油气储层中自生伊利石K-Ar同位素年代学研究若干问题的初步探讨

对油气储层中自生伊利石K Ar体系产生影响的有关问题如砂岩岩性、伊利石 /蒙皂石间层矿物的间层比和绿泥石进行了初步试验和讨论。结果表明 :中、细砂岩的应用效果相对较好 ,粉砂岩、泥质粉砂岩则难度较大 ;I/S有序间层的应用效果相对较好 ,I/S无序间层则难度较大 ;绿泥石对自生伊利石K Ar体系测年结果的影响不明显。油气注入可能是引起伊利石成岩作用终止的原因之一。最后对各种典型年龄剖面可能的成因解释进行了简要介绍和初步探讨。

DISCUSSIONS ON K-Ar ISOTOPIC GEOCHRONOLOGICAL STUDIES OF AUTHIGENIC ILLITES IN HYDROCARBON RESERVOIRS

As a new technique, K-Ar dating of authigenic illites in oil and gas reservoirs is becoming one of the important research subjects in studying hydrocarbon accumulation history in China. Based on preliminary experiment data, this paper discusses the possible impact of sandstone lithology, percentage of smectite layers in interstratified illite/smectite, and development of chlorite on authigenic illites K-Ar system in oil/gas reservoirs, and concludes that for being used in this technique, medium-fine sandstones are better than siltstones, and ordered I/S are more suitable than random I/S. The development of chlorites are unlikely to have much impact on the K-Ar system of authigenic illites. Oil charging is only one of the possible causes to stop the diagenesis of illites. Some possible interpretations for hypothetical K-Ar age profiles of fine-size authigenic illites are introduced and discussed briefly.