Research Of Shale Gas Reservoir Protection Fluid

At present,there is a very prominent problem that is water sensitive damage and liquid trap caused by water-based drilling fluid invasion in the process of shale gas drilling and exploitation,seriously affecting drilling safety and production of shale gas well,even related to the value of industrial exploitation of gas wells.Therefore,there is an urgent need to develop a new type of water-based drilling fluid system that can protect shale reservoirs.Based on the unique properties of copolymer emulsions and their optimization theory,combined with the surface free radical polymerization mechanism,methyl methacrylate(MMA),methacrylic acid(MAA),PFMA and butyl acrylate(BA)are the main raw materials,Under the action of sodium alkyl benzene sulphonate(LAS)emulsification and ammonium persulfate(APS),a fluorinated acrylate copolymer emulsion with a core-shell structure was prepared using a semi-continuous core-shell emulsion polymerization process,the anti-water blocking agent FCAM.The molecular structure of the copolymer was characterized by infrared spectroscopy and XPS.Thermal stability,particle size and distribution,and shale contact angle were investigated by means of thermogravimetric analysis,laser diffraction particle size distribution analyzer,and contact angle tester.The shale hydration dispersion experiment,linear expansion experiment,core self-priming experiment and core permeability recovery experiment were used to evaluate the comprehensive performance of different concentrations of FCAM emulsion system.The waterproof lock agent FCAM can effectively reduce the surface tension of the system and increase the page-to-page ratio.The contact angle of the rock reverses the surface of the hydrophilic shale into a hydrophobic and oleophobic effect,which has a good waterproof lock effect.Based on the existing shale gas reservoir protection drilling fluid system at home and abroad,a newly developed shale gas reservoir waterproof lock agent FCAM was used as the main treatment agent to optimize the drilling fluid treatment agent and construct a set of pages.Rock reservoirs protect drilling fluid systems and reveal the protective mechanism of shale gas reservoirs.The experimental formula was: 4% bentonite slurry + 1.0% SFY-1 + 1.5% FCAM + 1.5% CMS + 0.3% KPAM + 2.0% RH-3.The evaluation results show that the shale gas reservoir protection drilling fluid has good rheological properties,filtration loss resistance,anti-pollution performance and high temperature resistance,strong inhibition performance,excellent reservoir protection effect,and is conducive to improving shale Gas well production.