The Corrosive Laws Of Oil Well Cement By CO₂ And Applied Research

The CO₂ of turf bed and mixing each other drives CO₂ carried to understand the giving riseto carbonization to the cement ring to corrode in the oil gas construction in the wet environment,leads to that cement sheath the permeability rate becomes and the compressive strength reduces,and brings out the fluid channeling to flow greatly and the wall of an oil well on plasticity stratumstriding collapsing etc the accident, creates hugely economy loses. Therefore how to raise theresisted CO₂ of cement corrosion ability, and has got high opinion of concerned experts, andbecoming the impatient problem in the CO₂ of turf bed in oil-gas production. This text is theapplication background it is deep layer of development gas in Daqing, and cement corrosion lawby CO₂ and anticorrosion slurry system development give first place to that the important articleis marked and the open-minded research.On the base that the capability of the analysis DaqingXuJia defensive district CO₂'s distribution circumstances, stratum water integrant characteristicand CO₂'s physicochemical property, with the imitation XuJia defensive stratum water integrantcharacteristic is the corrosion experiment environment, by HTHP apparatus, energy spectrometerand SEM etc equip, be aimed at the corrosion law and mechanism of cement sheath by CO₂develops ingoing and systematic experiment and theory research;The major corrosion influentialfactor and law of cement sheath by CO₂ is pull out, the results manifest it is major criticalinfluential factor that is the corrosion time, corrosion temperature and CO₂ DP of corrosioncement by CO₂, with the increase of the corrosion time, corrosion temperature and CO₂ DP,compressive strength of cement varying degrees declines,but the strength of cement systemitself grows increases trend, the permeability is also all enlarged.It is announced that corrosionmechanism of cement sheath by CO₂, it is internal displayed that chemical reaction of wet CO₂and cement different hydrated product, thus the original structure and the character of cementstone have been changed;It is established that evaluation criterion of CO₂ corrosion cementstone,it is compressive strength, permeability of cement stone and corrosion depth, and amongthem corrosion depth is visual general embodiment,therefore a large number of experiments ismade in this text is be aimed at corrosion depth, forecast model of corrosion depth is builtutilizing semi-empirical model and non-linear regression;by every evaluation criterion analyzedthe best CO₂ anticorrosive virtue of DC-R cement slurry is optimized, DC-R cement slurry systemis field used in cementing operation of about ten wells in Daqing XuJia defensive district,obtaining approved above-ground construct impact.Research achievements of this text have the important theoretic meaning for furtherresearching corrosion mechanism and influential factors and influential laws;It presents veryimportant practical application value for prolonging oil-gas well's production life and boostingproduction efficiency and avail spreading stimulation treatment of CO₂ miscible displacementtechnique.