Managed pressure drilling (MPD) technique can stop and remove a kick without shut-in procedure while keeping the bottomhole pressure relatively constant while a kick was detected. But the key for a successful kick removal operation depend on accurate, real-time knowledge of wellbore hydraulics. Therefore, the transient multiphase flow calculation for MPD kick control should be developed for obtaining high-precision hydraulics.
Firstly, a real-time multiphase hydrodynamic model for kick control of MPD was proposed, in which the gas solubility in drilling fluids is take into account. Because of the well head pressure need to adjust in real-time during MPD, therefore the influence caused by real-time adjusting of WHP for gas migration and phase change was take into account too. And as a consequence there are more boundary conditions and dynamic parameters of this model than the traditional multiphase model. Secondly, the finite difference method was used to solve the proposed model, and then a comprehensive solution procedure is proposed, in which the different boundary conditional mode of MPD is considered, based on which the numerical solution of kick control for different MPD mode can be obtained easily. Moreover, a series of system calculation software were developed to predicted pit gain, flow patterns, circulating pressures, gas top, bottomhole hydraulics and the related control parameters for control the kick while MPD.
The proposed model has been verified with experimental data collected from scientific experimental well of SINOPEC, there is an excellent match between the calculated and measured data and the calculation accuracy is higher than 95%. Furthermore, this calculation software has been used for analyzing the MPD kick control during drilling shale gas horizontal wells of SINOPEC, and it runs smoothly with convenient operation. Therefore it can be seen this system can be applied to provide more convenient fast and precise dynamic parameters monitoring for control kick while MPD.
This paper established a novel real-time multiphase hydrodynamic model and a systematic calculate software, which has been verified with experimental data and applied in shale gas field. Through the field application, the results show that it can provide more accurate prediction of wellbore multiphase flow parameters. Therefore it can be seen that this novel method can be applied for MPD kick control to provide more precise dynamic parameters for kick control while MPD.