琼东南盆地崖南凹陷崖13-1构造与崖21-1构造成藏条件的比较

中国的最大气田--崖13-1气田位于崖南凹陷西缘,位于崖南凹陷东南缘的崖21-1构造就目前几口钻井显示成藏条件并不理想.总体来说,崖21-1构造烃源条件差、储层条件差、区域能量条件差.崖13-1气田天然气主要来自于琼东南盆地的崖南凹陷和莺歌海盆地埋深分别大于4 450 m和4 700 m的崖城-陵水组烃源岩.崖21-1构造的主要源岩为乐东凹陷,其浅海A型和浅海B型源岩的发育条件均很差.据沉积相的研究,崖21-1构造的陵水组为滨海相沉积,相对于崖13-1构造来说,粒度变细,以细砂岩为主.两构造的能量场配置和流体活动也有明显的不同,崖13-1构造盖层发育超压,储层为常压,为侧向流体充注,反映了能量场的黄金配置;而崖21-1构造储层和盖层均为超压,为垂向流体泄放.通过对2个构造的成藏条件的比较说明了崖21-1构造目前未能成藏的原因.

A Comparison of Petroleum Accumulation between YA13-1 Structure and YA21-1 Structure in Yanan Depression within Qiongdongnan Basin

YA 13-1 gas field, the best gas field, is located in the west of Yanan depression. In the southeast, there lies YA 21-1 structure, which in general has "three poor" conditions, that is, source rock, reservoir and energy field. The natural gas of YA 13-1 comes from Yachen and Lingshui formation of Yinggehai and Qiongdongnan basin. However, the source rock of YA 21-1 comes from Ledong depression, which is the first poor. The reservoir of YA 21-1 is worse than that of YA 13-1, which is the second poor. Regarding the energy fields, it is shown that the cap rocks and reservoirs have over-pressure, which is the third poor. So, the source rock, reservoirs and energy fields controlled the petroleum accumulation of YA 21-1.