Experimental Study of Sand Migration under Distinct Sand Control Methods during Gas Hydrate Decomposition by Depressurization

Natural gas hydrate is a promising and abundant new clean energy source that is widely distributed in marine sediments. There are currently several challenges in the research and development of offshore gas hydrate exploitation, and one of these challenges is sand production during the exploitation process. Without an appropriate sand control apparatus, sand production can lead to a series of problems, including abrupt production cessation and even wellbore burial. At present, the sand control performance of some new sand control materials, such as polyurethane foam, still needs to be studied. This paper aimed to identify the effective sand control methods for hydrate reservoir development. Different sand control methods, including ceramic filling, gravel filling, and polyurethane foam, were selected as the independent variables to determine whether they could reduce sand production in a hydrate reservoir during the hydrate dissociation via depressurization. To achieve this purpose, an independently developed laboratory device was used to conduct sand production and sand control simulation experiments during hydrate exploitation. Additionally, a group of experiments without using sand control methods were carried out as a control group for the experiments with sand control methods. The experimental results showed that the experiments without sand control methods experienced significant sand production, while the experiments with sand control methods were all able to reduce sand production in these hydrate reservoirs. Significantly, gas production of the reservoir with the sand control method of polyurethane foam was more effective than that of the ceramic filling during hydrate decomposition. Accordingly, a confirmatory experiment was further conducted using polyurethane foam for reservoirs that were more likely to produce sand. The experimental results also supported this conclusion, demonstrating that polyurethane foam can effectively prevent sand production under these conditions.