Numerical Simulation Research On Horizontal Well Outside Casing Gravel Packing In Unconsolidated Sandstone Reservoir

Gravel packing technology in horizontal wells has many good effects,such as sand control and improvement of production,which is widely used in oilfield.Currently,the technique of casing outside gravel packing in horizontal wells of unconsolidated sandstone is still in the stage of preliminary application.Based on logging data,the paper builds the attenuation model of rock strength considering the factor of production time and sand production.Based on the stress formula near wellbore,this paper applies finite element software analysis the stress distribution.The result shows,geo-stress is the function of overburden pressure,max principle horizontal stress,min principle horizontal stress,inclination angle,et al.When knows the value of above parameters,the geo-stress distribution of horizontal well depends on the down hole pressure.According to the stress law,builds the mode of formation rock break model,the result shows that,when max principle horizontal stress greater than compressive strength,causes crushing failure.When hoop stress greater than the tensile strength,the formation generates crack and extends.Based on the law of Mohr-Column and axial symmetry plane strain theory,divides the near wellbore formation into packing area,plastic compaction area and elastic area,and analyzes the rock destruction discipline.The result shows,internal friction angle,outside press near wellbore and elasticity modulus have greater influence on wellbore expansion ratio,with the increase of wellbore pressure,the influence degree of expansion ration improves.The Poisson’s ratio has less effect on expansion,and can be neglected.The plastic expansion ratio depends on the outside pressure and internal friction angle,et al.With the improvement of wellbore pressure,the plastic expansion ratio liner increase.