地质科技通报 (May 2024)
Interpretation and evaluation methods of image logs and their geological applications
Abstract
Significance To systematically address problems related to the interpretation and evaluation of image logs and expand their application range in geology and engineering fields, firstly, the development history, data processing steps and interpretation process of image log acquisition series are reviewed, and then fine interpretation methods for image logs, constrained by "four levels" (direct interpretation of images, conventional logging constraints, core constraints and geological theory constraints), are proposed in this paper. Progress The image log facies models can be divided into seven categories: massive, banded, cross-stratified, spotted, convoluted, graded and symmetrical groove modes. Image logs can be used for core orientation, formation attitude acquisition, fracture evaluation, fault property analysis, in situ stress direction discrimination, sedimentary characteristic pickup, palaeocurrent direction discrimination, etc. Through the inverse calculation of Archie's formula, the image log data matrix can generate porosity spectra and apparent formation water resistivity spectra, which can be used for reservoir quality evaluation and fluid property identification, respectively. Slab images can reveal information such as sedimentary laminae, fine-grained sediment lamina textures can be identified, and high-resolution logging can be used to evaluate unconventional oil and gas reservoirs. Poro Tex image structure analysis technology can be used to identify the characteristics of reservoir spaces such as pores and fractures and to quantitatively calculate parameters such as porosity and fracture porosity. Therefore, it is widely used in comprehensive logging evaluations of highly heterogeneous carbonate reservoirs. Conclusions and Prospects These research results can help us to avoid misunderstandings in image logs interpretation and expand the application field of image logs.
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