Gas Rises Rapidly Through Drilling Mud

Abstract

ABSTRACT To understand the development of a gas kick, we must know the rate at which gas migrates upward through drilling mud. Migration rates measured in laboratory experiments are much greater than those commonly accepted by the drilling industry. To address this controversy, we use a computer simulator to model field data and test-well experiments in detail. Both the experiments and the Held data show that gas migrates as fast as 6000 ft/hr [0.5 m/s] through drilling mud. The field data show that gas migration can drive surface pressure up as fast as 3000 psi/hr [4.9 kPa/s], These conclusions agree with laboratory experiments and contradict what is generally accepted in die industry. The results from the simulation of the field kick were incorporated in a case study. The study increases drill crew awareness of the speed at which gas can arrive at surface and demonstrates that a reduction in pump pressure can be a very late kick indicator.