裂缝性火成岩储层的井孔声波传播规律及时频特征

Formation fracture characteristics description is one of the key research issues for fractured igneous reservoir, but till now there is still lack of an efficient logging evaluation method. The multi-pole array acoustic logging behave the advantages of 3D column measurement in borehole and big probe radial depth, it can obtained a great amount of information, such as lithology, fracture, porosity and anisotropy, etc. In practice, because of the mechanism of acoustic propagation in the fractured formation is very complicated, just part of the information in time domain and frequency domain was used, and a few of research on time-frequency characteristics of the reservoir fracture properties were implemented, a lot of information measured in the borehole had not made full utilization effectively. This research project is planning to make use of Herbert-Huang Transform and fractional Fourier Transform technique to analyze the borehole acoustic field full array train in fractured formation, and make a deeper understanding of the acoustic propagation mechanism in borehole. By using the time-frequency analysis technique, studying the variation situation of the calculated full acoustic train in the time-frequency domain, revealing the acoustic field distribution law for different fractured formation, and then providing some new parameters for evaluating the properties of fractured igneous reservoir. By establishing more objective mathematic model to probe the internal relations between borehole acoustic fields and fractured formations, making full utilization of the obtained waveform information, this research program tried to providing more accurate basis for igneous reservoir evaluation. This is the main object of this research project.

裂缝特征描述是裂缝性火成岩油气藏的一项重要研究内容，至今仍缺乏有效的测井评价方法。多极子阵列声波测井以其三维柱体测量、探测深度大的优势，可获取极为丰富的地层信息，由于裂缝性火成岩储层中的声波传播机制复杂、测量记录的信息远远没有被充分有效利用。充分挖掘其所包涵的信息，并将其所蕴涵的特征参数用于实际测井资料的处理分析和储层评价是非常有意义的。针对裂缝性火成岩井孔弹性波传播分析评价的难题，本项目采用分数阶傅里叶变换及希尔伯特－黄变换分析裂缝性井孔声场全波列，利用时频分析方法，对数值模拟以及测量得到的全波列在时－频域的变化特征进行研究，揭示不同裂缝类型储集层的声场时－频分布规律，为储层裂缝性质的评价提供新的参数。通过建立更为客观的数理模型研究井孔声场与裂缝之间的内在联系，充分利用所测得的阵列声波波列信息，为裂缝性火成岩储层评价提供更为准确的依据，这也是本研究目标所在。

本项目的研究课题主要来源于裂缝性火成岩储集层的测井评价难题。裂缝特征描述是裂缝性火成岩油气藏的一项重要研究内容，至今仍缺乏有效的测井评价方法。多极子阵列声波测井以其三维柱体测量、探测深度大的优势，可获取极为丰富的地层信息，由于裂缝性火成岩储层中的声波传播机制复杂、测量记录的信息远远没有被充分有效利用。充分挖掘其所包涵的信息，并将其所蕴涵的特征参数用于实际测井资料的处理分析和储层评价是非常有意义的。针对裂缝性火成岩井孔弹性波传播分析评价的难题，本研究利用了交错网格有限差分方法进行数值模拟、计算，采用了分数阶傅里叶变换及希尔伯特－黄变换分析裂缝性井孔声场全波列，利用时－频分析方法，针对不同岩性、不同流体性质储集层的多极子阵列声波测井时－频响应和相应分析数据的相关关系，揭示了不同岩性、不同流体性质裂缝类型储集层的声场时－频分布规律，为储层裂缝性质的评价提供了新的参数，可以更加充分地利用所测得的声波全波列信息，为裂缝性火成岩储层评价提供了更为准确的依据。