煤层气井钢质筛管与非金属筛管强度对比实验

Comparision experiments on steel and non-steel slotted screen pipes used in coalbed methane wells

为了改变煤层气井钢质割缝筛管完井成本高的现状,探索研制较低强度的非金属完井管材进而实现煤层气井的低成本完井,采用电测法对J55钢质筛管和PVC非金属材质筛管的抗挤和抗弯强度进行测定,并对比分析割缝宽度和割缝密度对两类筛管性能的影响规律。结果表明:钢质筛管的破坏形式主要是刚度/径向失稳破坏,主要表现为整体变形或筛管短轴内壁割缝变宽而外侧割缝变窄并伴有缝端撕裂;而PVC筛管的破坏形式主要是强度破坏;无论对钢质筛管还是PVC材质筛管,增加缝宽和缝密都会降低筛管的抗挤、抗弯强度,但PVC材质筛管的强度随缝宽和缝密的变化不及钢质筛管明显,因而优选非金属新材料制作筛管时,可以适当增加缝密和缝宽,以提高筛管过流面积。

To reduce the current high completion cost for steel slotted screen pipes in coalbed methane wells and to develop low-intensity non-metal completion pipes to perform low-cost completion, this paper adopts electric survey to measure the collapsing strength and bending strength of J55 steel screen pipe and PVC non-metal screen pipe, and makes a comparative analysis of the effect of slot width and slot density on the strength of both kinds of screen pipes. The research results indicate that： the collapse of steel screen pipes mainly results from stiffness reduction or radial unstableness, showing the whole pipe deformation or the slot becoming wide or narrow at the internal or external wall along the short axis, accompanied with the tearing at the slot end-point; while the PVC screen damage mainly results from the material itself. For both steel and PVC screen pipes, the pipe＇s collapsing/bending strength declines with increase of the slot width and density, but the PVC screen pipes do not show such an obvious trend, making it possible to apply wider and denser slots on PVC pipes to increase the passing area.