A new model for quantitative prediction of sand production during natural gas hydrate exploitation by depressurization recovery

The domestic and abroad experience of production test of natural gas hydrate shows that the problem of sand production is a key factor restricting the effective development of hydrate resources. From the perspective of the flow in porous media of formation fluid, in combination with rock mechanics theory, this study establishes a new model for quantitatively predicting sand production during the natural gas hydrate exploitation by depressurization recovery through deriving gas production rate and sand production rate within the sand production radius. When formation, fluid and other parameters are determined in the model, the sand production rate of the formation has a positive correlation with gas production rate. Therefore, the corresponding sand production rate can be quantitatively predicted by determining gas production during the natural gas hydrate exploitation by depressurization recovery. Combined with the simulation of sand production of rock particles, this paper describes the dynamic evolution characteristics of sand production of particles of hydrate during the decomposition process at different stages, and verifies the accuracy of model prediction. The research results show that the gas production rate and sand production rate are closely related with differential pressure of formation during the natural gas hydrate exploitation by depressurization recovery. The research results have certain enlightening function on the prediction of sand production of natural gas hydrate, and are also of great significance for the subsequent large-scale production test of natural gas hydrate in the oil field. © 2019, Editorial Office of ACTA PETROLEI SINICA. All right reserved.