塔里木盆地和田河气田天然气裂解类型  

Types of cracking gas in Hetianhe gas field in Tarim basin

作　　者：秦胜飞[1] 李梅[2] 戴金星[1] 肖中尧[2] 张秋茶[2] 

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油塔里木油田公司勘探开发研究院,新疆库尔勒841000

出　　处：《石油与天然气地质》2005年第4期455-460,共6页Oil & Gas Geology

基　　金："十.五"国家重点科技攻关项目"中国大中型气田勘探开发关键技术研究"(2001BA605A-06);国家重点基础研究发展规划项目(973)(2002CB211705)

摘　　要：和田河气田天然气来自寒武系高-过成熟烃源岩,气田大体上呈长条状东西向展布。和田河气田天然气组分具有随C1/C2增加C2/C3变小、碳同位素δ13C2-δ13C3值变化较大、ln(C2/C3)值变化较小的特点。根据目前惯用的干酪根裂解气和原油二次裂解气判识标准,和田河气田的天然气应属于干酪根裂解气。和田河气田东、西部井区天然气干燥系数、甲烷碳同位素值及二氧化碳含量存在明显的差异。伴随晚喜山期和田河圈闭的形成,干酪根裂解生成的天然气以水溶方式自东部高压区向西部低压区运移,由于甲烷在水中的溶解度大于重烃、δ13CH4溶解度大于1δ2CH4、CO2在天然气组分中溶解度最大,造成天然气组分和甲烷碳同位素的分馏,使西部井区天然气具有干燥系数偏高、甲烷碳同位素值偏重、二氧化碳含量明显偏高等特点。Natural gas in Hetianhe gas field, which is distributed in an elongated E-W direction as a whole, have been sourced by the high- and over-mature Cambrian source rocks. The components of natural gas in Hetianhe gas field have the following characteristics： C2/C3 decreases with increasing C1/C2 , variation of carbon isotope value of δ^13CC2 - δ^13C3 is relatively large, while variation of ln（ C2/C3 ） value is relatively small. According to the conventional diagnostic criteria of kerogen cracking gas and secondary cracking gas from oil, the gas in Hetianhe gas field should be of kerogen cracking gas. The dry coefficients, methane carbon isotope values and CO2 contents of natural gas are obviously different in the western and eastern wellblocks of Hetianhe gas field. Accompanying the formation of Hetianhe trap in late Himalayan, the kerogen cracking gas migrated from the high pressure zone in the east to the low pressure zone in the west in the form of dissolved gas. The solubility of methane in water is larger than that of heavy hydrocarbons, the solubility of δ^13CH4 is larger than that of δ^12CH4, and CO2 has the largest solubility among the components of natural gas, all these would lead to the fractionation of natural gas components and methane carbon isotope. As a result, the natural gas in the western wellblock is characterized by larger dry coefficient, heavier methane carbon isotope and obviously higher CO2 content.

关 键 词：裂解气 水溶气 运移 和田河气田 塔里木盆地 

分 类 号：TE112.1[石油与天然气工程—油气勘探]