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

Well cementing is one of most important process of oil and gas exploitation and thefluid loss additive play a very critical role in cementing. With the increase of thehigh-temperature and deep well, it demands the fluid loss additive have bettercomperehensive performance. At present, the normal fluid loss additive in China,which often has relatively poor ability of salt-tolerance and temperature-resistance, iseasy to hydrolyze with the increase of temperature resulting in far delayedsolidification of cement slurry, so it is hard to satisfy the needs of cementing incomplicated stratums. What is more, the cement slurry prepared mainly by polymericfluid loss additive often presents poorly comprehensive properties at high temperaturesuch as high filtration, settlement at high temperature, the bulge of thickening curve inconsistency test and so on.Considering the problems above, the fluid loss additive was preliminarysynthesized by the method of radical polymerization in aqueous solution according tothe design of molecular structure.Through the test, the polymeric structure acquiredby the monomers of AMPS, DMAA and novel XX was chosen. Then lots of sampleswere prepared based on the structure and the effects of reaction conditions are studied.Finally, the optimal formula of the temperature-resistant fluid loss additive H-1wasacquired.Via the characterization and evaluation of application performance for H-1，theresults show that the polymer with the structure of all the monomers has a excellentthermal stability and its relative molecular mass is about6.03×10~5. And it is showedthat the H-1has strong ability of salt-tolerance and temperature-resistance. The APIloss can be controlled below100mL at180℃and in saturated brine cement slurry.And the problem of hydrolysis due to high temperature and the bulge of thickeningcurve in consistency test could be solved with H-1. What′s more, the cement slurryprepared mainly by H-1presents good comprehensive properties such as goodflowability, low filtration, rapid development of strength in low temperature,adjustable thickening time, high compressive strength and so on. The cementingquality of Well Chengu1-3and Shen308in Liao He oilfield are superior after using the fluid loss additive H-1.Furthermore, the difficult problem of settlement at high temperature was studiedbased on the fluid loss additive H-1. Through the experiment, it is showed that theproblem of settlement at high temperature could be relieved by the method of addingcrosslinking agent, decreasing the content of dispersive group and optimizing thestructure of molecule via introducing special monomers.