鄂尔多斯盆地张家滩页岩液态烃特征及对页岩气量估算的影响  

The characteristics of liquid hydrocarbon in Zhangjiatan shale,Ordos Basin and its effects on the estimation of shale gas amount

作　　者：雷裕红[1] 王晖 罗晓容[1] 王香增[2] 俞雨溪 程明[1,3] 张立宽[4] 张丽霞[2] 姜呈馥[2] 高潮[2] 

机构地区：[1]中国科学院油气资源研究重点实验室 中国科学院地质与地球物理研究所,北京100029 [2]陕西延长石油(集团)有限责任公司,陕西西安710075 [3]中国科学院大学,北京100049 [4]中国科学院油气资源研究重点实验室中国科学院地质与地球物理研究所,北京100029

出　　处：《石油学报》2016年第8期952-961,共10页Acta Petrolei Sinica

基　　金：国家自然科学基金项目(No.41102078,No.41372151);国家重大科技专项课题(2011ZX08005-004)资助

摘　　要：鄂尔多斯盆地上三叠统延长组张家滩页岩为一套湖相富有机质页岩,已在其中发现了工业性页岩气。张家滩页岩的有机质成熟度相对较低（Ro为0.7%～1.3%）,页岩中滞留有大量液态烃,其对页岩气的赋存状态和原地气量的估算具有重要影响。利用荧光显微镜、扫描电镜和能谱分析技术,结合索式抽提、热解和甲烷等温吸附测试等手段分析了张家滩页岩中液态烃的赋存状态及含量,研究了液态烃对页岩气赋存状态、含气量的影响。结果表明,张家滩页岩中液态烃含量高,氯仿沥青“A”含量介于0.2%～1.2%,平均0.72%;热解S1含量主要变化在1.00～7.00 mg/g,平均3.87 mg/g。显微观察与测试结果表明,液态烃主要以游离态赋存于页岩的孔隙、裂缝中,或吸附于有机质及黏土矿物表面。进一步研究发现,液态烃的存在会导致页岩的甲烷吸附能力明显降低,降低程度达35%～57%,平均约45%。在地层温度、压力条件下,张家滩页岩的液态烃中会溶解大量的天然气,溶解气量变化在0.21～1.21 mL/g,平均0.65 mL/g,约占总含气量的20%。如果考虑损失的轻烃部分,溶解气含气量还会更高,平均约0.91 mL/g,约占总含气量的28%。此外,张家滩页岩中的液态烃还影响到了各种赋存状态页岩气的含气量。在评价类似延长组张家滩页岩这类较低成熟度的页岩气资源量时,除了需要对液态烃含量进行轻烃校正和重烃补偿外,还需要考虑液态烃中的溶解气含量、液态烃所占据的孔隙空间大小、液态烃对吸附气量及游离气量的影响,这样获得的页岩气资源评价结果才更为客观、可靠。Industrial shale gas has been discovered in the lacustrine organic-rich Zhangjiatan shale of the Late Triassic Yanchang Formation, Ordos Basin. However, a large amount of liquid hydrocarbon are retained in shale due to the low organic-matter maturity （Ro is 0.7% -1.3%）of Zhangjiatan shale, which exerts great influences on the occurrence state of shale gas and the assessment of origin gas in place. Using fluorescence microscope, scanning electron microscope （SEM）and energy dispersive spectrometer （EDS）in combination with Soxhlet extraction, Rock-Eval pyrolysis, methane isothermal adsorption test and other means, this paper analyzes the occurrence state and content of liquid hydrocarbon in Zhangjiatan shale, and studies the effects of liquid hydrocarbon on the occurrence state and content of shale gas. The results show that Zhangjiatan shale has a high content of liquid hydrocarbon; the content of chloroform bitumen A ranges between 0.2% and 1.2%, with a mean of 0.72%; the content of pyrolysis S1 mainly varies from 1 mg/g to 7 mg/g, with a mean of 3.87 mg/g. The microscopic observations and test results show that liquid hydrocarbon mainly exists in the pores and fractures of shale in a free state, or may be absorbed on the surface of organic matter and clay mineral. Further research has revealed that the liquid hydrocarbon can cause a significant decline in the methane absorption capability of shale; it is decreased by 35% -57%, with an average of 45%. Under the formation temperature and pressure conditions, a large amount of natural gas may be dissolved in the liquid hydrocarbon of Zhangjiatan shale; the amount of dissolved gas mainly rangs from 0.20 mL/g to 1.20 mL/g and has an average of 0.65 mL/g, accounting for about 20% of the total. If considering the loss of light hydrocarbon, the amount of dissolved gas will be higher with an average of 0.91 mL/g, accounting for about 28% of the total. In addition, the liquid hydrocarbon in Zhangjiatan shale has certain influences on the content of shale gas in

关 键 词：液态烃 页岩气 赋存状态 含气量 张家滩页岩 鄂尔多斯盆地 

分 类 号：TE122.14[石油与天然气工程—油气勘探]