| Hydraulic sand blast slotting (for short hydraulic slotting) is a new perforation technology .In order to solve the casing and oil layer's damage problems which was caused by hydraulic slotting , the technology parameters of hydraulic slotting have been optimized with the low damage degree and high index of fluid production in casing and oil layer. All of these have been laid a foundation for spreading and application in a large-scale. Stratum,cement mantle and casing are taken as research objects in this article, and three-dimensional finite element models have been established in different operational modes. The computational methods about the stress field have been deduced by the analysis of unity. Based on the relationship between the first stress invariable and permeability, the computational methods about the velocity of flow and the flow rate have also been deduced. Applied the finite element analysis software—ANSYS which has great functions, the stress analysis has been carried by the function of structure analysis and the seepage analysis has been carried by the function of fluid analysis. By calculating and comparing analysis in different operational modes, the descending degree of the casing strength has been defined and the applied range of the common used for craft parameters have been optimized in hydraulic sand blast slotting which is short for hydraulic slotting.The main results obtained in this paper are as following:①Described exactly the shape of slot by hydraulic slotting in casing and stratum by the ground simulative experimentation using normal concrete target, which established the foundation for the research of hydraulic slotting.②Established the three-dimensional finite element model by considering the whole of the casing ,the concrete loop and the stratum. Confirmed the hypothetical condition not impacting on the applied value of model as the rule of the same crunodes displacement to different material, which created the qualification for establishing the model of hydraulic slotting.③Base on the relation between the first invariable of ground stress and the penetrate rate, the finite element methods for forecasting the throughput was established. Which was used to analyze the changing law straight between the quantity of slot and through put and confirm the principle for choosing the quantity of slot. The absolute difference between prediction production and the data from oil field fall in the range of 0.07—12.6%.④The changes about the casing strength and the ground stress at different cases and the numbers of slotting and layers have been computed and analyzed in the state of cementing casing, perforation and hydraulic slotting. And the applied range of the common used for craft parameters have been optimized. Confirmed the best phase angle for two slots of monolayer was 90°and three slots of monolayer was 60°by calculating 14 condition of two layer hydraulic slotting, the space can reduce by adopting reasonable phase angle, and the condition distinguished the least space was the come forth of draught stress⑤The results show that the casing strength was declined after hydraulic slotting. Compared two slots with 20 centimeters'height in single population with those of no slots, casing strength was decreased by17.2 percent. Compared with the perforation, casing strength was decreased by 6.79 percent. Compared three slots with two slots that had the same height in single population, the casing strength was decreased by12.4 percent and the deliverability times was between 1 and 1.47. When tensile stress was formed between two slots, the interval between two-layer slot parts was the least.⑥It is also found that if two-layer slot parts generated angular phasing of 90 degree, equivalent stress and hoop stress of the casing were declined obviously. Consequently, we can reduce the intervals by increasing angular phasing.
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