墨西哥Sureste盆地成藏组合及勘探潜力

Hydrocarbon plays and exploration potential of the Sureste Basin of Mexico

Sureste盆地为墨西哥油气最富集的盆地,但与墨西哥湾北部相比仍存在很大的勘探潜力。在分析油气成藏要素、成藏模式的基础上,首次对成藏组合进行了划分与评价,指明了盆地的勘探潜力。研究表明:以上侏罗统提塘阶为主的4套烃源岩为盆地提供了丰富的物质基础,5套碳酸盐岩和碎屑岩优质储层为盆地提供了多样的勘探层系。受盐岩活动、构造运动和沉积负载的共同控制,盆地发育6种圈闭类型和4种成藏模式。据此,将成藏组合在纵向上划分为深部、中部、浅部3套,其展布范围、控制因素及勘探程度各不相同。目前油气发现在中部成藏组合最为富集,其中深部和中部成藏组合以断层沟通下生上储的挤压背斜油气藏为主,浅部成藏组合以"盐岩+断层"沟通下生上储的盐刺穿相关油气藏为主。盆地未来勘探潜力主要集中在陆上深层和海上深水。陆上深层深部成藏组合的牛津阶风成砂岩勘探程度很低。海上深水至今未有油田投产,其西侧以浅部成藏组合为目标,东侧以中部成藏组合为目标,南侧以深部成藏组合为目标。

The Sureste Basin is the richest petroliferous basin in Mexico and it still has significant exploration potential compared with the Northern Gulf of Mexico. In this study, the hydrocarbon play was divided and evaluated for the first time based on the analysis of accumulation elements and models, unrevealing the basin＇s exploration potential. Studies show that four sets of source rocks and five sets of reservoirs provided abundant material basis and multiple exploration layers, respectively, for the basin. Controlled by salt activity, tectonics and deposition load, the basin has developed six trap types and four accumulation models. Hydrocarbon plays can be vertically divided into the Deep, the Middle and the Shallow Play of different distributions, controlling factors and exploration levels. In the present discovery, hydrocarbons were found to be enriched in the Middle Play; the Deep and Middle Plays are mainly compressional anticline reservoirs, consistent with the ＂fault communicate-lower generation-upper storage＂ model; and the Shallow Play is mainly salt diapir related reservoir, in agreement with the ＂salt＋fault communicate-lower generation-upper storage＂ model. Clearly, the Sureste Basin has great potential in deep horizon onshore and deepwater offshore exploitations. The potential onshore target is the Oxfordian eolian sandstone of the Deep Play, whilst the offshore targets are the Shallow Play in the west, the Middle Play in the east and the Deep Play in the south.