为分析井径非线性变化对油气井注水泥顶替效率的影响,利用 W-M 分形函数、体积填充等理论,研究变井径环空几何形态表征及注水泥顶替效率计算,建立实测井径曲线的分形函数特征参数计算方法及变井径环空顶替流动分析模型,开展注水泥顶替流动数值模拟.结果表明:变井径环空的顶替效率低于均匀井径环空的顶替效率;标度参数、分形维数增大,井壁壁面凸起、凹陷高度增大,不规则程度增高,顶替效率降低;高标度参数、高分形维数范围内,顶替效率降低幅度高,顶替效率相对变化率大;顶替注入流速增大,顶替效率相对变化率减小;井斜角增大,顶替效率相对变化率增大;计算顶替效率时,当标度参数、分形维数低于阈值时,可将井眼环空近似考虑为均匀井径环空,而当标度参数、分形维数较高时,采用均匀井径环空简化处理会造成很大偏差;工程中,应注意处理计算模型选择及有效解决顶替效率问题.该结果为解决注水泥顶替效率计算的准确性、推进科学化固井设计与施工提供基础.

为有效提高石油钻井过程中井壁稳定性预测及分析可靠性,深入对比分析了3种常用井壁稳定模型,包括传统Kirsch 模型、常规孔隙弹性模型及双孔介质孔隙弹性模型.结果 表明:运用传统Kirsch模型,结合Mogi-Coulomb强度破坏准则,能够成功预测合理钻井液密度,但该模型仅能运用于稳定状态;常规孔隙弹性模型能有效地解释井壁失稳延迟现象以及井壁内部起裂现象,能成功应用于瞬时压力传递状态;双孔介质孔隙弹性模型所需参数繁多,目前不适合现场实际应用.基于现场实际钻井情况,将传统Kirsch模型和常规孔隙弹性模型协同使用,可灵活选择合理钻井液密度,有效预防井壁坍塌.研究成果可有效指导钻井现场井壁应力模型选择和井壁稳定分析,为安全高效钻井提供可靠保证.

致密砂岩储层具有低孔低渗的特征,水平井多裂缝压裂是致密砂岩储层油气增产的重要手段,合理预测裂缝扩展趋势是进行水力压裂开采的关键.为了准确认识水平井多裂缝压裂过程中尖端应力场变化,综合考虑地应力分布、井筒内压等因素,建立二维均质流固耦合有限元数值分析模型.模拟了致密砂岩储层不同裂缝半长、不同裂缝条数、不同裂缝间距及不同裂缝位置的应力场,进一步分析裂缝尖端应力干扰情况.结果表明,裂缝尖端附近存在明显的应力干扰现象,多裂缝同时压裂时,裂缝半长越长,裂缝条数越多,裂缝间距越小,应力干扰现象越明显.中间位置裂缝应力受附近裂缝的应力干扰,裂缝尖端应力集中值明显降低,不利于裂缝延伸和扩展,两侧裂缝尖端的应力集中有所增加.该研究深入认识水平井多裂缝压裂裂缝起裂和延伸机制,对制定压裂方案具有一定的指导意义.

地层类型制约地应力对固井水泥环的力学作用方式,明确地层类型对水泥环应力和结构完整性的影响特征,是建立井筒完整性保障技术的基础.以蠕变、弹性、刚性地层为研究对象,建立套管—水泥环—地层固结体有限元力学模型,分析地层类型、施工项目等对水泥环界面应力的影响.结果表明:蠕变地层中,地应力增加,界面接触压力增大;弹性、刚性地层中,地应力对界面应力无影响.蠕变、弹性地层中,地层弹性模量对界面应力的影响与地层、应力类型有关;刚性地层中,地层弹性模量对界面应力无影响.弹性地层中,加载时,水泥环易发生周向拉伸破坏,危险部位为窄间隙内界面.套管试压施工时,存在水泥环拉伸破坏的危险,危险井段为井口及深部弹性地层井段;储气库井注气施工时,存在的主要危险为加载过程中弹性地层井段水泥环本体拉裂破坏.

In order to determine the method of protecting the cement sheath structural integrity in oil and gas wells, the finite element mechanics models of the Casing-Cement sheath-Stratum Combination Body (CCSCB) were established based on different stratum action mechanism. The effect of stratum type, well depth, crustal stress and stratum elastic modulus on the interface stress and structural integrity of cement sheath were researched. The results show that, in the creep stratum, the interface contact pressure of cement sheath increase and the circumferential stresses reduce with the increase of crustal stress. There is no effect of the crustal stress on the interface stress in the elastic and rigid stratum. In elastic stratum and low crustal stress creep stratum, circumferential tensile stress would be generated at cement sheath when loading. The cement sheath is easy to crack by this tensile stress and the structural integrity is destroyed when the load was higher. The effect of stratum elastic modulus on the interface stress is related to the stratum and stress type. There is no influence of the elastic modulus on the interface stresses in the rigid stratum. The influence of the elastic modulus on the interface contact pressure is obvious in the elastic stratum, and the effect on the circumferential stress is obvious in the creep stratum.

钻井工程中,最重要的一步就是固井,固井质量的好坏影响到合理开发油气资源的能力以及保证油气井寿命的关键.而影响到固井质量的主要因素便是井眼的清洁程度.随钻钻井液被水泥浆顶替干净的程度与水泥环是否具有长期的稳定的密封性能是保证固井顶替效率的关键问题.净替是保证水泥环密封性能的关键因素,也是保证水泥环密封好坏的先决条件,因此,只有有效的把钻井液以及产生的粘附泥饼驱替完全才能保证水泥浆的固井界面质量,进而获得良好的固井顶替效率,从而达到良好的水泥环密封性能.泥饼的性能决定着泥饼是否容易剥落,而泥饼性能是由钻井液决定的,良好的钻井液体系在钻进过程中形成的泥饼更容易被驱替.本文主要采取流体力学里的边层流理论对几种不同的钻井液进行评价,从中选取优良的钻井液体系,提高泥饼的驱替效率.

随着石油院校课程改革的不断深入,实践类课程考核的重要性逐渐得到认可,但是实践类课程依然存在重理论轻实践和教学体系不完整的弊端.若要使石油院校能适应社会发展需要和学生自身发展的需要,实践类课程考核改革迫在眉睫.

For reasonable choice of mechanical parameters and keeping long-term sealing performance of cement sheath, effect laws of yield strength and elastic modulus on the interface stress of cement sheath at well head were researched. Finite element mechanical model of the casing-cement sheath-stratum combination was established. Damage conditions of cement sheath structural integrity were analyzed. Results showed that every interface stress increased with the increase of the yield strength while cement sheath yielding deformation occurred. And the yield strength could not affect all interface stresses while the deformation was elastic. For lower elastic modulus, elastic deformation occurred in cement sheath and every interface stress increased with the increase of elastic modulus. For high elastic modulus, Cement sheath was partially or fully yielded. With the increase of elastic modulus, the interface contact stress increased, the inner interface circumferential stress decreased, and the interface contact stress was turned into tensile stress after unloading.

To identify optimal mechanical parameters and achieve reliable sealing performances of cement sheath, impact of yield strength, elastic modulus, load of cement sheath on interfacial stress and mode of destruction has been studied, and mechanical adapt-ability among strength, elastic modulus and load have been reviewed, based on the finite-element mechanical model representing the in-corporation of casing-cement sheath-formation, in the creep formation at different well depths. Research results show the cement sheath around wellhead is susceptible to circumstantial stretching with load in casing, whereas the downhole cement sheath is susceptible to yield and high compressive stresses. During loading, cement sheath may have elastic deformation, whereas yield strength of the cement sheath may produce no impact on various stresses on interface. At the same time, various stresses on interface may increase with the increase of elastic modulus. When the cement sheath experiences yield deformation, yield strength of the cement sheath may increase, together with the increase in various stresses on interface. When elastic modulus increases, interfacial contact pressure may increase too, whereas the circumferential stress on internal surface may decrease. During unloading, cement sheath around the wellhead may susceptible to tearing of cementation interface. Generally speaking, cement sheaths have low elastic modulus, moderate yield strength, high tensile strength, and high carrying capacity in high cementation interfacial strength.

To design oil well cement paste system and ensure well cementation quality of adjustment well in work area of tertiary oil recovery (EOR), the composition, microstructure and strength of cement paste matrix eroded by producing water were tested and studied by HTHP Curing Chamber, HTHP corrosion tester, X-ray diffraction, scanning electron microscope (SEM), universal testing compressor and some other laboratory equipment according to the condition that producing water contains sulfate (SO42-) and bicarbonate (HCO3-). The corrosion law and mechanism of oil well cement paste matrix were analyzed. The problem for designing corrosion resistance oil well cement paste system was investigated. The corrosion law and mechanism of oil well cement paste matrix by SO42- and HCO3- were raised. The corrosion resistant oil well cement paste system was designed, which was suitable to the adjustment well in area of EOR in Daqing. The results show that the compositions of cement paste matrix changed after corrosion by SO42- and HCO3- for a long term. The secondary gypsum, ettringite and calcite were produced, which changed the microstructures and declined the compressive strength of cement paste matrix. The change degree of compressive strength of cement paste matrix was affected by corrosion media concentration, corrosion time and other conditions. The higher concentration of corrosion media and the longer of corrosion time were, the greater decline of cement strength occurred. The formula of corrosion resistance oil well cement paste system was designed, for which the high sulfate resistant cement as architectural substrate and the PZW as admixtures were used to improve the strength and penetration resistance ability of cement.

本文在阐述了海洋油气工程是全国石油院校开设的新专业,在当今低油价形势下面临着机遇和挑战.本文从专业改革和人才培养、改革教师培养等方面,讨论了东北石油大学海洋油气工程专业的一些做法和经验,分析了新形势下海洋油气工程专业的发展动向,尤其是海洋油气工程专业建设和多元化发展提出了一些建议,如加强产学研一体化,动用多种手段强化专业学生的实践能力.

本文分析了应用型本科人才的特点,探索了构建以能力培养为重心的应用型本科人才培养的培养模式,提出了办学特色是应用型本科教育发展的生命线,对于深化应用型本科院校的教学改革,培养高素质的应用型本科人才具有重要的意义.

为了解决抗高温高密度油基钻井液存在的静态沉降稳定性与动态沉降稳定性难以控制的技术难题,采用改进的VST沉降测试法对抗高温高密度油基钻井液的动态沉降稳定性进行了测量,分析了有机土、提切剂、润湿剂以及提切剂与有机土配比对钻井液沉降稳定性及流变性的影响.结果表明,有机土加量越大,钻井液静态与动态沉降稳定性越好,密度差越小,但钻井液黏度越高;提切剂与有机土达到合理配比时,可以提高钻井液沉降稳定性;抗200℃、密度为2.0 g/cm3全油基钻井液优化配方为:有机土加量为3.5％～4.5％,提切剂加量为0.25％～0.3％,提切剂与有机土加量最佳配比为1∶(17～18),润湿剂加量为2.5％.

Carbon dioxide CO2could corrode the oil well cement paste matrix under agreeable moisture and pressure condition in deep oil wells, which could decrease the compressive strength and damage the annular seal reliability of cement paste matrix. The problem of oil well cement paste matrix corrosion by CO2was researched in the paper for obtain the feasible corrosion prevention technical measures. The microstructure and compressive strength of corroded cement paste matrix were examined by scanning electron microscopeSEMand strength test instrument etc. under different corrosion conditions. The mechanism and effect law of corrosion on oil well cement paste matrix by CO2were analyzed. And the suitable method to protect CO2corrosion in deep oil wells was explored. The results show that the corrosion mechanism of cement paste matrix by CO2was that the wetting phase CO2could generate chemical reaction with original hydration products produced from cement hydration, which CaCO3were developed and the original composition and microstructure of cement paste matrix were destroyed. The compressive strength of corrosion cement paste matrix always was lower than that of un-corrosion cement paste matrix. The compressive strength of corrosion cement paste matrix decreased with increase of curing temperature and differential pressure. The corroded degree of cement paste matrix was intimately related with the compositions of cement slurry. Developing and design anti-corrosive cement slurry should base on effectively improving the compact degree and original strength of cement paste matrix. The compounding additive R designed in the paper could effectively improve the anti-corrosive ability of cement slurry.

The compressive strength of oil well cement would be damaged by high temperature in deep oil wells, which was caused by the obvious change of the components and microstructure of cement hydration products. The adaptability of common oil well cement for cementing under higher temperatures was confined by above reasons. Characteristics of development and change of compressive strength of Class G oil well cement were studied under different temperatures by using Static Gel Strength Analyzer and High Temperature-High Pressure curing chamber. The influence law of temperature and silica sands on compressive strength was analyzed. The results showed that the critical temperatures at which the compressive strength begun to decline were about 110°C and 150°C respectively; The compressive strength increased with curing time during the initial period and would reduced after it reached a certain value when temperature exceeded 110°C; For cement with silica sands, the compressive strength development trend was in the shape of two-stage form with increase of curing time within the range of 110~150°C, but for 160~200°C temperature range the development form was in the shape of single stage; The reasonable amounts of silica sands which would be added to cement slurry to enhance the compressive strength of hardening paste were determined to be 30%~40%.

Leakage creates extreme damage to oil and gas drilling and well cementation.Aiming at the problem that the leakage layer information cannot be figure out through existing calculation model with the on-site data,starting from stretching back leakage process,calculation model of permeable leakage layer depth and pressure was analyzed and established by utilizing non-Newtonian fluid mechanic and seepage mechanics.Then we established functional relation between leakage depth and total amount of liquid leakage by analyzing the relation of leakage occurrence time,leakage amount of drilling fluid and bits footage;and figure out the function relationship among leakage pressure,leakage flow and thickness of leakage layer according to the permeability loss mechanism.Therefore,a new computation model which calculates the leakage depth and pressure was put forward and was applied to a particular block in some oil field to analyze the leakage problems.This method provides the basis not only for determining the leakage layer information accurately,but also for selecting and designing drilling fluid system,cement slurry and parameters of drilling and cementing reasonably.

"卓越计划"作为工程教育改革的突破口,将培养造就一大批创新能力强、适应经济社会发展需要的高质量各类型工程技术人才。东北石油大学作为石油行业院校,开展了本科层次的卓越计划实施工作,对试点专业的培养方案、课程结构、教师队伍建设、管理体系等进行了深入的研究与实践。

In the process of the oil and gas well operations such as casing pressure test,fracturing,etc.,casing-cement ring-strata cementing combination will have stress and deformation response.Under the condition of high load,the cement ring body damage,cementing interface tear,and other forms of structural failure may occur,which may make the effect of cement ring sealing worsen.The casing-cement ring-strata cementing combination finite element mechanics model was established by using the mechanics theory and finite element theory in the paper.The impact of elastic parameters of cement on the casing-cement ring-strata cementing combination structural integrity was analyzed.The results showed that,when the elastic modulus of cement ring was smaller,the deformability was better,and cement stone was more difficult to be hardness crushed after load,while the tear resistance was better after unload;The smaller the poisson ratio was,the harder the cement was to be crushed under the geological conditions of high in-situ stress.The larger the poisson ratio was,the harder the cementation interface was to be tore under the geological conditions of low in-situ stress.The optimization of cement ring elastic perameters should be based on specific circumstances such as cementing well depth in the comprehensive consideration of loading and unloading methods in engineering designing.

The corrosion products,microstructure and compressive strength of corroded cement matrix were examined by using X-ray diffraction(XRD),scanning electron microscopy(SEM) and strength test instrument.Corrosion of oil well cement stone by sulfate(SO42) and bicarbonate(HCO3) during enhanced oil recovery(EOR) in adjustment wells was analyzed.The erosive effects on the compressive strength were studied to provide theoretical foundation for reasonably designing corrosion resistance cement system.The results show that the main corrosive products of cement cooperatively eroded by SO42 and HCO3 were gypsum,ettringite and calcite under the temperature between 38 ~60 ℃,which has changed the material composition and microstructure of cement.Otherwise,the compressive strength of cement stone eroded by both of SO42 and HCO3 were much lower than that singly eroded by SO42 or HCO3 for all samples.When the corrosion time reached or exceeded 21 d,the compressive strength of corrosive cement was lower than that of un-corroded stone.The compressive strength of corrosive cement paste matrix precipitously declined with the increase of corrosion time and concentration of blend liquid of SO42 and HCO3.When the corrosion time was within 14 d,compressive strength of the corrosive cement paste matrix increased with the rise of corrosion temperature.And when the cement was eroded over than 21 d,compressive strength decreased with the increase of temperature.