Establishment And Evaluation Of Reservoir Geological Model In Exploration Stage

Three-dimensional reservoir geological modeling has been successfully applied in the reservoir development stage,but in the exploration stage,due to the different requirements of data base,geological tasks and model accuracy,the modeling methods in the reservoir development stage will have many inapplicabilities in the process of establishing the exploration grand model,which will affect the accuracy and usage effect of the grand model.In response to the problems of less drilling data and large target range in the exploration stage,this paper carries out reservoir geological modeling in the exploration stage based on the Box 8 reservoir in the Qingjian area,conducts research on geological model uncertainty evaluation and well deployment application in the study area with few wells,and establishes corresponding technical specifications and processes.Firstly,the core,logging,dynamic and other data are integrated,the reservoir is finely divided and compared,and a high-resolution time stratigraphic grid is established;on this basis,the research on the distribution law of reservoir sedimentary micro-phase within the time stratigraphic grid is carried out to determine the distribution law of different reservoir micro-phases.Taking the reservoir microphase as the subdivision object,identify and delineate various depositional interfaces within different reservoir microphases,determine the reservoir configuration element level and delineation scheme.Describe the depositional characteristics of different single sand bodies and the logging response characteristics,and establish different single sand body rock and electrical response models to guide the identification and delineation of single sand bodies in noncoring wells.On this basis,the outcrop,modern sedimentation,and dense well network research results are used as a guide to carry out the study on the combination model of single sand body elements in plan and profile.To reveal the combination style of different configuration unit planes and profiles,determine their spatial distribution pattern,and establish the deposition pattern of different configuration elements.Select typical horizontal and vertical profiles and planar results to form 2D training images;use 2D reconstruction 3D model technology to establish 3D reservoir configuration geological model and evaluate the model results to provide model guarantee for oilfield exploration and development.The results of the study showed that:(1)The Box 8 reservoir in Qingjian area is deposited at the front edge of the shallow braided river delta,and four micro-phases,namely submerged diversion channel,estuarine dam,mat sand and shallow lake mud,are identified.After the sand dams were deposited,the topography was changed,resulting in the diversion of the river channel and its further advancement,forming a new phase of the river channel-estuary dam complex,and finally forming a continuous fan-shaped sand deposit.(2)By finely dissecting the boundaries of the contiguous river-estuary dam unit of the Box 8 reservoir in Qingjian area,four types of boundary identification criteria,including sedimentary phase change,relative elevation difference,thickness difference and curve morphology difference,were established to complete the delineation of the boundary of the single river-estuary dam unit,and the results showed that the Box 8 reservoir in Qingjian area developed six types of configuration patterns,namely,front accumulation type,lateral splicing type,lateral migration type,lateral separation type,vertical stacking type and vertical separation type.(3)Statistics on the scale of the Box 8 reservoir configuration unit in the Qingjian area,the results show that the width of the river in the study area is distributed between 600-1,200 m,partly over 1,500 m,the average is 800 m,the thickness is distributed between 3-8m,some of the river reaches 10 m,the average thickness is 5.6m,the length of the estuary dam is mostly concentrated between 3,000-5,500 m,the length of the individual layer estuary dam can reach 6500 m with an average of 4100 m,width mostly concentrated between 2000-3500 m,individual layers of estuarine dams can reach 4500 m in width with an average of 2700 m,thickness mostly concentrated between 3-8m,some estuarine dams reach 10 m in thickness with an average thickness of 5.5m,compartment thickness between 0.2-37.8m,developed throughout the region.(4)The effective sand body of Box 8 reservoir in Qingjian area is mainly developed in the river channel area,and the effective sand body accounts for 82.5%.The river channel superposition area and the lateral migration area are easy to form a continuous thick layer of effective sand body,and the effective sand body as a whole is characterized by bandlike-dolphin-like distribution.(5)Adopt the method of reconstructing 3D model by 2D profiles to establish 3D geological model of Box 8 reservoir in Qingjian area,and establish 3D model by 5 groups of different numbers of 2D profiles and 5 groups of different combinations of search window radius sizes to compare the error of pumping diluted wells,the results show that the error gradually decreases with the increase of the number of profiles,and the decrease rate gradually slows down;with the gradual increase of the search window radius,the error also gradually decreases,but after reaching a certain size,the error no longer changes significantly.However,after reaching a certain size,the error no longer changes significantly.By analyzing the factors influencing the model,the main and minor factors affecting the accuracy of the model were identified,which guided the selection of parameters in the exploration phase of the model,and the average error of the final model was 5.37% in pumping diluted wells.