Dispersion Stabilization And Regulation Of Barium Sulfate Particles In Gas-to-oil

Solid particles have good stability,high hardness,acid and alkali resistance and other properties,are widely used in oil drilling,coatings,ceramics and other fields.As the main fluid for drilling deep and ultra-deep wells,oil-base drilling fluid is essentially a suspension.When BaSO4 particles are used as weighting material and added into non-aqueous media such as Isomeric alkane gas-to-oil(GTL)and White oil,strong agglomeration often occurs.The agglomeration leads to the deterioration of dispersion stability of weighting material in dispersion medium and the increase of viscosity,which seriously affects drilling operation.In this study,oil-based drilling fluid was used as the research background to improve the dispersion stability of BaSO4 particles in GTL,and to explore the interaction between the dispersant and the BaSO4 particles as well as the mechanism of dispersion among particles.In addition,a second liquid-water was added into the C12E9Ac stabilized BaSO4-GTL suspension to increase the interactions between particles in the system,improve its redispersibility and viscosity.The outline and contents of this dissertation are as follows:(1)In view of the dispersion stability of solid particles in non-aqueous media,referring to the research methods of the dispersion stability of solid particles in non-aqueous media,fatty alcohol polyoxyethylene ether carboxylic acid(CiEjAc)was used as dispersant to improve the dispersion stability of barium sulfate particles in GTL.When C12E9Ac and BaSO4 particles are added to GTL,due to "adsorption of phase with similar polarity",the polar-COOH and(EO)j of the dispersant C12E9Ac will be close to and adsorbed on the surface of BaSO4 particles,and the non-polar part will extend to the GTL.The adsorption of dispersant molecules on the surface of BaSO4 particles,on the one hand,reduces the interfacial tension between BaSO4 particles and GTL,which reduces the solid-liquid interface energy and makes the particles more easily dispersed in the GTL.On the other hand,there is a layer of surfactant molecules on the surface of particles,which increases the repulsive force between particles,inhibits particle aggregation,and further improves the dispersion stability of particles.(2)To investigate the influence of water on the stability of BaSO4-GTL suspension stabilized by fatty alcohol polyoxyethylene ether carboxylic acid(C12E9Ac).With the increase of water addition,the particles in the system appeared Like-dispersive state,Cluster state and Cell state,successively.Compared with the system without water,the dispersion stability and viscosity of the particles in the nearly dispersed state are almost the same,but the redispersion of the sediments is improved.Therefore,adding a small amount of water to the BaSO4-GTL suspension can increase the interparticle attraction and the settlement stability of the suspension.