盐酸对碳酸盐岩储层渗透率的影响

酸化是油气田开发过程中有效的增产措施之一,可通过酸岩反应改善储层渗透性,但目前酸岩反应的模拟理论较少。为了直观反映酸化对储层渗透性的影响,以盐酸为主体酸,碳酸盐岩为储层,基于多孔介质渗流、传质模型与酸化渗流耦合模型,利用有限元分析的方法,建立酸岩反应的物理-化学耦合模型,模拟了盐酸进入储层后的浓度变化,直观地反映了酸化对储层渗透性的改善程度。结果表明:由于射孔位置渗流速度较大,对流作用使盐酸快速进入地层并发生酸岩反应,致使地层孔隙度增大,渗透率由原始8.1×10~(-4)μm~2增加到2.053×10~(-2)μm~2,储层渗透性得以改善。该方法证实了酸化可以有效增渗,能够为酸化设计和现场施工提供理论指导。     

基于ANSYS-FLOTRAN的水平井筒内温度场分布研究

在水平井注水驱油过程中,地层温度和注水初始条件直接影响到井筒内水温的变化。依据实际驱油作业工况,研究注水过程中流体和地层的传热特点,采用ANSYS-FLOTRAN建立井筒内流体-地层热量的热传递有限元模型,讨论不同注水条件下井筒内水温变化特点。结果表明,当注水温度低于地层温度70oC时,井筒内水温随着作业深度增加而逐渐升高,在200米处水温均接近于70oC。相同注水温度下,注水流量越大,水温上升越慢,可选取作业的深度范围越大。此温度曲线为实际注水驱油作业提供参考和借鉴。     

BZ-51酸化缓速剂的研制

酸化是油井增产、水井增注的重要措施之一.在酸化施工中,所使用的常规酸液,如盐酸与土酸对灰岩和砂岩地层的酸化,由于酸、岩反应速度快,酸的作用距离短,只能消除近井地层的堵塞,达不到疏通深部地层通道从而增产的目的.甚至容易造成近井地带过度酸化,引起溶洞或出砂,破坏地层渗透性,严重影响油井增产、水井增注效果.为此,以不同的原料为起始剂,研制出了系列聚氧丙烯聚氧乙烯醚,筛选出了符合要求的酸化缓速剂.     

关于注CO_2井井筒温度场的模型研究

注二氧化碳提高采收率是一种很具潜力的增油措施,在注入二氧化碳的过程中由于地层和井筒内存在温差,热量会由地层向井筒内传递。主要以注二氧化碳井筒温度场计算模型-注二氧化碳井井筒瞬态温度-压力耦合模型的演变方式为研究目标。     

CO_2碳酸化石灰岩酸解产物回收乙酸及副产沉淀碳酸钙

乙酸酸解石灰石造腔是一种建造地下储库同时环保地开采石灰岩制备沉淀碳酸钙的新方法。通过耦合乙酸酸解石灰石及酸解产物乙酸钙CO2碳酸化的工艺过程,研究了乙酸酸解石灰岩的表面反应动力学和乙酸钙CO2碳酸化的工艺技术条件。采用正交实验分析法,研究了CO2碳酸化反应中乙酸钙浓度、反应温度、CO2压力、反应时间对乙酸钙碳酸化反应制沉淀碳酸钙的影响,并通过正交实验确定了最优化操作条件。实验结果表明,乙酸酸解反应速率主要受乙酸浓度控制。CO2碳酸化反应在当乙酸钙溶液浓度为0.631 mol·L-1,CO2压力为5.0 MPa,温度为80℃,反应时间为50 min时CO2碳酸化效率达到最高(23.13%),生成的沉淀碳酸钙产品各项指标均符合中国国标优级要求。     

水平井砂岩酸化的布酸方法研究

钻完井作业在生产过程中不可避免造成地层污染,大幅降低油气井产能,酸化能以较低成本恢复产能。合理的流体布置方法在酸化设计中是关键因素。尤其在长井段水平井或厚层酸化中,因为渗透率差异、污染程度差异或进酸时间早晚差异,高渗透或污染较轻的地方进酸多,低渗透带或污染严重的地方得不到足够的酸液,酸流入低阻力地层后进一步发生酸岩反应,使酸化不能达到解除所有污染的目的。为解决此问题,本文在对国内外相关研究成果进行调研和分析的基础上,提出了多种布酸方法。     

低渗油田高压注水井在线酸化技术研究与试验

为实现对注水井的酸化解堵及增注降压的效果，保障低渗油田开发的高效性与安全性，对低渗油田高压注水井在线酸化技术进行研究和试验分析。制备复合酸液体系，确定在线酸化施工中的注酸速度与强度等参数，并设计在线监测装置实时监控在线酸化施工，检验结果表明，该复合酸液具有较高的螯合性与沉淀抑制性，具有较高的岩粉溶蚀率；应用该复合酸液实施在线酸化施工，施工后试验注水井的地层吸液性及注水量显著上升，井口油压及施工压力显著下降，增注降压效果明显，可解除注水井储层的堵塞物，为提升低渗油田开发的安全性与高效性提供保障。实验结果表明，所提技术使井口的油压由9.11MPa降到1.71MPa、泵注压力由9.77MPa降到7.51MPa，说明能有效缓解井口油压以及泵注压力，加大整体的施工排量，实现增注降压的目标。     

低渗砂岩油藏深度酸化技术研究

随着油田开发的深入,油井产量面临着衰减,以往大都采用酸化或者压裂的方式进行增产.近年来由于技术的不断提高,各大油田也在不断探索新的增产措施,酸压工艺技术的成熟度越来越高,新型高效深度酸化技术成为了重点研究方向.通过一系列的实验,探究了酸岩反应、酸液配方优选等问题,并将研究的成果应用到现场的油田作业中.运用多氢酸体系进行实验分析,获得了深度酸化处理效果,能够弥补土酸等砂岩储层酸化酸液体系的缺点.与此同时,低渗砂岩油藏深度酸化技术实施效果也受注水井地层参数影响,因此实际应用过程需要结合酸液体系和注水井储层情况.     

空气钻井环空气固两相流三维数值模拟

应用CFD软件对空气钻井环空气固两相流动进行数值模拟研究。模拟结果显示,不同入口速度条件下,压强分布的趋势基本一致,气体入口速度越大,压强速率变化越快;在斜井中,空气和岩屑的速度分布并不均匀,环空区域明显大于近壁面区域,最大流速发生在井筒环空区域上部,当气体流速与岩屑速度接近时,携岩效果并不理想;井筒内岩屑浓度的分布并不相同,环空区域岩屑的平均浓度明显大于近壁面处。     

纳米膜润湿酸化解堵技术的研究与应用

低渗透油田具有储层渗透率低、岩石敏感性强、近井地带易污染堵塞等特点,导致部分水井注水困难或注不进水,而常规酸化解堵药剂无法进入地层微小孔隙,措施增注效果差,为此研究应用了纳米膜润湿酸化解堵技术,利用低浓度、低摩阻、高液量的纳米膜润湿酸化体系,增大药剂处理体积,增加酸岩反应时间,处理地层微小孔隙;同时纳米膜增注剂进入储层微孔道,发生静电吸附,在岩石微孔道壁面形成纳米级的中间润湿型沉积膜,降低渗流阻力,解除水锁,室内实验表明,药剂体系腐蚀速率≤4.8g/m2·h,降阻率≥41.2%,渗透率提高幅度≥41.7%;试验后平均单井注水压力下降4.9MPa,日增注12.4m3,截至目前平均单井已累计增注2472m3,有效的解除地层深部污染堵塞,实现了欠注水井降压增注。     

Acidization—IV: Experimental correlations and techniques for the acidization of sandstone cores

The experimental variables that affect the acidization of sandstone cores in a permeameter are discussed. It was found that as HCl/HF acid mixtures are injected into porous sandstone cores a reaction front between selective minerals and the acid is formed. This reaction front and a corresponding permeability front move through the core with a constant axial velocity. The time for the permeability front to move through the core is defined as the break-through time. The breakthrough time is directly proportional to the core length but inversely proportional to the HF acid concentration and the rate of injection.     

Effect of medium heterogeneities on reactive dissolution of carbonates

The influence of medium heterogeneities on wormhole formation in carbonates is studied using a two-scale continuum model. The model describes the coupling between the transport and reaction processes occurring at the pore and Darcy scales. The medium heterogeneity is represented through initial porosity (or permeability) field by introducing a randomly generated normal distribution of local porosity values. Heterogeneity in the rock is characterized by the magnitude of maximum variation in local porosity value from the average porosity and by the length scale over which this variation occurs. It is found that heterogeneity in a rock affects not only the structure of the patterns formed during reactive dissolution but also the amount of acid required to achieve a given increase in permeability. The volume of acid required decreases as the heterogeneity magnitude or length scale are increased and this is particularly noticeable at high injection rates of acid. At intermediate injection rates, the required acid volume decreases gradually and an optimum value in heterogeneity magnitude may exist. This has been attributed to excessive branching in a pattern when the medium becomes extremely heterogeneous. In addition, the amount of acid required to breakthrough is found to depend on the initial rock porosity and dimensions of the rock being acidized. Finally, a novel way to characterize heterogeneity is defined, where heterogeneity at the core-scale is expressed using a heterogeneity parameter, ? as a product of the heterogeneity magnitude and length scale, and is validated for a given rock type at different injection conditions.     

Characteristics of exothermic reaction fronts in the gasless combustion system

Gasless combustion model of the self-propagating high-temperature synthesis process was numerically studied in the non-adiabatic cylindrical sample. The model equations, which are very stiff in the dimension of length as well as time, were solved using finite difference method on adaptive meshes. Travelling waves with constant pattern were observed for adiabatic systems. For higher values of heat of reaction and activation energy, combustion fronts started to oscillate for adiabatic and non-adiabatic systems. Simple and complex oscillatory fronts were observed. Multi-peak and irregular oscillations were also detected to presumably result in the gasless chaotic combustion. In oscillatory fronts the temperature can overshoot the adiabatic reaction temperature to result in the complete conversion of solid reactant. In the two dimensional non-adiabatic cylindrical sample in the domain of longitudinal and angular directions, oscillatory piston waves were observed. In addition asymmetrical fingering as well as rotating waves were detected for an asymmetrical perturbation. For the adiabatic annulus cylindrical sample, the velocity of propagating fronts increased with time and the temperature overshooted the adiabatic reaction temperature if the sample were ignited from the inside. If the sample were ignited from the outside, the velocity of propagating fronts decreased with time and the temperature again overshooted the adiabatic reaction temperature. For smaller diameter of sample, the temperature increased very slowly with time for inside ignition. The temperature after ignition increased very fast overshooting the adiabatic reaction temperature for outside ignition. After several oscillations, the reaction rate decreased and the region with very slow reaction was established.     

Self-Diverting Acid System with Retarding Function for Heterogeneous Carbonate Reservoirs Stimulation

Matrix acidization, an important technology for reservoir stimulation, has encountered challenges regarding heterogeneity. In addition to not achieving desired results, conventional acidization makes reservoir heterogeneity more prominent. In this study, we investigated the efficacy of a surfactant-based functional acid system for uniform acidization in carbonate reservoirs. The two surfactants used in such acid systems are industrial initial products, which can be converted to a hydrochloride surfactant in hydrochloric acid. The conversion alters viscosity in reaction processes and can slow down reaction rates to allow for deeper rock penetration while at the same time forcing fresh acid into the untreated areas. The acid system can enhance well production considerably. It was found that the surfactant solution exhibited a relatively high viscosity at 90°C and is conducive to acid diverting. The retarding rate of the acid system was found to be up to 48%, allowing for deeper penetration. Parallel core flood testing indicates that the acid system exhibits superior diverting performance when compared to regular acid at 20 wt% HCl.     

Effect of heat transfer on the transient dynamics of temperature swing adsorption process

The effect of radial heat transfer on temperature swing adsorption (TSA) was studied by using an air-drying TSA experiment. The experimental dynamics of water adsorption and thermal regeneration in a fixed bed packed with zeolite 13X were used to evaluate the predicted results from the developed models. One-and two-dimensional models for energy balance with various equations describing internal velocity were compared in terms of the prediction of transient dynamics of TSA. Since the heat effect in adsorption step depended on the isosteric heat of adsorption, a dynamic simulation was performed under adiabatic, near-adiabatic, and constant wall temperature conditions. A comparison between one-and two-dimensional models was also made under near-adiabatic condition, which reflected on the experimental condition. There was little difference between adsorption breakthrough curves predicted by the one- and two-dimensional models because the radial distribution of temperature was negligible at the adsorption step. In the case of the regeneration step, a small difference between two models was expected just at the early period of time because the radial effect disappeared with time. One-dimensional model could provide an adequate prediction of the transient dynamics in this system when the wall energy balance was included.     

载体孔结构对裂解汽油一段加氢Ni/Al2 O3催化剂性能的影响

氧化铝载体的孔结构对裂解汽油一段加氢催化剂性能的影响至关重要。通过优化原粉配比、载体焙烧温度和柠檬酸浓度优化载体孔结构,以获得较大比表面积、大孔容和大孔径的载体。与未优化载体相比,孔体积提高24%,孔径提高40%。在反应器入口温度50℃、反应压力2.6 MPa和体积空速3.0 h~(-1)条件下,使用优化载体制备的催化剂对裂解汽油进行加氢评价试验,结果表明,催化剂稳定性好于参比剂,双烯值稳定在1.5 gI_2·(100g油)~(-1)。     

Effect of mode of agent removal on pore structure of liquid ammonia treated cotton cellulose

The pore structures of three liquid-ammonia-treated cottons were compared via a reverse gel permeation chromatographic technique. Cotton battings were treated with liquid ammonia which was removed by volatilization at ambient temperature or at elevated temperature and by water exchange. Three series of water-soluble solutes were used to study the elution characteristics of whole fiber columns prepared from these battings. The solutes were oligomeric sugars, ethylene glycols, and glymes (ethylene glycol dimethyl ethers) having molecular dimensions in the range of conventional finishing agents for cotton. All three liquid ammonia treatments increased the internal pore volumes accessible to small molecules. The greatest increase was noted when the ammonia was removed by water exchange and the least when volatilization at elevated temperature was employed. Ambient temperature volatilization had an intermediate effect. Decreases in the volumes of large pores were effected by ammonia treatments followed by volatilization at ambient or elevated temperature. Water exchange of the ammonia resulted in an increase in the volume of large pores as well as of the small pores.     

Ce-Cu-Al-O复合金属氧化物吸附剂低温脱除H2S

用共沉淀法制备了一系列Ce-Cu-Al-O复合金属氧化物吸附剂,用于低温下脱除CO₂气体中的微量H₂S。采用XRD、N₂物理吸附、SEM及XPS等手段对脱硫前后的吸附剂结构进行表征。研究了Ce含量、煅烧温度、气体空速、杂质气体及吸附温度对吸附剂脱除H₂S性能的影响。结果表明,Ce-Cu-Al-O系列吸附剂在40℃条件下可有效脱除CO₂气体中的H₂S,Ce含量为10%的吸附剂（10Ce-Cu-Al-O）具有最大H₂S穿透吸附量,为94.1mg/g。研究发现,引入CeO₂能有效改善CuO的分散性,提高吸附剂的比表面积和孔容。提高煅烧温度,较大空速均不利于吸附剂的脱硫效果;平衡气CO₂会抑制H₂S的吸附;吸附温度不高于100℃时,10Ce-Cu-Al-O的穿透吸附量随温度升高而增加且不会生成COS副产物。表征结果显示,硫化后吸附剂的组分团聚导致了比表面积和孔容降低。此外,失活后的脱硫剂可在100℃用空气再生。     

弱碱三元体系对孔隙结构影响研究

ASP三元复合驱能扩大波及体积并且提高驱油效率,同时能极大的降低表面活性剂用量,使具有极其良好的技术经济可行性。通过常规压汞实验及扫描电镜实验分析研究了岩心在弱碱三元驱后的孔隙结构特征,对比分析了弱碱三元体系渗流前后岩心的孔隙结构特征变化。对其结果分析可知,由于弱碱三元体系对储层岩石有一定的溶蚀作用,当弱碱三元体系进入小孔道时,对小孔道的溶蚀导致小孔道半径变大,减少小孔道的数量,增多大孔道的数量,从而略微增大整体岩心的渗透率。弱碱三元复合驱前岩石致密,孔隙较小且比较均匀。弱碱三元复合驱后,出现斑驳状凸起,孔隙发育比较明显,岩石上有可动碎屑附着。碱的浓度越高,三元体系对岩心的溶蚀作用强烈,对岩心伤害程度更大。     

FCC提升管反应器中终止剂注入对裂化反应的影响

通过对催化裂化提升管注入终止剂前后的工况进行数值模拟,研究了终止剂注入对提升管内速度分布、催化剂颗粒浓度分布、温度分布以及组分浓度分布的影响,考察了不同注入量以及注入高度的终止剂在提升管内的作用区域及其对裂化反应的影响。研究表明,终止剂的注入大幅提升了提升管内的油气速度,降低了催化剂浓度、油气和催化剂的温度,使得提升管内原料的裂化程度降低,二次反应减少。且不同注入量和注入高度的作用区域不同,对裂化反应的影响不同,应根据实际工况进行分析。