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切入艾伯塔省(Alberta)东南部侏罗系和密西西比系地层的下Mannville河谷复合体可以从常规的地震剖面上识别。在河谷钻了井,并从目的层段中获得了20m的泥质砂岩岩心。在岩心内可见油渍,但测试表明只有泥水。相反,靠近河道的薄砂层测试后日产气可达300m~3,日产油800m~3。靠近河谷的沉积物被解释为占据该河谷的一条河道的同期沉积的天然堤和决口扇,而河道内的泥质砂岩不是细粒点沙坝沉积,就是废弃河道充填沉积。在后一种情况下,在河道系统的另一处预期可发现粗粒的砂质点沙坝沉积。油被圈闭于披覆在密西西比系隆起上的决口扇内而不是该河谷内的河道砂岩中,因为后者的储集性能差。由于该河道规模小,因此河谷充填的几何形态不能直接根据地震资料分辫。然而,该河谷正上方沉积物的反射形态表明该河谷充填是有变化的,并意味着测试部位上的河谷充填为一废弃河道沉积。本文认为下Mannville河谷之上的反射几何形状可能为确定河谷充填的类型提供一种手段。
The lower Mannville Valley complex cut into the Jurassic and Mississippian formations in southeastern Alberta can be identified from conventional seismic profiles. Wells were drilled in the valley and 20 m of shaly sandstone cores were obtained from the target interval. Visible in the core oil, but the test showed that only muddy water. On the contrary, after the thin sand layer close to the riverbed, the daily gas production can reach 300m ~ 3 and the daily output of oil can reach 800m ~ 3. Sediments near the river valley are interpreted as natural dikes and rift fans deposited over the same period of a river channel in the valley, whereas the sandstone in the river channel is not deposited as fine-grained sandbars, but rather as abandoned river fill sediments. In the latter case, a coarse grained sandy barrage can be found deposited elsewhere on the river system. The oil was trapped in rivulets draped over the Mississippi uplift rather than fluvial sandstones in the valley as the latter had poor reservoir properties. Due to the small size of the channel, the valley fill geometry can not be directly assigned to the seismic data. However, the reflections of the sediment directly above the valley indicate that the valley filling is variable and implies that the river valley at the test site is filled with an abandoned river sediment. This paper argues that the reflection geometry above the Mannville Valley may provide a means of determining the type of valley fill.