鸡西盆地致密砂岩气存在的可能性

Possibility of tight sand gas reservoirs in Jixi Basin

鸡西盆地的油气勘探程度较低,尤其是对致密砂岩气的研究尚处于起步阶段。在总结国内外成功地区致密砂岩气成藏条件的基础上,从构造、烃源岩以及储层条件等方面探讨了鸡西盆地致密砂岩气的成藏条件。依据鸡D8井暗色泥岩样品的地球化学资料,使用化学动力学法计算了研究区致密砂岩气的资源量。研究表明,鸡西盆地属于小型断陷盆地,多期构造演化与储层快速沉积等特点,决定了研究区不具备类似北美阿尔伯达等成功地区的大型致密砂岩气成藏的地质条件。但鸡西盆地城子河组大规模发育的煤系地层长期生气,为致密砂岩气藏的形成提供了充足的气源,烃源岩与储集层紧密叠置接触也有利于致密气的运移和保存。在鸡西盆地的中央凹陷构造稳定区域,寻找致密储层的甜点区,将有机会获得致密砂岩气藏的勘探突破。

Jixi Basin is still immature in petroleum exploration, especially for tight sand gas. Based on summari- zing accumulation conditions of tight sand gas reservoirs at home and abroad, we discussed the tight sand gas ac- cumulation conditions in Jixi Basin in respects of structure, source rock and reservoir. According to the geoche- mical data of the dark mudstone samples of Ji D8 well, the tight sand gas resources was estimated by the method of chemical kinetics. The results show that Jixi Basin is a small rifled basin featuring in multiple-cyclic tectonic evolution and rapid deposition. Its tight gas geological conditions are quite different from the large tight sand gas reservoirs in North America. However, large-scale eoalbeds in the Chengzihe Formation in Jixi Basin provide abundant gas source for the tight sand gas reservoirs. Superimposition and closely contact of source rocks and re- servoir are also in favor of the migration and accumulation of gas. Sweet spots of tight sand gas may exist in the tectonieally stable region of the central depression in Jixi Basin.