| Linpan Oilfield is located in Linyi Country, Shandong province, which is a typical continental deposited oil and gas field with complex minor fault block. Lin7fault block is located in the middle part of central Huimin sag in Jiyang depression, in which Sha3member(i.e.Es3) is the main oil-bearing formation. With the gradually enrichment of well drilling and well logging data, and the carefully division of layer series of development, the geological research is lagged behind the production requirement obviously. For instance, the detail study of sedimentary microfacies can not meet the deeds of the development program adjustment. With the detail study of sedimentary microfacies, the distribution of sand bodies and the heterogeneity characteristics can be predicted, the program design of infill well can be directed effectively, which will provide geological basis for the development program adjustment of ES3in Lin7fault block. In this paper, the layer of ES3of the study area have been divided and compared, with the high-resolution sequence principle; Combine with the results of strati graphic correlation and the data of seismic, the top surface structural map of each sand groups have been newly-builted and modified; Based on the core observation, combined with the data of well logging, logging, thin section analysis, the sedimentary microfacies have been divided accurately; The time and space evolution law have been summed up, the sedimentary model have been established, through the analysis of single well, single well and in-plane facies; The reservoir have been analyzed synthetically, based on the study of sedimentary microfacies, combined with the testing data.Lin7fault block of Linpan oilfield is in the mid-latter stage of the reservoir exploitation, the traditional method "based on the cycle and correlating from larger to smaller" can not meet the comprehensive research for the reservoir. With the high-resolution sequence principle, based on the core observation and logging analysis, taken the base level cycle and the accommodation space changes as the criterion, stratigraphic contact relations and lithologic association as the principle, with maker beds control, cycle division and correlation, a feasible comparative model has been established, the stratigraphic correlation of52wells of Es3have been completed, the layer of ES3of the study horizon have been divided into4sand groups,22layers, which lay a foundation of the sedimentary environment study.The structure of ES3of Lin7fault block is fault terrace, the layer uplifted from west to east. There is three-classes faults on north and south sides of the study horizon separately, and a eastward downthroun fault are developed in the west, which join two faults of north and south sides. According to the size of the faults and the control effect on the layer, structural, and oil and gas, three-four-level faults in the study area can be divided approximately. Combine with the results of stratigraphic correlation and the data of seismic, the top surface structural maps of upper ES3-1have been newly-builted, and the upper ES3-3,4, middle ES3, lower ES3-1,3,4have been modified, which suggested that, the structure of ES3of Lin7fault block is a fault terrace, each sand groups is relatively simple in lower ES3, and slightly complex in middle and upper ES3, with obvious inheritance tectonically.Sedimentary micro-facies control the distribution of sand body, and reveal the characteristic of sand body in3dimensional space, which is the foundation for the reservoir study. The facies of ES3of study horizon have been analyzed systematically, mostly by core observation, secondly by thin section analysis and combined with the data of well logging, logging, testing and regional geological.Based on the analysis, the rock types of ES3in Lin7fault block is dominated by siltstone, fine sandstone and mudstone (shale), minor light gray medium sandstone. Lower ES3is dominated by grey-brown and brown-grey fine sandstone, dark gray and gray mudstone (shale), fine sandstone is mainly consist of feldspar-lithic quartz packsand and lithic packsand, with grain supported, pore cementation, low compositional maturity and textural maturity; the grain size probability cumulative curves displays the features of saltation and suspension populations, and the saltation population is central, which represents the characteristics of delta deposit; mudstone (shale) interbeded with sandstone; Small scale cross-beddings, wavy beddings, parallel beddings and bioturbationstructure are produced in sandstone, parallel beddings are produced in shale. Base on the comprehensive analysis, the sedimentary deposition is considered as delta, which includes micro facies of underwater distributary channel, mouth bar, distal bar, interdistributay bay and prodelta mud.The rock types of middle and upper ES3are dominated by brown-grey, grey-brown siltstone and fine sandstone, dark gray, gray mudstone (shale), and minor by light gray medium sandstone, siltstone is mainly consist of feldspathic lithic quartzsiltite siltstone, fine sandstone is mainly consist of feldspathic lithic quartzsiltite packsand and lithic packsand, with grain supported, pore cementation, low compositional maturity and textural maturity; one-piese-modal grain size probability curves, represent the typical characteristics of turbidity current deposit; small scale cross-beddings, wavy beddings, parallel beddings, massive beddings, convolute beddings, fiamme structure, bioturbationstructure, mud pebble are produced in sandstone, parallel beddings are produced in shale. Base on the comprehensive analysis, the sedimentary deposition is considered as turbidite fan, which consists of microfacies of channel, lateral margin channel, interchannel, frontchannel and outer fan mud middle fan.The lower content of grey oil shale mainly distributed in the middle and lower part of middle ES3in study area, which represent the reducing environment, the sedimentary deposition is considered as lacustrine, which mainly consists of semi-deep to deep lake mud.The analysis of single well facies indicated that, the delta front-prodelta deposite mainly distributed in lower ES3, and the middle fan-outer fan-semi deep to deep lake deposite mainly distributed in middle and upper ES3, the lake level was proved to be raising on the whole. Through section facies contrast, sand thickness contour interval and plane facies analysis, the spreading regularity of the sedimentary facies has been clarified and established. In lower ES3, the underwater distributary channel deposit mainly distributed in the west of the study area, which spreading along WN-ES direction; The " U " shape mouth bar deposit distributed in the estuary of underwater distributary channel; The interdistributay bay deposit distributed between underwater distributary channels or intercalated with underwater distributary channel and mouth bar; the prodelta mud deposit have a extensive distribution. In middle and upper ES3, the channel deposit spreading from N, WN to E, ES, the lateral margin channel deposit distributed laterally to the channel, the sheet like frontchannel deposit distributed around channel contiguously, the interdistributay bay deposit distributed between channels, the deposit of outer fan mud and semi-deep to deep lake mud spreading extensively in study horizon. In vertical profile, the delta deposit mainly distributed in lower ES3in the west of study area, the turbidite fan mainly in middle ES3in the middle of study area, and in upper ES3distributed in the east of study area, with microfacies superimposed mutually.The mainly reservoir types of Es3are feldspar-lithic quartz sandstone and lithic sandstone, The reservoir space of the sandbodies is dominated by intergranular dissolution pore, and subsequently by intragranular dissolution pore. Based on the data of logging well, the reservoir of Es3is low-middle, middle pore, low, super-low permeability. Combine with the porosity, permeability, microfacies of each member, the physical changes of the reservoir of Es3is mainly controlled by microfacies. The testing data suggested that the plane heterogeneity of lower ES3is weak, while the interlayer heterogeneity is relatively strong; The plane heterogeneity of middle ES3is relatively strong, while the interlayer heterogeneity is relatively week; The plane heterogeneity of upper ES3is week, while the interlayer heterogeneity is relatively week. Finally, based on different lithology, and the development characteristics of the reservoir with different genetic type, the distribution of favorable reservoir of Es3have been predicted, which indicates that the favorable reservoir is mainly located in the central and eastern regions. |
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