春光探区石炭系火山岩有效储层展布特征

Distribution characteristics of effective reservoirs of Carboniferous volcanic rocks in Chunguang exploration area

石炭系是春光探区的增储潜力层系,火山岩有效储层展布特征不清是制约石炭系油气勘探的关键因素。利用岩心薄片、物性分析、测井响应等资料,对石炭系火山岩储层进行了识别,通过开展有效性评价,明确了孔隙型、裂缝-孔隙型和裂缝型三种储集空间类型,储层的形成和分布与火山机构、风化壳、断裂密切相关。其中,孔隙型储层分布相对局限,在火山机构附近的近火山口亚相和溢流相形成物性相对较好的储层;裂缝-孔隙型储层分布范围广,在风化壳区受风化淋滤作用,形成裂缝和溶蚀孔隙发育的储层;裂缝型储层分布在石炭系“内幕”的断层附近,多呈“蜂窝状”分布。结合岩性、电性建立有效储层测井响应特征,针对性地开展有效储层识别,在明确储集空间基础上,将有效储层分为三类:Ⅰ类储层条件有利,但分布局限;Ⅱ类储层条件较有利,分布较广;Ⅲ类储层物性条件较差。其中,Ⅰ类、Ⅱ类储层发育区是下一步石炭系的增储潜力区。

Carboniferous reservoirs have a good exploration potential in Chunguang area,while the unclear distribution characteristics of effective volcanic reservoirs restrict the oil and gas exploration.Carboniferous volcanic reservoirs are identified by using the data of core thin section,physical property analysis and logging response.Through effective evaluation,three reservoir space types are defined,namely porous type,fracturedporous type and fractured type.The reservoir formation and distribution are closely related to volcanic mechanism,weathered crust and faults.Among them,the distribution of porous reservoirs is relatively limited,and reservoirs with good physical properties are formed near Crater sub-facies and overflow facies around the volcanic edifice.Fractured-porous reservoirs are widely distributed.In the weathering crust area,the reservoir with developed fractures and dissolution pores is formed by weathering leaching.Fractured reservoirs are distributed near the"inside"faults of Carboniferous system,mostly in"honeycomb"distribution.Combined with the logging response characteristics of effective reservoir established by lithology and electricity,effective reservoir identification is carried out.Based on clarified reservoir space,the effective reservoirs are divided into three categories.Class Ⅰ has favorable conditions but limited distribution,class Ⅱ has favorable conditions and wide distribution,while class Ⅲ reservoir has poor physical property conditions.In general,the reservoirs of class Ⅰ and class Ⅱ are potential areas of Carboniferous system in the next step.