四川盆地拔山寺向斜泰页1井页岩油气重大突破及意义

Major breakthrough of shale oil and gas in Well Taiye 1 in Bashansi Syncline in the Sichuan Basin and its significance

2021年1月,在四川盆地涪陵北部拔山寺向斜针对侏罗系凉高山组实施的第一口页岩油气探井--泰页1井,通过水平井钻井及分段压裂测试,试获日产气7.5×10^(4)m^(3)、日产油9.8m^(3),实现了侏罗系凉高山组湖相页岩油气新层系勘探重大突破。基于泰页1井的钻探成果,系统分析了涪陵北部地区凉高山组湖相页岩油气成藏条件和富集规律。研究表明:泰页1井突破层系为凉高山组二段(凉二段)半深湖相富有机质泥页岩,其中(4)小层厚度约为25.20m,TOC均值大于1.5%,有机质类型以Ⅱ型为主,Ro为1.01%~1.41%,孔隙度平均为3.52%,以无机孔(黏土矿物层间孔、粒间孔、粒内孔等)为主,仅局部发育有机质孔,孔隙类型以介孔(孔径为2~50nm)和大孔(孔径大于50nm)为主,含气量约为1.81m^(3)/t。相对于其他小层而言,(4)小层泥页岩连续厚度最大、TOC和孔隙度最高、含气性最好,为自生自储的"纯页岩型"页岩油气藏。涪陵北部地区半深湖相优质页岩分布广泛,有利于页岩油气富集,其中保存条件好、地层高压、微裂缝发育有利于页岩油气高产。探索形成了以"少段多簇+暂堵转向+大排量+中粗砂强加砂"为主要特点的体积压裂关键技术,可实现陆相页岩的有效改造。泰页1井的突破对于中国湖相页岩油气的商业开发具有重要意义。

In January 2021,Well Taiye 1,the first shale oil and gas exploratory well targeting at the Jurassic Lianggaoshan Formation,was deployed in the Bashansi Syncline in the northern part of Fuling area in the Sichuan Basin,and obtained oil and gas flow rate of 9.8 m3/d and 7.5×104 m3/d respectively,after multi-staged fracturing and testing of the horizontal section,achieving a major breakthrough in lacustrine shale oil and gas exploration.Based on drilling results of Well Taiye 1,hydrocarbon accumulation conditions and enrichment rules of lacustrine shale oil and gas in the Jurassic Lianggaoshan Formation were analyzed in detail.Results indicate that the producing layer in Well Taiye 1 is organicrich shale in the 2nd member of Lianggaoshan Formation(Liang 2 member)developed in semi-deep lake facies.In this layer,the sub-layer 4 is about 25.20 m in thickness,with the average TOC greater than 1.5%,organic matter type predominately by Type II,R o ranging from 1.01%-1.41%,gas content of 1.81 m3/t,and an average porosity of 3.52%.Inorganic pores are dominant(clay mineral interlayer pores,intergranular pores,intragranular pores,etc.),and organic pores are developed locally,with pore diameter mainly of mesopores(2-50 nm)and macropores(>50 nm).Compared with other thin layers,sub-layer 4 has the largest continuous thickness,the highest TOC,porosity,and gas content,representing a self-generation and self-storage shale oil and gas reservoir of“pure shale type”.The high-quality semi-deep lacustrine shale are widely developed in the northern part of Fuling area,which is favorable for shale oil and gas enrichment.The area with good preservation conditions,high formation pressure,and well-developed micro-fractures are conducive to the high production of shale oil and gas.Key technology of volume fracturing with characteristics of“less stages and more clusters+temporary plugging and diversion+high pumping rate+medium to coarse sand proppants and high intensity injection”has been researched and developed,which enables effective stimulation of lacustrine shale.In conclusion,the breakthrough of Well Taiye 1 is of great significance to the commercial development of lacustrine shale oil and gas in China.