摘要
勘探证实 ,煤系地层是有效烃源岩之一。通过对煤成气的研究 ,发现煤系烃源岩 ,特别是以煤层作为烃源岩的评价存在以下三个方面的误区。第一 ,煤层属于高有机碳含量的烃源岩 ,随着热演化程度的提高 ,有机碳含量亦不断增加 ,利用有机碳含量评价煤的生烃能力已失去意义 ;随着热演化程度的提高 ,氢含量逐渐降低 ,建议利用煤的氢含量代替有机碳含量评价煤的生烃能力。第二 ,煤的镜质体反射率 (Ro)与温度并不呈线性关系 ,而是温度与深度呈线性关系 ,因而利用镜质体反射率与深度的关系预测深部烃源岩的成熟度存在一定的局限性。第三 ,热模拟试验存在两方面的不足 ,首先有机质在地下生烃过程中 ,始终处于开放系统 ,而热模拟是处于封闭系统 ;其次热模拟试验测定的生气量 ,特别是对于煤 ,没有考虑模拟样品的吸附作用 ,因此建议进行样品的解吸试验 ,以准确地确定有机质的生气量。
Exploration proves that coal?measure formation is one of the effective hydrocarbon source rocks. Through the study of coal?derived gas, it is found that there are three mistaken ideas on the evaluation of coal?measure hydrocarbon source rocks. First, coal bed belongs to source rock with high content of organic carbon that increases continuously as thermal evolution degree improves, so there will be no point in evaluating hydrocarbon generation capacity by using the content of organic carbon. Hydrogen content decreases gradually with the improvement of thermal evaluation degree, so evaluating hydrocarbon generation capacity using hydrocarbon content of coal instead of organic carbon is suggested. Second, the linear relationship between vitrinite reflectance of coal (R o ) and temperature does not exist, otherwise exists between temperature and depth. So there are some limits in forecasting the maturity of deep hydrocarbon source rock by using the relationship between R o and depth. Third, thermal simulation experiment has two shortcomings: one is that organic matter is in open system all the time during underground hydrocarbon generation, however thermal simulation is in close system; the other is that adsorption of simulated samples isn't considered when measuring the gas generating amount by thermal simulation experiment, especially for coal. So it's suggested that desorption experiment of samples should be done to determine the gas?generating amount of organic matter exactly.
出处
《油气地质与采收率》
CAS
CSCD
2001年第1期78-80,共3页
Petroleum Geology and Recovery Efficiency
关键词
煤成气
烃源岩
有机碳
含量
热模拟
生气量
coal-derived gas
hydrocarbon source rock
organic carbon
content
thermal simulation
gas-generating amount
