Research And Evaluation Of Mosaic Shielding Drilling Fluid System

One of the important reasons of causing oil and gas production is oil and gas reservoir damage,strengthening the protection of oil and gas reservoir is helpful to improve the recovery efficiency of oil and gas.The mosaic shielding drilling fluid system using mosaic blocker to block reservoir pore,through this way can prevent drilling fluid and solid phase particles into oil and gas reservoir,and ultimately achieved the purpose of the protection of oil and gas reservoirs.Using acrylamide(AM),2-acrylamide-2-methylpro panesulfonic acid(AMPS)and inorganic reagents A as raw materials to synthesis a new mosaic shielding agent.Determining the optimum synthesis conditions of the mosaic shielding agent by single factor experiment and evaluating its performance.The experiment results showed that the optimum synthesis conditions of the mosaic screening agent were the concentration of monomer was 30%,the reaction temperature was 40 ?,the system pH was 7-8,the concentration of crosslinker agent was 0.04%,the concentration of initiator was 0.6%,the ratio of monomer was n(AM):n(AMPS)=6:1 and the concentration of inorganic reagents A was 50%,The mosaic shielding agent has good sealing properties and fluid loss properties.0,5%of the mosaic screening agent,the depth of invasion in 40-60 mesh sand layer was 5.9cm and in 80-100 mesh sand layer was 2.3cm,the API fluid loss was 8.5ml.If the mosaic screening agent,sulfonated asphalt and LV-CMC were compounded which could significantly improve the sealing properties and fluid loss properties,this explained that these three substances had good synergistic interaction which could prevent the drilling fluid and the solid particles to invade the oil and gas reservoir porosity.This paper describes the use of free radical solution polymerization,with acrylamide,2-acrylamide-2-methylpro panesulfonic acid,sodium p-styrenesulfonate(SSS)and methacryloxyethyltrimethyl ammonium chloride(DMC)as raw materials to synthesis the tackifier used for drilling fluids.Determining the optimal synthesis conditions of the tackifier by single factor and orthogonal experiment.Characterizing the polymer molecular group use infrared spectroscopy and evaluating the performance of thickening,heat resistance,salt resistance,stability and fluid loss performance of product.The experiment results showed that the tackifier had the best performance when the reaction conditions were the concentration of monomer was 37.5%,the ratio of monomer was n(SSS):n(AMPS):n(AM):n(DMC)=1.5:4.5:9:1,the reaction temperature was 45 ?,the concentration of initiator was 0.75%and the system pH was 9.Under this synthesis condition,the polymer had better performance of conversion rate,temperature resistance,salt resistance,rapid increase viscosity,stability,fluid loss and clay inhibition.The polymer had better compatibility with other additives in drilling fluids.The result of IR spectra showed that the synthetic polymer was AM/AMPS/SSS/DMC quaternary copolymer.Added the new mosaic shielding agent and tackifier into the traditional solid-free drilling fluid system to preparation a new type of mosaic shielding drilling fluid system,and evaluated the performance of the drilling fluid system in laboratory.The experiment results showed that the drilling fluid system had good stain resistance,increased resistance,blocking resistance,inhibition and anti-collapse properties,which could effectively inhibit shale hydration expansion,to prevent wall collapse,and ultimately achieved the purpose of the protection of oil and gas reservoirs.