Abstract
With the development of the petroleum industry, the importance of low-permeability reservoirs becomes clear. The fracture, which serves as the notable characteristic of a low-permeability reservoir, controls the flow system of reservoir fluid and restrains the development effect. Finding ways to recognize the fracture by using the normal data and building the fracture 3-D model are the important and difficult points of low-permeability development. According to this problem, the authors use a helpful probe. First, from similar outcrop and drilling core study of the fractured original model, the knowledge base of the fracture was built. Second, based on the analysis of the principle of dual-later log identification fracture, the core calibration was used to make logging, and using dual-later log, the fracture in wells was recognized. Third, based on the analysis of the principle of the fractal kriging method, the inter-well fractures were predicted. Finally, the 3-D model of fracture was built with fractural random simulation. The result shows that the 3-D model is in accordance with the fact of the development. So, the method is correct.
Highlights
From a study of a similar crop in the research area, we find the following characteristics of fractures (Table 1) (Figure 1)
The study area is mainly based on compensated acoustic logging, and the detected longitudinal wave head waves are more sensitive to horizontal fractures and low-angle fractures, and cycle jumps and abnormal high-value characteristics of acoustic waves may occur in the fracture section
The characteristic of a micro log is as follows: micro-resistivity of sections with fractures is lower than 7 Ω m, while that of the near sections without fracture is higher than 10 Ω m; difference on a micro-log of fracture sections changes from 4 Ω m–10 Ω m for normal sections to 1 Ω m–3 Ω m, and even 0 Ω m locally
Summary
Oil and gas in tight and low-permeability reservoirs is an important replacement resource and development field in China (Ding et al, 2015; Sun et al, 2019). 3) Other qualitative methods are used to predict fractures, that is, based on the relationship between fracture development and structure and lithology, to qualitatively understand the distribution characteristics of fractures. Qualitative methods to predict fractures are mainly based on the relationship between fracture development and structure and lithology, to qualitatively understand fractures and distribution characteristics. From the observation of drilling cores of Xinli oil field, we get the following results (Figure 2A): 1) Fuyang reservoir in Xinli oil field develops multiple groups of fractures with different angles, aperture, and cutting depth. The study area is mainly based on compensated acoustic logging, and the detected longitudinal wave head waves are more sensitive to horizontal fractures and low-angle fractures, and cycle jumps and abnormal high-value characteristics of acoustic waves may occur in the fracture section. Preferable fracture identification results can be obtained with resistivity tools if the electrical resistivity of bedrock is large
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