川西北古生界烃源岩特征及生烃潜力评价

Paleozoic Source-Rock Properties and Hydrocarbon Generation Potential in Northwest Sichuan

川西北地区已经成为四川盆地近几年勘探的热门地区,但至今对该区烃源岩的展布和生烃潜力仍缺乏较客观的评价,从而导致该区油气资源前景不明朗,影响下一步勘探方向的选择。在野外露头和重点钻井烃源岩发育特征与有机地球化学分析的基础上,利用烃源岩展布特征和有机质丰度、类型、成熟度以及生烃强度等参数对区内海相烃源岩进行了系统评价。结果表明:研究区发育的6套烃源岩有机质丰度均较高;有机质类型好,主要为Ⅰ型、Ⅰ—Ⅱ_1型以及Ⅱ_1—Ⅱ_2型;成熟度较高,现今处于高成熟—过成熟阶段,以生气为主。下寒武统筇竹寺组烃源岩生油条件最好,是该区的主力烃源岩,平均生烃强度为67.05×108m^3/km^2;广元朝天、旺苍以西地区以及剑阁地区为3个生烃中心。研究结果对于明确川西北地区下一步的重点勘探方向具有重要意义。

The Northwest Sichuan has become a hot area for hydrocarbon exploration in the Sichuan Basin in recent years.However,there is still no objective assessment of source-rock distribution and hydrocarbon generation potential,which leads to uncertain prospect of hydrocarbon resource and influence the further exploration.Based on field outcrop observation,source-rock properties from drilling and geochemical analysis,the marine source-rock in this region is systematically assessed by using source-rock distribution pattern,organic matter abundance,type,maturity and hydrocarbon generation intensity.Result shows that all the six sets of source-rocks in this region show a relatively high organic matter abundance.The organic matter type mainly includes Type I,Type I-II1 and Type II1-II2.The relatively high maturity is within high-maturity to over-maturity stage,which mainly results in gas generation.The source-rock in the Lower Cambrian Qiongzhusi Formation with better hydrocarbon generation condition is considered as the major source-rock in this region and the average hydrocarbon generation intensity is 67.05 ×108 m^3/km^2.Guangyuanchaotian,west Wangcang and Jiange are three hydrocarbon generation centers.This research could provide a great significance for determine the key exploration direction in the northwest Sichuan Basin.