Multidimensional Evaluation for Safe and Efficient Killing Using Dynamic Kill Method: A Case Analysis in China

Abstract

Well control in gas reservoirs with high pressure has been of growing interest in the industry in recent years. It has been widely recognized that challenges of well leakage and ground equipment damage will be faced in well-control work. Unfortunately, current well-control procedures do not allow us to kill with confidence and serious accidents occur sometimes. To ensure a safe and successful kill operation, before drilling, utilizing multiple well-control approaches to simulate the kill operation and after blowout, determining reasonable kill parameters to accomplish the kill should be of great significance. In this study, the Qing Xi 1 well was taken as an example to perform the first and second dynamic kill simulations by the Drillbench software to evaluate the effectivity of different kill operations with various choke pressures. The feasibility analysis of the dynamic kill was conducted by switching the displacement of mud pump, ascertaining the values of laminar coefficient A and turbulence coefficient B skillfully, and employing the known parameters of pump pressure, gas influx from formation and fracture pressure. The simulation results demonstrated that, under the limited geological conditions and the site environment of the Qing Xi 1 well, the second killing scenario will succeed when 40MPa choke pressure was employed in the dynamic kill operation, which differs dramatically from the realistic failure of the second killing scenario in the site of the Qing Xi 1 well. Accordingly, the maximum of choke pressure should be suggested in the future site operation of killing scenario when the equipment conditions are allowable. Although higher choke pressure may make the well leak-off, it will generate smaller losses compared with serious blowout out of control. In addition, a reliable pre-prevention and post-processing well-control procedure for implementation of our method was proposed, which is the most efficient and easy to apply. Our work in this paper should provide a basis for guiding field operations involving kill efficiency and should assist engineers in ensuring personal and property safety.