石油学报 ›› 2010, Vol. 31 ›› Issue (5): 867-870.DOI: 10.7623/syxb201005031

• 学术论坛 • 上一篇    

启动压力梯度真的存在吗?

李传亮   

  1. 西南石油大学油气藏地质及开发工程国家重点实验室  四川成都  610500
  • 收稿日期:2010-01-19 修回日期:2010-04-14 出版日期:2010-09-25 发布日期:2010-11-30
  • 通讯作者: 李传亮
  • 作者简介:李传亮,男,1962年10月生,2000年获中国科学技术大学博士学位,现为西南石油大学教授,主要从事油藏工程的教学和科研工作。
  • 基金资助:

    国家科技重大专项(2008ZX05049-05-04)资助。

Is a starting pressure gradient necessary for flow in porous media?

LI  Chuanliang   

  • Received:2010-01-19 Revised:2010-04-14 Online:2010-09-25 Published:2010-11-30

摘要:

一些室内实验测量到了低渗透储层存在启动压力梯度的现象,由于该现象对油田开发十分重要,关于启动压力梯度是否存在的问题,需要进行深入的研究。由于测量启动压力梯度时采用的是单相流体,单相流体并不存在毛管压力,因此,毛管压力不是启动压力梯度存在的原因。边界层中的流体并非不流动,而是流动滞缓,因此,边界层效应也不是启动压力梯度存在的原因。研究结果表明,实验室测量到启动压力梯度现象,主要是由于流量测试困难和测试时间太短所致,表皮效应加剧了启动压力存在的假象,注水井存在启动压力是由于井底污染和润湿滞后所致,流体在地层中流动并不需要启动压力梯度。

关键词: 油气藏, 岩石, 低渗透, 压力梯度, 启动压力梯度

Abstract:

A starting pressure gradient of flow in porous media is commonly reported in some laboratories. Due to its importance to oilfield development, whether a starting pressure gradient really exists requires further researches. Since a single-phase fluid is usually used in measuring a starting pressure gradient and there exists no capillary pressure for single-phase fluids, the capillary pressure can not be the cause of a starting pressure gradient. Fluids in boundary layers flow in retard rather than keep still, so a boundary layer effect can not be the cause of a starting pressure gradient either. The present paper showed that a starting pressure gradient measured in labs can be probably ascribed to the difficulty in measuring flow rate and to the insufficient time of measurements. The skin effect may strengthen the false phenomenon of the existence of a starting pressure gradient. The starting pressure for water injection is due to the formation damage and the wettability hysteresis at well bottom. Flows in porous media do not need a starting pressure gradient at all.

Key words: oil-gas reservoir, rock, low permeability, pressure gradient, starting pressure gradient