Organic geochemical analysis shows that oils in the lower Oligocene reservoirs in Gas Hure

western Qaidam basin

are of typical salt lake origin and have the characteristics of both low mature oil and mature oil. Source correlation shows that oils in the lower Oligocene reservoirs in Gas Hure were mainly sourced from the lower Tertiary near mature or mature source rocks buried over 3500m in the adjacent area

which were deposited in salt lakes with high concentration of calcium and salt in strong reducing environment. Salt and high carbonate content in the source rocks significantly inhibited isomerization of steroid and terpenoid

wich would delay the maturation of lower Tertiary source rocks. Oils currently discovered in the lower Oligocene reservoirs in Gas Hure are mainly low mature oil

with rare immature and mature oils. Analysis shows that mature source rocks are mainly distributed in deep layers with a burial depth of over 4000m

thus deep layers would be the potential targets for discovering mature oils.