Research on the detection method of abnormal structural planes in shale reservoirs in Hongxing area

Abstract: [Objective] abnormal structural plane of shale reservoir refers to hard and soft surface, including limestone interlayer, bedding fracture and natural fracture. It is closely related to reservoir formation, reservoir fracturing and oil and gas production. Accurate identification of abnormal structural plane and type is of great significance for oil and gas exploration and development. [method] firstly, the hard surface of limestone interlayer is identified by using the energy difference between fast and slow shear waves of array acoustic logging; Then the Gini coefficient of electrical imaging logging is introduced to characterize the development of bedding fractures according to the oscillation degree of Gini coefficient; Finally, according to the parameters such as array acoustic correlation coefficient and waveform information, the identification of natural joints is realized. [result] the results show that: in the identification of abnormal structural plane of shale reservoir, the energy difference information has a good response to the hard surface of limestone interlayer, and the identification of bedding fracture by Gini coefficient improves the problem that there are too many single strips and the effect is not good in the past. The dark strips in the waveform and array acoustic correlation coefficient are introduced to have a more intuitive representation of natural fractures, and the location and size of natural fractures are visually determined. [Conclusion] the application shows that for vertical wells, this method can accurately and quickly identify limestone interlayer, bedding fracture and natural fracture development section; For horizontal wells, the judgment of limestone interlayer and quantitative identification of natural fractures can be realized according to the array acoustic logging parameters and waveform. Combined with the lost circulation data, it is found that the results are mutually corroborated with the results of fracture identification, which proves the feasibility of the above method in horizontal wells.