梨树断陷双龙地区火山发育特征及油气成藏规律

松辽盆地梨树断陷双龙地区白垩系火石岭组发育中心式和裂隙式两种喷发型火山,其在发育规模、油气成藏等方面存在不同。中心式喷发型火山活动剧烈,持续时间长,火山岩分布面积广,厚度大,岩性从基性火山岩逐渐向中性火山岩转变;裂隙式喷发型火山活动弱,持续时间短,火山岩分布面积小,厚度薄,岩性主要为中性火山岩。中心式喷发型火山与湖盆水体相邻,形成火山-湖泊沉积环境,火山岩、砂砾岩、深湖-半深湖泥岩交替沉积,使得中心式喷发型火山发育区的火石岭组具有良好的生、储、盖条件,并形成自生自储型生储盖组合方式;裂隙式喷发型火山远离湖盆水体,火山岩的分布与深湖相泥岩没有直接接触,加之储层物性差,因此裂隙式喷发型火山发育区的火石岭组油气成藏条件差。通过对研究区钻井、试油、地震等资料的综合分析认为,研究区西部中心式喷发型火山发育区是火石岭组有利的勘探区域,其烃源岩为深湖-半深湖泥岩,储集体包括火山碎屑岩、砂砾岩和火山岩,储集空间主要为裂缝和孔隙。

Volcanic characteristics and rule of hydrocarbon accumulation of Shuanglong area in Lishu faulted depression

Cretaceous Huoshiling Formation of the Shuanglong area in Lishu faulted depression of Songliao Basin developed two types of eruptive volcanos，including the central vent eruption and fissure eruption． They dif- fer in terms of the development scale and hydrocarbon accumulation． The central vent eruption has the characteris- tics of violent activity，long duration，extensive distribution scale of volcanic rocks，large thickness and the lithol- ogy progressively shift from the mafic to the neutral． The fissure eruption has the characteristics of weak activity， short duration，less distribution scale of volcanic rocks，thin thickness and the lithology is mainly neutral． The central vent eruption volcano is adjacent to lake basin，forming the environment of volcanic- lacustrine deposit． With the alternate deposition of volcanic rocks，conglomerate and deep and semi- deep lake mudstone，the Hu- oshiling Formation of central vent eruption area has good association pattern of source rocks，reservoirs and caps rock，and forms self- generation and self- bearing combination of source- reservoir- cap． The fissure eruption volcano is far away from the lake basin and the distribution of volcanic rocks has no directly contact with the deep lacustrine facies mudstone，coupled with poor reservoir properties，the Huoshiling Formation of the fissure eruption volcano area has poor conditions of hydrocarbon accumulation． According to the comprehensive analysis of the data of drill- ing，oil testing and earthquake，it could be considered that the central vent eruption volcano in the western studied area is the favorable exploration area of Huoshiling Formation，in which the source rocks are deep and semi- deep lake mudstones，reservoir including pyroclastic rock，conglomerate and volcanic rocks，the reservoir space are mainly fracture and pore．