冀中拗陷新生代火成岩分布及含气特征

DISTRIBUTION AND GAS-BEARING CHARACTERISTICS OF THE CENOZOIC IGNEOUS ROCKS IN THE JIZHONG DEPRESSION

刘前志

Liu Qianzhi

中国石油天然气总公司物探局 河北涿州 072751

Geophysic Bureau of CNPC, Zhuozhou, Hebei

新生代火成岩分布于下第三系地层中,为基性的喷发岩或侵入岩,由南向北,时代变新,厚度及分布范围增大。北部的廊固凹陷规模最大,分布面积近千平方公里,厚度超过500m,以辉绿岩为主。由于岩浆的侵入和喷发的热力作用,提高了生油门限深度,有形成大量油气的条件。与火成岩有关的有四种储集层:玄武岩、辉绿岩、凝灰岩和斑点板岩,均以次生溶蚀孔隙和裂缝为主。其中以斑点板岩储集性能最好。可形成上倾尖灭、透镜体和构造-岩性三种圈闭。已发现的油气藏以构造-岩性为主。

In the Jizhong Depression, the Cenozoic igneous rocks, distributing within the Eogene strata, trend to be younger in age but increase in thickness, and in area from the south toward the north. The maximum distributing area occurs in the Langgu Depression, approximate to 1000km2, with a thickness exceeding 500m, dominated by diabases. The thermal alteration of the intrusions and erup tions improves the conditions of oil/gas generation, and provides favourable conditions for large amount of oil and gas accumulations. The reservoirs relating to igneous rocks consist of basalts, diabases, tuffs and spotted slates, mainly characteristic of secondary dissoluted pores and fissures, among which the spotted slates is the best one in property. As a result, three types of traps would be developed, i. e. updipping thin-out, lenticle and structure-lithology traps. The oil/gas pools discovered up to date are principally of structural lithological traps.

https://doi.org/10.11781/sysydz199202188