Optimal Design And Experiments On Hydraulic Sandblasting Perforation Nozzle

Hydraulic sandblasting perforation technology is an effective measure to increasethe gas output in low permeability and porosity reservoirs, and nozzle is one of the keytools of this technology. However, the commonly used nozzle in hydraulic sandblastingperforation process is cone-shape, which has the characteristics of low energyconversion efficiency, lead to that the perforating depth is short. Therefore, the effectof the construction is limited. Hence, it is significant to design a kind of new nozzle.By integrating theory with experiments in this paper, and based on the theory ofengineering fluid mechanics and water jet, theoretical analysis and numericalsimulation of energy loss of the commonly used nozzle (its total length is23mm, exitdiameter is4.5mm), which was used in gas wells of5inch casing, was conducted.Based on it, the structure of the commonly used nozzle was improved and a kind ofnew nozzle was put forward. The performance of the new nozzle was evaluated, afterits structure was optimized. The main research results were as followed:In order to improve the performance of the nozzle, in this paper. The resultsshowed the entrance energy loss was big. What was more, the Fluent software wasused to make preliminary optimization of new nozzle’s and3D-PIV technology wasused to measure the velocity field of nozzle exit. Finally, based on the flow coefficientand erosion experiments, the performance of new nozzle and commonly used nozzlewas compared and the results showed the new nozzle was better.①The energy loss of commonly used nozzle’s entrance was researched,according to numerical simulation. The result of the research showed that under theinfluence of centrifugal force and secondary flow the energy loss of the commonlyused nozzle’s entrance was large, which was mainly caused by local energy loss.What’s more, a local energy loss formula of nozzle’s entrance was established;②According to the theory of engineering fluid mechanics and water jet, thestructure of the commonly used nozzle entrance was improved, and a kind of newnozzle with transition path was put forward. The local energy loss of the new nozzle’sentrance was less, and the performance of the new nozzle was better due to thetheoretical analysis;③The transition structure of the new nozzle was optimized by Fluent software.Furthermore, experiments of flow coefficient and the velocity field of nozzle exit were conducted, which studied the effects of length and chamfer angle of the transitionsection on performance of new nozzle. When the length of the transition section was2mm and chamfer angle was45°, the new nozzle had a best performance which meanthighest export velocity;④Experiments were conducted to compare the performance of the optimizednew nozzle and the commonly used nozzle, contrasting their flow coefficient, velocityfield of nozzle exit and erosion ability. The results showed that, compared with thecommonly used nozzle, the new nozzle’s flow coefficient increased8%, axis velocityof nozzle exit increased16%and depth of cement test piece’s erosion hole increased16%.