柴达木盆地西部坳陷区混源气判识

通过柴达木盆地西部坳陷区13个油气田的34个天然气样品组分和碳同位素值分析,运用天然气的甲烷、乙烷和丙烷碳同位素组成判识,柴达木盆地西部坳陷区天然气可划分为腐泥型原油伴生气,混合型原油伴生气,煤型气和混合成因气等4种类型混源气。西部坳陷区的大多数天然气属同源同阶的腐泥型原油伴生气、混合型原油伴生气或煤型气,由生物气或未熟混合型原油伴生气和低熟混合型原油伴生气复合而成的混合成因气仅分布于尕斯断陷亚区尕斯库勒油田浅层(上第三系),跃进二号西交点,以及油砂山油田和昆北断阶带乌南油田。

Discrimination of mixed gases in western depression of Qaidam basin

Chemical compositions and carbon isotopes of 34 natural gas samples, collected from 13 oil and gas fields in western depression of Qaidam basin, are measured and analyzed. Based on the carbon isotopes of methane, ethane and propane in the gas samples, the natural gas in western depression of Qaidam basin can be divided into 4 different types, including sapropel type oil associated gas, mixed type oil associated gas, coal related (humic) gas and hybrid gas. Most of the gases in western depression are cogenetic and synchronous sapropel type oil associated gas, mixed type oil associated gas and coal related gas. Hybrid gas, consisted of biogas, immature mixed type oil associated gas and low mature mixed type oil associated gas, distribute only in the shallow layers (Neogene) in Gas Hure oilfield in Gas faulted depression, the Yuejin No. 2 west intersection point, Youshashan oilfield and Wunan oilfield in Kunbei fault bench zone.