西南石油大学学报(自然科学版)

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Study of Water Locking Damage Mechanism and Water Unlocking of Low
Permeability Reservoir

1. Postdoctoral Research Station,China University of Geosciences,Haidian,Beijing 100083,China
2. Exploration and Development Research Institute,Henan Oilfield Company,Nanyang,Henan 473400,China   

  1. 1. Postdoctoral Research Station,China University of Geosciences,Haidian,Beijing 100083,China
    2. Exploration and Development Research Institute,Henan Oilfield Company,Nanyang,Henan 473400,China
  • Online:2013-06-01 Published:2013-06-01

Abstract:

Water locking phenomenon is the typical of low and extra low permeability reservoir. Which is a common problem
in low permeability oil wells,and is of low formation pressure(pressure coefficient less than 1)and of low water cut(less than
50%). Capillary effect and Jiamin effect is the main mechanism of the occurrence of water locking phenomenon. Through
experimental analysis we find out that the lower the permeability is,the worse the water locking degree is. The pressure of the
core which is less than 10 mD rise about 25%. But the pressure of the core which is more than 10 mD rise about 15%. The
injection of a surfactant displayed remarkable water unlocking effect,especially when the permeability is low,and the maximum
displacement value of pressure drops by almost 50%,which proves that surfactant is very effective in water unlocking.

Key words: water locking, low permeability, reservoir damage, surfactant