吐哈盆地北部山前带下侏罗统储集层特征研究

The Characteristics of the Lower-Jurassic Reservoir in the Northern Mountain Front of Tuha Basin

北部山前带下侏罗统是吐哈盆地天然气勘探的主要领域,沉积体系研究认为:北部山前带下侏罗统三工河组和八道湾组物源来自北部,沉积相带为辫状河三角洲,河流相厚层块状砂岩与煤系源岩互层叠置,厚度大且横向分布稳定,具备整体勘探、连片含气的潜力,是开展精细勘探、拓展致密砂岩气规模储量的重要领域。通过岩心观察和各种分析化验资料,对研究区储集层特征进行了研究,认为形成特低孔、特低渗储集层的主控因素是成岩作用、沉积作用,而构造作用形成的微裂缝改善了储集层的渗流能力,因此,寻找裂缝发育带是勘探获得成效的重要途径。

The Lower-Jurassic in the northern mountain front was the main area for gas exploration in Tuha Basin.The study of sedimentary system indicated that the source of Lower-Jurassic Sangonghe and Badaowan Formations in the northern mountain front came from the north,and the sedimentary facies was braided river delta.The massive sandstone of fluvial facies was laminated with coal bed source rock and distributed stably on plane ,it was favorable for overall exploration with the potential of bulk gas-bearing.Thus it was an important area for fine exploration and expanding the tight sandstone gas reserves.Core observation and various analyses were carried out to identify the characteristics of the reservoir in this area.The result shows that the main factors causing extreme low porosity and permeability reservoirs in the area include diagenesis and sedimentation,while the fractures created in tectonics improve the percolation capacity of the reservoirs,hence,the key of success exploration is to find zones of fracture growth.