流固耦合模型在定量预测油水井出砂过程中的应用

A fluid-solid coupling model and its application in quantitative sand production prediction of oil and water wells

在综合考虑流体渗流、储集层变形或破坏等因素的基础上,建立了流固耦合形式的出砂定量预测模型。提出了2类出砂机理:流体渗流剥蚀作用下的细砂产出和储集层结构破坏情况下的粗砂产出,并采用Drucker-Prager准则研究了出砂过程中的砂岩储集层骨架应力和变形。有限元法数值模拟结果表明:在整个出砂过程中,地层渗透率的变化与生产压差、储集层物性密切相关。在相对平衡的地层压力条件下,由于剥蚀或储集层骨架破坏,地层渗透率可以增加30%;过高的生产压差可能造成井眼局部储集层压实,渗透率下降幅度可达50%。因此,保持适当的地层压力是控制渗透率下降进而保持产能的关键。

With fluid percolation, reservoir deformation or damage and other factors under consideration, a fluid-solid coupling model for predicting sand production volume is generated. Two types of sand production mechanisms are proposed： producing fine sands under hydro-dynamical erosion and producing coarse sands when reservoir structures are destructed. The matrix stress and the deformation of sandstone reservoirs in sand production are studied using the Drucker- Prager criterion. The results of finite element numerical simulation indicate that the change of formation permeability correlates closely with producing pressure drop and reservoir properties in the whole sand production. Under relative balanced pressure, because of the erosion of reservoirs and the destruction of reservoir skeleton structures, the formation permeability can increase by 30%; while under over high production pressure drop, because of the possible reservoir compaction near well-bores, the formation permeability can decline by 50%. A balanced pressure depletion strategy is the key to controlling permeability declining and retaining production.