松辽盆地南部长岭断陷火山岩岩性岩相特征及其对储层的控制作用

Lithologic and Lithofacies Characteristics of Volcanic Rock and Their Controlling Effects on Reservoirs of Changling Fault Depression in the South of Songliao Basin

长岭断陷是松辽盆地南部最大的断陷,其深层勘探程度低、油气资源丰富、火山岩分布面积大,是很好的油气储集空间。为了明确长岭断陷层火山岩的分布规律以预测有利的储层,本文通过对火山岩的岩心观察、薄片鉴定、测井资料、二维、三维地震资料的综合分析,提出长岭断陷层火山岩主要发育于火石岭组和营城组,以火山熔岩和火山碎屑岩为主;发育出爆发相、溢流相、火山通道相、侵出相和火山沉积相5种火山岩岩相及11种亚相,其中以爆发相和溢流相为主;长岭断陷深层火山岩主要沿深大断裂呈带状分布,裂隙式和中心式喷发兼有,在垂向上表现为多期次喷发序列的叠置;营城组发育三个火山喷发旋回。统计显示溢流相上部和下部亚相的流纹岩和爆发相热碎屑流亚相的凝灰岩的气孔、溶孔和裂缝发育,储集物性最好。

The Changling fault depression is the largest fault depression in the south of Songliao Basin. The deep formation in the depression with a low exploration degree contains abundant hydrocarbon resources, where volcanic rocks are distributed extensively, as a good reservoir of oil and gasses. According to core observation, thin section identification and integration of well log and 2D/3D seismic data, the Yingcheng formation and Huoshiling formation are rich in volcanic rocks, mainly consisting of lava and pyroclastic rocks. 5 types of volcanic lithofacies and 11 types of volcanic subfacies such as explosive facies, overflow facies, volcanic conduit facies, extrusive facies and eruptive-sedimentary facies can be identified, which are mainly overflow facies and explosive facies. The volcanic rocks in the depression are distributed along big deep faults and superimposed by many times of volcanic eruption in the vertical direction in models of eruption of both central type and fissure type. And three volcanic eruption cycles can be identified in the Yingcheng formation. Statistics show that the rhyolite in the lower part and the upper part subfacies of overflow as well as the tuff in pyroclastic flow subfacies of explosive have many gas pores, solution pores and fractures, which may serve as a good reservoir.