非均质油藏负压钻井渗透率剖面计算模型参数敏感性分析

负压钻井减小甚至避免钻井液侵入污染,因此近年来负压钻井技术越来越得到重用。在钻井工程中,为准确调整钻井液配比以确保井底压力低于油藏压力,需准确计算井筒流入的液量,这使得水平井钻井过程中渗透率剖面的估算尤为重要。地层非均质性对渗透率剖面计算影响较大,本文对非均质油藏参数进行了敏感性分析。     

一种钻井液滤液侵入储层深度的评价方法

本文利用高温高压动态滤失仪测试了不同时间钻井液污染岩心的滤失量,拟合得到滤失量跟时间平方根的线性方程,由此可计算出该钻井液体系在储层的滤失体积,而此滤失体积跟被污染储层的孔隙体积相等,据此可计算出滤液的侵入深度。计算公式表明:钻井液滤液侵入储层的深度与泥饼的渗透率、固体含量因素、渗滤压差、滤液粘度的复合影响参数及储层孔隙度、井眼半径有关。利用此方法评价了NB31-1-3H井和上海残雪北区块储层侵入深度,结果显示无固相弱凝胶钻井液体系侵入深度浅,具有较好的储层保护效果。     

钻井液滤液侵入储层深度的评价方法

本文利用高温高压动态滤失仪测试了不同时间钻井液污染岩心的滤失量,拟合得到滤失量跟时间平方根的线性方程,由此可计算出该钻井液体系在储层的滤失体积,而此滤失体积跟被污染储层的孔隙体积相等,据此可计算出滤液的侵入深度。计算公式表明:钻井液滤液侵入储层的深度与泥饼的渗透率、固体含量因素、渗滤压差、滤液粘度的复合影响参数及储层孔隙度、井眼半径有关。利用此方法评价了NB31-1-3H井和上海残雪北区块储层侵入深度,结果显示无固相弱凝胶钻井液体系侵入深度浅,具有较好的储层保护效果。     

影响钻井液封堵性能因素研究

当钻井液与井壁地层接触,如果钻井液泥饼质量和封堵性能不好,滤液侵入地层会导致孔隙压力升高和地层岩石力学性质发生变化。由于孔隙压力升高和地层岩石力学性质的变化,改变了井筒围岩的应力分布,引起井壁岩石强度的降低,导致地层坍塌压力的升高,当井壁岩石所受到的周向应力超过岩石的剪切强度时,就会发生井壁坍塌。可见提高钻井液封堵性能,减少滤液侵入,有利于抑制地层水化,控制井壁坍塌压力的升高,保持井壁稳定。本文从室内实验着手,开展影响钻井液封堵因素的研究,通过大量实验得出钻井液对地层的封堵效果受以下等因素控制。     

钻井液侵入的数值模拟与实验研究

本研究通过物理模拟来验证数值模拟,证实在钻井液动态侵入条件下,地层电阻率与地层参数、流体性质以及测井时间有关;储层物性越好受到泥浆固相颗粒的污染越严重,滤液侵入越浅;储层含水饱和度越高,滤液侵入速度越快。通过对钻井液侵入数值模拟和物理模拟的结合研究,开展钻井液侵入对储层电阻率测井响应变化规律的探索。     

沿着水平井钻井液侵入对储层污染评价

钻井液侵入会对油层造成不同程度的污染,一方面使油层孔隙堵塞,另一方面钻井液侵入后由于流体的饱和度发生变化后导致相对渗透率下降,都将导致油井产量降低。因此,必须对水平井井筒周围的污染区进行污染评价。运用有限元数值模拟方法计算两相渗流中沿水平井钻井液的侵入深度,将污染区含水饱和度和相对渗透率曲线相结合,计算出污染区平均渗透率及表皮系数。通过单因素分析的方法研究钻井液侵入对水平井近井筒油层的污染程度与泥浆粘度、正压差的关系。泥浆粘度和污染程度关系的研究表明,四个泥浆粘度方案中,随着泥浆粘度的增加,污染程度变弱。方案一较方案二的表皮系数高50.7%,方案二较方案三高48.2%,方案三较方案四高36.5%。正压差和污染程度关系的研究表明,随着正压差的增加,污染程度变强。正压差1、3 MPa对应的表皮系数分别为0.039、2.003,正压差3 MPa较正压差1 MPa表皮系数增加显著。     

超低渗透钻井液工艺技术分析

随着钻井过程中遇到的地层复杂性增加,在使用常规钻井月钻井时会出现井眼液注压力较地层孔隙压力高的情况,造成地钻井液对地层的侵入,降低了油气层的渗透率。研究超低渗透钻井液的相关特点、机理以及关键技术会更有实际意义。     

钻井液侵入下的阵列侧向测井正演响应特征

钻井液侵入原始地层必将引起井周介质的电阻率的变化,进而使得阵列侧向仪器所测得的视电阻率失真,无法正确对储层流体的性质进行识别,因此研究钻井液侵入对阵列侧向仪器响应的影响具有十分重要的理论与实际价值.利用两项渗流方程结合有限元数值模拟技术,直接对钻井液侵入后的模型模拟阵列侧向测井的响应,定量分析了低侵条件下侵入时间、井柱与地层压力差、泥饼渗透率、含水饱和度、矿化度差异等因素对阵列侧向正演响应研究的影响.结果表明:钻井液侵入严重影响了阵列侧向测井响应,阵列侧向测井在钻井液侵入0.1 d时,4种不同探测模式下的视电阻率值R1、R2、R3、R4相较于未侵入时分别下降了39.8％、30％、24％、17％.钻井液侵入1 d、井柱与地层压力差?pd为2 MPa时,R1、R2、R3、R4相较于未侵入时分别下降了31％、23％、17％、8％;在地层含水饱和度达到40％时,R1视电阻率值下降了76％,R2、R3、R4视电阻率值分别下降了60％、56％、40％.     

一种高温高压钻井液的性能评价及现场应用

钻井液抗温能力差,高温高压地层钻井频繁出现井漏、井壁失稳、机械钻速慢等复杂情况。室内评价了低固相抗高温DURATHERM钻井液的抗温性能、封堵性能、抑制性能及储层保护性能。180℃高温热滚实验前后流变性变化幅度较低,在10cm距离内可有效封堵模拟储层渗透率的砂岩柱;膨胀实验中膨胀率6%,与饱和氯化钾溶液相当;侵入地层岩心后反排渗透率为原始渗透率92.7%。针对高温高压地层特点,提出DURATHERM钻井液现场应用措施。现场应用表明DURATHERM钻井液适用于高温高压钻井。     

泥饼渗透率影响因素研究

页岩气水平井钻进过程中,由钻井液失水形成泥饼质量的好坏会直接影响钻井生产效率,同时也影响井壁稳定性。通过制备泥饼,利用高温高压失水仪来考察钠膨润土、不同种类加重剂以及不同添加剂的质量分数对泥饼渗透率的影响。实验数据表明,从经济性和效果来看,钠膨润土质量分数为8%时,泥饼渗透率及厚度处于较低值,且变化趋势不明显,可视泥饼质量较佳;当重晶石质量分数在固相颗粒90%以下时,泥饼渗透率随质量分数增加而减小,当重晶石质量分数超过90%时,泥饼渗透率与质量分数呈正相关性;随着无机盐处理剂NaCl和KCl质量分数的增加,泥饼渗透率和厚度有着不同程度变化,且均呈正相关性;当重晶石质量分数为泥浆质量分数的80%,10μm碳酸钙质量分数为20%,6μm碳酸钙质量分数为6%时,泥饼的渗透率达到最低。分散剂加入后,会使黏土颗粒之间不易发生絮聚,同时增强颗粒间静电斥力,改变其表面亲水性,使黏土颗粒均匀地分散在水中,综合作用下导致泥饼渗透率降低。降滤失剂、稀释剂和包被剂都对降低泥饼渗透率起到一定作用。通过对泥饼渗透率影响因素研究,为现场施工过程中钻井液剂的加量优选提供数据支持。     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.