Oil & Gas Geology ›› 2013, Vol. 34 ›› Issue (5): 584-591.doi: 10.11743/ogg20130502

• Petroleum Geology • Previous Articles     Next Articles

Gas source conditions of quasi-continuous accumulation of the Upper Paleozoic in Ordos Basin

Cao Qing1, Zhao Jingzhou1, Fu Jinhua2, Yao Jingli2, Liu Xinshe2, Zhao Huitao2, Hou Yundong2, Fan Liyong2   

  1. 1. School of Earth Sciences and Engineering, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China;
    2. Exploration and Development Research Institute, PetroChina Changqing Oilfield Company, Xi'an, Shaanxi 710021, China
  • Received:2013-03-31 Revised:2013-08-15 Online:2013-10-08 Published:2013-10-08

Abstract:

A comprehensive analysis of the Upper Paleozoic gas source conditions in Ordos Basin shows that high quality source rock is the major factor controlling the formation and distribution of large tight sandstone gas field in the study area.The lower limit of gas generation intensity for large tight sandstone gas field is determined based on analysis of gas production test results.A correlation analysis is first performed on the thickness,total organic carbon content (TOC) and maturity of the Upper Paleozoic source rocks in Ordos Basin,and gas generation intensity of the sources rocks is then calculated based on the correlation analysis.The calculation results are finally integrated with gas production tests to perform comprehensive analysis.The analysis of gas source conditions indicates that the Upper Paleozoic source rocks are characterized by high quality,wide distribution,high maturity,high intensity of gas generation and wide gas supply.In general,the intensity of gas generation ranges from 10×108 m3/km2 to 40×108 m3/km2.However,the gas generation intensity is not equilibrium in the whole basin.It ranges from 10×108 m3/km2 to 20×108 m3/km2 in the western basin,whereas,it is more than 16×108 m3/km2 in most part of eastern basin.In conclusion,high quality source rock is one of the major factors controlling the formation of large tight sandstone gas field,and it also controls the distribution of gas-water contact in the Upper Paleozoic tight sand reservoirs.As gas accumulation is closed to the source rocks and the accumulation efficiency is high,the lower limit of gas-generation intensity can be reduced to about 10×108 m3/km2 for Upper Paleozoic quasi-continuous tight gas accumulation in Ordos Basin.

Key words: gas source condition, gas generation intensity, tight sandstone, Upper Paleozoic, Ordos Basin

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