Title: An efficient approach for simulation of kill.
Abstract: A kick is one of the most dangerous and difficult problems in drilling operations. The methods for simulating kill operations to suppress a kick are classified into steady state, pseudosteady state, and fully transient analysis depending on calculation of the gas hold-up.Steady state analysis has been widely used in field calculation due to its simplicity and convenience. However, the effects of the formation cheracteristics, additional gas influx after well shut-in, and multiphase behavior in the annulus are not considered in steady state analysis. Fully transient analysis can describe kill operations with accuracy. However, fully transient analysis requires too much application time and it is known to be not effective method to simulate kill operations on the spot.In order to raise fleld availability of fully transient analysis, a new model is proposed in this study by combining fully transient analysis for the period prior to the kill mud injection and the pseudosteady state analysis for the period after the kill mud injection. To check the availability of the new model, it is compared with the Nickens model that makes use of the fully transient analysis. Results reveal that the two models are generally in good agreements if the difference of well configuration is compensated. The example results of Driller's method and Wait & Weight method are exhibited to show the validity of the new model. From the quantitative analysis of parameters, it is found that the pressure difference between the bottomhole and formation has strong influences on the annular pressures and then, has tendency to suppress the gas expansion. The effects of permeability and ROP i, e., rate of penetration) reveal that the volume of gas inflow before well stabilization determines pressures and the gas expansion after well stabilization.