西昌盆地奥陶系大箐组油气成藏地质条件评价  

Reservoir-forming conditions of Ordovician Daqing Formation, Xichang Basin

作　　者：吴长江[1] 陈双玲[1] 张禄权 谢忱 Wu Changjiang;Chen Shuangling;Zhang Luquan;Xie Chen(Key Sub Laboratory of Carbonate Gas Reservoir Formation Mechanism Key laboratory of Gas Reservoir Formationand production. CNPC)

机构地区：[1]中国石油天然气集团公司天然气成藏与开发重点实验室碳酸盐岩天然气成藏机理重点研究室

出　　处：《天然气勘探与开发》2019年第1期8-14,共7页Natural Gas Exploration and Development

摘　　要：西昌盆地奥陶系上统大箐组白云岩厚度大,分布面积广,多见溶蚀孔洞,周边野外露头可见沥青,井下取心多段见气泡冒出,表明其具有一定的勘探潜力。目前西昌盆地大箐组勘探程度低,油气地质条件尚不清楚,有待持续进行深入的研究工作。因此根据野外剖面、钻井取心与测井等资料,结合区域地质背景,在前人基础上进一步对西昌盆地大箐组油气地质条件开展系统研究。结果认为:①西昌盆地大箐组发育大套厚层滩相晶粒白云岩,溶蚀孔洞较为发育,为较好储集层;②上覆志留系下统龙马溪组灰黑色页岩厚度大,可为大箐组白云岩良好烃源与直接盖层;③大箐组白云岩野外与镜下均见沥青,表明大箐组具备油气成藏条件;④位于米市坳陷中部区域七里坝背斜带未见通天断裂,油气保存条件相对较好。结论认为:七里坝背斜带可作为该区大箐组下一步天然气勘探主攻方向。Upper Ordovician Daqing Formation,composed of thick dolomite,is widely distributed in Xichang Basin.Solution pores are common,bitumen may be directly seen in outcrop,and gas bubble also emerges from many intervals during downhole coring,all indicating a certain exploration potential.At present,however,this formation is less explored and its hydrocarbon geological conditions have been made unclear.So,these conditions were studied systematically based on some data on profile,drilling,coring,and logging,as well as previous research,combined with regional geological setting.Results show that,(1)in this basin,there is a large set of thick shoal-facies dolomite developed in Daqing Formation,in which solution pores are common,so it is better reservoirs;(2)it is overlain by grayish black,and thick shale of Lower Silurian Longmaxi Formation,which can serve as better source rock and direct caprock for Daqing dolomite reservoirs;(3)bitumen is discovered in outcrop or thin section,indicating that Daqing Formation is favorable for hydrocarbon accumulation;and(4)there are no fractures extending to the surface appeared in Qiliba anticline,central Mishi depression,revealing better preservation.In conclusion,Qiliba anticline can be taken as the main exploration direction of Daqing Formation in this area.

关 键 词：西昌盆地 奥陶系上统 大箐组 龙马溪组 白云岩 砂屑滩 储层特征 

分 类 号：P618.13[天文地球—矿床学]