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基于对Chaco盆地的详细解剖,通过分析其古生界天然气的成藏条件和成藏特征,总结其成藏主控因素,进而类比和分析南美前陆盆地古生界天然气的成藏特征和勘探潜力。Chaco盆地天然气资源丰富,为南美天然气储量最大的盆地,且天然气资源主要集中在古生界;其古生界天然气成藏模式优越,成藏具有优生、多储、圈闭规模大、新生古储、多期成藏、近源成藏及集中分布的特征,天然气成藏受主力成藏组合和断裂的双重控制。由于构造演化的差异,南美前陆盆地古生界有效储层仅在中部3个盆地发育;除Chaco盆地外,其他2个前陆盆地古生界与Chaco盆地具有相似的天然气成藏条件,成藏背景有利,具有一定的勘探潜力。研究指出Chaco盆地古生界天然气勘探程度较高,下一步勘探仍以次安第斯带和前渊带泥盆系为主要目的层系,兼探深层和斜坡带浅层非构造圈闭。Beni盆地和Madre de Dios盆地古生界勘探程度非常低,下一步应加强断裂最为发育的次安第斯带和前渊带的勘探力度,以构造圈闭为最有利勘探目标。
Based on the detailed anatomy of the Chaco basin, the gas accumulation conditions and reservoir forming characteristics of the Paleozoic natural gas are analyzed, and the main controlling factors of gas accumulation are summarized. Then the gas accumulation and exploration of the Paleozoic natural gas in the South American foreland basin are analyzed and compared potential. The Chaco basin is rich in natural gas and is the largest reserve of natural gas in South America. The natural gas resources are mainly concentrated in the Paleozoic. The Paleozoic natural gas accumulation mode is superior. The gas accumulation in the Chaco Basin is characterized by eugenics, multi-reservoirs, large traps, , Multi-stage gas accumulation, near-source gas accumulation and central distribution, and natural gas accumulation under the dual control of the main reservoir-forming assemblage and fracture. Due to the differences in tectonic evolution, the Paleozoic effective reservoirs in the South American foreland basin developed only in three basins in the central part. The Paleozoic and the Chaco Basin in the other two foreland basins, except for the Chaco Basin, have similar natural gas accumulation conditions. Tibetan background is favorable, with some exploration potential. The study indicates that there is a high degree of exploration for gas in the Paleozoic in the Chaco Basin. In the next exploration, the sub-Andean belt and the Devonian Devonian are the main target strata, and the shallow non-structural traps in the deep and slope zones are explored. The Paleozoic exploration is very low in the Beni and Madre de Dios basins, and the next step should be to intensify the exploration of the sub-Andean and foredeep belts with the most developed fractures. Structural traps are the most favorable targets for exploration.