CAJ | 학술논문

为了分析鄂尔多斯盆地西北部奥陶系已发现气藏的气源，探讨该区奥陶系天然气藏的分布规律，综合利用地球化学实验分析与石油地质综合研究，对研究区天然气组分进行了分析。研究表明，研究区奥陶系天然气干燥系数在0．958～0．986。气源分析认为，奥陶系天然气主要为来自石炭系－二叠系煤系烃源岩生成的煤成气，但不排除有奥陶系海相气源的少量混入。奥陶系烃源岩分析结果亦支持这一结论。研究区奥陶系泥岩和碳酸盐岩的有机质丰度普遍不高。其中，泥岩有机碳含量以乌拉力克组为最高，平均为0．54％；其次是克里摩里组泥岩，平均0．52％；拉什仲组泥岩最低，平均为0．43％；灰岩有机碳含量3个组的平均值分别为0．35％，0．31％和0．25％。综合分析表明，鄂尔多斯盆地西北部奥陶系天然气藏的形成和分布主要受构造、储层、盖层、优质烃源岩及天然气运移通道5大因素控制，天然气主要富集在以下5要素的耦合处：斜坡高部位、溶蚀缝洞储层发育带、乌拉力克组－拉什仲组盖层分布区、优质烃源岩有利区及上古生界天然气“倒灌”运移通道发育区。
위료분석악이다사분지서북부오도계이발현기장적기원，탐토해구오도계천연기장적분포규률，종합이용지구화학실험분석여석유지질종합연구，대연구구천연기조분진행료분석。연구표명，연구구오도계천연기간조계수재0．958～0．986。기원분석인위，오도계천연기주요위래자석탄계－이첩계매계경원암생성적매성기，단불배제유오도계해상기원적소량혼입。오도계경원암분석결과역지지저일결론。연구구오도계니암화탄산염암적유궤질봉도보편불고。기중，니암유궤탄함량이오랍력극조위최고，평균위0．54％；기차시극리마리조니암，평균0．52％；랍십중조니암최저，평균위0．43％；회암유궤탄함량3개조적평균치분별위0．35％，0．31％화0．25％。종합분석표명，악이다사분지서북부오도계천연기장적형성화분포주요수구조、저층、개층、우질경원암급천연기운이통도5대인소공제，천연기주요부집재이하5요소적우합처：사파고부위、용식봉동저층발육대、오랍력극조－랍십중조개층분포구、우질경원암유리구급상고생계천연기“도관”운이통도발육구。
In order to determine the source of natural gas and to reveal the factors controlling the accumulation and dis-tribution of natural gas in the Ordovician reservoirs of the study area, we studied the composition of the natural gas through geochemical analysis and comprehensive geologic studies.The Ordovician gases are revealed to be entirely dry gas and their dryness indices range from 0.958 to 0.986.Geochemical analysis indicates that the Ordovician gases are mostly derived from the Carboniferous-Permian coal measure source rocks, whereas the marine Ordovician source is assumed to be a minor contribution.This is also supported by the Ordovician source rock analysis,which has revealed that the organic matter content of the mudstones and the carbonates is commonly not high.The average TOC of the mud-stones in the Wulalike,Kelimoli,Lashizhong formations are only 0.54%,0.52%and 0.43%,respectively,and that of the carbonates in the above three formations are 0.35%,0.31% and 0.25%,respectively.Comprehensive studies suggest that the gas accumulation and distribution is principally controlled by structure, reservoirs, cap rocks, quality source rocks and migration pathways.Gases mainly enrich in places where the following 5 factors couple,namely struc-tural highs of the slope,highly developed reservoirs with dissolution fractures and vugs,cap rocks of the Wulalike and Lashizhong formations,quality source rocks,and migration pathways for downward charging of gas from the Upper Pale-ozoic source rocks.