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对南海北部珠江口盆地番禺低隆起—白云凹陷北坡地区的断层特征及封闭性主控因素作了初步归纳和总结,并对断层封闭性与油气成藏的关系进行了分析。研究区长期处于张应力场背景之中,反向正断层发育。这些断层都在晚期(10 Ma左右)形成,控制了该区圈闭的形成与分布,同时,也影响和控制了油气的运移、聚集及油气分布范围。断层封闭性影响因素较多,侧向封闭性主要影响因素为地层砂岩质量分数,其次是断距。纵向封闭性影响因素有断层性质、断层活动强度及构造应力场等。该区研究认为,所处地层砂岩质量分数小于30%,断层断距适宜(500 m以下且未断穿上部盖层),且走向上延伸较短的,具有较好的侧向封闭性。该区气藏在纵向上能够得以封闭的原因主要在于断层晚期形成,平面上呈雁行式排列组合,具有扭性特征,纵向封闭条件相对较好,且该区天然气属晚期充注,气藏受构造运动影响小,使得油气得以保存。同时,由于研究区的烃源供给非常充足,在局部地区,即使断层在纵向上泄露了油气,但只要天然气的充注速度大于散失速度,圈闭仍可使油气聚集成藏。封闭有利地区为研究区的南部及东部,其珠江组上段砂质质量分数小于30%,属古珠江三角洲前缘—浅海陆棚相的区域。
The characteristics of faults and their main controlling factors in the Panyu low uplift - the northern slope of Baiyun sag in the Pearl River Mouth Basin in the northern South China Sea are summarized and summarized. The relationship between fault sealing and hydrocarbon accumulation is also analyzed. The study area is in the background of tensile stress field for a long time, and the reverse normal fault develops. These faults are formed in the late period (about 10 Ma), which control the formation and distribution of traps in the area, and also influence and control the migration and accumulation of oil and gas and the distribution range of oil and gas. There are many influencing factors of fault sealing, and the main factors affecting the lateral sealing are the sandstone mass fraction, followed by the fault distance. Longitudinal closure of the influencing factors are fault nature, fault activity intensity and tectonic stress field. According to the study of the area, the mass fraction of sandstone in the formation is less than 30%, the fault fault is appropriate (less than 500 m without breaking through the upper cap layer), and has short lateral extension and better lateral sealing. The reason why the gas reservoirs in the area can be closed in the vertical direction is that the faults are formed in the late stage and are arranged in a geese array on the plane with torsional characteristics. The longitudinal sealing conditions are relatively good, and the natural gas in the area is of late filling. The impact of tectonic movement is small, so that oil and gas can be preserved. At the same time, due to the sufficient supply of hydrocarbon sources in the study area, even in some areas, oil and gas leaked in the longitudinal direction even if the fault was filled in the longitudinal direction. However, as long as the filling speed of natural gas is faster than the rate of loss, the trap can still accumulate hydrocarbons into reservoirs. The closed favorable areas are the southern and eastern parts of the study area. The sandy mass fraction of the upper part of the Pearl River Formation is less than 30%, belonging to the area of the paleo-Pearl River Delta front-shallow shelf.