四川盆地简阳-三台地区二叠系火成岩油气成藏新模式及勘探前景

New model and exploration prospect of Permian igneous oil and gas accumulation in the Jianyang-Santai area of the Sichuan Basin

简阳—三台地区YT1风险探井在二叠系火山岩爆发相测试获得工业气后,已发表文章一致认为,四川火成岩勘探取得了重大发现和突破,存在大型构造-岩性复合圈闭气藏。依据最新三维地震成果及钻测井资料,综合分析认为,该区不存在大型构造-岩性复合圈闭,主要论据有:1)火山岩储层非均质性很强,横向上储层不连通;2)火山岩浆多点喷发,筇竹寺组生烃能力遭到破坏;3)构造形成喜山晚期,晚于侏罗纪—三叠纪排烃高峰期,圈闭充气不足;4)二叠系火成岩区为微型低幅度背斜圈闭,不利于大规模油气聚集。基于上述分析,简阳—三台地区火成岩是独立的、分散的低效油气藏。文章最后指出,一口风险探井获得油气后,若要确定为“重大发现和突破”,需要1~3年后的探井和评价井的检验。

After the YT1 risk exploration well in the Jianyang-Santai area to obtain industrial gas from the Permian volcanic eruption facies test,the published articles agreed that a major discovery and breakthrough had been made in the exploration of igneous rocks in Sichuan,and large structure-lithology composite trap gas reservoir existed.According to the latest 3D seismic results and drilling and logging data,comprehensive analysis concluded that there was no large-scale structure-lithology composite trap in this area.The main arguments are as follows:1)the volcanic rock reservoir is highly heterogeneous and the transverse upper reservoir is not connected;2)The hydrocarbon-generating capacity of the Qiongzhusi Formation is destroyed by the multi-point eruption of volcanic rocks;3)The structure formed in the late Himalayan period,later than the peak of hydrocarbon expulsion in the Jurassic-Triassic period,so that the trap is under-inflated;4)The Permian igneous rock area is a micro low-amplitude anticlinal trap,which is unfavorable to large-scale oil and gas accumulation.Based on the above analysis,the igneous rocks in the Jianyang-Santai area are independent,dispersed,and inefficient reservoirs.The article pointed out that after a risk exploration well obtains oil and gas if it is to be identified as a“major discovery and breakthrough”,it needs to be tested by exploration and evaluation well one to three years later.