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- Title
成岩作用对致密砂岩储层微观结构的影响差异 ——以鄂尔多斯盆地姬塬和镇北地区长7 段为例.
- Authors
郭轩豪; 谭成仟; 赵军辉; 赵信; 王进
- Abstract
Tight oil has become a research focus in the field of global unconventional petroleum. The dense oil resources of Chang 7 member in Ordos Basin are abundant and have great exploration and development potential. In this study, different influence of diagenesis on micro pore-throat characteristics of tight sandstone reservoirs in Chang 7 member in Jiyuan and Zhenbei areas of Ordos Basin were studied by using the test and analysis data of rock slice, casting slice, scanning electron microscope(SEM), mercury injection test, porosity-permeability analysis and X-ray diffraction analysis. The results showed that:The sandstone of Chang 7 member in Jiyuan and Zhenbei areas of Ordos Basin is dominated by feldspathic and lithic arkose. The main clastic compo⁃ nents in Jiyuan area are feldspar, followed by quartz;while the dominate components for Zhenbei area are quartz, followed by feldspar. The compositional maturity is generally low with medium sorting for these two areas. Reservoir pore types are mainly residual intergranular pore and feldspar dissolved pore for Jiyuan area, while Zhenbei area are mainly feldspar dissolved pore and residual intergranular pore. The radius of pore and throat for these two areas are similar, but the porosity, throat sorting coefficient and pore throat connectivity show obvious differences. Different influence of diagenesis is the main reason for the heterogeneity of reservoir in these areas. Because of the development of biotite and clay matrix in Jiyuan area, the compaction leads to the loss of primary pores, while the dissolution is weak. Chlorite hinders the formation of other authigenic minerals, thus preserving part of the remaining primary intergranular pores, and the reservoir connectivity is relatively better than Zhenbei area. The content of plastic volcanic rocks in Zhenbei area is high, and the compaction leads to more loss of primary pores. Illite is well developed, which is easy to be eroded and broken by high-speed fluid in the pore throat. After migration, the pore throat is blocked, resulting in the decrease of reservoir permeability and the number of effective pore throat and effective pore throat radius. Although Zhenbei area experienced stronger dissolution, it has no obvious improvement on reservoir connectivity.
- Subjects
PORE fluids; SCANNING electron microscopes; VOLCANIC ash, tuff, etc.; ROCK analysis; FELDSPAR; QUARTZ
- Publication
Natural Gas Geoscience, 2021, Vol 32, Issue 6, p826
- ISSN
1672-1926
- Publication type
Article
- DOI
10.11764/j.issn.1672-1926.2021.02.006