试论渤海湾盆地油气富集规律与勘探

Hydrocarbon Accumulation Regularity and Hydrocarbon Potential in Bohaiwan Basin

渤海湾盆地至今已发现油气田226个,探明油气地质储量114.4×108t,油气资源量为285×108t。盆地内的油气富集规律与盆地东界的郯庐深大断裂带紧密相关。靠近郯庐断裂带的东部坳陷区,其探明油气地质储量和油气资源量是远离断裂带的西部坳陷区的3.6倍和3.3倍;根据探明油气地质储量进行划分,东部坳陷区以大油气田为主,而西部坳陷区则以中、小油气田为主;东部坳陷区发现的浅层油气藏、稠油油藏、火成岩油藏及非烃CO2气藏比西部坳陷区多得多,但两者的潜山油气藏的数量和储量却很相近。研究表明,郯庐深大断裂不仅控制了盆地的发育和形成,而且还控制了油气的生成、运移和聚集。渤海湾盆地既是中国大盆地中油气富集程度最高的盆地,也是具有独特油气富集规律的盆地。尽管该盆地油气探明率已达40.1%,但仍有170.7×108t的油气剩余资源量可供再勘探,勘探潜力仍十分巨大。

Bohaiwan Basin is the one with a unique regularity of hydrocarbon accumulation and trapping. Two depression regions, the eastern and the western ones, can be roughly divided in the basin. A deep and large fracture belt Tan-Lu Fracture Belt, through the basin from northeast to southwest predominates generation, migration and accumulation of hydrocarbon in the basin. The petroleum proved reserves in-place and the resource extent are as 3.6 and 3.3 times in the eastern region near Tan-Lu Fracture Belt as those in western region far from the belt. Based on the proved reserves in-place, large oil and gas fields commonly concentrate in the eastern region while small ones focus in the western region. Shallow reservoirs, viscous oil reservoirs, volcanic rock reservoirs and CO2 gas reservoirs in the eastern region are much more than those in the western region but buried hill reservoirs are as similar in amount and reserves in the eastern region as those in the western region. Up to present, 226 oil and gas fields has been discovered in Bohaiwan Basin, in which petroleum proved reserves in-place is up to 11.44 × 10^9t and resource extent is up to 28.5 × 10^9t. The present 40.1% of demonstrated reserves rate means that there still are oil and gas exploration potential and prospect in the basin.