Research of dynamic mechanical performance of cement rock

As Daqing Oilfield is developing oil layer with a big potential, the requirement for the quality of well cementation is higher than ever before. Cement rock is a brittle material containing a great number of microcracks and defects. In order to reduce the damage to cement ring and improve sealed cementing property at the interface, it is necessary to conduct research on the modification of the cement rock available. According to the principle of super mixed composite materials, various fillers are added to the ingredients of cement rock.Dynamic fracture toughness of cement rock will be changed under the influence of filler. In order to study the damage mechanism of the cement circle during perforation and carry out comprehensive experiments on preventing and resisting connection, a kind of comprehensive experiment equipment used to simulate perforation and multi-functional equipment for testing the dynamic properties of the material are designed. Experimental study of the dynamical mechanical performance of original and some improved cement rock and experiment used to simulate the well cementation and perforation are carried out. Standard for dynamical mechanical performance of the cement rock with fine impact resistance and mechanical properties of some improved cement rock are also given.

DRK韧性水泥浆体系的研制

为了提高油井水泥环抗射孔、压裂等动态冲击能力,提高水泥环射孔后层间密封能力,进行了提高水泥石韧性试验研究。研制出了抗冲击韧性水泥外加剂。该外加剂主要是在胶联剂的作用下通过高分子聚合物型增韧剂提高水泥石的韧性和变形能力,并在室内进行水泥浆常规性能评价试验基础上,利用材料动态力学性能测试装置和射孔模拟实验装置进行了抗射孔冲击能力的评价试验和现场射孔对比试验。试验表明,DRK韧性水泥浆具有速凝、早强、低失水和“直角稠化”的特性,有利于防止和控制水、气窜的发生,不仅能有效地提高固井质量,而且能够提高水泥环的抗射孔(或压裂)冲击能力,有利于延长油井寿命,提高产能。

纤维与胶乳改善油井水泥石动态力学性能实验

油井水泥石属于脆性材料,其在动态下的力学性能与静态下的情况相比有显著的差异。确定了水泥石的动态力学性能评价参数为水泥石的弹性模量和水泥石的破碎吸收能。利用霍布金森装置对纤维与胶乳改善水泥石在动载条件下的力学性能进行了试验研究,结果表明,纤维和胶乳的加入可使水泥石的弹性模量大幅度降低,使水泥石的破碎吸收能得到提高,动态力学性能得到明显的改善。

油井水泥增韧剂BF的室内研究

针对油井水泥石固有的极限应变小、抗冲击性能差、脆性大的缺点,研制出了以混合短纤维为主要成分的油井水泥增韧剂BF,并对加有BF增韧剂水泥浆的力学性能进行了系统评价,同时还考察了BF增韧剂与油井水泥降失水剂F17B及油井水泥减阻剂USZ的配伍性能。室内实验表明,BF增韧剂能使水泥浆的流动度减小,凝结时间延长,析水率和失水量减小,且BF增韧剂与外加剂USZ和F17B的配伍性良好;BF增韧剂能够显著提高水泥石试样的韧性,使水泥石韧性增长20％,有效降低射孔对水泥环的破坏,改善水泥石的力学性能,抗折强度增长幅度为16％～29％,抗冲击功增量为17％～64％,而且水泥石抗压强度均大干14MPa;BF增韧剂掺量小(2.6％),其增韧效果优于中国现有的油井水泥增塑剂S(掺量为4％)。

提高混凝土抗裂能力的机理分析

本文从界面过渡区结构的改善、水泥石韧性的提高、骨料性能、混凝土强度和外加剂等方面分析了提高混凝土抗裂性能的机理,为高抗裂性混凝土的配制提供了理论依据。

粉煤灰对水泥石冲击韧性的影响及机理

为了研究粉煤灰的参量对水泥基材料抗冲击性能的影响,实验了标准养护龄期分别为1 d、3 d及7 d水泥石在粉煤灰等量取代水泥量为0、12.5%、25%、40%和60%时的冲击韧性,结果表明:1 d和3 d龄期时,粉煤灰降低水泥石的冲击韧性;7 d龄期时,冲击韧性随着粉煤灰掺量的增加而提高;不掺粉煤灰时,水泥石的冲击韧性随着龄期增长而下降,掺粉煤灰时,各掺量下水泥石的冲击韧性均随着龄期增长显著增强。