川中古隆起震旦系-寒武系天然气地球化学特征与太和气区的勘探潜力  

Geochemical characteristics of Sinian-Cambrian natural gas in central Sichuan paleo-uplift and exploration potential of Taihe gas area

作　　者：谢增业[1,2] 李剑 杨春龙[1,2] 田兴旺 张璐 李谨[1,2] 李志生[1,2] 国建英 谢武仁[1] 郭泽清 齐雪宁[1,2] 郝爱胜 XIE Zengye;LI Jian;YANG Chunlong;TIAN Xingwang;ZHANG Lu;LI Jin;LI Zhisheng;GUO Jianying;XIE Wuren;GUO Zeqing;QI Xuening;HAO Aisheng(Research Institute of Petroleum Exploration and Development,Beijing100083,China;CNPC Key Laboratory of Gas Reservoir Formation and Development,Langfang,Hebei 065007,China;Research Institute of Exploration and Development,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China)

机构地区：[1]中国石油勘探开发研究院,河北省廊坊市065007 [2]中国石油天然气集团有限公司天然气成藏与开发重点实验室 [3]中国石油西南油气田公司勘探开发研究院

出　　处：《天然气工业》2021年第7期1-14,共14页Natural Gas Industry

基　　金：中国科学院战略性先导科技专项(A类)(编号:XDA14010403);国家科技重大专项“大型气田成藏机制、富集规律与勘探新领域”(编号:2016ZX05007-003);中国石油天然气股份有限公司科研项目“四川盆地震旦—寒武系重大勘探领域成藏条件与富集规律研究”(编号:kt2020-01-03)。

摘　　要：2020年,相继在四川盆地川中古隆起北斜坡PT1井上震旦统灯影组二段和JT1井下寒武统沧浪铺组获得了高产工业气流,分析结果表明两者的天然气地球化学特征不同,并且与安岳气田的天然气地球化学特征也存在着明显的差异。为了深化对于川中古隆起北斜坡天然气成因的认识,基于大量探井、评价井和开发井的天然气组分、天然气碳同位素、天然气氢同位素等分析实验数据,对该区天然气成因进行了系统研究,并结合目前的勘探认识,明确了该区下一个万亿立方米天然气重点区块——太和气区。研究结果表明:①太和气区的天然气与安岳气区震旦系—寒武系具有相似的组分,并且湿度系数均为小于0.2%,在天然气成因类型判识图版中,均属于原油裂解气;②较之于沧浪铺组,太和气区灯影组天然气C_(2)H_(6)含量低、δ^(13)C_(2)重、δ^(2)H_(CH)_(4)轻,造成C_(2)H_(6)含量和δ^(13)C_(2)差异主要与热演化程度有关,并且δ^(2)H_(CH)_(4)主要受原始母质沉积水介质盐度的影响;③太和气区与安岳气区都聚集了不同演化阶段的原油裂解气,其中太和气区聚集古油藏早期—晚期的原油裂解气,早期原油裂解气占比越大δ^(13)C越轻,而安岳气区主要聚集晚期阶段原油裂解气,晚期原油裂解气的比例越大δ^(13)C越重。结论认为,太和气区具备保存早—晚原油裂解气的封闭条件,发育多层叠置的规模优质滩相储层,古油藏范围内或紧邻古油藏储—盖组合好的区域是下一步天然气拓展勘探的有利区。In 2020,Well PT1 and Well JT1 in the north slope of central Sichuan paleo-uplift of the Sichuan Basin successively obtained high-yield industrial gas flow from the second Member of the Upper Sinian Dengying Formation and the Lower Cambrian Canglangpu Formation,respectively.Analysis results show that their geochemical characteristics of natural gas are different,and they are also different from those in the Anyue Gas Field.In order to further understand the natural gas origins in the north slope of central Sichuan paleo-uplift,this paper systematically studies the natural gas origins in this area based on the analysis of experimental data of natural gas composition,natural gas carbon isotope and hydrogen isotope in abundant exploration wells,appraisal wells and development wells.And combined with current exploration understandings,the next key natural gas block of one trillion cubic meters is ascertained,i.e.,the Taihe gas area.And the following research results are obtained.First,Sinian-Cambrian natural gas in Taihe gas area and that in Anyue gas area are similar in compositions and the humidity coefficient is less than 0.2%.It is shown in the natural gas origin type identification chart that they both are oil cracking gas.Second,compared with Canglangpu Formation natural gas,Dengying Formation natural gas in the Taihe gas area has lower C_(2)H_(6) content,heavierδ^(13)C_(2) and lighterδ^(2)H_(CH)_(4).The difference of C_(2)H_(6) content andδ^(13)C_(2) is mainly related to the thermal evolution degree,andδ^(2)H_(CH)_(4) is mainly affected by the salinity of water medium of original parent material deposits.Third,oil cracking gas of different evolution stages accumulates in Taihe and Anyue gas areas.In the Taihe gas area,the early-late oil cracking gas of the paleo oil reservoir accumulates.The higher the proportion of the early cracking gas is,the lighter theδ^(13)C is.In the Anyue gas area,the late oil cracking gas mainly accumulates.The higher the proportion of the late cracking gas is,the heavier theδ^(1

关 键 词：四川盆地 川中古隆起北斜坡 天然气 原油裂解气 地球化学特征 安岳气区 太和气区 天然气拓展勘探 

分 类 号：P618.13[天文地球—矿床学]