油井水泥复合增韧剂FD性能研究

Performance Properties of Compound Flexibility Agent FD for Oilwell Cement

所研制的油井水泥复合增韧剂FD由直径10～12μm、长4～7mm的无机纤维F和粒径150～230μm的细切合成纤维D按13:2的质量比复合而成.F在一定掺量下可提高水泥石的抗折强度、抗冲击功(掺量0.5%～2.0%,BWOC)和抗压强度(掺量～1.0%),D在掺量0.05%～0.3%时可提高水泥石抗冲击功,使抗压强度下降,不影响抗折强度.掺入1.5%FD使3个简单配方水泥石抗折、抗压强度和抗冲击功分别增长17%～30%、11%～19%、33%～45%,弹性模量降低7.4%～18%;3个配方水泥浆的滤失量、析水率、稠化时间、流动性均满足固井施工要求;当配方中掺有降滤失剂和减阻剂时,稠化曲线规范.基于水泥石断面电镜照片和文献资料讨论了FD这一纤维/微粒复合物增韧水泥石的机理.用压汞法测定,掺FD水泥石的孔隙率由33.5%降至30.0%,直径＞10-1μm的有害孔比例由22.4%降至19.5%,这是FD增强水泥石的机理.图5表4参5.

Compound flexibility agent FD for oilwell cement is composed of an inorganic fiber, F, 10-12μm in diameter and 4--7 mm long and a cut synthetic fiber, D, of particle size 150---230μm in mass ratio 13：2. Fiber F increases flexible strength （FS） and absorbed in fracture energy （AiFE） at dosage 0.5--2.0% （BWOC） and compression strength （CS） at dosage-1.0% and fiber D at dosage 0.05--0.3% increases AiFE, decreases CS and does not change FS of hardened cement of grade G. For 3 formulated cement samples with 1.5% FD added, the FS, CS, and AiFE are increased by 17--30%, 11--19%, and 33--45% and the modulus of elasticity is decreased by 7.4--18%, respectively; the 3 cement slurries fulfil the cementing operation requirements in filtrate loss, water separation, setting time, and flow ability; the setting curve is conventional in form for an FD treated cement stuffy with a filtrate loss reducer and a friction reducer added. The toughening mechanisms of FD as fiber/particle mixture axe discussed on the basis of fracture surface morphologies and of evidences published else where. According to mercury instruction measurements, introducing FD into cement slurry leads to decrease in porosity of hardened cement from 33.5% to 30.0% and in proportion of damageable pores of diameter 〉 10^-1 μm rom 22.4% to 19.5%, which indicates the reinforcing mechanisms of FD in oilwell cement.