渤中地区不同热解实验条件下的烃源岩生烃动力学研究

Hydrocarbon Generation Kinetics of Source Rocks under Different Pyrolysis Conditions in Bozhong Area

为了对比不同类型烃源岩样品在不同的热解模拟实验条件下生油和生气的活化能,选取渤中地区多个湖相泥质烃源岩原岩和干酪根样品进行了开放体系无水热解和封闭体系加水热解实验,烃源岩样品取自不同的洼陷和烃源层位,具有不同的有机质丰度、类型和成熟度。对比结果表明,有机质类型和成熟度对烃源岩生油活化能有重要影响,平均生油活化能随有机质类型变差和成熟度增大而增大。不同的洼陷、烃源层位和样品类型对平均生油活化能无明显影响,而样品类型则影响活化能的分布,原岩活化能分布相比干酪根更加集中。处于成熟阶段烃源岩的生气活化能比处于低熟阶段烃源岩的生油活化能高11~17kJ/mol。相对于开放体系无水热解实验,封闭体系加水热解实验活化能分布集中且能够包含初次裂解和二次裂解过程。本研究应用封闭体系加水热解模拟实验,分别选择低熟烃源岩原岩样品和成熟烃源岩干酪根样品进行生油和生气活化能研究,取得了良好的效果。

To study oil and gas generation activation energy of different samples under different pyrolysis experiments,open system anhydrous pyrolysis and confined system hydrous pyrolysis are performed on lacustrine shale source rock,raw rock and kerogen samples from Bozhong area.Source rock samples are from different sags and different intervals,and have different organic matter abundance,kerogen type and maturity.The results shows that kerogen type and maturity have important influence on oil generation activation energy,and mean oil generation activation energy increases as organic matter type becomes poorer and maturity is higher.Different sags,source rock intervals and sample type have no obvious influence on mean oil generation activation energy,but sample type influences the distribution.Hydrocarbon generation activation energy distribution of raw rocks is more concentrated than kerogen.Gas generation activation energy of mature source rocks is 11-17 kJ/mol higher than that of low mature source rocks.Compared with open system anhydrous pyrolysis,confined system hydrous pyrolysis has more concentrated activation energy distribution including primary and secondary cracking.Confined system hydrous pyrolysis of low mature source rock raw samples and mature source rock kerogen samples for oil and gas generation kinetics respectively are recommended.