天然气水合物降压开采出砂定量预测新模型

国内外天然气水合物试采经验表明,出砂问题是制约水合物资源有效开发的关键因素。从地层流体渗流角度出发,结合岩石力学理论,通过在出砂半径内对出砂量与产气量关系的推导,建立了天然气水合物降压开采出砂定量预测新模型。模型在确定地层和流体等参数情况下,得出地层出砂 量与产气量呈正相关关系,因此确定水合物降压开采产气量就可以定量预测对应的出砂量。结合岩石颗粒出砂模拟,描述了不同时期水合物分解过程颗粒出砂动态演化特征,并验证了模型预测的精度。从研究结果可以看出,水合物降压法开采过程中产气量、出砂量与地层压差关系密切。该研究成果对天然气水合物出砂预测具有一定启示作用,对后续水合物规模矿场试采也具有重要的意义。

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..