在套管或衬管与周围的水泥环之间所形成的小间隙，这些间隙是由于在固井期间或固井之后温度或压力的变化所致。
A small gap that can form between the casing or liner and the surrounding cement sheath, most commonly formed by variations in temperature or pressure during or after the cementing process.
射孔枪与套管之间的间隙过大会影响射孔效果，太小容易出现工程事故。
Perforation effect is seriously affected by the clearance between perforator and casing.
端面有间隙、无凸台对接是指在上、下套管之间留有一定间隙，上、下主弦杆端面同时接触对接。
End face with a gap, no boss butt is refers to the upper and lower casing left a certain gap between the upper and lower main chord rod end face at the same time contact.
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