Abstract: Four indicators have been mentioned for identifying gas from oil and gas from coal measure. (1)the carbon isotope of methane (σ~(13)C_1)in gas from coal measure is generally heavier than that from oil; (2) the content of mercury vaor in gas from coal measure is higher than that from oil; (3) in a basin or formation with Ro ranging 0.4 to 1.35% producing primarily gas and only a small amount of associated oil, the gas is from coal measure; and(4) if condensate oil is observed in the gas from a formation with Ro ranging 0.4 to 1.0%, the gas is from coal measure. Examples have been cited for illustrative purpose.

摘要： 鉴别煤成气和油型气的普遍性标志初步认为有:1.煤成气的甲烷碳同位素(δ¹³C₁)一般比油型气的重:在Ro≤0.5%,煤成气和油型气δ¹³C₁除-55‰至-74‰是重迭数域值外,当δ¹³C₁<-74‰为油型气型生物成因气;在Ro>0.5%至-2.5%时,δ¹³C₁-43‰至-30‰是煤成气与油型气重迭数域值,故δ¹³C₁≤-43‰至-55‰的气是油型气;而δ¹³C₁>-30‰的气是煤成气。2.煤成气中的汞蒸气比油型气的一般含量高。煤成气中平均汞含量一般在700毫微克/米³以上,多数大于1000毫微克/米³,而油型气中平均汞含量在600毫微克/米³以下,多数小于400毫微克/米³;煤成气中最高含汞量一般大于1000毫微克/米³,而油型气中的一般小于700毫微克/米³。3.当Ro为0.4%至1.35%时,一个含油层系形成以气为主以油为辅,这种气是煤成气。4.在与Ro0.4%至1.0%有成因关系的气中,若普遍见到凝析油,这种气是煤成气。

关键词: 煤成气, 油型气, 凝析油, 初步探讨, 毫微克, 甲烷碳同位素, 生物成因气, 四川盆地, 天然气, 鄂尔多斯盆地