Study On Hollow Glass Spheres Injection And Separation Techniques For Deepwater DGD

Dual Gradient Drilling (DGD) is also known as Dual Density Drilling, which is a new type of drilling technology for deepwater drilling. It has peculiar advantages to use lightweight Hollow Glass Spheres (HGS) to reduce the density of mud in riser in Hollow Glass Spheres Dual Gradient Drilling. The technology of HGS DGD requires recycling HGS in order to reduce the costs of drilling, and hydrocyclone is researched to recycle HGS at sea surface in this paper. The concept of HGS DGD and correlation theories are firstly introduced, hydrocyclone models are designed under some certain conditions and mathematical turbulence model of eddy flow is established. The flow field in the hydrocyclone is simulated by Computational Fluid Dynamics (CFD) software, which shows that velocity and pressure field accord with theoretical flow field of hydrocylone. The separation efficiency of hydrocyclone is affected intensively by the geometry structures and operating condition. The elements, whose parametric sensitivity is analyzed, determine the separation efficiency of HGS and solid-cuttings and the pressure lost of hydrocylone, and the influence tendencies are described. Optimization of hydroclyone structures is carried out by orthogonal numerical simulation analysis (Latin Square design) at some certain levels, and relatively ideal geometry model is obtained. Successful injection of HGS underwater to riser is the one pivotal technique of HGS DGD technology, injection of high concentration spheres can reduce the density of drilling fluid effectively. The best injection scheme is selected via analytical hierarchy process which determine the weighing factor, the process of chosen injection scheme are theoretically researched. Hydrocylone separation while drilling downhole is concept designed, and finally the designed model is numerically simulated and analyzed by CFD.