鄂尔多斯盆地长7段页岩生烃动力学特征与原位转化温度条件  

Hydrocarbon generation kinetics and in-situ conversion temperature conditions of Chang 7 Member shale in Ordos Basin

作　　者：张紫芸 侯连华[1] 罗霞[1] 何坤[1] 张岩 ZHANG Ziyun;HOU Lianhua;LUO Xia;HE Kun;ZHANG Yan(Research Institute of Petroleum Exploration and Development,Beijing 100083,China)

机构地区：[1]中国石油勘探开发研究院,北京100083

出　　处：《天然气地球科学》2021年第12期1849-1858,共10页Natural Gas Geoscience

基　　金：中国石油天然气股份有限公司“中低熟页岩油原位转化机理与高效传热机制研究”(编号:2021DJ5202)资助.

摘　　要：中国中—低熟页岩油/油页岩的资源潜力巨大,原位转化技术作为实现其工业化开采的有效途径日益受到各界重视。鄂尔多斯盆地三叠系延长组7段(长7段)是国内可采资源量最大的原位转化主力地层,除低熟页岩外,中等成熟度页岩的生烃特征和动力学过程可能不同,它们也可以作为页岩油/油页岩原位转化的潜在对象,现阶段缺乏相关机制研究。针对鄂尔多斯盆地长7段不同成熟度的天然页岩和半开放—半封闭体系模拟后页岩样品开展了开放体系热解实验,通过平行一级反应计算得到低熟页岩的频率因子为5.47×10^(10) s^(-1),活化能分布范围为38~61 kcal/mol,主峰为49 kcal/mol,占比66.91%。成熟度越高,生烃平均活化能越高,原位转化耗能越大,热解S_(2)峰所表征的生烃潜力越低。依据分布特征将活化能划分为<47 kcal/mol、47~52 kcal/mol和>52 kcal/mol的低活化能、主峰活化能、高活化能3组,随成熟度增加,低活化能、高活化能组占比增加,主峰活化能组占比降低。将动力学参数外推至原位转化条件下,建议选择成熟度较低的页岩(RO<1.0%),快速升温到主生烃期后慢速升温充分转化,并依据页岩成熟度的不同设置不同的原位转化温度区间。In-situ conversion technology has been paid more and more attention as an effective way to realize the industrial development of huge medium-and low-mature shale oil/oil shale resource in China.Ordos Basin has been recognized as the main basin containing the biggest in-situ conversion recoverable resources of China.Researchers have revealed the hydrocarbon generation kinetics of low mature oil shales in the 7^(th) Member of Yanchang Formation(Chang 7 Member).However,the kinetics of medium mature shales may be different from that of low mature shales,and they can also be used as potential targets for in-situ conversion.At present,there is a lack of research on the in-situ hydrocarbon generation kinetics of medium-and low-mature shale oil/oil shale.In this paper,open system pyrolysis experiments were carried out on natural shales and shale samples derived from semi-open system pyrolysis with different maturity respectively in Chang 7 Member of Ordos Basin.Using the parallel first-order reaction theory,the frequency factor of low-mature shale was calculated to be 5.47×10^(10) s^(-1),and the distribution of activation energy ranged from 38 kcal/mol to 61 kcal/mol.The main peak of activation energy is 49 kcal/mol,and accounted for 66.91%of all.With the increase of maturity,the average activation energy becomes higher,and therefore more in-situ conversion energy is needed.At the same time,the hydrocarbon generation potential characterized by S_(2) peak of pyrolysis decreases during the maturation process.The activation energy is divided into three groups according to its distribution characteristics:low,main peak and high activation energy groups,representing<47 kcal/mol,from 47 kcal/mol to 52 kcal/mol and>52 kcal/mol respectively.The proportion of low and high activation energy groups increased with the increase of maturity,while the proportion of main peak activation energy groups decreased.When the kinetic parameters are extrapolated to the condition of in-situ conversion,it is better to choose shales with low matu

关 键 词：原位转化 页岩油 生烃动力学 活化能 成熟度 长7段 鄂尔多斯盆地 

分 类 号：TE121[石油与天然气工程—油气勘探]