Study Of Novel Low Temperature And Salt-resistant Fluid Loss Additive For Well Cementing

Well cementing is one of the most important processes of oil and gas explorationand exploitation and the cement additive is performing crucial role in cementing. Withthe continuous development of exploration and production technology, the fluid lossadditive should have excellent overall properties. At present, the commonly used fluidloss additive in china has the problems of poor salt tolerance, strong retarding abilityand narrow wide range of temperature application in medium and low temperature;and often present strong dispersive and settlement at high temperature, the poorcomprehensive properties of the fluid loss additive result in hardly satisfy the needs ofcementing in complicated stratums.Considering the problem of fluid loss additive above, considering the design ofmolecular structure, the fluid loss additive was synthesized by the method of radicalpolymerization in aqueous solution. Through the result of test, the copolymerstructure acquired by the monomers of2-acrylamido-2-methyl-propane sulfonic acid(AMPS), acrylamide (AM), acrylic acid (AA) and novel cationic monomer DC werechosen. Then more detailed samples were prepared based on the copolymer structureand the effects of reaction conditions were studied. Finally, the optimal formula andprocess conditions of the medium and low temperature application and salt-resistancefluid loss additive HTF-100L was acquired.The HTF-100L was characterized by Fourier transform infrared spectroscopy andproton nuclear magnetic resonance spectroscopy, and the analysis results revealed thatthe polymer is target product polymerized by all the monomers; the heat resistanceanalysis results reveal that the HTF-100L has excellent heat-resistance property.Via the evaluation of application performance for the fluid loss additive HTF-100L,the result show that HTF-100L have great fluid loss control performance infresh-water slurry and saline-water slurry, the API fluid loss in wide range oftemperature application can be controlled within requirements. The fluid loss additiveshowing weak retarding and less effective on the growth of cement strength under lowtemperature. And the problem of hydrolysis due to high temperature and “hang upsidedown” in thickening time can be solved by HTF-100L. The cement slurry preparedmainly by HTF-100L presents good comprehensive properties such as good rheological properties, low fluid loss, short transition time, rapid development ofstrength in low temperature, high compressive strength and so on, so it can satisfiedthe needs of cementing in different salt concentration, different temperature range anddifferent density of cement slurry and have good application prospects.