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本世纪五十年代和六十年代曾发表过许多文章,讨论了检波器组合的问题。例如,史密斯(Smith,1956)和霍尔兹曼(Holzman,1963)等作者都曾对组合响应理论作过很好的论述.后来,大多数地球物理人员把这个课题作为“旧事物”收藏入档,而且大多都被遗忘了.1980年出版的《地球物理学》杂志题录总索引表明,自1970年以来仅发表过两篇有关检波器组合的论文。这就是纽曼(Newman)和马奥尼(Mahoney)的经典著作(1973)以及里彻(Rietsch)的一篇短文。这两篇论文为了获得霍尔兹曼结果而提出了另外一种算法. 这些早期的文章断言,输出不同的、等距检波加权组合是最佳的组合方式。关于什么样的组合是最好的加权系统,是有些争论的,但争论的不是其基本原理. 霍尔兹曼论文发表之后十八年,地震勘探上使用的是等距、等加权系数的组合,或简单的加权系数组合,它是一种“组合的组合”。对于变化的检波器输出的情况,几乎毫无所知. 这样会出现什么问题呢?有两个因素是很重要的:其一,难于产生一个成本低而且十分可靠的电子加权系统;其二,难于验证纽曼和马奥尼进行的理论计算以及其它地球物理学家类似的推论。第二个因素是我们不使用理想加权组合的主要理由。但是,去年我们观察了许多实际中使用的组合情况。理论组合是大家都知道的,即间距为30英尺的“8×3”的加权组合。在理论上,对于250英尺至90英尺的波长的波(典型的地滚波),至少衰减27分贝。计算实际组合的特性曲线说明,其最小平均衰减为15分贝,在同样的加权系数组合下,这种衰减要比理想的衰减好(这些组合的布置是很不规则的)。很明显,正如实际应用所说明的那样,加权组合是值得研究的. 变距加权组合所以能被选用的原因有: (1)这种组合易于用标准设备; (2)它们不受检波器数目的任何限制; (3)它们很稳定,在间距和传感系数改变时不会在主要方面改变其总响应。
Many articles published in the 1950s and 1960s addressed the issue of geophone combinations. For example, authors such as Smith (1956) and Holzman (1963) have made good expositions on combinatorial response theory, and most geophysicists later put the subject as a collection of “old things” Most of the files have been forgotten, and the total index of titles in Geophysics published in 1980 shows that only two papers on geophone combinations have been published since 1970. This is the classics of Newman and Mahoney (1973) and an essay by Rietsch. These two papers propose another algorithm to obtain the Holzman result, and these earlier articles asserted that outputting the different, equidistant detection weighted combinations is the best combination. There is some debate as to which combination is the best weighting system, but not the argument. The 18 years after the publication of the Holzman essay, the seismic survey uses equidistant combinations of equal weighting factors , Or a simple weighting factor combination, it is a “combination of combinations.” There is little to be known about the changing detector output. What are the problems with this? Two factors are important: first, it is difficult to produce a low-cost and very reliable electronic weighting system; secondly, It is difficult to verify the theoretical calculations made by Newman and Mahoney and similar inferences by other geophysicists. The second factor is the main reason why we do not use the ideal weighted combination. However, last year we looked at many of the combinations actually used. The theoretical combo is a well-known, “8 × 3” weighted combination of 30-feet spacing. In theory, for a wave of 250 feet to 90 feet (typical ground roll), attenuate at least 27 dB. The calculation of the characteristic curve of the actual combination shows that the minimum average attenuation is 15 dB, which is better than the ideal attenuation with the same weighting combination (the arrangement of these combinations is very irregular). Clearly, weighted combinations are worth studying, as the practical application illustrates. The reason for the choice of variable-weight combinations is that: (1) this combination is easy to use with standard equipment; (2) they are insensitive to geophones Any number of restrictions; (3) They are stable and do not change their overall response to changes in spacing and sensor coefficients in the main.