摘要
四川盆地南部地区(简称"川南地区")海相页岩气资源潜力巨大,目前埋深2 000~3 500 m的中浅层优质页岩气资源已实现有效开发,埋深3 500~4 500 m的深层页岩气也取得了战略突破。通过系统总结川南地区下志留统龙马溪组页岩气勘探地质认识,重点分析了川南地区页岩气高产的关键因素,提出了下一步的勘探方向。研究表明:①海相陆棚沉积环境水体相对深度控制储集层发育和分布。深水陆棚的相对深水区发育Ⅰ类储集层且连续厚度更大。海相陆棚沉积环境水体相对深度可以用氧化还原条件来确定,铀、钍质量比大于1.25时为缺氧还原环境,水体为相对深水区。铀、钍质量比为0.75~1.25时为弱还原弱氧化环境半深水;铀、钍质量比小于0.75时为强氧化环境相对浅水。②页岩储集层压裂改造支撑缝高一般为10~12 m,若Ⅰ类储集层连续厚度大于10 m,支撑段则均为优质储量,钻遇Ⅰ类储集层连续厚度越长,产量越高。③川南地区3 500~4 500 m深层页岩气具有地层压力大、压力系数高、孔隙保存好、孔隙结构优以及游离气占比大的特征,是页岩气勘探最有利的新领域,压力系数大于1.2是页岩气井获得高产的必要条件。④深层页岩气建产区高产井模式为龙一11—龙一13小层厚度大于10 m区域,水平段长1 500 m,Ⅰ类储集层钻遇率超过90%,应采用密切割+高强度加砂+大排量+大液量的主体工艺技术。⑤深水陆棚内相对深水区与3 500~4 500 m埋深区域在川南地区表现出较好的重合,重叠区域是今后川南地区页岩气最有利的勘探开发区带。通过理论技术进步,川南地区页岩气有望实现年产450×10~8 m^3的目标。
The marine shale gas resources in the south of the Sichuan Basin in China have great potential. At present, the high-quality shale gas resources at buried depth of 2000-3500 m have been effectively developed, and strategic breakthroughs have been made in deeper shale gas resources at buried depth of 3500-4500 m. To promote the effective production of shale gas in this area, this study examines key factors controlling high shale gas production and presents the next exploration direction in the southern Sichuan Basin based on summarizing the geological understandings from the Lower Silurian Longmaxi Formation shale gas exploration combined with the latest results of geological evaluation. The results show that:(1) The relative sea depth in marine shelf sedimentary environment controls the development and distribution of reservoir. The relative deep water area in deep-water shelf developed class I reservoirs with good continuity and larger thickness. The relative depth of sea in marine shelf sedimentary environment can be determined by redox conditions. Through research, the mass ratio of uranium to thorium greater than 1.25 indicates deep water in anoxic reduction environment, and the mass ratio of uranium to thorium of 0.75-1.25 indicates semi-deep water in weak reduction and weak oxidation environment, and the mass ratio of uranium to thorium less than 0.75 indicates relatively shallow water in strong oxidation environment.(2) The propped fractures in shale reservoirs are generally 10-12 m high, if the classⅠreservoirs are more than 10 m in continuous thickness, then all the propped section would be high quality reserves;in this case, the longer the continuous thickness of classⅠ reservoirs is drilled, the higher the production is.(3) The shale gas reservoirs at 3500-4500 m depth in southern Sichuan are characterized by high formation pressure, high pressure coefficient, well preserved porosity, good pore structure and high proportion of free gas, making them the most favorable new field for shale gas explora
作者
马新华
谢军
雍锐
朱逸青
MA Xinhua;XIE Jun;YONG Rui;ZHU Yiqing(PetroChina Research Institute of Exploration&Development,Beijing 100083,China;PetroChina Southwest Oil&Gas Field Company,Chengdu 610051,China)
出处
《石油勘探与开发》
SCIE
EI
CAS
CSCD
北大核心
2020年第5期841-855,共15页
Petroleum Exploration and Development
基金
国家科技重大专项“大型油气田及煤层气开发—长宁—威远页岩气开发示范工程”(2016ZX05062)
中国石油科技重大专项“西南油气田天然气上产300亿立方米关键技术研究与应用——四川盆地页岩气建产有利区评价优选及开发技术政策优化研究与应用”(2016E-0611)
四川省国土科学技术研究院项目“四川省页岩气资源调查评价与有利区优选”。
关键词
四川盆地南部
下志留统龙马溪组
深层页岩气
高产控制因素
深水深层
页岩气储集层
southern Sichuan Basin
Lower Silurian Longmaxi Formation
deeply buried shale gas
high production control factors
deep water and deep burial
shale gas reservoir
