摘要
水力压裂能使油井周围地层形成对称的垂直裂缝面,是有效的增产措施。垂直裂缝井采液时诱发地层中的平面二维椭圆渗流,形成以裂缝端点为焦点的共轭等压椭圆和双曲线流线族。基于扰动椭圆的概念和等价的发展矩形的思想,建立了具有启动压力梯度的油水两相非达西椭圆二维渗流数学模型。这种模型属于具有活动边界的非线性问题,分别用特征线法和有限差分法求解,得到了含水饱和度分布和活动边界的变化规律。还基于非活塞驱替理论,导出垂直裂缝井注水水开发低渗透油田时的产油量、压差及井排见水时间的计算公式,并进行实例计算分析,认为在此情况下,启动压力梯度和注入率对含水率、含水上升速率、含水饱和度分布、活动边界变化规律影响较大,对产油量、压差随时间变化规律及井排见水时间的影响也较大;还认为,低渗透非达西流条件下存在可获得最经济开发指标的最佳注入率。为垂直裂缝井注水开发低渗透油田的研究提供了数值模拟的模型和动态分析及预测的理论依据。图4表1参8(王孝陵摘)
Hydraulic fracturing, which can form a symmetrical and vertical fracture in the formation around the wellbore, is an effective measure of production stimulation. A vertical fractured well can bring out two dimensional flow in the direction of normals of developing ellipse—conjugate ellipse isobar and hyperbola streamline bunches with the two ends of the fracture as their focuses. A mathematical model of oil and water two phase non Darcy fluid flow in the direction of normal of the ellipses with initial pressure gradient (IPG) is taken into account, which is a nonlinear equation with moving boundary and is established according to concepts of perturbable ellipses and equivalent developing regulations. Characteristic solution and finite difference solution are derived respectively and water saturation distribution curves are presented and the law of the moving boundary is found. Results show good agreement between the characteristic solution and finite difference solution. Moreover, formulas of waterflooding indices of oil with IPG included for vertical fractured wells are derived. Laws of change of production and pressure difference with time are recognized. Influence of IPG and injection rate on the flow and the development indexes is discussed. The paper provides numerical simulation and dynamic analysis and prediction of waterflooding development of low permeability oil fields in the case of vertical fractured wells with theoretical basis. The mathematical model is also fit for waterflooding development of Bingham viscous oil fields in the case of vertical fractured wells. The study on waterflooding development of higher permeability oil fields under the condition of vertical fractured wells is a special case of the paper.
出处
《石油勘探与开发》
SCIE
EI
CAS
CSCD
北大核心
2000年第1期60-63,75,共5页
Petroleum Exploration and Development
关键词
垂直裂缝井
水力压裂
试井
渗流
两相流
计算
Hydraulic fracturing
Vertical fracture
Oil well performance
Non Darcy flow
Percolation model
Elliptical equation
Characteristic equation
Calculus differences
Low permeability pools
Development index
