出砂量对射孔套管力学性能的分析计算

ANALYSIS AND CALCULATION OF MECHANICS PERFORMANCE OF SAND PRODUCTION RATE IN PERFORATED CASING

油井生产中地层出砂会严重影响射孔套管的力学性能,造成套管损坏。建立射孔套管在出砂层段的三维力学有限元模型,应用Ansys有限元软件分析该出砂层段射孔套管力学性能。研究认为,在出砂地层射孔套管力学性能变化较大,表现为射孔处套管的抗挤强度减小,套管最大应力在射孔处产生。均匀载荷下,套管应力与地层中出砂高度成抛物线关系,生产中应减小或增加出砂量达到远离出砂高度临界值,以减小套管应力。非均匀载荷下,随着出砂量增加,产生的空洞高度增加,套管的应力逐渐减小。因此,在非均匀载荷下,应提高出砂量以增加空洞高度,达到提高套管的抗挤强度,延长套管使用期限。

Sand production will severely impact the perforated casing mechanical properties during well production,which can damage the casing.The 3D mechanical finite element model of perforated casing is established at the sanding formation.The mechanical characteristics of casing are analyzed with the Ansys finite element software.The analysis indicates that the perforated casing mechanical properties of sanding formation change obviously,the collapsing strength of casing decreases at perforation location,but the max stress generates there.Under even load,the casing stress is parabola relation with sand production height,sand production rate should be away from the critical sand production height by increasing or decreasing sand production rate in order to reduce the casing stress.Under un-even load,the cavity height increases with the sand production rate increases,and the casing stress reduces gradually.Hence the sand production rate should be increased in order to enhance the casing collapsing strength,and prolong the service life of casing.