测井曲线谱分析方法及其在沉积旋回研究中的应用

测井曲线包含了丰富的地层信息，能够敏感、连续地反映所测地层的成层性和旋回性特征。测井解释的目的在于综合利用各种技术手段，充分挖掘测井资料所包含的地层信息，建立测井数据向地质目标的映射关系，描述目的的层的地质特征。储集层沉积旋咽研究的主体是地层中的规模旋回，测井资料以其数量、连续性好等优点，成为小规模旋回研究中的主要资料来源。某一沉积事件周期性出现的频繁程度可用时间序列中的频率来表示。地层沉积过程中的周期性规律会相应地体现在测井资料所包含的信息中，设计一定的数据处理系统提取这些信息，可以分析、描述和识别地层沉积特征。提出最大熵谱分析方法，即对测井曲线提取主成分和进行最大熵谱分析、谱特征分析，进而依赖谱展宽及其韵律和识别研究沉积旋回。与其它谱分析方法（如傅立叶谱和周期图法）比较，最大熵谱分析方法具有不受取样长度限制、对频谱分辨率较高等优点。对塔里木盆地实际资料的处理结果表明了该方法的可行性和有效性。

The application of spectral analysis of logs in depositional cycle studies

The characters of strata are shown continually and sensitively by well logs, which include a great amount of geological information. The purpose of well log interpretation is using various tools and technologies comprehensively to tap the strata information which is involved in logging data, to set up the relations between logging data and geological objective and to describe the geological characters of the targets. The subject of studing sedimentary cycles of the reservoir is small scale cycles of strata. Well logging data became the main sources of small scale cycle study duo to their many good characters such as good continuity and large quantity. The periodic occurrence of any sedimentary event may be expressed by the frequency in the time series. During the course of deposition, the periodicity of sedimentary cycle may be embodied in the logging data. Some data processing systems can be designed for extracting the information from the logging data and the deposition characters can be analyzed, described and identified with the information extracted from the logging data. The authors of this paper put forward a method called the maximum entropy spectra analysis, which can extract the major composition from logging data, do the the maximum entropy spectra analysis and spectra character analysis, and then identify and study sedimentary cycles according to the width of spectra and its rhythm. Compared with other spectra analysis, such as Fourier entropy and periodic picture, this method has many advantages such as no limit to sampling length and higher resolution to the spectra. The results of processing actual data from the Tarim basin show the feasibility and validity of this method.