Abstract: For the oil fields which is entering late-stage development,the plugging is an essential measurement to improve the oil recovery significantly. However,the common non-selective blocking agent will not only plug water but also plug the oil and cause damage to the formation which lead to the decrease of permeability. The water-in-oil emulsion blocking agent has good prospects in terms of plugging. The water-in-oil emulsion blocking agent is pumped into the well under high pressure. The emulsion flows into the oil channel and dissolves in the oil,then it can be taken out from the well. On the other hand,the emulsion which flows into the water channel is further emulsified with the formation water to form a W/O emulsion. This new type of emulsion has high viscosity and it plays the role of plugging the large pore to achieve the ultimate goal of plugging water. The influencing factors and laws of the stability of water-in-oil emulsion plugging agents were studied through experiments. The emulsion was prepared by adding active agent to diesel oil,and the colorimetric tube was used to quantitatively evaluate the stability of water-in-oil emulsion.

Key words: water-in-oil, emulsion, blocking agent, stability