盆内侵入体热传递影响有机质成熟度的定量研究

This project aim at establishing a quantitative model of magmatic intrusion effects on organic matter. The model can be used dispensing with lots of analysis and test. Firstly, determine the temperature range when magma intruded into the sedimentary strata. The liquidus temperature or crystallization temperature of magmatic intrusion can be regarded as the lower limit temperature of magma intrusion. The liquidus temperature can acquire from melting experiment. The crystallization temperature can calculate by cation numbers of whole rocks and plagioclase phenocryst numbers. The cation number can be achieved by major elements analysis and calculation. The plagioclase phenocryst numbers can get from electron probe microanalysis. Some characteristic minerals is stable at high temperature. Make rock-mineral identification and find characteristic minerals. Take the stable temperature of characteristic minerals observed from slices as the upper temperature. Then study the source rock temperature before magmatic intrusion and paleo-geothermal field. These two research work need to recover paleo-geothermal gradient first. In this study, paleo-geothermal gradient recovery base on inclusion thermometry, apatite fission track and vitrinite reflectance test. Thirdly, study the source rock temperature after magmatic intrusion. The after temperature should be the before temperature plus increased temperature by magma intrusion. So if only obtain increased temperature, then get after temperature. In this study, the increased temperature, i.e. variation of temperature field around magma intrsion calculates by thermal conduction and radiation equation without considering convection for few liquid exist underground. The temperature range, scale and shape of magmatic intrusion are initial value of thermal conduction and radiation equation, rock thermophysical parameters, structure and tectonic data are also needed in the equation. Fourthly, calculate maturity of source rock before and after magma intrusion by using EASY%Ro model and establish the quantitative model of magmatic intrusion effects on organic matter. The EASY%Ro model need source rocks temperature before and after magmatic intrusion, paleo-geothermal field and age of magmatic intrusion. Except the age of magmatic intrusion, the other information have acquired according to the research above. The age of magmatic intrusion ascertain by zircon SHRIMP U-Pb age and Ar-Ar age.Take Yaoyingtai area of southern Songliao basin as an example, test and improve the quantitative model of magmatic intrusion effects on organic matter.

本项研究旨在建立一种无需大量测试分析，即可直接计算岩浆活动影响有机质演化的定量模型。解决侵入体影响有机质演化定量研究的热点问题。首先通过全岩阳离子数及斜长石斑晶号码法计算结晶温度，结合熔融实验结果确定岩浆侵入时下限温度，进行岩矿鉴定，以特征矿物稳定温度为岩浆侵入上限温度，从而确定岩浆侵入时温度范围；通过包裹体测温、磷灰石裂变径迹等的研究恢复研究区古地温梯度，结合埋藏史，恢复古地温场及岩浆活动前烃源岩温度；综合岩浆侵入时岩浆温度范围、岩浆活动前烃源岩温度、热传导和热辐射方程计算热源附近研究区温度场的变化，研究岩浆活动后烃源岩的温度；采用EASY%Ro模型，结合岩浆活动前后烃源岩温度、古地温场、岩浆侵入时间的研究，计算岩浆活动前后烃源岩成熟度，建立岩浆活动影响有机质演化范围及程度的定量模型。选择松辽盆地南部腰英台地区为研究靶区，测试并改进研发的定量判定岩浆侵入体影响有机质演化范围及程度的技术。

近年来火山岩油气藏勘探开发已引起了广泛的关注，其中火山岩主要作为油气的储集空间进行研究。同时，火山活动为有机质的演化提供催化剂和热能也引起了专家和学者的重视。其中侵入体因其分布范围便于追踪，能够更好的识别其对有机质演化影响的程度及范围，而成为众多学者研究的热点。但研究成果显示侵入体附近围岩中有机质成熟度明显升高，关于影响的范围，认识尚不统一。本项研究以侵入体为研究对象，寻求定量判定岩浆侵入体对有机质演化影响范围和程度的一个有效途径。. 本项研究以辽河盆地东部凹陷为主要研究区，通过分析计算研究岩浆侵入体初温、钻井与地震剖面揭示侵入体规模、测年判断岩浆侵位时代。在此基础上，恢复埋藏史，恢复岩浆活动前烃源岩温度，依据热递方程计算岩浆活动后，烃源岩温度。计算岩浆活动前后有机质成熟度。从而得出岩浆侵入对有机质影响的程度。. 辽河盆地东部凹陷钻井揭示基性侵入岩体发育广泛，岩性主要为辉绿岩。从辉绿岩侵入地层情况看，分别侵入沙三段和沙一段地层。测年数据显示，侵入岩于古近纪未期侵入。东部凹陷共可划分出六大侵入岩体，主要表现为顺层侵入，其分布受研究区驾掌寺断裂和驾东断裂控制。侵入体厚度50-240m，侵入距离约为1.3-5.6 km。侵入岩地化分析计算显示，岩浆侵入时温度应不低于1100oC。. 研究区烃源岩以泥岩为主，含少量碳质泥岩，有机质类型以Ⅱ－Ⅲ型为主。通过钻遇侵入岩钻井揭示，因岩浆顺层侵入，岩体上下烃源岩有机质受到影响明显。岩浆活动使围岩温度快速升高，加快有机质成熟。影响范围与岩体规模密切相关，影响范围一般为岩体的1-1.5倍。. 在研究中发现，由于岩浆顺层侵入，使得侵入岩体上下均受到烘烤，烃源岩有机质成熟加快。侵入体的影响范围与侵入体本身规模大小有关。在侵入体初温计算时发现，温度与岩浆成分有关。而岩浆喷出形成的火山岩，尽管喷出地表后岩浆快速冷却，往往面积大厚度也很大。研究中发现，火山岩厚度较大的岩体，其下伏烃源岩中有机质同样存在明显的加速成熟现象。