Research On Reservoir Characteristics And Water Injection Technology In Sazhong Oilfield East Area Of Bei ? Fault Block Gaotaizi Reservoir

In this paper,the geological characteristics of the eastern part of the Bei-I Fault Block is studied to recombine the developed production zones.By considering the pressure loss of the fluid flowing through the wellbore,the injecting nozzle and the reservoir the network analysis model is established to achieve efficient separate-layer water injection.Well-log and seismic data are used for description of the sedimentary sand and the reservoir characteristics in this block.Based on the study the development plan of formation of the layer of the combination is formulated.Based on The equivalent resistance method for water flowing through porous media,the parallel model is established for the multi-zone water injecting well.The equation between total resistance flowing through porous formation in the well and the resistances of the separate formation layers is derived and verified by the field experiment data with very satisfactory accuracy.Based on the empirical equation under the laminar flow and Nikuradse experiment equations,the pressure drop along the water injection string is calculated with result showing that the pressure drop is small to be neglected unless flow rate is high above 250m3/d.Based on Bernoulli equation and the law of conservation of momentum,the equation is derived to calculate the pressure drop which indicates that the pressure drop is proportional to the square of the flow rate of injecting water.The energy consumption formula of water injection process is established,which provides a means for optimizing water injection technology to achieve energy saving.Based on above studies on the parallel model and the pressure drop of the nozzle,a series-parallel network model of the separate water injection system is established.the concepts of threshold pressure of separate zone and the threshold pressure of the well are proposed,which provides very useful method for determining the injecting pressure of the separate injection well.The sensitivity analysis based on the series-parallel network model is carried out.The equitions such as the influence of the injection pressure of the wellhead injection on the injection rate of each well,and the influence of the injection pressure change on the total injection rate are derived,which is useful to improve the efficiency of field operation.