. Through data fitting, The relationship equation between them and bottom hole pressure is obtained, and the flow regulation method of RMR system when controlling bottom hole pressure under gas influx condition is formed.