柴西北区新近系湖相细粒沉积岩油气富集条件  

Hydrocarbon accumulation conditions of neogene lacustrine fine-grained sedimentary rocks in northwestern Qaidam Basin

作　　者：张旭 刘成林[1] 郭泽清[4] 桂和荣[2] 田继先[4] 吴小平[5] 洪唯宇[1] 班东师 徐思渊 张蔚 张智辉 ZHANG Xu;LIU Chenglin;GUO Zeqing;GUI Herong;TIAN Jixian;WU Xiaoping;HONG Weiyu;BAN Dongshi;XU Siyuan;ZHANG Wei;ZHANG Zhihui(College of Geosciences,China University of Petroleum,Beijing 102249,China;National Engineering Research Center of Coal Mine Water Hazard Controlling,Suzhou University,Suzhou 234000,China;Geological Exploration Technology Institute of Anhui Province,Hefei 230041,China;Research Institute of Petroleum Exploration and Development,PetroChina,Langfang 065007,China;School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249 [2]宿州学院国家煤矿水害防治工程技术研究中心,安徽宿州234000 [3]安徽省勘查技术院,安徽合肥230041 [4]中国石油勘探开发研究院廊坊分院,河北廊坊065007 [5]中国科学技术大学地球和空间科学学院,安徽合肥230026

出　　处：《煤炭学报》2020年第8期2824-2837,共14页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(41872127);安徽省自然科学基金资助项目(1908085MD105);中国博士后科学基金资助项目(2019M662200)。

摘　　要：柴西北区是柴达木盆地重要的油气资源接替区,新近系湖相细粒沉积岩沉积厚度大,有较好的非常规油气资源潜力。然而,由于咸化沉积环境、粒度小、岩石致密等条件的限制,细粒沉积岩成烃与成储机制复杂,油气富集条件尚不明确,勘探程度较低。以柴西北区新近系主力烃源岩上干柴沟组为研究对象,采集19口代表性钻井岩芯样品,分析样品有机质丰度、类型和成熟度,结合X衍射、岩石薄片、高压压汞、低温液氮吸附实验和扫描电镜,系统分析了其烃源岩特征、矿物组成、储集条件及影响因素,并优选出有利勘探区。研究表明:柴西北区上干柴沟组细粒沉积岩厚度普遍>500 m;烃源岩有机碳含量不高,有57%样品TOC含量<0.4%,20%样品TOC含量高于0.6%,少量样品TOC含量超过1.0%;有机质以Ⅱ1型和Ⅲ型为主,少量Ⅰ型有机质;样品Ro为0.54%~1.24%,处于低成熟—成熟阶段。样品非均质性强,孔隙结构复杂,介孔较发育,介孔孔隙体积增量为0.0010~0.0152 cm3/g,平均为0.0075 cm3/g。样品中氯仿沥青“A”含量与TOC含量、介孔体积均呈正相关性,与Tmax,BET比表面积及宏孔体积均无明显相关性。样品孔隙体积受到TOC含量、矿物含量及热成熟度控制。综合细粒沉积岩烃源岩及储集条件,初步优选干柴沟—油泉子—南翼山地区为柴西北区上干柴沟组致密油/页岩油勘探有利区。Thick Neogene fine-grained sedimentary rocks were developed in the northwestern Qaidam Basin,where is an important replacement area for oil and gas resource exploration in the Qaidam Basin and has a tremendous unconventional oil and gas resource potential.However,limited by the salinized depositional environment,poor reservoir properties,and the largely unknown enrichment mechanisms of unconventional oil resource,the prospections on the fine-grained sedimentary rocks in northwestern Qaidam Basin are still situated at the initial stage.This research focused on the Shangganchaigou Formation of Neogene,that is a primary hydrocarbon source rock in the northwestern Qaidam Basin.Core samples from 19 representative drilling wells were collected to analyze the abundance,type,and maturity of organic matter.Based on X-ray diffraction,rock thin section,high-pressure mercury intrusion,low-temperature liquid nitrogen adsorption,and SEM(scanning electron microscopy)data,the hydrocarbon source rock characteristics,mineral composition,accumulation conditions and their controlling factors in the fine-grained rocks of the Shangganchagou Formation was systematically investigated.Moreover,this research also identified the favorable horizons for hydrocarbon exploration.The result shows the thickness of the fine-grained rocks of the Shangganchaigou Formation in the study area is generally more than 500 m.Relatively low TOC contents present in the all studied samples,with 57%samples are less than 0.4%,20%samples are more than 0.6%,and a few more than 1.0%.Organic matter in these rocks samples is mainly typeⅡ1,Ⅲand few typeⅠ.The vitrinite reflectance(Ro)is ranging from 0.54%-1.24%exhibiting thermally low mature to mature stage.Pores with complex structure and strong heterogeneity are developed in the samples.The incremental pore volume of mesopores is 0.0010-0.0152 cm3/g,and the mean mesopore volume is 0.0075 cm3/g.The chloroform bitumen“A”content of the samples has a positive relationship with TOC content and mesopore volume,

关 键 词：致密油/页岩油 细粒沉积岩 柴西北区 孔隙结构 咸化湖盆 

分 类 号：P618.11[天文地球—矿床学] P618.13[天文地球—地质学]