Development Of Novel High Temperature-Resistance Oilwell Cement Retarder

With gradually reducing of easily exploited and recoverable reserves of oil andgas, exploration and development of oil and gas field have been faced to deep well,ultra-deep well and complex well. The complexity of target stratum’s geologicconditions has brought a lot of difficulties and challenges to cementing engineering,and high temperature cement slurry technology plays an important role in cementingengineering. Therefore, with increasing of the bottom hole temperature and pressure,some high-temperature oilwell cement retarders should be added to the cement slurrysystem so as to control the thickening properties of cement slurry, and ensure thesafety of cementing construction. Nowadays, in some extent, domestic retarders stillhave some defects, such as the narrowly applicable temperature range, the poor high-temperature retarding properties, the strong high temperature dilution, and easy tocause the abnormal gel of cement slurry, and so on, which would have brought manyinconveniences to the cementing operation.In this paper, aiming at the above-mentioned problems of oilwell cement retarder,we will contact the molecular mechanism of the polymer and the hydration process ofoilwell cement to design a new-style retarder, and which is in the basis of existingpolymeric retarder, and AMPS (2-acrylamide-2-methyl propane sulfonic acid) as themain chain, and carboxylic functional groups as main retarding groups, and throughthe introduction of new polymerization monomer in order to design the polymericmolecular structure. Besides, the polymeric retarders are prepared by free-radicalaqueous solution polymerization, and in the process, through the scientific orthogonalexperiment and the comparative study of the polymer properties, we ha ve finallydeveloped a new-style polymer retarder which has good comprehensive propertiesand temperature-resistance by selecting the optimum ingredient and synthesis processof polymers and a lot of laboratory experiments and performance evaluations, whichis named GWH-300L.In this paper, the molecular structure of high-temperature retarder GWH-300L ischaracterized by infrared testing, and the temperature-resistance performance ischaracterized by DSC and TG spectra, as well as there is the comprehensiveperformance evaluation of of cement slurry. The results of IR spectra indicate that allof the polymerization monomers are involved in the copolymerization reaction, andthe results of DSC and TG spectrum show that the retarder GWH-300L has good temperature-resistance performance, which assumes that there are not obvious loss ofheat and quality until266degrees Celsius. The results of comprehensive performanceevaluation of the polymer retarder GWH-300L show that its performance is stability,and its wide applicable temperature range determines that it can effectively adjust thethickening time of cement slurry among the range of70-200degrees Celsius; thepolymeric retarder has the good compatibility with the other oilwell cement additivesand the different kind of oilwell cement. The cement slurry system containing theretarder GWH-300L has a good comprehensive properties, such as the rapiddevelopment of the early-stage compressive strength of cement stone, and nosuper-retarded and long-termed dis-solidified phenomenon on the top of cement slurryin deep and ultra-deep well with long cementing intervals and large temperaturedifference, and meeting the need of cementing for temperature difference with60-130degrees Celsius as well. Meanwhile, the polymer retarder GWH-300L can beapplicable for high density, general density and low density cement slurry system, andcan satisfy the cementing requirements of high temperature cement slurry systems indeep, ultra-deep wells, and complex well cementing operations, as well as in deep andultra-deep wells with large temperature difference and long cementing intervals,which has a good application prospect.