Identification method and device for tight sandstone reservoir microcrack development

Abstract

The invention provides an identification method and device for tight sandstone reservoir microcrack development. The identification method comprises obtaining mercury saturation of a rock sample in a target layer under different capillary pressures, respectively calculating logarithms of the capillary pressures and a logarithm of the mercury saturation, building a scatter diagram according to the logarithms of the capillary pressures and the logarithm of the mercury saturation, performing linear fitting for target data points in the scatter diagram so as to obtain a target fitting straight line, and identifying whether a target layer micro crack is developed according to a slope of the target fitting straight line. The technical scheme provided in the invention is simple and convenient, and whether the microcrack is developed can be quantificationally identified.

Description

technical field [0001] The invention relates to a method and a device for identifying the development of micro-fractures in tight sandstone reservoirs, belonging to the technical field of geological analysis. Background technique [0002] How to quantitatively evaluate tight sandstone microfractures has always been a research hotspot in this field, which is crucial for subsequent reservoir exploration and development. [0003] Taking the Paleozoic in the Ordos Basin as an example, it has abundant natural gas resources. The results of the third resource evaluation show that there are 1.5 trillion cubic meters of natural gas resources in the Paleozoic in the southern part of the basin, and the exploration prospects are very huge. The Longdong Oilfield is located in the southwest of the Ordos Basin, straddling the two cities of Qingyang and Pingliang, with an area of ​​about 5×10 4 km 2 , accounting for 25% of the area of ​​the main part of the basin, is the most important b...

AI Technical Summary

Problems solved by technology

[0005] 1) Using imaging logging to identify fractures: FMI imaging logging technology is mainly used to identify and evaluate tight natural gas reservoirs. However, due to the limitation of resolution, this method can only give conclusions from a macro perspective, and cannot effectively identify and evaluate tight natural gas reservoirs. Fractures developed in sandstone reservoirs

For example, when using Schlumberger's full-bore micro-resistivity imaging instrument (FMI) to study the Long 1, Long 2 and Qingtan 3 wells in the Shan 1 member of the Ordos Basin, it was found that it can only visually analyze the macroscopic However, it is difficult to effectively identify micro-cracks (cracks from microns to millimeters)

[0006] 2) Using scanning electron microscopy to identify fractures: SEM, FIB-SEM and other instruments are mainly used to characterize micro-nano scale rock pores. The experimental cost is also relatively high; ②Due to the small size of the sample of the scanning electron microscope, although the anatomy of the local structure is more detailed, especially in the nanoscale range, the technology mostly stays at the level of morphological description and quantitative evaluation of pores The ability of the structure is limited; ③ There are still some limitations in the identification of primary and secondary cracks, especially because the sample is small, some induced cracks generated during the sample preparation process have a great impact on the results

However, these parameters do not directly provide information about reservoir fractures

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