鄂尔多斯盆地下寺湾地区山西组泥页岩生气特征

1.陕西延长石油(集团)有限责任公司研究院,陕西 西安 710075; 2.陕西省陆相页岩气成藏与开发重点实验室,陕西 西安 710075

地质资源与地质工程; 页岩气; 生气特征; 生烃热模拟; 生烃量

Hydrocarbon generation characteristics of source rocksin Shanxi Formation of Xiasiwan Area,Ordos Basin
ZHAO Qian-ping1,2,GAO Chao1,2,YIN Jin-tao1,2,ZHANGLi-xia1,CAO Cheng1,2,LIU Gang1,YANG Xiao1,2,XU Jie1,2,CHEN Yi-yi1

(1.Research Institute of Shanxi Yanchang Petroleum(Group)Co.,Ltd,Xi'an 710075,China; 2.Shaanxi Key Laboratory of Lacustrine Shale Gas Accumulation and Exploitation,Xi'an 710075,China)

geological resources and engineering; shale gas; hydrocarbon generation; pyrolysis experiment; hydrocarbon generation potential

DOI: 10.13800/j.cnki.xakjdxxb.2018.0116

备注

鄂尔多斯盆地山西组页岩气有较好的资源潜力,但其生气机理研究薄弱,为研究其泥页岩生烃过程及机理,文中采用高压釜-封闭式金管的生烃热模拟实验,分别对山西组山1和山2烃源岩生烃过程和生烃量分析,结果发现:2个层位中甲烷和非烃类气体具有相似产出特征,两者产率随着成熟度升高而增加,且低升温速率下产率更高; 重烃气C2-5和液态烃两者产率随着成熟度升高都表现出“先升后降”型抛物线特征,山1和山2等2个页岩样品总热解气量分别为444.94 mg/gTOC和343.66 mg/gTOC,总热解气产率中,烃类气体(C1-5)产率分别为98.69 mg/gTOC和126.44 mg/gTOC,非烃类气体(H2,CO2和H2S)产率分别为346.25mg/gTOC和175.79 mg/gTOC.山1和山2泥页岩生烃过程历经三段式的演化模式,至146 Ma(晚侏罗世末),Ro达到0.78%,甲烷累积产率分别达到7.28 mL/gTOC,7.41 mL/gTOC.至距今96 Ma(早白垩世末)地层温度达到最大值201.82 ℃,Ro达到2.15%,泥页岩甲烷瞬时产率达到最大值,分别为3.21,3.80 mL/gTOC·Ma,达到高峰。从晚白垩世开始至55 Ma(始新世早期),Ro保持在2.31%,生气停止,山1泥页岩甲烷累积产率保持在103.8 mL/gTOC,山2泥页岩甲烷累积产率保持在113.6 mL/gTOC.对比发现,山2泥页岩的气态烃和液态烃产率均远远高于山1泥页岩,且山1泥页岩烃类气体含量始终低于40%,证实该地区山西组泥页岩具有较好的生气潜力,其中山2生气能力较大。

Shanxi Formation shale gas of Ordos basin has good resource potential,but the Hydrocarbon generation mechanism research is weak.In order to study the hydrocarbon generation process and mechanism of the shale,the autoclave-enclosed gold-tube hydrocarbon generation thermal simulation experimentwas carried out on the samples of Shan 1 and 2,and the process and quantity of hydrocarbon hydrocarbon generation were analyzed.The results showed that:Methane and non-hydrocarbon generation have similar characteristics,and the yield rate increases with the increase of thermal evolution,and the yield rate is higher at low heating rate.The generation rate of heavy hydrocarbon gas C2-5 and liquid hydrocarbon both showed the characteristics of “ascending and then descending” as the maturity level increased.The total pyrolysis gas of the Shan 1 and 2 were 444.94 mg/gTOC and 343.66 mg/gTOC,production rate of hydrocarbon gases(C1-5)were 98.69 mg/gTOC and 126.44 mg/gTOC,nonhydrocarbon gas(H2,CO2 and H2S)generation were 346.25 mg/gTOC and 175.79 mg/gTOC,respectively.The hydrocarbon generation processes of Shan 1 and 2 have undergone a three-phase evolution model,to 146 Ma(late Jurassic period),and the Ro reached 0.78%.The cumulative generation of methane reached 7.28 mL/gTOC and 7.41 mL/gTOC,respectively.To 96 Ma ago(at the end of the early cretaceous),Formation temperature reached 201.82 ℃,Ro reached 2.15%,Instantaneous methane production rate reaching maximum,were 3.21 mL/gTOC Ma,3.80 mL/gTOC Ma.Starting from the late cretaceous to 55 Ma(early Eocene),Ro kept at 2.31%,stopped hydrocarbon generation,cumulative methane production rate of Shan 1 shale is 103.8 mL/gTOC,cumulative methane production rate of Shan 1 shale is 113.6 mL/gTOC.Contrast found that the gaseous hydrocarbon and liquid hydrocarbon production rate of Shan 2 shale are much higher than Shan 1 shale,the gas content of Shan 1 shale is lower than 40%.It is proved that the shale of shanxi formation has good hydrocarbon generation potential,and the Shan 2 shale have more hydrocarbon generation.