柴达木盆地西部干柴沟区块下干柴沟组上段页岩油储层特征及勘探潜力  

Characteristics and exploration potential of shale oil reservoir in the Upper Member of the Xiaganchaigou Formation in the Ganchaigou area,western Qaidam Basin

作　　者：黄建红[1,2] 蒋威 谭先锋 吴松涛 蔡鑫勇 伍坤宇 张庆辉[1,2] HUANG Jianhong;JIANG Wei;TAN Xianfeng;WU Songtao;CAI Xinyong;WU Kunyu;ZHANG Qinghui(Research Institute of Exploration and Development,Qinghai Oilfield Company,PetroChina,Dunhuang Gansu 736202,China;Plateau Saline Lacustrine Basin Oil-Gas Geology Key Laboratory of Qinghai Province,PetroChina,Dunhuang Gansu 736202,China;Chongqing Key Laboratory of Complex Oil and Gas Exploration and Development,Chongqing 401331,China)

机构地区：[1]中国石油青海油田公司勘探开发研究院,甘肃敦煌736202 [2]中国石油青海省高原咸化湖盆油气地质重点实验室,甘肃敦煌736202 [3]复杂油气田勘探开发重庆市重点实验室,重庆401331

出　　处：《地质科技通报》2024年第4期141-153,共13页Bulletin of Geological Science and Technology

基　　金：国家自然科学基金青年科学基金项目(42102133);重庆市杰出青年科学基金项目(CSTB2022NSCQ-JQX0031);重庆市教委科技重大项目(KJZD-M202101502);中国石油天然气集团公司重大科技项目(2023ZZ15;2021DJ1808)。

摘　　要：柴达木盆地西部干柴沟区块C902井在古近系下干柴沟组上段Ⅳ~Ⅵ油层组获得高产油气流,实现了柴达木盆地古近系页岩油的重大勘探突破。然而,古近系页岩油的评价标准和资源潜力不清等问题制约了干柴沟区块高效开发。基于C902井及其他探井的勘探成果,利用岩性、物性、孔隙结构、生烃潜力等资料,综合评价了干柴沟区块古近系下干柴沟组上段Ⅳ~Ⅵ油层组页岩油的勘探潜力。结果表明,该套页岩层系混积特征明显,岩相类型包括纹层状和层状灰云岩、纹层状和层状云灰岩、纹层状黏土质页岩和层状泥岩,具有较高脆性指数,可压性强;晶间孔和纹层缝是重要的储集空间,占比达85%,属于低孔-特低渗储层;w(TOC)均值高于0.9%,氯仿沥青“A”和S_(1)+S_(2)共同指示生烃潜力大,且有机质类型以Ⅰ~Ⅱ_(1)型为主。因此,下干柴沟组上段Ⅳ~Ⅵ油层组具有烃源岩品质好、源储一体、可压性强、发育广泛等特征,生储盖组合在空间上广泛发育且密封性好,有利于压裂改造后提高油气采收率,对干柴沟区块页岩油的高效开发具有重要理论指导意义。[Objective]Well C902,located in the Ganchaigou area of the western Qaidam Basin,achieved a breakthrough in shale oil exploration as indicated by the high-production oil flow in theⅣ-Ⅵlayers of the Upper Member of the Palaeogene Xiaganchaigou Formation.However,ambiguities in evaluation criteria and resource potential limit the efficiency of shale oil development in the Upper Member of the Xiaganchaigou Formation in the Ganchaigou area.[Methods]Thus,the exploration potential of shale oil in theⅣ-Ⅵlayers of the Upper Member of the Xiaganchaigou Formation in the Ganchaigou area was comprehensively evaluated by comparing the lithology,physical properties,pore structure,and organic geochemistry between Well C902 and other wells.[Results]The complicated lithofacies of laminar/lamellar dolostone,laminar/lamellar limestone,laminar clay shale,and lamellar mudstone suggest the mixed carbonate and siliciclastic deposition of theⅣ-Ⅵlayers.The high brittleness index implies the good fracability of theⅣ-Ⅵlayers.The intergranular pores and laminar fractures,with a total proportion of 85%in the pore system,were dominant in theⅣ-Ⅵlayers that can be roughly classified as low-porosity and ultralow-permeability reservoirs.The organic matter,dominated by typeⅠ-Ⅱ_(1),shows an average TOC content of more than 0.9%in theⅣ-Ⅵ layers.Both chloroform asphalt"A"and S_(1)+S_(2)indicate a high hydrocarbon generation capacity.[Conclusion]Summarily,the widely deposited theⅣ-Ⅵlayers of the Upper Member of the Xiaganchaigou Formation have the characteristic of source-reservoir integration and show not only good quality of source rock but also strong fracability of the shale oil reservoir.The excellent source-reservoir-caprock assemblage is also widely developed,which ensures good sealing ability and favors improving oil and gas recovery after fracturing.This study can theoretically improve the development efficiency of shale oil in the Ganchaigou area.

关 键 词：页岩油储层 下干柴沟组上段 古近系 资源潜力 干柴沟区块 柴达木盆地 

分 类 号：P618.13[天文地球—矿床学]