Structural Characterization Of Braided River Reservoir In The Lower Stratum Of The Minghuazhen Formation In Penglai 19-9 Oilfield

The Penglai 19-9 oilfield is located in the northeast of the Bonan Low Uplift Belt in the Bohai Bay Basin.The study target section of this oilfield belongs to braided river sediments.Due to the high frequency of braided river channels and the complex fault system,it is difficult to predict the shape and distribution of reservoir sand bodies.The understanding of reservoir distribution between wells has affected the well locations in the oilfield.Optimize deployment and formulation of later oilfield development plans.In this paper,braided river reservoirs in the lower section of Minghuazhen Formation of Penglai 19-9 Oilfield are taken as research objects,guided by sequence stratigraphy theory,and combined with methods of well-seismic and hierarchical control,the high precision of the target zone in the study area is established Temporal stratigraphic framework;The comprehensive use of coring data,logging data,three-dimensional seismic data,etc.,determines the types of reservoir sedimentary microfacies and their basic characteristics;finally,the high-precision isochronous stratigraphic framework is used as the framework to establish the Braided river reservoir structure division scheme,summarizes various types of reservoir structure,and uses seismic attribute slicing method under well control constraints to predict the profile and plane distribution of the reservoir structure,deepening the braided river reservoir in the work area Geological understanding.The study shows that the target sections of the lower section of the Minghuazhen Formation in the Penglai 19-9 oilfield can be divided into 2 long-term cycles,5 mediumterm cycles,and 12 short-term cycles;the main oil-bearing intervals are braided river sediments,and the main types of reservoir genesis There are two types of microfacies,including Xintan and braided channels.Based on the hierarchical nature of braided river reservoir sand bodies,a five-level,four-level,and three-level reservoir structural unit division scheme was established.The fifth-level configuration unit is a braided riverbed filling and sedimentation,which is a composite sand body of core beach and braided river channel.The fourth-level configuration unit is a single-genetic type reservoir sand body,including a single core beach and a single braided river channel.Sand bodies,the tertiary configuration is a single genesis sand body including the heart beach and the accretion body inside the braided channel.The braided riverbed filling of the fifth-level reservoir structural unit in the study area extends near the east-south direction.A braided riverbed develops a four-stage reservoir configuration unit core beach and braided water channels.A single core beach long is about 800m?1500m,the width of 500 m ? 1000 m,and the thickness is about 20m?25m.The plane is nearly rhombic,and the top of the profile is flat.It is convex and has good storage properties.Braided watercourses are developed between heart beaches,with a width of 20m?60m and the thickness is about 3m?5m.The width and thickness are smaller than the heart beach.A three-level reservoir structural unit proliferative body is developed inside the heart beach,with a thickness of3m?4m and poor connectivity.It exists as an interlayer in the heart beach.The analysis of the formation grid and reservoir configuration in the study area revealed the crosssection and vertical structural styles of the reservoir sand bodies,predicted the distribution of the reservoir sand bodies between wells,and planned for the later well deployment and oilfield development the optimization provided favorable geological basis.