Oil & Gas Geology ›› 2013, Vol. 34 ›› Issue (5): 708-716.doi: 10.11743/ogg20130519

• Sequences and Reservoirs • Previous Articles    

Reservoir characteristics of the organic-rich shales of the Triassic Yanchang Formation in Ordos Basin

Er Chuang1,2, Zhao Jingzhou1,2, Bai Yubin1,2, Fan Hao1, Shen Wuxian1,2   

  1. 1. School of Earth Sciences and Engineering, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China;
    2. Shaanxi Key Lab of Petroleum Accumulation Geology, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China
  • Received:2013-03-31 Revised:2013-08-15 Online:2013-10-08 Published:2013-10-08

Abstract:

Reservoir characteristics study is very important to understand the hydrocarbon potential of organic-rich shales.A series of analyses and tests,including thin sections,SEM,XRD,physical property,total organic carbon(TOC),specific surface area and pore size distribution,were made to reveal the reservoir characteristics of the organic-rich shales of the Triassic Yanchang Formation(Fm)in Ordos Basin.This paper also defined the lithofacies,mineral types,diagenesis,pore types and physical properties.Three types of lithofacies are identified in the organic-rich shales,including muddy shale,silt-bearing shale and silty shale.The muddy shale has the highest TOC content,clay content of more than 50% and relatively weak diagenesis.The dominant pore types of the organinc-rich shales in the Yanchang Fm are intragranular and intergranular pores.The pore sizes of micropores are mainly within 0.4 to 1 nm and those of mesopores are mainly within 3 to 5 nm.The contribution of the mesopores to pore volume and specific surface area is larger than that of the micropores.The high content of ductile minerals and weak diagenesis of the organic shales in the the Yanchang Fm make the reservoir stimulation more challenging.

Key words: lithofacies, pore type, pore structure, reservoir characteristics, organic-rich shale, Yanchang Formation, Ordos Basin

CLC Number: