Dynamics Simulation Of Jet Penetration Under Down-hole Environment

Perforation is a major factor in improving productivity and protecting reservoir.It plays an important role in oil or gas exploration and development.Usually,It puts the special shaped charge perforator down and reach desired depth,then detonates the shaped charge perforator and the metal jet formed will establish the channel between the wellbore and reservoir.Perforation is a complex physical process,involving explosive detonation,large deformation,high strain rate and fluid-structure interactions.Solving such problems needs the help of numerical simulations.According to these problem,this paper has carried out the following works.(1)In this paper,a numerical model of perforator is established with Euler method.AUTODYN is used to perform jetting analysis,jet formation,jet stretch and break.The velocity,pressure and kinetic energy of jet are studied in detail.In addition,the influences of liner angle and charge mass on jet formation and jet parameters are studied.It shows that liner angle plays a key role on the velocities,the shape and mass of jet.Charge mass is a main influence factor of jet velocity and kinetic energy.(2)In this paper,the numerical model of jet penetrating multi-layer target is established with Lagrange method.Jet interaction(penetration)with target is calculated by AUTODYN.The large deformation,high strain rate dynamic processes of penetrating perforation gun,casing and concrete by jet is studied in this paper.Numerical results show consistent agreements with experimental results,the errors of penetration depth and diameter are 4.27% and 5.26% respectively.The dynamic response of the penetration process is discussed,including the shock wave and velocity at collision point,and the damage around the tunnel.The influences of liner angle,charge mass and concrete compressive strength on penetration depth are also studied.There is a positive correlation between the liner angle,the charge mass and penetration depth.It shows the increase of concrete strength leads to large decrease of penetration depth.(3)In this work,the numerical model of penetrating under the wellbore is established with CLE(Coupled Lagrangian Eulerian)method.The initial pressure in wellbore and the confinement of rock are considered in this model.The Fluid-solid coupling method is used to perform the interaction between all fluid domain and solid domain.The results show the shape of perforation channel,the state of the fluid movement and the variety of wellbore pressure during perforation.Furthermore,the influence of liner angle,charge mass,initial wellbore pressure and confinement to penetration depth was also studied.It shows that the increase of initial wellbore pressure and confinement leads to large decrease of penetration depth.This work can provide a reference for the optimization of the perforating charge and the correction of down-hole penetration depth.