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陵水17-2大气田位于琼东南盆地陵水凹陷深水区。该凹陷是继承性深大凹陷,面积达5 000km2,新生界最大厚度达13km。凹陷内发育始新统、下渐新统崖城组、上渐新统陵水组3套烃源岩,其中崖城组是主力烃源岩,包括煤系和海相泥岩。陵水凹陷是高温凹陷,崖城组烃源岩底部温度可达250℃以上,烃源岩镜煤反射率可达2%~5%。开放和封闭体系的高温生烃模拟实验显示,该套烃源岩生气下限Ro值可达4.38%以上,约为4.4%,因此崖城组主体处在生气窗内,资源量近万亿立方米,是富生烃凹陷。莺歌海组—黄流组是陵水凹陷首选勘探目的层,储层主要发育于中央峡谷水道内。该峡谷长约425km、宽度3~25 km、深度270~700 m,平行于陆坡近东西走向。峡谷水道内共充填了5期次级水道,发育轴部砂、侧向加积砂、天然堤和侵蚀残余砂4类储集体,物性极好,并形成岩性或构造-岩性圈闭。陵水凹陷北部边缘和南部边缘发育两个串珠状分布的底辟带,类型为泥-流体底辟,南部底辟带沟通了深层崖城组烃源岩与浅层峡谷水道砂岩,崖城组生成的天然气垂向运移至水道砂体,再在水道储层内发生侧向运移,呈T型运移模型,在圈闭内形成天然气田。
Lingshui 17-2 gas field is located in the deep water area of the Lingshui sag in the Qiongdongnan Basin. The depression is a deep inherited depression, an area of 5000km2, the maximum thickness of the Cenozoic up to 13km. Within the depression, there are three sets of source rocks of the Eocene, the Lower Oligocene Yacheng Formation and the Upper Miocene Lingshui Formation. The Yacheng Formation is the main source rock, including coal measures and marine mudstones. The Lingshui sag is a high-temperature depression. The temperature of the bottom of source rocks in the Yacheng Formation can reach above 250 ℃ and the reflectivity of the source rock can reach 2% -5%. The open-system and closed-system high-temperature hydrocarbon generation simulation experiments show that the lower limit of the gas generation rate of this set of source rocks is above 4.38%, which is about 4.4%. Therefore, the main body of the Yacheng Formation is in the window of vitality and has nearly 1 trillion cubic meters of resources , Is rich in hydrocarbon sags. Yinggehai Formation - Huangliu Formation is the preferred exploration target reservoir in Lingshui Depression. The reservoirs mainly develop in the central canyon waterway. The gorge is about 425km long, 3-25 km wide and 270-700 m deep, parallel to the nearly east-west direction of the slope. There are 5 sub-channels filled in the canyon waterway. Developed four types of reservoirs, such as shaft sand, lateral accretion sand, natural embankments and erosion residual sand, with excellent physical properties and lithologic or tectonic-lithological traps. There are two types of diapir belts distributed in the northern margin and the southern margin of the Lingshui sag, of the type mud-fluid diapirs. The southern diapir belt communicated with the deep Yacheng Formation source rock and shallow canyon channel sandstone and Yacheng Formation The generated natural gas migrates vertically to the channel sand body and then moves sideways in the channel reservoir, showing a T-type migration model, forming a natural gas field within the trap.