挤压型盆地油砂富集条件及成矿模式

世界上绝大部分油砂资源分布于挤压型盆地。通过对西加拿大盆地、东委内瑞拉盆地和准噶尔盆地西北缘这些典型的挤压型盆地油砂成矿条件进行分析，认为丰富的烃源岩是形成油砂矿的物质基础；良好的烃类运移通道和充足的烃类运移驱动力，影响了油砂成矿的规模和分布的地理位置；地下水对烃类的水洗作用和生物的降解作用使烃类稠化，黏度升高，密度加大，形成油砂；挤压型盆地斜坡区三角洲相、滨岸相及河流相砂体发育，为大型油砂矿的成矿提供了储集空间，区域分布的泥岩作为盖层，促进了烃类横向运移，充满砂体。最后，根据油砂成矿在挤压型盆地的位置，提出了缓倾单斜油砂成矿模式和受压盆缘油砂成矿模式。

151OIL SANDS GATHERING CONDITIONS AND ACCUMULATION MODES IN COMPRESSIONAL BASINS

Most of oil sands resources has been discovered in those compressional basins. Through analysis on how oil sands gathered and accumulated in those typical compressional basins like West Canada basin, East Venezuela basin, and Northwest Junggar basin, this paper thought that rich hydrocarbon source rocks were the fundamental for oil sands reservoirs to come into being; favorable channels and enough drives for hydrocarbons migration played important roles in the area and locations of oil sands reservoirs; oil sands generated from the densified hydrocarbons due to the degradation reaction and flushed by the ground water; sand bodies well developed in the slope regions of the compressional basins like delta, shoreland, and fluvial facies provided large reservoirs for oil sands, while regional claystones as caprocks for hydrocarbons to migrate horizontally to fill up in sand bodies. Finally according to the location where oil sands accumulated in the compressional basins, this paper put forward two oil sands reservoirs models, i.e., one in light pitch monocline and another one in compressive basin edge.