Method for calculating shale content of high and low gamma interaction reservoirs

Abstract

Disclosed is a method for calculating a shale content of high and low gamma interaction reservoirs. The method includes step one, influencing correction by means of a logging information environment; step two, calculating the shale content by means of spontaneous potential logging; step three, calculating the shale content by means of resistivity logging; step four, calculating the shale content by means of a compensated neutron-density method; step five, calculating the shale content by means of natural gamma-ray logging; step six, determining the shale content using a minimum value method on the basis of the shale contents calculated by using the previous four methods. According to the method for calculating the shale content of the high and low gamma interaction reservoirs, shale content calculations of a high gamma reservoir and a conventional reservoir are organically integrated, a calculated shale content curve basically overlaps with a shale content analyzed and tested by a lab, and accuracy of calculation of the shale content is greatly increased.

Description

technical field [0001] The invention belongs to oil and gas exploration and development technology, in particular to a method for calculating the shale content of high- and low-gamma interactive reservoirs. Background technique [0002] The Jiyuan and Baibao areas in the Ordos Basin are important oil and gas development areas in my country, but there are high- and low-gamma alternating reservoirs in this area, which brings a lot of inconvenience to the calculation of shale content parameters in reservoir evaluation. [0003] The so-called high gamma reservoirs are sandstone layers with high natural gamma values ​​compared with conventional sandstone reservoirs and close to mudstone intervals; low gamma reservoirs are conventional reservoirs. High natural gamma anomalies were found in sandstones in the Jiyuan and Baibao areas, and the overall natural gamma was high, and its natural gamma value was close to that of non-reservoirs, which could easily be interpreted as non-reser...

AI Technical Summary

Problems solved by technology

Natural gamma ray logging can only calculate the shale content of conventional (low gamma) reservoirs, and high natural gamma values ​​appear in some sandstone sections with less shale, if the conventional natural gamma curve is used to calculate the shale content , you will get a wrong high shale content value; some tight sandstone with less shale content and sandstone with higher calcareous content have poor physical properties, and the spontaneous potential curve does not shift or the shift is very small, basically located near the baseline , if these formations use the natural potential curve to calculate the shale content, the wrong high value of shale content will be obtained; the resistivity of shale sandstone reservoirs is affected by shale content, porosity, oil saturation, formation water salinity, etc. Affected by many factors, it is difficult to accurately calculate the shale content of argillaceous sandstone reservoirs by using resistivity logging. Because the neutron and density logging are sensitive to shale and oil and gas, the natural gamma ray cannot well reflect the formation shale content in high-gamma reservoirs, and the matching relationship between neutron and density is good. , the shale content can be calculated by the neutron-density intersection method, but it is difficult to calculate the shale content of high and low gamma interaction reservoirs

[0006] Judging from the existing shale content calculation methods, they are mainly concentrated on conventional (low gamma) reservoirs and high gamma intersecting reservoirs, and there is no shale content calculation method for high and low gamma intersecting reservoirs , which brings inconvenience to the computer automatic processing and calculation of shale content in high- and low-gamma interactive reservoirs

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