机构地区:[1]西南石油大学地球科学与技术学院 [2]中国石油西南油气田公司勘探开发研究院
出 处:《天然气工业》2023年第7期35-43,共9页Natural Gas Industry
基 金:国家自然科学基金项目“鄂西裂陷槽在扬子古大陆裂解中的沉积响应及其油气地质意义”(编号:41972121);中国石油—西南石油大学创新联合体科技合作项目“深层超深层碳酸盐岩气田勘探开发基础理论与关键技术研究”(编号:2020CX0101)。
摘 要:四川盆地震旦系海相碳酸盐岩天然气资源丰富,随着川中古隆起北斜坡埋深快速增加,超深层(大于6000 m)古老碳酸盐岩经过复杂的成岩演变,储层趋向致密且具有强烈的非均质性,在一定程度上制约了超深层天然气勘探的进一步拓展。为此,在最新三维地震资料走滑断裂识别的基础上,结合最新钻井成果与成藏资料分析,研究了川中古隆起北斜坡走滑断裂的分布特征和控储控藏作用。研究结果表明:(1)研究区发育25条总长达1480 km的主干走滑断裂带,平面上具有斜列/雁列构造组合的分段性、剖面上具有直立线性构造与花状构造的分层性;(2)震旦系古老碳酸盐岩基质储层多致密(渗透率小于0.5 mD),但断裂发育部位丘滩体储层渗透率可提高1~2个数量级、孔隙度增幅超过20%;(3)通过走滑断裂沟通气源,可能沿走滑断裂带形成一系列有利于天然气运聚成藏的丘滩体“甜点”区;(4)沿走滑断裂带震旦系碳酸盐岩的钻探已获高产气流,揭示走滑断裂叠加改造的丘滩体“甜点”储层有利于天然气的富集与高产。结论认为,四川盆地震旦系碳酸盐岩走滑断裂具有“增储控富”的关键作用,其中断—相共控“甜点”是超深层斜坡区天然气勘探的有利新类型,具有广阔的天然气勘探前景。The Sinian marine carbonate rocks in the Sichuan Basin are rich in gas resources.As the northern slope of the Central Sichuan paleouplift got deeper rapidly,however,the ultra-deep(>6000 m)ancient carbonate rocks experienced complex diagenetic evolution,so the reservoirs tend to be tight with strong heterogeneity,which restricts the further exploration of ultra-deep gas to some extent.This paper identifies the strike-slip faults based on the latest 3D seismic data,and then combined with the latest drilling results and hydrocarbon accumulation data analysis,studies the distribution characteristics and reservoir/accumulation-controlling effects of strikeslip faults in the northern slope of the Central Sichuan paleouplift.The following results are obtained.First,25 main strike-slip fault zones with a total length of 1480 km are developed in the study area,which are characterized by segmentation of oblique/en echelon fault assemblage on the plane,and layering of upright linear structure and flower structure in the profile.Second,most of the Sinian ancient carbonate matrix reservoirs are tight(permeability<0.5 mD),but the permeability of the mound-shoal reservoir with developed fractures is 1–2 orders of magnitude higher and the porosity is 20% higher.Third,the strike-slip faults can connect the gas source,which makes it possible for the formation of"sweet spot"of mound-shoal body along the strike-slip fault zones gas to facilitate natural gas migration and accumulation.Fourth,high-yield of gas flow was obtained through drilling in the Sinian carbonate rocks along the strike-slip fault zones reveal that the reworked"sweet spot"reservoir of mound-shoal body superimposed with strike-slip faults are favorable for the enrichment and high production of natural gas.In conclusion,the strike-slip faults in the Sinian carbonate rocks of the Sichuan Basin play a key role in"reserve increase and enrichment control",and the"sweet spot"under the joint control of fault and facies is a new field favorable for natural gas exploratio
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