Mechanisms and Experimental Research on Sand Transport and Settlement of a New Sand Cleaning System.

In this paper, in view of the existing mechanical sand cleaning technology, circulating sand flushing technology, and negative pressure sand cleaning technology, which cannot establish circulation, the pump lift is limited, the sand cleaning efficiency is low, and many other problems when cleaning the sand in deep wells that are prone to leakage, a new type of sand cleaning system that can realize the local circulation and storage of sand fluid at the bottom of the well is designed. The critical problem to be solved in this design is how to simultaneously meet the dual requirements of local circulation and storage, that is, how to coordinate the contradiction between gravel carrying and settlement. Therefore, studying the mechanism of sand transport and settlement in the new type of sand cleaning cylinder is necessary. The discrete phase model of the sand liquid flowing in the sand cleaning cylinder was established using EDEM-FLUENT. The numerical simulation and analysis of the movement law of sand grains, the trajectory line clouds of sand grains, and the variation law of sand settling rate, sand mass flow rate, and sand-carrying liquid flow rate under different working parameters were obtained. The conclusion shows that when the mass flow rate of sand particles is 0.5–0.8 kg/s, and the flow rate of sand-carrying liquid is 0.5– 1 m/s, the grit removal effect of the sand cleaning cylinder is better. In order to verify the sand cleaning effect of this new sand cleaning system and the accuracy of the numerical analysis model, the ground simulation test platform of the sand cleaning cylinder was built, and simulated sand cleaning tests were carried out under different sand particle sizes and different sand-carrying fluid flow rates. The test results show that the new sand cleaning system clears sand well. Comparing the numerical simulation results with the experimental results, the two have the same variation pattern, which verifies the feasibility of this new sand cleaning system and the correctness of the numerical analysis model. The study provides a new sand cleaning system solution, which solves the problem that existing sand cleaning techniques cannot quickly and efficiently clean up sunken sand from leaking oil and gas wells and provides a basis for the selection of field operating parameters for the new sand cleaning system. [ABSTRACT FROM AUTHOR]