WATER QUALITY OPTIMIZATION FOR EFFECTIVE WATER INJECTION INTO LOW PERMEABILITY RESERVOIRS.

In low permeability reservoirs, water injection is the main means to supplement formation energy, and water quality is a key factor influencing the effect of waterflooding. However, the water quality is defined corresponding to large ranges of permeability under the current standard, which restricts the effective implementation of fine water injection into low permeability reservoirs. In this paper, throat distribution and contribution of mainstream throat to the permeability of low permeability reservoirs were analyzed, and the range of throats that influences water injection effect in such reservoirs was illustrated. Laboratory waterflooding physical simulation experiments on cores were conducted to quantitatively analyze the impacts of clay particle migration and hydration expansion on the seepage ability, and depending on the characteristics of throat distribution, quantify the damages to reservoirs caused by particle size and concentration of suspended solids in injected water. The particle size and concentration limits of suspended solids in injected water were proposed for low permeability reservoirs. [ABSTRACT FROM AUTHOR]