渤海湾盆地歧口凹陷沙河街组三段一亚段地质特征与页岩油勘探实践

Geological characteristics and shale oil exploration of Es^(3(1))in Qikou Sag,Bohai Bay Basin

歧口凹陷沙河街组三段一亚段[Es^(3(1))]页岩油勘探获得高产、稳产工业油流,证实湖相页岩油具有较大勘探潜力,并形成亿吨级规模战场,对渤海湾盆地广泛分布的沙河街组页岩油勘探具有重要借鉴意义。针对歧口凹陷沙河街组三段页岩层系沉积环境、岩性、储集性、脆性和含油性等方面展开综合研究,Es^(3(1))半深湖-深湖区泥页岩孔缝发育,脆性指数高、储层敏感性差、含油气性好,具备页岩油富集的生烃、储集、含油和工程改造条件,页岩油成藏地质条件优越。纵向上,将Es^(3(1))划分6个甜点段,由上至下依次为C1—C6,平面分布稳定,单段厚度分布在7~96 m,累计厚度434 m,分布面积在87.4~194.3 km^(2),平面甜点叠加面积为256 km^(2),采用体积含油率法,初步计算资源量为4.1×10^(8) t。按“老井控面、水平井提产”的原则,在Bin60-56和F38x1两口大斜度井试油获工业油流,针对C1甜点段部署水平井勘探,QY10-1-1井获得日产百吨高产油气流,Bin56-1H井自喷试采206 d后,累产油3043.11 t,反排率为7.77%,歧口凹陷沙三段页岩油勘探取得重大突破。

The high and stable industrial shale oil flow from the first submember of the third member of Shahejie Formation(Es^(3(1)))in Qikou Sag,Bohai Bay Basin,reveals a possible 100 million tons of oil resource in the lacustrine shale of the member and serves as a significant reference for shale oil exploration in the whole Shahejie Formation of the basin.Based on a comprehensive study of sedimentary setting,lithology,reservoir properties,brittleness and oil-bearing property of the shale series in the member,we found that the shale series are of semi-deep lake-deep lake environment and characterized by well-developed pores and fractures,high brittleness,low reservoir sensitivity and high oil-gas bearing potential.They are favorable for hydrocarbon generation and accumulation and can be easily stimulated.Longitudinally,the member can be divided into 6 sweet-spot sections,namely sections C1 to C6 downwards of 7 to 96 m thick and 434 m in total.Horizontally,the sections are distributed in areas from 87.4 to 194.3 km^(2) with a cumulative area of 256 km^(2).Preliminary assessment using volumetric oil content method indicates the sections have a resource of 4.1×10^(8) t.Guided by the development strategy of“using old wells to control the range of sweet spots and horizontal wells to increase production”,two highly deviated wells,Wells Bin 60-56 and F38x1 were tested with industrial oil flows.Deploy horizontal well exploration for C1 sweet spot,Well QY10-1-1 was tested with 100 equivalent tons of hydrocarbon per day.Furthermore,Bin56-1H produced 3043.11 t in total after 206 days of production,and the reverse drainage rate was 7.77%,indicating a major breakthrough in the shale oil exploration of Es^(3(1))in Qikou Sag,Bohai Bay Basin.