疏松砂岩油藏水力压裂的数值模拟（英文）

Numerical simulation of hydraulic fracture propagation in weakly consolidated sandstone reservoirs

压裂充填防砂技术有效改善了疏松砂岩油藏开发效果,具有实现增产与防砂的双重效果。由于疏松砂岩物性及力学的特殊性,其裂缝起裂与延伸机理较为复杂。为了研究水力裂缝延伸的机制,揭示压裂参数对疏松砂岩裂缝形态的影响,利用有限元软件建立了流固耦合有限元数值模型,重点分析了地层渗透率、压裂液黏度及排量对于裂缝延伸规律的影响。结果表明,低弹性模量有利于诱导形成短且宽裂缝并控制裂缝长度,而泊松比几乎不产生影响。高排量和高黏度压裂液裂缝有利于裂缝的起裂和延伸。当注入速率为3～4 m^3/min和流体黏度超过100 mPa·s时将形成合适的裂缝。压裂液的滤失量随着地层渗透率的增加而上升。

Frac-packing technology has been introduced to improve the development effect of weakly consolidated sandstone.It has double effects on increasing production and sand control.However,determining operation parameters of frac-packing is the key factor due to the particularity of weakly consolidated sandstone.In order to study the mechanisms of hydraulic fracture propagation and reveal the effect of fracturing parameters on fracture morphology in weakly consolidated sandstone,finite element numerical model of fluid-solid coupling is established to carry out numerical simulation to analyze influences of mechanical characteristics,formation permeability,fracturing fluid injection rate and viscosity on fracture propagation.The result shows that lower elastic modulus is favorable for inducing short and wide fractures and controls the fracture length while Poisson ratio has almost no effect.Large injection rate and high viscosity of fracturing fluid are advantageous to fracture initiation and propagation.Suitable fractures are produced when the injection rate is approximate to3–4m3/min and fluid viscosity is over100mPa?s.The leak-off of fracturing fluid to formation is rising with the increase of formation permeability,which is adverse to fracture propagation.The work provides theoretical reference to determine the construction parameters for the frac-packing design in weakly consolidated reservoirs.