| Block Z is a typical ultra-low-permeability lithologic reservoir with a simple structure,near-horizontal distribution of rock formations,and interbedded or thin interbedded distribution of mudstone and sandstone siltstones with shallow reservoir depth.These factors lead to horizontal fractures after fracturing.There is a clear difference seepage law between the horizontal fractures and the conventional vertical fractures.But the original development scheme is mainly based on the normal vertical fractures.In order to establish a reasonable development method for the reservoir and improve the exploitation of the reservoir,The thesis studies the water injection development method and parameter optimization of low permeability reservoirs with horizontal fractures.In this paper,the seepage characteristics of the fracture horizontal seam in low permeability reservoir are investigated,and the geological model of the block is established by comparing the formation of the Chang 6 oil layer and distribution of sand body;The two-phase seepage model of oil and water in low permeability reservoirs with fractured horizontal fractures is studied,The embedded grid is used to describe the seepage law of horizontal fractures;In addition,The law of water injection development and the distribution of residual oil saturation in the development process are studied,Reservoir engineering theory and numerical simulation methods are used to compare and demonstrate the development methods;Finally,we optimize the block injection-production patterns and horizontal fracture parameters.and finally develop and optimize the water injection development plan of Z block.The conclusions and understanding of the thesis are as follows:(1)Based on the geological characteristics of the low permeability reservoir in Z block.The results show that:The structure of the Z block is a wide and gentle slope with low east and high west,and a series of low-amplitude nasal microstructures are developed.The reservoir is extra-low porosity and permeability,a strong heterogeneity is observed,The reservoir is a low permeability reservoir with an average porosity of 6.5%and an average permeability of 0.86mD.The main oil layers of long 6 are 61 and 62,followed by 63 and 64.(2)The mathematical model of two-phase seepage of oil and water in low permeability reservoirs is studied.The discrete fracture model represented by embedded grid technology can not only effectively describe the seepage law of horizontal fractures,but also maintain high computational efficiency.(3)Through the analysis of the dynamic data of single well production,Reserve fitting and single well history fitting for the block,The influence of different development methods(depletion development,continuous water injection and cyclic water injection)on the development of fracturing horizontal seam reservoir was studied by means of reservoir numerical simulation.(4)Different well patterns and well spacings were demonstrated.According to the remaining oil distribution by the water injection in the fractured horizontal seam well,the remaining oil is separated in the upper and lower parts of the fracture,because the injected water can not reach these areas and lead to the dead oil area.In order to further improve the scope of water flooding,The parameters such as fracture length and fracture density under different well pattern conditions and geological conditions are optimized,And optimize the horizontal seam parameters and injection and production parameters.(5)Based on well pattern,well spacing and parameter optimization,combined with the development characteristics and remaining oil distribution of low permeability reservoirs in Z block,We carry out well pattern adjustment and performation measures for Z block reservoir,design and optimize the block,and choose the best water flooding development plan. |
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