启动压力梯度对压裂井生产动态影响研究

低渗透油藏往往不遵循达西定律,具有启动压力现象,常规的方法难以实现该类油藏的高效开发.通过室内实验,研究了大庆肇源油田不同渗透率岩心启动压力梯度,建立了启动压力和渗透率关系式,并应用黏度和渗透率组合参数来判断流体的渗流形态;应用数值模拟的方法研究了启动压力梯度对压裂油井日产量、累积产量、含水率、采出程度、地层压力分布等的影响.结果表明,启动压力梯度对压裂油井各项生产参数的影响很大.因此,在低渗透油藏的开发过程中不能忽略启动压力梯度的影响.

Effect of starting pressure gradient on the production performance of fractured wells

The proportion of the reserves of low permeability reservoir in incremental reserves becomes more and more great,and the development of the low permeability reservoirs also becomes a difficult problem in oilfield development.The fluid seepage in low permeability reservoir don't follow Darcy's law and there is a starting pressure gradient.The relationship between core starting pressure gradient and permeability is established through laboratory experiments.Based on the correlation,the graphic mode for determining the fluid seepage state in the low permeability reservoirs according to the reservoir permeability and the fluid viscosity is also established.The effects of the starting pressure gradient on the daily output,cumulative output,water cut and recovery percent of the fractured wells and the formation pressure distribution are studied by numeral simulation.It is shown that the starting pressure gradient has great influence upon oil and gas production indexes,and the influences are all negative.Therefore the influences cannot be neglected in the development of the low permeability reservoirs.