古巴前陆盆地三区块石油地质特征及勘探潜力分析

Petroleum geological characteristics and exploration potential in Block Ⅲ of Forland Basin,Cuba

古巴三区块是2005年中国石化获得的风险勘探开发合同区块,位于墨西哥湾西南部,是古巴西部的前陆盆地之一。结合该盆地勘探现状,对相关的钻井、物探以及地球化学等资料进行石油地质综合分析,评价了该盆地的油气成藏条件及其勘探潜力,预测了有利区带。三区块主要发育上侏罗统—下白垩统的泥灰岩、泥质灰岩和中—下侏罗统泥页岩两套主要烃源岩,储层以泥晶灰岩、灰岩和砂砾岩为主,区内早期形成的圈闭在造山期基本遭到破坏,有效的圈闭主要形成于晚古近纪,圈闭类型有背斜、断鼻、断块和地层圈闭等,推测可能发育多套储盖组合。据区域对比和钻井资料分析,区内的前陆冲断带是本区最有利勘探区带,南盆地北缘发育较厚的第三系,推测是本区有利远景区。

Block Ⅲ of Cuba is a contractual block of risk exploratory development in the foreland basins in Cuba. It is located in the southwest of Mexico Gulf and registered by SINOPEC. Petroleum geology of this block was analyzed synthetically, its hydrocarbon accumulation conditions and exploration potential was evaluated and the favorable oil/gas exploration zone was predicted combining the database of drilling, geophysical exploration and geochemistry in view of current status of the studies. Source rocks （Upper Jurassic-Lower Cretaceous marlite and argillaceous limestone, and Mid-Lower Jurassic shale） occurred in Block Ⅲ, and reservoirs were mainly composed of micrite limestone, limestone and sand-conglomerate rocks. The early traps were almost destroyed during orogenic phase and effective .traps formed mainly in Paleogene including anticlines, fault nose, faulted blocks, and lithologic traps, ： from which it was speculated that several assembling types of the oil-generating strata, reservoir strata and overlying strata developed. Analysis of regional correlation and the drilling information showed that the foreland thrust belt in this area was the most favorable exploration area, and the thick tertiary strata occurred in the north margin of south basin was predicted to be the favorable potential area.