油层结构破坏和出砂导致油层污染的数值模拟

NUMERICAL SIMULATION OF OIL FORMATION POLLUTION CAUSED BY STRUCTURE DAMAGE AND SANDING

在油田开发过程中，由于胶结疏松的砂岩地层本身的胶结脆弱性、压力不平衡以及流体对砂粒的剪切、拖曳作用，会造成油层结构的破坏和出砂，影响到油田的正常开发。研究了造成油层结构破坏和出砂的机理，建立了相应的地质模型和数学模型，并采用有限元法对模型进行了求解。对常见的油层结构破坏的３种情况和实例进行了模拟计算。结果表明，本模型可以很好地模拟和预测由汕层结构破坏和出砂造成的油层污染过程及该类油层近井地带不同开发阶段的污染程度，对于油层的评价、增产措施的实施等具有重要意义。

During development of oilfields, unsolidated sandstone will be damaged and sanding in oil formation because of its fragileness, unbalance of pressure, gravel shearing and traction caused by flow liquid. Therefore, oil production, will be declined, and normal development of oilfield will be influenced. The principles of oil formation damage and sanding are presented, and the geological and mathematical models to describe the process are developed. The finite element method is employed to solve the models. Three cases about formation structure damage are simulated, and one calculation example is given. The results show that these models are very adaptable to simulating or predicting the process of oil formation pollution caused by formation damage and sanding. The simulator is an efficient caluclator for simulating the damage process near wellbore in different development periods, and it is significant for formation evaluation and stimulaton of oil wells.