川东石炭系溶蚀岩性气藏

CORROSION-LITHOLOGICAL GAS POOL OF CHUANDONG (EAST SICHUAN) CARBONIFEROUS SERIES

本文根据川东石炭系储层孔隙的发育,主要是由于沉积后曾上升为陆,长期遭受大气淡水溶蚀淋滤,使各地孔隙段的发育很不一致这一特点,认为当其被二叠系泥页岩覆盖后,由于未被溶蚀的部分仍处致密状态而具不渗透性,各孔隙段也可能相互连通,也可能各自成一独立的孔渗体系,而其周缘均被不渗透层所封闭,这样就可能形成大气淡水溶蚀岩性油气藏。从这一观点出发,作者对板西和卧龙河地区石炭系气水分布异常进行了较详细的讨论,认为板西地区石炭系为断层-溶蚀岩性圈闭气藏,卧龙河气田北段石炭系气水分布的殊异主要是由于溶蚀岩性圈闭所致,从而解决了卧龙河石炭系气藏多年来遗留下来的南北段气水界面不一致的问题。

Based on the features of pore-fracture development of Chuandong Carbonife- rous reservoir,mainly because of its uplift to the surface after deposition,subje- cted to a long-term corrosion and leaching by atmospheric fresh water,thus re- sulting in an extremely inconsistent,the paper deems that,after the deposition of permian mudstone andshale,and thus possessing impermeability,various porous intervals may be interconnected,or may be isolated pore system owing to tightness an impermeability of the uncorroded portion and are surrounded by impermeable rock formation;thus fig is possible to form an atmospheric fresh water corroded-lithological gas pool.With this point of view,the author has discussed the anomalous Carboniferous gas-water distribution for Banxi and Wo- longhe districts in more detaile,and suggest that the Carboniferous system of Banxi district is a gas pool of lithological trap fomed due to fault and corrosion, and the abnormality in Carboniferous gas-water distribution in the northern part of Wolonghe gas reservoir is mainly a special feature of a corrosion-lithological trap.Thus the problem of inconsistent gas-water interface in the southern and northern portion of Carboniferous gas pool,which has been left over many ye- ars,is answered.