特低渗透油藏油井压裂裂缝参数优化

Optimization of Fracturing Parameters for Ultra-Low Permeability Reservoirs

油井压裂开发是目前提高特低渗透油藏开发效果的有效手段。为了充分发挥水力裂缝的作用,裂缝参数必须设计得合理。以某特低渗透油藏为例,采用矩形网格剖分与PEBI网格剖分相结合的方法模拟水力裂缝,在300m反九点井网条件下,运用油藏数值模拟方法对裂缝方位、导流能力及裂缝穿透比进行了优化,并采用正交试验法分析了裂缝参数对特低渗透油藏开发动态的影响规律。结果表明:压裂裂缝方位应考虑井网形式与最大主应力方向;裂缝的导流能力和穿透比不是越大越好,而是存在一个最佳值;在文中特低渗透油藏条件下,裂缝方位是影响采出程度的主要参数,其余依次为裂缝的导流能力和穿透比;裂缝导流能力是影响含水率的主要参数,其余依次为裂缝的方位和穿透比。

Hydraulic fracturing is an effective method to improve ultra-low permeability reservoir development.Proper fracturing parameters selection is required to take advantage of the fracture.Taking ultra-low permeability reservoir as an example,hydraulic fracture is simulated using rectangular and PEBI grid.Through reservoir simulation,fracture azimuth and conductivity,penetration ratio in inverted nine-spot pattern are optimized.The effect of fracture parameters on development performance of ultra-low permeability reservoir is analyzed using orthogonal experiment.The result shows that well pattern should consider fracture azimuth or the maximum horizontal stress orientation.It is not true the higher the fracture flow conductivity and penetration ratio,the better of development performance.Instead,an optimum value exists.For ultra-low permeability reservoir,the main parameter that affects recovery is fracture azimuth,followed by fracture conductivity and penetration ratio.The main parameter that affects water cut is fracture conductivity,followed by fracture azimuth and penetration ratio.