塔里木盆地库车坳陷烃源岩热模拟实验及油气源对比

塔里木盆地库车坳陷侏罗系煤系地层为该区的主力烃源层。在对塔里木盆地库车河、阳霞河和它什店剖面的三叠系、侏罗系碳质泥岩、泥岩和煤3类不同的烃源岩热模拟实验的基础上,以库车坳陷东部库1井天然气组分(干燥系数)及乙烷碳同位素为参数,用内插法求出该参数条件下模拟样品所对应的模拟温度及热成熟度。结果表明,在与地质背景相吻合的可能的成熟度区间内,只有侏罗系煤系地层的YM-4煤样的模拟结果与库1井一致,表明采用热模拟实验干燥系数内插法,结合同位素以及组分成熟度等资料可以指示天然气的气源岩。这种方法能将油气与烃源岩动态演化过程结合起来进行对比研究,为油气源对比研究提供新的思路。 

Thermal simulation experiment of source rock and gas-source correlation in the Kuqa Depression of the Tarim Basin

9 samples from the Kuqa Depression of the Tarim Basin were collected and thermal simulated with a step of 40 ℃ from 260 ℃ to 540 ℃. The components and ethane carbon isotopic compositions of gases generated from simulated samples were analyzed. The drying coefficients (C_1/(C_2+C_3)) were figured out. Using drying coefficient of natural gas from Well Ku-1 as parameter for interpolation method, the possible thermal maturities of source rock as well as temperatures are calculated. According to geological background and the possible maturity range, the study showed that only the gas generated at about 420 ℃ from sample YM-4 of Jurassic coal formation is consistent with Well Ku-1 both in hydrocarbon components and ethane isotopic composition. That means Jurassic coal formation is the main source rock of natural gas from Well Ku-1. Combined with ethane carbon isotope, component and maturity data, the simulating gas drying coefficient can be used in gas－source correlation. The interpolation method overcomes the influence caused by organic thermal maturity and provides a new way for study of oil－gas－source correlation.