论文部分内容阅读
塔拉纳基盆地陆区气藏的高 CO_2含量可据富镜质组第三系煤的脱羧作用作定量解释,该区第三系煤的煤级范围是褐煤——早期高挥发分烟煤。最高CO_2含量见于垂向上邻接始新统煤层的砂岩储层中,始新统煤层已实现其CO_2生成潜力的约 50%。储层条件下以超临界流体形式存在的气体,其生成数量似乎很大,足以与液态烃相比。当CO_2大量生成期与主生油期一致时,有助于油从煤中直接排出;而在主生油期之前大量CO_2快速生成期间,压裂微裂缝有助于油的间接排出。就这些已知的作用而言,相对于CO_2移失量的CO_2产生速率被认为是关键因素,而有利的条件可能只局限于那些经历过相对快速增热的盆地。在这方面,塔拉纳基盆地为认识许多东南亚第三纪盆地的CO_2演化提供了一种模式。
The high CO 2 content of the gas reservoirs in the Taranaki basin can be quantitatively explained by the decarboxylation of Tertiary coal in the Fuji Group. The Tertiary coal rank in this area is lignite-early high-volatile bituminous coal. The highest CO 2 content is found in sandstones that vertically adjoin the Eocene coal seams, and the Eocene coal seams have achieved about 50% of their CO 2 potential. Gases present in the form of supercritical fluids at reservoir conditions appear to be large enough to be produced in comparison with liquid hydrocarbons. When CO2 is generated in a large amount during the main oil-producing period, it is helpful for the oil to be directly discharged from the coal. However, during the rapid formation of large amounts of CO2 before the main oil-producing period, fracturing microfractures are helpful for indirect oil discharge. For these known effects, the rate of CO 2 production relative to the amount of CO 2 removal is considered a critical factor, while favorable conditions may be limited to those basins that have experienced relatively rapid heat build-up. In this regard, the Taranaki Basin provides a model for understanding the evolution of CO 2 in many Tertiary basins in Southeast Asia.