This paper analyzed the geochemical characteristics and the sources of natural gas in the western Qaidam Basin based on isotopes and gas composition. The natural gas in the western Qaidam Basin is mainly comprised of hydrocarbon gases, including sapropelic, humic and mixed gas. In the southwestern Qaidam Basin, the main gas is sapropel gas, with some mixed gas and a small amount of humic gas. In contrast, the northwestern Qaidam Basin contains mainly humic gas, some mixed gas, and a small amount of sapropel gas. The dryness coefficient varies between 0.6 and 0.95. The carbon isotopes of methane, ethane, and propane are distributed between -32.9 ‰ ∼ -51.4 ‰, -34.2 ‰ ∼ -22.4 ‰, -30 ‰ ∼ -17.4 ‰, respectively. The calculated R_o value of the natural gas is between 0.5% and 1.87%. In general, the natural gas shows the characteristics of high dryness coefficient, heavy carbon isotopes, and high thermal maturity. The gas-source correlation makes it clear that the main hydrocarbon source rocks in the western Qaidam Basin are the lower Ganchaigou (E₃), the upper Ganchaigou (N₁) and the lower Youshashan formations (N₂¹). The gas-producing layers in the northwestern Qaidam Basin are primarily from the lower Ganchaigou (E₃), the lower Youshashan (N₂¹), and the upper Youshashan formations (N₂²). The primary gas source rocks are the lower Ganchaigou (E₃), the upper Ganchaigou (N₁), and the lower Youshashan formations (N₂¹). The main gas-producing layers in the southwestern Qaidam Basin are the lower Ganchaigou (E₃), the upper Ganchaigou (N₁), the lower Youshashan (N₂¹) and the upper Youshashan formations (N₂²), with the main gas source rocks being the lower Ganchaigou Formation (E₃).

本文根据同位素和天然气组成，分析了柴达木盆地西部的地球化学特征和天然气来源。柴达木盆地西部的天然气主要由烃类气体组成，包括腐殖质，腐殖质和混合气。在柴达木盆地西南部，主要气体是腐殖质气体，其中有一些混合气体和少量腐殖质气体。相反，柴达木盆地西北部主要含有腐殖质气，一些混合气和少量的腐殖质气。干燥系数在0.6和0.95之间变化。甲烷，乙烷和丙烷的碳同位素分别在-32.9‰--51.4‰，-34.2‰--22.4‰，-30‰--17.4‰之间分布。计算的R _o天然气的价值在0.5％至1.87％之间。通常，天然气具有高干燥系数，重碳同位素和高热成熟度的特征。气源的相关性清楚地表明，柴达木盆地西部的主要烃源岩为下部干柴沟（E ₃），上部干柴沟（N ₁）和下部油砂山地层（N ₂ ¹）。柴达木盆地西北部的产气层主要来自赣柴沟下部（E ₃），尤沙山下部（N ₂ ¹）和尤沙山上部地层（N ₂ ²）。主要的气源岩为甘差沟下游（E ₃），上部的甘cha沟（N ₁）和下部的油砂山地层（N ₂ ¹）。柴达木盆地西南部的主要产气层为下甘柴沟（E ₃），上甘柴沟（N ₁），下游沙山（N ₂ ¹）和上游沙山地层（N ₂ ²），其中气源岩为甘开沟下部（E ₃）。