松辽盆地北部深层原油的碳同位素特征及成因探讨

CARBON ISOTOPE CHARACTERISTICS AND ORIGIN OF DEEP CRUDE OIL IN THE NORTH SONGLIAO BASIN

吴河勇 李景坤

WU Heyoug LI Jingkun

中国石油, 大庆油田有限责任公司, 勘探开发研究院, 黑龙江, 大庆, 163712

Research Institute of Exploration and Development, Daqing Oilfield, CNPC, Daqing, Heilongjiang 163712, China

松辽盆地北部深层烃源岩大部分处于高成熟—过成熟阶段,仅在4口井发现了深层原油.松辽盆地深层泥质烃源岩干酪根碳同位素比较重,但由于其脂肪支链上富集12C,因此生成的烃类碳同位素却比较轻.随成熟度的增加,深层烃源岩干酪根碳同位素略微变重.受母质类型的影响,深层烃源岩干酪根碳同位素比青山口组一段大约轻7‰.碳同位素对比结果表明,芳深1井和芳深2井原油来自昌德地区东部的沙河子组泥质烃源岩,升深1井和宋3井原油可能主要为煤岩所生.

Most of deep source rocks were in high-mature or over-mature stages,and deep oil was found in only three wells in the North Songliao Basin.Carbon isotope of kerogen was heavier in deep formations of the Songliao Basin,but lighter carbon isotope may generate because the enrichment of 12C in fatty side-chains.Carbon isotope was bascally not related to its thermal maturity,but was affected by its origin.Carbon isotope fractionation of oil in the deep was resulted from the primary migration of oil and the crac-king of large molecules in reservoirs.The fractionation resulted in different slopes between the n-alkane carbon isotopic profile of oil and that of its source rocks.Comprehensive analysis indicated that the high mature oil in the deep was generated by the source rocks deeper than the No.1 member of the Qingshankou Formation.

https://doi.org/10.11781/sysydz200303300