三种成因天然气生成时限与生成量及其对深部油气资源预测的影响  

Time-limit and yield of natural gas generation from different origins and their effects on forecast of deep oil and gas resources

作　　者：张水昌[1] 胡国艺[1] 米敬奎[1] 帅燕华[1] 何坤[1] 陈建平[1] 

机构地区：[1]中国石油勘探开发研究院中国石油天然气集团公司油气地球化学重点实验室,北京100083

出　　处：《石油学报》2013年第S01期41-50,共10页Acta Petrolei Sinica

基　　金：国家重大科技专项(2011ZX05007-001)资助

摘　　要：中国天然气主要由煤成气、原油裂解气和生物气组成。通过热模拟实验等方法对3种成因类型天然气生成时限及生气量进行了研究,结果表明,生物气、煤成气和原油裂解气3种成因天然气在生成深度、温度或成熟度上均有不同程度的增加,普遍向深部延伸。基于柴达木盆地三湖地区深部地层中检测到大量微生物、热力作用所产生的次生活性有机质可为深部微生物生存提供营养物质的认识,提出生物气生成的温度上限有可能突破传统的75℃。煤系烃源岩生气特征与湖相或海相有机质明显不同,前者没有明显的生烃高峰,生气的成熟度上限由以前认为的Ro为2.5%延伸到5.0%,总生气量由以前的不高于200 m3/t TOC增加到至少300 m3/t TOC。原油裂解热模拟与动力学研究表明,原油开始裂解的对应地层温度为190℃,大量裂解对应地层温度大于210℃,原油裂解约在230℃结束;若地温梯度恒为30℃/km,则开始裂解对应的深度应大于6 000 m。3种成因天然气生成时限的新认识为中国深部地层天然气资源评价和油气勘探深度范围的预测提供了重要依据。In China, natural gas resources mainly include coal-derived gas, oil-cracked gas, and biogenic gas （biogas）. In the present study, the time limit and yield of natural gas generation from three different origins are investigated through a thermal simulation ex periment combined with other methods. Results show that the formation depth, geothermal temperature, and organic matter maturi- ty for generation of biogas, coal-derived gas, and oil-cracked gas from different origins increase to various extents generally towards deeper depth. It is recognized that a large quantity of microorganisms were detected in deep formations of Sanhu area, Qaidam Basin, and that the secondary organic matter produced by thermal action could provide nutrients for the survival of deep microorganisms. Therefore, the upper temperature limit for biogas generation may break the conventional record of 75℃. As for gas generation from coal-measure source rocks, there exists obvious difference from marine or lacustrine organic matter with no evident peak stage of hy- drocarbon generation the upper limit of organic matter maturity for gas generation rises from 2.5% previously thought to 5.0%; to- tal gas yield increases from less than 200 m3/t TOC formerly known to more than 330 m3/t TOC. Results of experimental simulation and kinetic research show that crude oil cracking initiates at the formation temperature of 190℃, amplifies at greater than 210℃, and ends at about 230℃ ; in case the thermal gradient is at a constant of 30℃/km, crude oil cracking initiates at the depth should be more than 6 000 m. These results contribute to understanding of the time-limit and yield of natural gas generation from three major origins and thus provide reference data for evaluating deep gas resources and forecasting the depth range for petroleum exploration in China.

关 键 词：生物气 煤成气 原油裂解气 生气模式 生气量 

分 类 号：TE112.11[石油与天然气工程—油气勘探]