断层在油气成藏中的控制作用——以川西东坡地区须二段气藏为例

Control effect of faults on hydrocarbon accumulation: a case study of gas reservoir of  the second member of Xujiahe Formation, Dongpo area, western Sichuan Basin 

冯英,邓美洲,李亚晶,陈俊,毕有益,严焕榕

FENG Ying, DENG Meizhou, LI Yajing, CHEN Jun, BI Youyi, YAN Huanrong

中国石化西南油气分公司勘探开发研究院，四川 成都 610100

Exploration and Production Research Institute, Southwest Oil & Gas Company, SINOPEC, Chengdu 610100, China

由于多期构造活动，川西东坡地区须二段气藏存在断层发育特征、裂缝分布规律及成藏主控因素不明确等问题，影响气藏的效益开发。通过分析该气藏的断层分布特征、断层活动性及组合样式，深化了断层对油气输导、裂缝形成、储层改造等方面作用的研究。结果表明：合兴场￣丰谷地区保存条件好于知新场￣石泉场￣中江￣回龙地区，二—四级断层沟通了下伏马鞍塘组—小塘子组烃源岩，可作为天然气垂向运移通道；“Y”字形及反“Y”字形断层组合样式双向供烃，油气运聚条件最为有利；现今有效的构造缝主要为晚期断层和褶皱所形成的裂缝，通过多属性融合裂缝预测，明确了裂缝在晚期发育的近南北向断层附近最为发育；晚期构造活动形成的四级断层与五级断层搭配，有利于有效断缝储渗体的形成，提高了储层的物性及渗流能力，形成中高产的“甜点”；从烃源岩、主成藏期等方面剖析断层活动与成藏之间的关系，建立了“晚期调整控富、有效裂缝控产、优质储层控效”的成藏模式，优选出合兴场￣高庙地区为评价潜力区。

Due to multi-stage tectonic activity, there are some unclear problems in  the second member of Xujiahe Formation gas reservoir in Dongpo area of western Sichuan Basin, such as fault development characteristics, fracture distribution law and main controlling factors of reservoir formation, which affect the benefit development of gas reservoir. Through analysis of fault distribution characteristics, fault activity and combination pattern of the gas reservoir, the research of the influences of faults on oil and gas transportation, fracture formation and reservoir reconstruction is deepened. The results show that the preservation conditions in Hexingchang-Fenggu area are better than those in Zhixinchang-Shiquanchang-Zhongjiang-Huilong area， and the second to fourth-order faults connect the underlying source rocks of Maantang-Xiaotangzi Formation, which can be the vertical migration channel of natural gas; The "Y" type and anti "Y" type faults combination can provide two-way hydrocarbon supply, and the conditions for hydrocarbon migration and accumulation are the most favorable; The current effective structural fractures are mainly formed by late faults and folds. Through multi-attribute fusion fracture prediction, it is clear that fractures are most developed near the late north-south trending faults; The match between the fourth order fault formed by late tectonic activity and the fifth order faults is beneficial to the formation of effective fault-fracture reservoir and permeability body, which improves the physical properties and seepage capacity of the reservoir, it formed middle and high yield "sweet spot"; The relationship between fault activity and hydrocarbon accumulation was analyzed from the aspects of source rock and main accumulation period, and the accumulation model of "late adjustment controls enrichment, effective fracture controls production, quality reservoir controls effect" is established. Hexingchang-Gaomiao area was selected as the potential evaluation area.

10.6056/dkyqt202105002