Study On Fine Description And Tapping The Potential Of Remaining Oil In Lower Karamay Formation In 3₂ District Karamay Oilfield

With the growth of oil extraction,the domestic ashore oil field in general have high water cut, high-recovery stage, complex reservoir production performance, short period of stabilized production , oil wells water breakthrough fast, oil production declining quickly, it is difficult to predicate the development of oil field and a high uncertainty of predicated results; but for the old oil fields, the ground still contains a lot of residual oil, today's key goals are to accurately describe the distribution of remaining oil and increase oil recovery oil field exploration and development. To achieve these goals, we need scientifically to perform delicate description of reservoir, reservoir simulation, adjustment of development program,delicate geological model and the distribution of remaining oil, which is not only main content of reservoir description, but also the basis to develop oil possession,with great significance throughout exploration and development of the reservoir.In this paper, according to combination of the datum:observation of the rock core, well logging, laboratory analysis, production performance and many other dynamic and static information,guided by the theories of high-resolution sequence stratigraphy, petroleum geology, modern sedimentology, reservoir geology, development geology, reservoir engineering, reservoir simulation and other academic method, layers have been classified and then it has been studying on reservoir structure,microtectonics, microfacies, reservoir quality and their interrelationship,the technique of random model and facies controlled model has been used in 3D quantitative description of reservoir,reservoir simulation has been taken in study on distribution of remaining oil,plan optimization and index prediction. Finally,the summary of research results have been given.1.There are 3 well-marked index horizons in Kexia formation according to matching, by which Kexia formation is divided to 2 sand sections or 6 sand units or 12 sand layers. The unsophisticated geology structure is eastsouthern dipping.The thick of formations and sand bodys is gradually thickened from northeast to southwest. 2.There are 85 microtectonics developed in main sand body in work area,23 of which are positive microtectonics,29 of which are negative microtectonics and 33 of which are slope microtectonics. The structure in work area is unsophisticated and thickened from northeast to southwest.3.Stratum depositional particularity demonstrates that the sedimentary environments are proluvial fan-valley plain in fluposition and fan delta and beach sediment in shallow environment from sand unit S73 to sand unit S61, hydrodynamic force was changed from strong to weak, size of particles was from megascopic to fine,the sedimental scale was from up to down.There are 14 microfacies peged out according to single well facies and electrofacies analysis, main trench, trench beach, sheetflood, cay ,braided stream, flood plain, river channel, abandoned channel, underwater channel, underwater interdistributary area, sandy beach,sand dam,lake beach and as so on.4.Heterogeneous reservoir studies show that it is dominant sand reservoir,dominant intergranular pore of mesothyridid and least permeable medium. Heterogeneous degree of reservoir is rough-moderate. muddy intercalations and calcareous gravelstone interlayers are distributed sequentially and the thick range of them is 0.43 to 2.53 meter.Barrier layers are sequential partitions between sand sections, though the partitions between sand layers and bodies are not sequential. Heterogeneous degree is very rough between layers,the reservoir permeability is less responsive to flow velocity and saltness,and more responsive to water.5.Reservoir evaluation criterion has been created according to regular pattern of net thicknesses, permeabilities, porosities and shale contents in different microfacies. Reservoir evaluation tell us that reservoir conditions are profitable in work area for developing and the major sand layers are first order,the minor are second order and the third order layers are rare. The proportion of the first order layers in Kexia formation decrease from bottom to top and The proportion of the second order layers and The proportion of the third order layers increase.6.The studies of flow domain make known that there 4 kinds flow domains in work area reservoir,the majority is the first order,the minority is the second order and the third and the fourth order are seldomness.The most of high quality of flow domains are located the south of work area,the quality of flow domain in the north are poor.The way of distribution is accordant with orientation of provenance.7.The tools of reservoir engineering and technics of reservoir simulation have been utilized to study on distribution of remainder oil saturation and the match of well network to reservoir and the findings show that distribution and developing of remainder oil saturation was controlled by microtectonics,faults, reservoir heterogeneity, sedimentary facies and developing factors. The Oil has remained in the area where well pattern can not sweep out, structural high localization and lagging area between wells. As required,this paper have proposed developed technical policies and rectified plans which are fit for the reservoir. The key issue of this paper is "finding the remaining oil, developing remaining oil",which associated the data of structure,deposition,reservoir,well log,laboratory, development dynamics and so on, combined the dynamic and the static, analysed from the qualitative to the quantitative, mutual authentication, mutual inference, to be formed a valuable research idea and technical method which is fit for study on reservoir delicate description, distribution of remaining oil and raising ultimate recovery in production tail of grit reservoir development. It have been provided exploratory experiences of the efficient development for the similar mature reservoir.