塔河油田下奥陶统碳酸盐岩缝洞型储层结构特征及成因模式

发布时间：2018-09-07 08:55

【摘要】：塔河油田下奥陶统碳酸盐岩缝洞型储层经历了多期构造运动和漫长成岩作用改造,缝洞的类型、充填程度、组合关系及分布规律极其复杂。开展储层结构特征、主控因素及演化过程研究,对塔河油田下奥陶统碳酸盐岩储层油气勘探部署和提高采收率具有重要的指导意义。论文以碳酸盐岩沉积岩石学、碳酸盐岩储层地质学、岩溶地质学等多学科理论为指导,综合运用野外露头观察、岩心观察、地震反演、测井解释、铸体薄片观察、流体包裹体测温、同位素及微量元素测试等技术方法,对塔河油田六、七区下奥陶统碳酸盐岩缝洞型储层储集空间特征及分布规律、储层结构及主控因素开展了系统研究,主要取得了以下成果认识。塔河油田下奥陶统碳酸盐岩储层储集空间主要为大-中型溶洞,其次是小型溶蚀孔洞。依据溶洞的洞高、发育位置、组合关系及成因,将溶洞分为厅堂洞、落水洞、干流洞、支流洞、驻水洞、断面渗流井及末梢洞等缝洞结构。90%左右的溶洞被半充填和完全充填,溶洞充填物中沉积充填物约占88%,沉积充填物的成岩作用较弱,有利于碳酸盐岩储层储集空间的保存。塔河油田下奥陶统碳酸盐岩储层纵向上分为三个岩溶带,从浅到深依次为表层岩溶带、渗流岩溶带、径流岩溶带。表层岩溶带缝洞最为发育,在地表河发育区形成干流洞、支流洞及末梢洞,在坡折带或断崖等低部位容易形成落水洞,沿地表河方向缝洞连通性好,储层物性较好;渗流岩溶带主要发育由于流体垂向渗流作用形成的驻水洞,洞高较大,但横向延伸很小,在断裂附近容易形成断面渗流井;径流岩溶带主要顺层发育地下暗河,形成厅堂洞、干流洞、支流洞及末梢洞等规模不同的缝洞结构,缝洞沿同期地下暗河连通性较好。塔河油田下奥陶统碳酸盐岩储层形成、分布主要受主断裂作用、不整合风化剥蚀作用、成岩作用、潜水面、古地貌及岩性等因素综合控制。主断裂作用控制了表层岩溶带地表河和径流岩溶带地下暗河的发育位置,形成了“逢断必沟,逢沟必溶”的岩溶格局;海西早期的构造抬升,致使表层岩溶带储层暴露地表,遭受风化剥蚀,在不整合附近形成大量、规模较大的溶洞,但这类溶洞往往比较容易被砂泥沉积物充填;古潜水面的波动变化控制了径流岩溶带溶洞的纵向发育位置,同期地下暗河形成“层状”分布的溶洞,多期地下暗河形成了多层溶洞或溶洞的多旋回充填特征;碳酸盐岩储层发生溶解、溶蚀作用形成溶蚀孔、洞和裂隙,是碳酸盐岩储层形成的根本;渗流岩溶带和径流岩溶带溶洞沉积充填物,在洞壁刚性格架的支撑作用下,处于弱压实状态,保存了大量原生孔隙,形成已充填溶洞中油气的储集空间。塔河油田下奥陶统碳酸盐岩储层经历了复杂的演化过程。加里东运动晚期的构造挠曲,形成的少量逆断层,对储层岩溶作用的发生、岩溶缝洞的形成具有重要先导作用;海西运动早期,构造强烈挤压,储层暴露地表,断裂作用加剧,大部分主断裂沿着早期断裂发育,在断裂作用和不整合风化剥蚀的共同作用下,缝洞型储层大规模形成,在表层岩溶带形成落水洞、干流洞、支流洞及末梢洞;在渗流岩溶带形成驻水洞和断面渗流井;在径流岩溶带发育地下河,形成厅堂洞、干流洞、支流洞及末梢洞;该阶段缝洞充填物以砂泥沉积充填为主,其次是垮塌角砾充填。海西运动晚期大断裂持续活动,岩溶流体和深部热液沿大断裂下渗、上涌,溶洞发生化学沉淀充填和胶结作用。印支运动期及之后,储层进入埋藏成岩期,进一步发生溶蚀、胶结、交代及重结晶等作用,溶洞中的沉积充填物压实作用弱,溶蚀作用较弱,胶结作用强烈,保存了较好的储集物性。
[Abstract]:Lower Ordovician carbonate fractured-vuggy reservoirs in Tahe oilfield have undergone multi-stage tectonic movement and long-term diagenesis. The types of fractures and vugs, filling degree, assemblage relationship and distribution law are extremely complex. Reservoir structure characteristics, main controlling factors and evolution process are studied. Oil and gas exploration and deployment of Lower Ordovician carbonate reservoirs in Tahe oilfield are carried out. Guided by carbonate sedimentary petrology, carbonate reservoir geology, karst geology and other multidisciplinary theories, this paper comprehensively uses outcrop observation, core observation, seismic inversion, log interpretation, casting thin section observation, fluid inclusion temperature measurement, isotope and trace element measurement, etc. The reservoir space characteristics, distribution regularity, reservoir structure and main controlling factors of Lower Ordovician carbonate fractured-cavern reservoirs in 6 and 7 districts of Tahe oilfield are systematically studied. The main achievements are as follows. The reservoir space of Lower Ordovician carbonate reservoirs in Tahe oilfield is mainly large-medium caverns, followed by small-sized caverns. According to the height, location, Association and genesis of karst caves, the karst caves are divided into hall caves, falling caves, main flow caves, tributary caves, standing caves, cross-section seepage wells and terminal caves. About 90% of the caves are semi-filled and fully filled. About 88% of the caves are filled with sedimentary fillings. The diagenesis of sedimentary fillings is weak. Lower Ordovician carbonate reservoirs in Tahe oilfield are divided into three vertical karst zones, which are surface karst zones, seepage karst zones and runoff karst zones in turn from shallow to deep. Surface karst zones have the most developed fractures and caves, forming main flow caves, tributary caves and terminal caves in surface river developed areas, and slope break zones or faults. The karst zone of seepage flow mainly develops the standing water cave formed by the vertical seepage of fluid, the cave is high, but the lateral extension is very small, so it is easy to form the cross-section seepage well near the fault; the underground river is mainly developed along the runoff karst zone and formed. Fracture and cave structures of different sizes, such as hall cave, main stream cave, tributary cave and terminal cave, have good connectivity along the same period of underground rivers. The formation and distribution of Lower Ordovician carbonate reservoirs in Tahe oilfield are mainly controlled by main faults, unconformity weathering and erosion, diagenesis, phreatic surface, palaeogeomorphology and lithology. By controlling the development position of surface and underground rivers in surface karst zone and runoff karst zone, the karst pattern of "every fault must be gouge, every gouge must be karst" was formed; the early structural uplift in Hercynian resulted in the surface karst zone reservoirs exposed to the surface, eroded by weathering, and a large number of large-scale karst caves were formed near the unconformity. It is easy to be filled by sand and mud sediments; the fluctuation of paleo-phreatic water surface controls the vertical development of karst caves in runoff karst zone; the "stratified" karst caves are formed in underground rivers at the same time; the multi-layer karst caves or caves are formed in multi-stage underground rivers; the carbonate reservoirs are dissolved and the karst caves are formed by dissolution. Caves and fissures are the basis of the formation of carbonate reservoirs; cavern sedimentary fillings in seepage karst zone and runoff karst zone are in a weak compaction state under the support of the rigid framework of cavern wall, conserving a large number of primary pores and forming the reservoir space of oil and gas in the filled caverns. The tectonic deflection in the late Caledonian movement resulted in a small number of reverse faults, which played an important leading role in the formation of karst fractures and caves in the reservoir. In the early Hercynian movement, the structure was strongly compressed, the reservoir was exposed to the surface, and the faulting was intensified. Most of the main faults developed along the early faults, and the faulting and irregularity occurred. Under the combined action of weathering and denudation, fractured-cave reservoirs are formed on a large scale, forming water-fall caves, main flow caves, tributary caves and terminal caves in the surface karst zone, standing water caves and cross-section seepage wells in the seepage karst zone, underground rivers are developed in the runoff karst zone, forming hall caves, main flow caves, tributary caves and terminal caves, and the filling materials of fractured-caves are sand and mud. In the late Hercynian movement, the karst fluid and deep hydrothermal fluid infiltrated and upwelled along the fault, and the cave was filled with chemical precipitation and cementation. The sedimentary fillings in the cave have weak compaction, weak dissolution and strong cementation, thus preserving good reservoir properties.
【学位授予单位】：中国石油大学(华东)
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P618.13

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