Advances in Earth Science ›› 2008, Vol. 23 ›› Issue (10): 1013-1019. doi: 10.11867/j.issn.1001-8166.2008.10.1013

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Application of Cathodoluminescence Analyse to the Recovery of Feldspar Content in Sandstone—A Case Study of Upper Paleozoic of Ordos Basin and Xujiahe Formation of Western Sichuan Depression,Sichuan Basin

Huang Sijing,Tong Hongpeng,Huang Keke,Liu Lihong,Zhang Xuehua   

  1. State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation,Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China
  • Received:2008-07-10 Revised:2008-09-03 Online:2008-10-10 Published:2008-10-10

Huang Sijing,Tong Hongpeng,Huang Keke,Liu Lihong,Zhang Xuehua. Application of Cathodoluminescence Analyse to the Recovery of Feldspar Content in Sandstone—A Case Study of Upper Paleozoic of Ordos Basin and Xujiahe Formation of Western Sichuan Depression,Sichuan Basin[J]. Advances in Earth Science, 2008, 23(10): 1013-1019.

The Shanxi and Taiyuan sandstones in Ordos Basin and the Xujiahe sandstones in Sichuan Basin are very important gas reservoirs in China, which are characterized by very low feldspar contents and are extremely cemented by calcite. The sandstone fabric before calcite cementation happened was revealed by Cathodoluminescence analysis. The result studied here suggests that, dissolved feldspar in buried diagenesis, at least, accounts for 10%~20% of rocks. It is proposed that the high composition maturation and large inter-granular porosity volume of the sandstones in the coal-bearing stratum of both upper Paleozoic in Ordos Basin and Triassic in Sichuan Basin are not original, which should result from the dissolution of feldspar by the acetic fluid in coal-bearing strata. The Cathodoluminescence of remaining feldspar shows that the feldspar dissolved in buried diagenesis is mainly K-feldspar, suggesting that the K-feldspar is relatively stable during weathering and transportation and early buried diagenesis stages, and much plagioclase was dissolved before buried diagenesis. Therefore, the K-feldspar contributed a large amount of secondary porosity to sandstones of Shanxi, Taiyuan and Xujiahe Formations.

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