Research And Application Of Deep Profile Control & Oil Displacement By Gel In High-temperature Oilfield

Considering the disadvantages of the application of alcohol resin crosslinkers in deep profile control and oil displacement for Huabei High-temperature Oilfield, such as agglomeration, volatilization of alcohol and short validity, etc., completely water-soluble pre-polymerizing resin crosslinkers with multiple hydroxymethyl groups were synthesized via optimization of ratio of phenol and formaldehyde, usage of catalyst, reaction temperature and time and so forth. Furthermore, thermostable gel systems (no breaking at 110℃for 150 days) for Liuchu Oilfield were prepared. These profile control and oil displacement systems are characteristic of moderate ground viscosity (50~160mPa·s), controllable gelling viscosity (800~2500mPa·s) and wide range of temperature adaptation (60~120℃). In addition, these gel systems can be easily prepared with reinjection water.Based on model tests, profile control and oil displacement scheme of"pre-slug + principal slug + protective slug + displacing slug"was worked out. Differing from the traditional decreasing injection viscosity, this scheme designed an increasing gel viscosity with the injection sequence, which can not only take full advantage of the self-adjusting ability of the permeability, but also reduce the contamination of the working fluid, achieving a larger treatment radius and a better sweep efficiency of the subsequent water flooding.In field tests, 8 well groups have been successfully treated and the accumulated oil increment has reached 12168.6t, demonstrating a good effect in stabilizing the oil production by the water shutoff.