1.Technical principle
Nanometerpolisilica prepared via in-situsurface-modification technique has superhydrophobicity and can be stronglyadsorbed on the surface of micro-pore canal of stratum, forming nanoscaleadsorbed layer and endowing walls of the pore canal with strong hydrophobicity.As a result, the flow drag of water under high pressure is significantlyreduced, and water weakly adsorbed on the surface of rocks is easily displacedin the presence of capillary forces, resulting in thinned water membrane aswell as significantly increased seepage aperture and volume of pore throat ofstratum. In the meantime, nanoparticles of the decompression andinjection-augmentation agents are able to cover the surface of clay, preventingentrance of water and hence swelling of the clay, which also contributes tosignificantly improving the decompression and injection-augmentationperformance.
2. Technical features
(1). Introduction of acidification techniquefor cleaning of stratum surface helps to achieve remarkable decompression andinjection-augmentation effect.
(2). Byadopting water as a carrier of nanometer polysilica to replace organicdispersants like diesel oil, the cost for decompression andinjection-augmentation is greatly reduced.
(3). Ithas no direct pollution to ground and stratum, and it does not cause secondarypollution to stratum.
(4). It isvalid in long-term decompression and injection-augmentation operation.
3. Craft for operation and construction
(1).Preparation of liquid: hydrophobic nanometer silica is dispersed in watercontaining auxiliary agents under proper temperature to form a transparentliquid.
(2).The clog and sewage in the rock pores are eliminated using proper techniques inrelation to the situation of stratum, and the rocks are acidified to exposefresh surfaces so as to facilitate adsorption of the nanometer polisilica.
(3). The fluid of nanometer polysilica isinjected into wells with the assistance of anti-swelling fluid.
(4). Well shut-down and reaction: the fluidof nanometer polysilica is induced to de-emulsify under acidified chemicalenvironment, releasing hydrophobic nanometer particles to fully adsorb water.
(5). Well startup and water injection in aroutine manner.
4.Condition for well selection
(1). Shaft body is in a good state and free of poor orcomplicated operation history.
(2). Waterwell has been practiced for a period of water injection, and the rocks near thewell are water wettable.
(3).The permeability of oil layer is above 0.5 × 10-3μm2.
(4).There exists a good correlation between the water injection of the water well andoil extraction of the oil well, and water-injection pressure can be readilydissipated.
(5). Thequality of the injected water should be accepted; and oil content inre-injected sewage should be below specified level.
(6). Wells with a low amount of injected water butallow injection of well water can be preferentially selected and practiced.
Prepare and may be prepared NO. 1010502002104