火山地层界面的储层意义——以松辽盆地南部火石岭组为例

基于岩心、薄片、物性及核磁测井T₂谱等资料,从盆地火山地层界面分类及测井识别入手,开展火山地层界面与储层分布关系的研究,探讨了火山地层界面的控储机理。松南王府断陷火石岭组火山地层界面可划分为2级3类:喷发间断不整合界面构成一级界面,喷发整合和喷发不整合界面构成二级界面。火山地层界面与储层关系密切,距喷发间断不整合界面越近,储层物性越好,反之则越差,优质储层往往发育在喷发间断不整合界面之下30 m之内。在喷发整合、喷发不整合界面附近或该类界面集中发育带往往出现物性高值层段,形成相对较好的储集层段。火山地层界面类型及其分布控制储集空间的类型和组合关系,进而影响到储层的分布。火山地层界面所控制的储集层段在垂向上可划分为次生孔隙带、原生孔隙带和相对致密带3种,其中喷发间断不整合界面主要通过控制次生储集空间的发育而形成优质储层,喷发整合和喷发不整合界面主要表现为原生储集空间的集中发育而形成相对优质的储层。结合王府断陷勘探实例,认为火山地层界面附近发育的火山岩类组合,特别是喷发间断不整合界面处是需要重点关注的火山岩油气有利勘探领域。

Reservoir significance of volcanostratigraphic boundary: a case study of Huoshiling Formation,Southern Songliao Basin

Based on cores, thin sections, physical properties, T₂ spectrum in nuclear magnetic logging and other data, a research is carried out on the relationship between volcanostratigraphic boundary and reservoir distribution from the aspects of the types and logging identification of volcanostratigraphic boundary in the basin, so as to explore the reservoir control mechanism of volcanostratigraphic boundary. The volcanostratigraphic boundaries of Huoshiling Formation, Wangfu Depression, Southern Songliao Basin are divided into two grades and three types, i.e., the primary boundary consisting of eruptive interval unconformity boundary (EIUB), and the secondary boundary consisting of eruptive conformity boundary (ECB) and eruptive unconformity boundary (EUB). The volcanostratigraphic boundary has a close relationship with reservoirs. The closer to EIUB the reservoir is, the better the physical properties will be, or vice versa. High-quality reservoirs are often developed within 30 m beneath EIUB. Relatively better reservoirs are formed with high physical properties adjacent to ECB and EUB or in the concentrated development zones of such boundaries. The types and distribution of volcanostratigraphic boundary controls the types of reserving space and assemblage relationships, and further influences the reservoir distribution. The reservoir horizons under the control of volcanostratigraphic boundary are divided into three types vertically, i.e., secondary pore zone, primary pore zone and relative tight zone. The EIUB is able to control the development of secondary reserving space to form high-quality reservoirs; ECB and EUB are mainly presented as the concentrated development of primary reserving space to form relatively high-quality reservoirs. Based on the exploration cases in Wangfu Depression, it is suggested that volcanic rock assemblages developed adjacent to volcanostratigraphic boundary, especially at the EUIB, are favorable exploration areas of volcanic hydrocarbons to be focused on.