Lithologic Reservoirs ›› 2021, Vol. 33 ›› Issue (1): 131-144.doi: 10.12108/yxyqc.20210113

• PETROLEUM GEOLOGY • Previous Articles     Next Articles

Hydrocarbon accumulation differences and main controlling factors of Jurassic petroleum system in Altun piedmont of Qaidam Basin

TIAN Guangrong1, WANG Jiangong1, SUN Xiujian1, LI Hongzhe1, YANG Wei1, BAI Yadong1, PEI Mingli1, ZHOU Fei2, SI Dan2   

  1. 1. PetroChina Research Institute of Petroleum Exploration and Development-Northwest, Lanzhou 730020, China;
    2. Research Institute of Exploration and Development, PetroChina Qinghai Oilfield Company, Dunhuang 736202, Gansu, China
  • Received:2020-07-08 Revised:2020-09-24 Online:2021-02-01 Published:2021-01-25

Abstract: In order to clarify the differential accumulation and enrichment rules of oil and gas in the eastern part of Altun piedmont in Qaidam Basin,a large number of geological and geochemical test data were used to study the characteristics of oil and gas reservoirs around Jurassic petroleum system,analyze the accumulation periods, identify the key accumulation factors and establish the accumulation model. The results show that:(1)There are obvious differences in hydrocarbon accumulation in Altun piedmont. Natural gas maturity is low in Niudong area, dry gas and wet gas coexist,mainly in the middle and late Oligocene and the early and middle Miocene,with multi-layer accumulation vertically. Dongping area is dominated by dry gas,with great changes in maturity,and the gas reservoir is continuously filled and characterized by multi-stage accumulation from early Oligocene to Holocene, mainly enriched by bedrock. Jianbei area is dominated by dry gas with high maturity,and only bedrock enriches oil and gas in early and middle Miocene.(2)The vertical migration of oil and gas is controlled by the fault system connecting the Jurassic hydrocarbon-generating kitchen,the structural form of unconformity surface in the key accumulation stage controls the oil and gas migration direction,and the development degree of gypsum mudstone caprock in Lulehe Formation controls the enrichment layer series of oil and gas reservoir.(3) There are three kinds of hydrocarbon accumulation models in Altun piedmont:three-dimensional accumulation model with vertical fault transportation,step-by-step composite accumulation model with far-source transportation and subsalt accumulation model with far-source transportation. The research results have a guiding role in the exploration of Jurassic oil and gas system in foothill belt.

Key words: oil and gas system, accumulation stage, transport system, regional caprock, migration path, differential accumulation, Jurassic, Qaidam Basin

CLC Number: 

  • TE122.3+1
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