摘要
根据低渗透油藏的非达西渗流规律,利用椭圆流动模型和质量守恒的方法,建立并求解了考虑启动压力梯度影响的有限导流垂直裂缝井不稳定渗流的数学模型,获得了垂直裂缝井井底压力公式,绘制了试井典型曲线,分析了导流能力、井储效应、表皮效应和启动压力梯度等因素对试井曲线的影响。分析表明,当压裂井井储效应及表皮效应较大时,双线性流段甚至部分地层线性流段难以出现。垂直裂缝导流能力越小,则井底压力越低,表现为无因次压力越高;但当导流能力增大到一定程度时,压裂井试井曲线形态变化不大。启动压力梯度对垂直裂缝井试井典型曲线影响较大,主要表现为压力及压力导数曲线后期出现上翘趋势,并且随着启动压力梯度的增大,上翘趋势越明显。最后,给出了1口压裂井的试井解释实例。
Mathematical models for finite-conductivity vertical fracture wells with unstable flow concerning the influences of threshold pressure gradient are established and calculated according to the non-Darey flow rules for low-permeability reservoirs, adopting the ellipse flow models and mass conservation law. Through the mathematical models, we could achieve bottom pressure equation for vertical fracture wells, map the typical curve for well testing, and meanwhile, study the influential factors on testing curve such as conductivity, accumulation effect, surface effect and threshold pressure gradient. The study indicates that （ 1 ） double linear flow section or even partial strata linear flow section would not appear due to large accumulation effect and surface effect in the fracture well; （2） the weaker the conductivity of the vertical fracture, the lower the bottom pressure is, and presents higher dimensionless pressure, but when conductivity extends to a certain degree, the well testing curves for fracture wells won＇ t vary too much ; （ 3 ） the threshold pressure gradient has a larger influence on typical well testing curve of a vertical fracture well, pressure and pressure guide curve climb up at later stage, and the larger the threshold pressure gradient is the more oblivious the upwarping is. A practical example of fracture well testing explanation is given for illustration.
出处
《大庆石油地质与开发》
CAS
CSCD
北大核心
2007年第5期53-56,共4页
Petroleum Geology & Oilfield Development in Daqing
关键词
垂直裂缝
椭圆流
启动压力梯度
压力动态
有限导流
vertical fracture
ellipse flow
threshold pressure gradient
pressure dynamics
finite conductivity
