The low density drilling fluid has borehole excavation effect on compensated neutron porosity logging, and by this way apparent porosity is lower than the true value.
低密度井眼流体会对补偿中子孔隙度测井产生井眼挖掘效应，使视孔隙度值低于真孔隙度，且井眼流体密度越小，井眼尺寸越大，地层孔隙度越大，井眼挖掘效应越明显。
Because of the weak borehole sealing and inadequate use of the initial free face, the higher investment and unsatisfactory blasting effect still exist in the mine tunnel excavation blasting.
由于炮孔堵塞不牢和初始自由面利用不充分，井下平巷的掘进开挖爆破仍存在投入大、爆破结果欠理想等问题。
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