Development Of New Water - Based Nano - Polysilicon Additive

Water-flooding is the main development regime of low permeability reservoir. There is a problem of high water injection pressure and reservoir under injection and affects the development. Nano-materials received extensive attention as its unique performance and great potential. The application of poly-silicon nanoparticle (HLP, Hydrophobic and Lipophilic poly-silicon) to enhance water injection is an important attempt to combining nanotechnology and oilfield development. A great successful has been achieved in the field application. In consideration of cost, safety and on the tubing coating damage and water-based nanoparticle dispersions obtained the fast development. Field test shows that it also has good effect on injection rate increase. At present nanometer powder as raw material, Exists in the form of micro emulsion In the water under collaborative of the surfactant and oil phase The thermodynamics of no equilibrium system are often difficult to stabilize in harsh down hole environments, The dispersion can quickly become unstable and agglomerate when the fluid is subjected to changes in pH, or encounter sin creased salinity and/or temperature. In addition, nano-powder is very easy to agglomeration in the processing and storage process Agglomeration renders the fluid ineffective, and at worst can cause severe damage to the formation.(1) In this paper, the synthesis of nano particles of silica sol-gel method. The effect of various reaction parameters on the synthesis are discussed, particle size increased with high ammonia and high precursor (TEOS) concentration and temperature increased with particle size decrease, The key is to control the induction period.(2) Use in-situ modification method of reagents hexamethyldisilazane (HMDS)to make the nanometer hydroxyl silica surface grafting hydrophobic methyl groups Finally mono-disperse spherical hydrophobic nano silica particles was synthesized and average particle size is44nm, the particle size distribution range small then characterize their morphology and performance.(3) Analysis of agglomeration of nanoparticles after drying use SEM, Taking into account that the synthesis and application of nano material in the liquid phase, so omission steps of nano gel into powder processing. The one-step wet chemical method be used and Hydrophobic nano silica gel as raw material.(4) Selected surfactants which can stablly disperse nano particles in high temperature and high salinity formation water. Prepared a novel water-based nano injection agent, and the properties were characterized and studied. Results show that nano particles in the novel nano injection increasing agent dispersed evenly, Stable in strong acid and weak alkali environment. The wettability of surface of rock slices reverse to hydrophobic when nano particle concentration is0.2%.(5) Evaluated augmented injection performance of the new water-based injection agent by core plugs displacement experiment. Study the injection process with the change of nano particle concentration and injection rate. Determine that the optimal injection concentration is 0.1%, the optimal injection volume was2times of the pore volume (PV). Physical parameters of core plugs before and after treatment were measured to study the effects of nano materials on rock physical properties. The results showed that the porosity and absolute penneability of the injection increase agent treated co.e decreased slightly. This mainly caused by the nanoparticles adsorption on the pore surfaces. Bound water saturation decreased significantly and wettability changed from strong hydrophilic to neutral wetting. Therefore, water permeability increased significantly, The new injection agent has a good performance.