塔里木盆地玉北1井区奥陶系地层水成因及成藏条件分析

ANALYSIS ON THE GENESIS OF FORMATION WATER AND RESERVOIR FORMING CONDITIONS OF ORDOVICIAN IN YUBEI1 WELL AREA,TARIM BASIN

塔里木盆地麦盖提斜坡玉北1井区奥陶系鹰山组原油为中质油,原油饱和烃色谱分析表明存在一定程度的降解。油藏地层水为高矿化度CaCl_2型封闭型水,二者存在一定的矛盾。通过地层水氢氧同位素分析发现,玉北1井区地层水氢氧同位素特征与塔北阿克库木凸起塔河油田地层水相似,为海源沉积与古大气降水叠加混合型地层水。奥陶系鹰山组碳酸盐岩储层早期充注的原油遭受过古大气降水的破坏,海西晚期以来在石炭系泥岩和部分膏盐岩的封盖下,保存条件良好。其高矿化度地层水为海西晚期以来溶解上覆盖层中的盐类(NaCl)所致。

The crude oil in Yingshan Formation of Ordovician is medium oil at Yubei1 well area,Maigaiti slope,Tarim,and has been degraded to some extent shown by the saturated hydrocarbon chromatographic analysis. Butthe reservoir formation water is hypersaline with Ca Cl2 conflicting. Through analysis we find the hydrogen and ox-ygen isotopes characteristic of formation water in Yubei1 well area is similar to that of Tahe Oil Field at Arkekulesalient,which is mixed formation water with seawater fed and paleo-meteoric water. The crude oil charging earli-er in Yingshan formation carbonate of Ordovician was subjected to the damage of the paleo-meteoric water,andwas well preserved under the Carboniferous mudstone and gypsum rock which was the dissolve source of the hy-persaline formation water with NaCl since Late Hercynian.