沁水盆地南部安泽区块煤体结构测井识别研究

Study on well logging identification of coal structure in Anze Block of southern Qinshui Basin

为了给煤层气井压裂方案和排采制度的制定提供有力的理论依据,依据测井和取心资料,对煤体结构识别进行了研究。研究结果表明:利用夹矸自然伽马测井值(GR)增大的特点,可以提高煤心归位的准确性;原生结构煤声波时差测井值(AC)大、密度(DEN)和自然伽马测井值小,碎裂结构煤声波时差测井值小、密度和自然伽马测井值大,糜棱结构煤和碎粒结构煤的这3种测井值则处于原生结构煤和碎裂煤之间;利用GR-DEN和AC-DEN测井交会图识别准确率可分别达到86.8%、82.8%,能很好地识别原生结构煤和碎裂结构煤;其煤心的低收获率、裂隙中碳酸盐矿物的充填和泥岩的存在是引起煤体结构识别误差的主要因素,结合井径和电阻率测井曲线可以有效地减少对煤体结构的误判。

In order to provide convincing theoretical basis for hydraulic fracturing and drainage schedule,identification of coal structure studied by using logging and core data.The results demonstrated that the accuracy of coal core position restoring had been improved by the feature of GR increase caused by gangue.The characteristics of logging in unformaed coal were higher AC,lower DEN and GR.The characteristics of logging in cataclastic coal were lower AC,higher DEN and GR.Compared to unformaed and cataclastic coal,the log response in mylonite and granulated coal were medium.The accuracies of identification using GR-DEN and AC-DEN cross plots were respectively up to 86.8% and 82.8%.Undeformaed coal and cataclastic coal were well identified by using logging cross plots.Lower recovery of coal core,the filling of carbonate minerals in fracture and the existence of mudstone were the major factors which causd mistakes in identification of coal structures.Caliper log and resistivity log were favorable for reducing mistakes effectively.