大型火山岩气田成藏控制因素研究——以松辽盆地庆深气田为例

Main factors controlling hydrocarbon accumulation in large volcanic gas fields:A case study of the Qingshen gas field in the Songliao basin

松辽盆地大型火山岩气藏的发现,揭开了我国火山岩油气藏全面勘探的序幕。本文以油气钻探实践结果为基础,应用地质、地球物理和地球化学相结合的分析方法,探讨了松辽盆地大型火山岩气藏的成藏控制因素。结果表明,气源岩发育区控制气藏的宏观分布范围,气藏与源岩区的横向距离一般小于8km,源岩与火山岩厚度比大于2的区域对成藏尤为有利;大断裂控制火山岩体呈条带状或串珠状展布,延断裂带火山岩厚度大,最大厚度超过1600m;火山岩相和火山旋回控制储层发育状况,火山口或近火山口叠合相储层发育,储层厚度一般100～200m,有利储层常发育于火山旋回的顶部;火山机构中心部位具有局部构造高、储层物形较好、断裂发育等特点,在气源条件优越时,是短距离垂向运移成藏的最有利地区。

The discovery of large volcanic rock gas fields in the Songliao basin has opened the complete exploration of volcanic gas pools in China.Based on practical results of the drilling exploration,the paper discusses the main factors controlling hydrocarbon accumulatidn in large volcanic gas fields in the northern Songliao basin by combination of geological,geophysical and geochemical evidence.The results show that the area of gas source rock controlling the macroscopic distribution boundary of gas pools,the horizontal distance between gas pool and gas source rock is generally less than 8km and,the area with ratio of gas source rock to volcanic rock thickness less than 2 is profitable for hydrocarbon accumulation.Large fault control the eruptive body distribution like banding or beadsshaped and volcanic rock is thicker along fault zone with a maximum thickness more than 1600m.Volcanic facies and volcanic cycle control the reservoir develop,reservoir development in crater or near crater overlap phase,the thickness of reservoir generally 100- 200m.Profitable reservoir constantly develops in the top of volcanic cycle.The center of volcanic apparatus present high local structure,good reservoir physical property,faulting development,when gas source is advantageous,it is a favorable area for hydrocarbon accumulation of short distance vertical migration.