To select the size of detector crystal rightly for high -resolution density logging and enhance its response ability to formation and measurement precision. Using Monte Carlo numerical simulation, calculates the changing law of detector count with crystal length, and the law of detector sensitivity with the length for long,middle and short spacing detector with various radiuses. Calculated results show that the radius and length infiuence directly detector count sensitivity for a crystal; crystal radius of short spacing detector should be little relatively, and its length should be less than 1.7 cm; middle spacing detector can have a bit large crystal radius such as 1.4 cra, and its length can be between 2 cm and 3.5 cm; the radius of long spacing detector should be large as soon as possible in tool diameter range, and its length can be between 5 cm and 6.3 cm.%为了合理选择探测器晶体尺寸,以提高高分辨率密度测井探测器对地层的反应能力和测量精度,应用Monte Carlo数值模拟技术,对不同半径的长、中间、短源距探测器晶体,分别计算得到了探测器计数随晶体长度的变化规律,探测器对地层灵敏度随晶体长度的变化规律.由计算结果得出,晶体的半径和长度直接影响到探测器的计数和对地层的灵敏度;短源距探测器晶体半径以稍小为宜,长度应低于1.7 cm;中源距探测器晶体半径以稍大为宜,如1.4 cm,长度宜在2～3.5 cm之间;长源距探测器晶体半径应在仪器直径允许范围内以大为宜,长度宜在5～6.3 cm之间.
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