Dynamic Simulation Analysis And Matching Process Study For Additional Flow Rate Method

Killing well in deep water should be executed with a relatively slow circulating rate to avoid formation leaking or fracturing, and sometimes it is even cannot completed successfully due to the narrow safe operating mud window. Additional flow rate (AFR) method can overcome this problem beautifully by inject a kind of light and thin fluid into choke line to drop its pressure loss.The procedure of AFR well control method and the principle of choosing AFR fluid were described in detail in this paper. Based on this, a conceptual design to the AFR fluid injection and returned mixture processing system was made. The feasibility analysis on this method showed that there are no barriers on technical and equipment to carry out this method. By summed up constraint conditions in operation from the point of the view of safety and conjunct them with the principle of"the shortest kill time", a non-linear programming equations set was created, followed by solution steps and an example. Two models were used to carry out a simulation analysis on AFR method: Based on the"continuous gas column"model, the calculation formulas for drill pipe pressure, casing pressure and casing shoe pressure at different operating time were got; Grounded on the"multiphase flow"model, the multiphase flow control equation groups were created, accompanied with relevant definite conditions and solving method. Relied on the"Additional Flow Rate Method"software, the impact analysis of some important parameters on well killing was made with the exception of a well control simulation on a simulative well. As showed from results, set the killing parameters such as Additional Flow Rate properly can bring the AFR method into full play so that the operation time can be cut down.