Study On Jet Excavation Process In Wellhead Conductor Jetting In Procedure

The special character of the jetting in technique has made itself to be widely used in the development of deep sea oil and gas resources.Its higher efficiency and lower cost turn it to be the prime choice in the practice on the surface layer of deep water.However,both the studies and published papers of the mechanism of jetting excavation in clay soil are very limited.The field practices are mostly depending on obtained experiences for sake of lacking theoretical instruction.Thus,it’s very necessary to study the mechanism of the jetting in procedure.Firstly,to study the influence of the jetting velocity,the nozzle location and the soil strength on the jetting excavation,Fluent was used in this paper to simulate on the simplified 2D symmetric models.Based on the above simulations analysis using complex sliding mesh 3D model was proceed.The jetting excavation versus time was obtained and compared with the 2D simulation results.After the works above,we come to following conclusions: In 2D symmetric analysis,when the nozzle is 22 cm away from the bit’s centerline,the erosion effect was the best.The scour depth increase sharply at first 0.6s and then turns frank.The 3D simulation results shows that,when the bit rotates at the speed of 60r/s,the scour depth increased discontinuously and the increase of the scour depth mainly occurred in the first 0.5s.The comparison between the 2D and 3D simulations shows that the scour depth in 2D simulations are smaller than that of 3D results under the same mass flux.This probably because the jetting time in 2D simulation is too short,additionally,the velocity distribution may count as well.