苏北盆地古近系阜宁组致密油赋存状态与可动用性

利用多温阶热解与核磁共振测试技术，对苏北盆地古近系阜宁组阜二、阜四段泥页岩、夹层及邻层致密碳酸盐岩、致密砂岩样品系统分析，结合少量泥页岩油试采资料，探讨了阜宁组泥页岩、夹层及邻层致密储层的含油性和致密油可动用性。苏北盆地阜二、阜四段泥页岩中含致密油一般小于5.0 mg/g，油以吸附-互溶态为主，吸附-互溶态油占总滞留油的比例总体随埋藏深度的增大呈降低趋势，轻质游离油总体很低，可动油率小于3%；阜二、阜四段泥页岩夹层和邻层砂岩中含油一般大于5.0 mg/g，以游离油为主，轻质游离油量一般大于0.25 mg/g，可动油率一般在4%~7%之间，与北美Bakken中段致密砂岩油可动油率（5%左右）接近。阜宁组泥页岩内可动致密油主要赋存于裂缝中，即构造裂缝为可动致密油主要赋存空间，部分微孔隙（喉道半径大于0.18 μm）为次要赋存空间；致密油赋存相态应以游离态为主，吸附态次之。阜二、阜四段邻层（阜一、阜三段）裂缝型湖相碳酸盐岩致密油初期产量较高，但产量递减快，生产周期也短，经济可采性有限；相比之下，阜二、阜四段的源内夹层型致密砂岩油初始产量不高，但递减慢，生产周期长，具有较好的经济可采性。 

Occurrence and recoverability of tight oil in Paleogene Funing Formation,Subei Basin

The shale,interlayers and adjacent carbonate rocks and siltstones in the second and fourth members of the Paleogene Funing Formation in the Subei Basin were studied using multi-temperature pyrolysis and NMR.The oil-bearing capacity of shale,interlayers and adjacent tight reservoirs in the Funing Formation and the movability of tight oil were evaluated in combination with with shale oil production data.In the second and fourth members of the Funing Formation,the content of tight oil is generally less than 5.0 mg/g in shale.Adsorption-miscible oil is dominant,and the ratio of which to total retained oil decreases with the increase of burial depth.Light free oil generally has a low content,and the actual movable oil ratio is less than 3%.However,the tight oil content is generally greater than 5 mg/g in mud shale interlayers and adjacent sandstones(oily),dominated by free oil.The light free oil content is generally more than 0.25 mg/g,and the actual movable oil ratio is generally between 4%and 7%,which is close to the 5%recovery ratio in the tight sandstone layers before reconstruction in the middle of Bakken Formation in North America.The movable tight oil mainly exists in fractures in the Funing Formation in the Subei Basin.That is,tectonic fractures are the main host of movable shale oil,and some micro pores(with ramp radius greater than 0.18μm)work as secondary occurrence porosity.Free oil exceeds adsorbed oil.The initial production of tight oil is high in fissured lacustrine carbonates in the first and third members of the Funing Formation,but the production decreases rapidly with a short production cycle,and the economic recoverability is limited.In contrast,the initial production is lower in the tight interlayer sandstones of the source in the second and fourth members of the Funing Formation,which has a slower decline rate,longer production cycle and better economical recoverability.