海安凹陷曲塘次凹阜二段页岩油形成条件研究

A study on formation conditions of shale oil in Second Member of Funing Formation in Qutang Sub-sag,Haian Sag

海安凹陷曲塘次凹阜二段页岩油勘探取得新突破,为进一步加深地质研究提供了丰富的资料。为更好地指导曲塘次凹页岩油勘探方向,通过开展生烃条件、储集条件和工程条件这3方面的研究,明确了阜二段页岩油形成条件,以便评价优质“甜点”层段。阜二段泥页岩厚度较大,一般为150~300 m,有机质丰度中等,平均有机碳含量为1.69%,有机质成熟度为0.72%~0.84%,处于中低成熟成熟阶段,具有较好的生烃条件;总体为低孔特低渗储层,平均有效孔隙度为3.93%;脆性矿物含量较高,平均值为68.1%,地应力适中,两向应力差异系数较小,具有较好的可改造性。阜二段Ⅰ亚段和Ⅱ亚段有机碳含量为0.60%~4.16%,平均游离油含量分别为1.23 mg/g和1.61 mg/g,OSI>100 mg/g的页岩厚度57 m,脆性矿物含量为53.1%~92.3%,综合评价为优质“甜点”层段。开展曲塘次凹阜二段页岩油形成条件的研究对指导勘探方向具有重要意义。

A new breakthrough has been made in the exploration of shale oil in the Second Member of Funing Formation in Qutang Sub-sag,Haian Sag,providing rich data for further deepening geological research.To guide the exploration direction of shale oil in in Qutang Sub-sag,This article researches hydrocarbon generation,reservoir and engineering conditions to clarify the formation conditions of shale oil in the Second Member of Funing Formation and evaluate the high-quality sweet spot layer.The thickness of the mud shale is relatively large in the Second Member of Funing Formation,generally ranging from 150~300 m.The organic matter abundance is moderate,with an average total organic carbon(TOC)content of 1.69%and an organic matter maturity of 0.72%~0.84%.It is in the medium-low maturity stage and has good hydrocarbon generation conditions.Overall,it is a low porosity and ultra-low permeability reservoir,with an average effective porosity of 3.93%.The content of brittle minerals is relatively high,with an average of 68.1%.The in-situ stress is moderate,and the coefficient of difference between the two directions of stress is small,indicating good fracability.The TOC s of the first and second Submembers of the Second Member of Funing Formation range from 0.60%to 4.16%,with average free oil contents of 1.23 mg/g and 1.61 mg/g.Shale with OSI greater than 100 mg/g has a thickness of 57 m,and brittle mineral content ranges from 53.1%to 92.3%.It is comprehensively evaluated as a high-quality sweet spot layer.It is of great significance to research the formation conditions of shale oil in the Second Member of Funing Formation to guide the direction of exploration in Qutang Sub-sag,Haian Sag.