渤中坳陷流体包裹体特征及其对成藏研究的意义

CHARACTERISTICS OF FLUID INCLUSIONS AND THEIR SIGNIFICANCE FOR RESEARCH ON OIL ACCUMULATION IN THE CENTRAL BOHAI DEPRESSION

通过详细观察渤中坳陷部分钻孔岩心和充分认识坳陷沉积特征，对重点井段进行了流体包裹体的研究。研究表明：渤中坳陷次生流体包裹体主要赋存于石英颗粒的微裂隙、碳酸盐胶结物和方解石脉中，可分为4类：纯液相包裹体、纯气相包裹体、液态＋气态包裹体、盐水溶液包裹体。包裹体均一温度的测定显示其主要分为3期：88～100℃、115～140℃和140～155℃，说明渤中地区油气运聚期次至少存在3期。结合埋藏史和热史的资料分析表明，渤中坳陷总的成藏时间较晚，主要运聚期发生在13Ma（馆陶晚期）以来。

On the basis of intensive observation of a part of the core of well BZ25-1-7 in the Central Bohai depression and a full understanding of deposit fillings, the authors studied the fluid inclusions in a key core interval. The results show that secondary fluid inclusions mainly occur in micro-fractures of quartz, cements of carbonates or calcite veins. There are four types of fluid inclusion in the area： pure liquid inclusions, pure vapor inclusions, two-phase vapor-fluid inclusions and saline inclusions. Measurements of homogenization temperatures of most fluid inclusions display three stages of fluid flow： 88-100℃, 115-140℃ and 140-155℃, suggesting that there were at least three stages of oil/gas migration and accumulation in the Central Bohai region. According to the above-mentioned study, combined with an analysis of the burial history and thermal history, the authors think that the oil accumulation in the Central Bohai region occurred relatively late, and that the wain oil migration and accumulation stage occurred since the late Guantaoan period （13 Ma）.