阜新盆地东梁区浅层天然气成藏特征

RESERVOIRING CHARACTERISTICS OF SHALLOW GAS IN DONGLIANG AREA IN THE FUXIN BASIN

研究和评价了阜新盆地东梁区浅层天然气藏的成藏特征,认为气源岩为白垩系沙海组4段泥岩和沙海组3段煤层,巨厚的泥岩和煤层有强大的生烃能力,储层为低孔低渗的沙海组3段砂岩,沙4段泥岩、粉砂岩是区域性良好盖层,沙4段泥岩、沙3段煤层和沙3段砂岩由于渗透率的不同形成了完整的岩性圈闭。东梁背斜沙海组的圈闭面积达10km2,且向东南延伸呈穹隆构造,封闭良好,对天然气形成了一个良好的局部背斜圈闭。研究表明该区沙3段砂岩储层紧邻气源岩,盖层条件良好,局部圈闭,形成“上生下储型”和“自生自储型”的小型浅层气藏。

Reservoiring characteristics of shallow gas in Dongliang area in the Fuxin Basin are discussed in this paper. It is believed that sandstones in the 4th member and the coal beds in the 3rd member of Cretaceous Sahai Formation are source rocks with strong hydrocarbon-generating potentials, the sandstones in the 3rd member of Sahai Formation with low porosity and low permeability are reservoirs, and the shale and siltstone in the 4th member of Sahai Formation are good regional seals. A complete lithologic trap would have been formed due to permeability contrast among the shale in the 4th member and the coal beds and the sandstone in the 3rd member of Sahai Formation. The Sahai Formation in Dongliang anticline, with a trap area of 10 km2, extends in southeast direction to a dome structure and has good sealing conditions, constituting a good local anticline trap. The sandstones in the 3rd member of Sahai Formation in the study area are near gas source rocks and have good sealing conditions and good local trapping conditions, leading to the formation of small shallow gas pools with source rock being above reservoir rock or source rock and reservoir rock coexisting in the same layer. They are suitable for exploration and development.