【作者】 王伟；

【导师】 王冠民；

【作者基本信息】 中国石油大学(华东) ， 地质学， 2021， 硕士

【摘要】 本文以渤海湾盆地渤中凹陷石臼坨凸起南部、沙垒田凸起东南部和渤中19-6构造古近系砂体为研究对象,运用岩心观察、岩石薄片鉴定、扫描电镜分析、X射线衍射相分析、阴极发光、碳氧稳定同位素测试、流体包裹体分析、测井曲线分析、埋藏史恢复、热演化史分析等技术方法,在“客观现象—实验技术—表征现象—研究本质—总结规律—指导未知”的研究思路指导下,分析研究区古近系沉积特征、成岩演化特征,寻找时空上的相同点,分析差异性,最终建立研究区优质储层发育模式。研究表明:沉积环境控制了研究区古近系岩石组分和结构。研究区沙一段和沙二段、东三段沉积期,在近源陡坡带以扇三角洲相为主,储层岩性以砾质砂岩、粗砂岩和中砂岩为主;在远源的凹陷内发育重力流沉积,储层岩性以细砂岩和粉砂岩为主,缓坡带发育辫状河三角洲沉积。东二上亚段和东一段全区发育辫状河三角洲沉积,岩石组构同样受控于沉积相带。沉积相带差异是成岩作用差异的基础。在近源陡坡带,扇三角洲扇根水道微相发育多级颗粒支撑砾岩相、砂质支撑砾岩相、颗粒支撑细砾岩相、砾质砂岩相,虽然分选较差,但岩石快速埋深,碎屑颗粒多发育裂缝,流体溶蚀后仍能发育为优质储层。对于扇中水道、河口沙坝分选较好的粗砂岩相、中砂岩相,分选好,次生孔隙发育,是优质储层发育带。古近系储层中酸性流体环境持续时间长,超压促进了酸性流体向邻近碎屑岩储层运移,对储层贡献表现在:一是产生了大量次生溶蚀孔隙,为晚期烃类充注提供了赋存空间;二是伴随地层埋深不断加大,碎屑颗粒产生大量粒内裂缝,沿裂缝发育大量溶蚀孔隙,减缓了压实作用对储层物性的破坏作用;三是抑制了晚期碳酸盐胶结物胶结。优势岩石结构是浅层发育优质储层的前提,裂缝和优势岩石结构是深层储层发育的基础,溶解作用是古近系有利发育储层的关键。对于东营组一段和东二上亚段碎屑岩储层,分选好的砂岩原始孔隙度高,有利于流体溶蚀碎屑产生次生孔隙;埋藏较深的东三段、沙河街组、孔店组碎屑岩,原生孔隙少,裂缝为流体提供通道,有机酸溶解作用产生大量次生孔隙;局部地区长期处于浅埋藏成岩环境,大气淡水对储层的改造相当强烈。更多还原

【Abstract】 In this paper,the Paleogene sand bodies of southern Shijiutuo uplift,southeastern Shaleitian uplift and Bozhong 19-6 structure in Bozhong sag of Bohai Bay Basin were taken as the research objects.Core observation,rock thin section identification,scanning electron microscopy analysis,X-ray diffraction phase analysis,cathodoluminescence,carbon and oxygen stable isotope test,fluid inclusion analysis,logging curve analysis,burial history recovery,thermal evolution history analysis and other technical methods were used.Under the guidance of the research idea of’objective phenomenon-experimental technology-representation phenomenon-research essence-summary law-guide unknown’,the similarities and differences of sedimentary characteristics and diagenetic evolution characteristics in time domain and space domain of the study area were analyzed.Finally,the development model of high quality reservoirs in the study area was established.The result shows that:（1）Difference of sedimentary environment was the basis of difference of rock composition and rock structure.In the sedimentary period of E₂s₁,E₂s₂ and E₃d₃ in the study area,fan delta facies was the main facies in the near-source steep slope zone,and the reservoir lithology was mainly gravel sandstone,coarse sandstone and medium sandstone.Gravity flow deposits developed in depressions far from provenance and the reservoir lithology was mainly fine sandstone and siltstone.Braided river delta facies were developed in the gentle slope belt.During the sedimentary periods of E₃d₂^u and E₃d₁,braided river delta facies developed in the study area.The rock composition and rock structure was also controlled by the sedimentary facies.（2）The difference of sedimentary facies was the basis of the difference of diagenesis.In the near source steep slope zone,the distributary channel of root fan of fan delta microfacies developed multistage granular support conglomerate facies,sandy support conglomerate facies,granular support fine conglomerate facies and conglomerate sandstone facies.Although the sorting was poor,the burial rate was high during diagenesis,the fracture were well developed in detrital grains,and the high quality reservoir could be developed after acidic fluid flowed along fractures and dissolved clastic particles.For the distributary channel and mouth bar in the middle fan of the fan delta,the well sorted coarse sandstone and medium sandstone developed secondary pores,which were high quality reservoir development zones.（3）Long duration of acidic fluid environment during diagenetic evolution of Paleogene reservoir,Overpressure promoted migration of acidic fluid from source rock series to adjacent clastic reservoir.The contribution of acid fluid to reservoir was as follows:a large number of secondary dissolution pores were produced,which provided occurrence space for late hydrocarbon filling.With the increasing burial depth of strata,a large number of intragranular fractures were generated in clastic particles,and many secondary dissolution pores were developed along the fractures,which slowed down the damage of compaction on reservoir porosity.Acidic fluid inhibited late carbonate cement cementation.（4）The dominant rock structure was the prerequisite for the development of high quality reservoir in shallow strata.Fractures and dominant rock structure were the basis for the development of deep reservoirs.Dissolution was the key to the development of reservoirs in Paleogene.For the clastic reservoirs of E₃d₁ and E₃d₂^u,the well sorted sandstone had high original porosity,It was favorable for acidic fluid to dissolve clastic particles and form secondary pores.The clastic rocks of E₃d₃,E₂s and E₂k buried deeply had few primary pores.The fractures provided channels for fluids,and organic acid dissolution generated a large number of secondary pores.Some areas had long been in shallow burial diagenetic environment,and the transformation of reservoirs by meteoric freshwater was quite strong.更多还原