一种低黏韧性双防低密度水泥浆的室内性能研究

陆丰油田大位移井储层渗透率低、欠压稳，容易发生气窜，造成固井质量不佳，存在底部高温区域沉降稳定性差、易漏等固井技术难题。针对这些难点，室内筛选3M高强抗压中空玻璃微球来降低水泥浆密度为1.4 g·m^-3的同时可以提高水泥石的抗压强度，选用纤维与胶乳混合作为增韧材料，降低了水泥石的渗透率，有效达到目的层增韧防漏的效果。该增韧材料协同防窜剂CT-1和膨胀剂EXP-1，提高水泥石的胶结强度，具有防漏防窜的作用。由上述主要材料协同其他相关水泥浆添加剂构建了一套具有低黏韧性兼具防漏和防窜性能的低密度水泥浆体系，该低密度水泥浆体系具有良好的流变性，自由液为零，且水泥石上部密度和下部密度差值均小于0.03 g·m^-3，可以看出该韧性水泥浆体系具有优异的沉降稳定性能。低黏韧性双防低密度水泥浆具有良好的力学性能，抗压强度达28 MPa，弹性模量小于7 GPa，抗窜强度大于10 MPa·m^-2，且抗窜效果较普通低密度水泥浆抗窜能力提高了81.2%，说明该水泥浆具有较强封隔能力，可以有效提高固井质量。     

低密高强水泥浆体系在绥中36-1油田的应用

绥中36-1油田属于衰竭油藏,长期的开采使地层压力系数降低,井下漏失问题一直是钻井和固井过程中的最大难题,为解决低压易漏井固井的难题,采用低密度高强度水泥浆体系固井。经现场应用表明,低密度高强度水泥浆通过合理调整外加剂的加量,水泥浆的稠化时间和其它性能可任意调节,在温度为40～90℃之间,密度为1.3～1.6g/cm3时,该水泥浆体系稳定,流变性能良好,抗压强度高,失水量低,游离液低,凝结成水泥石后体积不收缩,结构致密,渗透率低并有一定的防窜能力。该水泥浆有效地解决了低压易漏层油气井固井过程中的难点[1],保证了固井施工质量,固井合格率为100%。     

有机硅消泡剂在油井水泥浆中的性能研究

以油井水泥浆的密度恢复率为评价指标,对有机硅消泡剂SK-1进行了性能评价,讨论了SK-1对不同体系的水泥浆的稠化性能、抗压强度、流变性能的影响.结果表明,SK-1在油井水泥浆中具有优良的消泡效果,能使水泥浆的密度恢复90%以上,最佳用量为水泥质量的0.15%～0.2%;加入SK-1不但能显著提高常规密度水泥石和低密度水泥石的抗压强度,而且能增加水泥浆的流动性,对常用水泥浆体系的稠化性能没有不利影响,有利于提高固井质量.     

C级油井水泥在深水固井中的应用前景

针对深水表层固井存在的低温、水泥石强度发展缓慢、浅层流、易漏失等难点,本文对深水固井水泥浆体系中油井水泥的选择进行了相关研究。与G级油井水泥相比,C级油井水泥更容易配制低密度水泥浆,低温条件下水化速度更快,水泥浆稠化时间短,水泥石抗压强度更高。     

微硅低密度固井水泥浆力学强度发展规律研究

固井水泥浆的抗压强度对于评价固井质量至关重要,针对不同微硅掺量与水泥石抗压强度之间的关系展开研究对水泥浆力学强度的发展和预测具有重要的现实意义。探讨了不同掺量微硅对水泥浆力学强度发展的影响规律,结合CT和SEM对对微硅低密度水泥浆的强度发展机理进行了探讨。研究结果表明：微硅对低密度水泥浆的力学强度的发展具有明显的促进作用,微硅掺量越高,促进作用越明显,且随水化龄期的增长,促进效果越显著。抗压强度与微硅掺量具有良好的线性关系,采用该模型可以快速计算水泥石抗压强度,从而可为水泥浆配方推荐和固井现场施工提供参考。     

碳酸钙晶须改善固井水泥浆性能研究

随着油气勘探向深部地层和低渗透油气藏的延伸,对固井水泥浆性能尤其是水泥环的力学性能提出了更高的要求.针对目前固井用纤维所存在的问题,研究了碳酸钙晶须这一无机矿物纤维对固井水泥浆性能的改善作用.实验包括:①晶须水泥浆的流变性和失水量等常规工程性能;②晶须水泥石的1d、3d、7d、14d和28 d抗压强度、抗折强度和劈裂抗拉强度,使用6265型机械性能测试仪,在不破坏水泥试样的情况下测试了水泥石的抗压强度和杨氏模量发展;③使用5265型静胶凝强度测试仪,测试了水泥浆的静胶凝强度发展,以评价其防气窜性能;④晶须水泥石的孔径和渗透率测试;⑤用扫描电镜对水泥石微观形貌进行观察,探讨了增强机理.结果表明:①晶须水泥浆工程性能良好;②碳酸钙晶须显著改善水泥石的力学性能,晶须加量为10％时,水泥石28 d抗压强度、抗折强度和劈裂抗拉强度提高33.34％、45％和39.28％;③碳酸钙晶须水泥杨氏模量发展稳定,静胶凝强度发展迅速,防气窜性能良好;④晶须加量为10％时,孔隙度较空白试样降低23.4％,渗透率下降14.3％;⑤增强机理在于碳酸钙晶须的桥联、控制微裂纹产生和扩展及纤维拔出耗能作用,减缓裂纹的产生和延展.     

漂珠低密度固井水泥石的力学性能研究

以漂珠为减轻材料的低密度水泥浆体系在低压易漏地层的固井工程中得到了广泛的应用。为全面探索漂珠低密度水泥石的力学性能,本文对低密度水泥石在不同温度下的抗压强度、抗拉强度进行测试,模拟井下环境对水泥石进行应力-应变测试,并对其微观形貌和孔径分布进行分析。结果表明：漂珠与水泥具有良好的相容性;漂珠具有抗压强度和刚性不阻裂等性质,致使漂珠低密度水泥石具有较高的抗压强度和较低的抗拉强度;高温养护水泥石的孔径分布较低温养护增大,高温水泥石致密性较低。     

针状硅灰石微粉改善固井水泥浆性能研究

油井水泥是一种脆性材料,其抵抗外力破坏的能力较差,不利于油气井开发.为解决这一问题,研究了一种兼有矿物微粉和纤维特性的硅灰石微粉对油井水泥性能的影响,评价了不同加量的针状硅灰石微粉水泥浆的常规性能、抗压强度、抗折强度、抗冲击强度,并测试了水泥石应力-应变曲线,最后使用扫描电镜对针状硅灰石微粉水泥石微观形貌进行观察.研究结果表明,与纯水泥浆相比,硅灰石微粉加量在0.5％～4％时,流变影响最大时流变仪300转读数大于300,稠化时间最大缩短18 min,失水量最大下降13 mL,养护1 d水泥石气体渗透率最大下降38.3％.养护28 d后,加入4％硅灰石微粉的水泥石较空白水泥石的抗压强度、抗折强度、抗冲击强度分别提高了17.6％、20.9％、21.1％.加入3％硅灰石微粉的水泥石弹性模量比空白试样降低约26.9％.针状硅灰石微粉在水泥石中分散,在水泥石内部形成"搭桥"作用,可在一定程度上阻止水泥石裂纹发生和扩展,起到增强水泥石力学性能的作用.     

短切纤维增强水泥基胶凝材料力学性能研究

为了改善油气井固井用硅酸盐水泥石的性能，通过测试水泥浆工程性能、水泥石力学性能及渗透性，结合SEM和XRD分析其微观结构及水化产物，探讨了两种纤维在增强水泥石力学性能方面的耐温耐久对比及作用机制。结果表明：1.0%的纤维对水泥浆工程性能促进效果最好；90℃下，玄武岩纤维耐温耐久性能较差，在水泥基体中被完全腐蚀，促进水泥水化产物及微裂缝的生成同时增强了水泥石强度，28 d后，水泥石抗压强度相比于空白样提高了16.71%；同龄期下，相比于空白样，耐碱玻璃纤维水泥石抗压强度降低了9.88%，抗折与抗拉强度分别提高了33.43%和23.17%，弹性模量降低了32.38%。表明耐碱玻璃纤维虽然一定程度上抑制了强度的发展，但其能够在水泥基体中稳定存在并能限制微裂缝的产生及扩展，拔出过程中消耗了大量能量，从而提高了水泥石的韧性。     

适合七元矿区煤层气井固井水泥浆的室内研究

本文以水泥浆体系的韧性为前提,水泥石抗压强度为主线,水泥浆体系的稳定性、低失水性为基础,对七元矿区煤层气井固井水泥浆的性能进行了设计与构建,并在水泥浆体系满足性能的基础上尽量降低其的成本,研发了满足煤层气井压裂井固井要求的低弹性模量、低失水、低成本的水泥浆体系,为低渗透压裂井固井施工水泥浆体系的选择提供了一种新途径。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.