非均质油藏水平井调剖注入压力和注入量预测方法的建立与应用

针对注入凝胶前后水平井注入参数的沿程分布问题,运用叠加原理与镜像反应原理,并考虑井筒摩阻的影响,建立了预测调剖前后注入压力与注水量沿程分布的解析方法,分析了凝胶对注入参数的影响。用此方法模拟预测了均质条件下和非均质条件下水平井注凝胶调剖前后注水量与注入压力的分布规律,为优化水平井调剖工艺参数、提高措施效果提供了保障。     

多孔介质内气泡熟化特性孔隙尺度研究

多孔介质内的气泡熟化行为广泛存在于CO₂封存等领域,为探究多孔介质内气泡的熟化特性,本文采用空气作为模拟气体,通过可视化实验和数值计算,对双孔隙和四孔隙气泡熟化过程进行了研究,阐释了多孔介质非均质性对熟化过程的影响规律。结果表明：在双孔隙气体饱和度较小情况下,虽然也发生正向熟化,但是孔隙结构的存在使熟化速率明显低于自由流体情况;四孔隙研究显示多孔介质非均质性对气泡熟化过程影响显著,由于孔隙的几何限制,气泡在某些情况下会发生逆Ostwald熟化,即生长的气泡在充满当前孔隙空间后会停止生长并反向熟化导致尺寸缩小;在非均质多孔介质中,由于熟化作用,气泡有传质到大孔隙区域趋势,导致大孔隙区域富集大气泡,存在泄漏风险,从而影响封存。     

油藏非均质性对CO_2驱效果影响研究

通过建立典型模型,模拟计算层间非均质性和存在窜流通道情况下对CO2驱油藏开发效果的影响,找出单因素影响的变化规律。结论证明了以上2种因素对采收率影响的存在,对类似油藏应用CO2驱开发提供了一定的借鉴,但该影响的定量分析仍需进一步进行。     

聚合物驱替后层内非均质储层受效研究

对于非均质储层,聚合物驱可有效抑制高渗层的指迚和无效循环,扩大注入剂波及体积,是提高常觃油田采收率的有效方法。但由于存在层内窜流,聚合物驱后储层内部受效情况极为复杂。通过人造岩心、物理模拟和数值模拟等方法,综合考察了聚合物驱后层内非均质岩心内部的受效情况。研究结果表明:层内非均质储层中正韵律储层聚合物驱替效率最高;正韵律储层中,渗透率越高,对驱油效率贡献越大,相邻两层级差越大,聚合物驱油效率越高;聚合物驱后,相对中渗层剩余油饱和度最高,中渗层是剩余油挖潜的主要对象;提高聚合物浓度、提高聚合物分子量是提高中渗层驱油效率的有效方法。该研究结果为指导聚合物驱后剩余油开采提供了良好的参考价值。     

超临界CO_2中合成的聚丙烯腈的相对分子质量及其分布研究

用凝胶渗透色谱法测试了超临界CO_2下合成的聚丙烯腈的相对分子质量及其分布,并详细研究了各种反应条件如:单体浓度、引发剂浓度、时间及CO_2压力对聚丙烯腈的相对分子质量、相对分子质量分布及转化率的影响。     

超临界CO_2/PS微孔塑料挤出成型中CO_2浓度对气泡成核影响的数值模拟

通过CFD软件对超临界CO_2/PS均相熔体在快速降压口模中流动状态的数值模拟,研究了CO_2浓度对CO_2/PS均相熔体气泡成核的影响。结果表明:当其他工艺条件不变时,在CO_2溶解度范围以内,增加CO_2浓度有利于提高成核率,从而产生更多的气泡,但不利于小尺寸泡孔的生成。     

渗透率非均质对二元驱的影响研究

开发三大矛盾制约了二元驱的开发效果,利用CMG软件的STARS模块研究了渗透率非均质对二元驱效果的影响。根据实际可能出现的非均质状况,设计了六种层内非均质模型、四种平面非均质模型及三种层间非均质模型,并对不同模型对二元驱的影响从二元驱提高采收率进行对比。     

超临界CO_2中甲苯氧化为苯甲醛的研究

以超临界CO_2为反应介质,用过氧化氢作为氧源,使甲苯在反应釜内发生均相氧化反应。反应结束后,将产物蒸馏回收,得到未反应的甲苯和苯甲醛产品．CO_2循环利用。研究发现,反应的最优化条件为反应压力25MPa,反应温度180℃,反应时间4h,苯甲醛的收率为1．535%,过氧化氢与甲苯的最佳物质的量比为2．5,氧化反应为一级反应,反应活化能为76kJ/mol。     

余家坪中区长2储层非均质特征

本区属典型的低渗储层,构造平缓。从层内、层间、平面等方面研究表明,本区储层具有较强非均质性,其成因为河道快速变迁,多期叠加。总体来说纵向变化速度要小于平面变化。     

高尚堡油田储层层内非均质特征及其对油气分布的控制

根据岩心和测井解释求取的渗透率参数,对高尚堡油田沙一下~沙三1亚段储层层内非均质性进行了详细描述。研究区储层为辫状河三角洲沉积,沉积砂体厚度和展布范围小,结合渗透率参数、韵律模式以及各种物性参数等对主要沉积砂体的储集性能进行了综合评价,同时建立了该区的非均质模式,发现油气分布主要受沉积微相的控制,分布在靠近断层、储集性质最好、层内非均质弱的辫状河三角洲前缘分流水道和三角洲平原分支水道储层中。     

Interfacial Evolution and Migration Characteristics of Acid Gas Injected into a Saline Aquifer

Acid gas injection into saline aquifers is one of promising ways to reduce greenhouse gas emissions and to dispose hazardous waste simultaneously. On the basis of Level Set method, an improved mathematical model that described interfacial dynamics of acid gas-brine system in a deep confined saline aquifer was proposed for predicting the propagation of the acid gas plume, which was featured by using Peng-Robinson equation and modified Lucas equation to describe variations of the density and viscosity of acid gas in saline aquifers. The evolutional characte~stics of acid gas plume were obtained through numerical simulations using COMSOL Multiphysics 3.5a. The results showed that under intrinsic characteristics of aquifers and operational conditions given, the variation of acid gas density was the major factor that influences the patterns and shapes of the plume. The leading edge position of acid gas plume was intensively dependent on the acid gas composition. Under the scheme of fixed mass flow rate injection, as the molar fraction of H2S increased, the position of leading edge advanced gradually towards the injection well. Moreover, the estimation of the storage efficiency of acid gas in saline aquifers was clarified and discussed. The proposed approach and the simulation results will provide insights into the determination of optimal operational strategies and rapid identification of the consequences of acid gas injection into deep confined saline aquifers.     

碳基材料吸附二氧化碳及电解吸的实验研究

利用碳基材料具有良好的导电导热性能,研发电解吸技术,取代传统的真空解吸工艺,进行吸附剂再生。估算能耗,为碳基材料吸附捕集温室气体CO2的研究和应用提供基础依据。筛选出十余种由椰壳、煤、沥青、木炭和聚合物基体制备成的颗粒状、纤维状以及蜂窝状的碳基吸附剂,进行实验研究。基于实验结果,比较捕集烟道气中CO2的吸附量、选择性、电加热升温速率、电解吸工艺的电能耗。探讨采用碳基材料吸附和电解吸技术捕集烟道气中CO2的有效性和可行性。实验结果表明:采用电加热碳基材料吸附剂,升温速率较快,能使吸附剂达到快速解吸再生的目的。而且电直接加热到吸附剂,电能利用率较高。通过表面改性等方法提高碳基材料吸附CO2容量,电解吸工艺在CO2吸附捕集技术中具有显著的优势。     

钙基CO_2吸收剂循环活性衰减原因初探

对钙基CO2吸收剂的循环活性衰减进行了实验研究,考察了随着循环次数的增加,吸收剂的表面形态、吸收剂分子孔径及比表面积等微观结构的变化,分析了钙基CO2吸收剂循环活性衰减的原因。结果表明,随着循环次数的增加,吸收剂晶粒中的片状结构已经完全消失,取而代之的是正方体状的大晶粒,晶粒生长严重,大量空隙被封闭。而由此引起的吸收剂的比表面积的不断减小和孔容积的降低以及孔分布的改变,导致了吸收剂循环活性的衰减,吸收剂的循环转化率降低。     

二氧化碳深盐水层埋存传质数值模拟

CO₂的深盐水层埋存被认为是埋存量最大、最有前景的CO₂埋存方式。通过针对我国地质特点,选取硅酸盐地质层为CO₂埋存层,利用TOUGHREACT软件,数值模拟研究了超临界CO₂埋存在硅酸盐地质层中的传质问题,得到以下结论：注入CO₂ 10年后,深度750 m处,盐水层pH值沿着远离注入井方向呈增大趋势;气体饱和度在近注入点附近区域为1,后沿径向逐渐降到0;方解石容积分数沿径向增加,最终回落到与盐水层中原有含量相同水平;矿物捕获的CO₂变化趋势与方解石相仿;HCO^-₃的变化趋势与CO₂气体和CO^2-₃浓度的变化密切相关,在注入中段区域增加,后回落到盐水层原有水平。这些结果有益于认识CO₂埋存机理。     

Visualisation of mechanisms involved in Co2 injection and storage in hydrocarbon reservoirsand water-bearing aquifers

Storage of carbon dioxide (CO₂) in hydrocarbon reservoirs and saline aquifers is considered as one of the promising mitigation strategies to reduce the negative impact of this greenhouse gas. The static and dynamic behaviour of CO₂ in these storage sites which are located at various depths and geographical locations, affects the efficiency of this strategy. Understanding the impact of the conditions of these storage sites on mechanisms involved in CO₂ flow, displacement and trapping is also critical for the purpose of site selection and the design of CO₂ storage projects. In this paper we report the results of a series of CO₂ injection (CO₂I) flow visualisation (micromodel) experiments conducted using high-pressure transparent porous media representing various aquifer and depleted oil reservoirs storage conditions. The impact of pertinent parameters on the interaction between the stored CO₂ and the reservoir fluids were investigated. Both sub-critical and supercritical CO₂ were used to investigate the effect of pressure (depth) of the storage site on CO₂ trapping mechanisms. A faster CO₂ breakthrough (BT) was observed in the micromodel test simulating CO₂I into depleted oil reservoirs, compared to that into aquifers, reducing the sequestration capacity of the depleted oil reservoirs. Compared to the injection of supercritical CO₂, the BT of gaseous CO₂ happened faster, adversely affecting the CO₂ displacement performance. The results of these direct flow visualization experiments significantly improve our understanding of the complex mechanisms and interactions involved in CO₂I and storage in geological formations. This knowledge is essential for identifying storage conditions that would lead to maximising CO₂ storage capacity, for better understanding the ultimate fate of the stored CO₂ and the storage safety.     

负载型K2CO3/Al2O3二氧化碳吸收剂的碳酸化反应特性

The carbonation characteristics of K₂CO₃/Al₂O₃ supported sorbent for CO₂ capture was investigated with thermogravimetric apparatus（TGA）,X-ray diffraction（XRD）,scanning electron microscopy analysis（SEM）and N₂ adsorption.The results showed that the carbonation rate of K₂CO₃ before being loaded on Al₂O₃ was slow.However,the K₂CO₃/Al₂O₃ upported sorbent showed excellent carbonation performance.The difference in carbonation behavior between K₂CO₃ nd K₂CO₃/Al₂O₃ supported sorbent was analyzed from the microscopic view.The analytical reagent K₂CO₃ sample was of monoclinic crystal structure and could react quickly with H₂O in the experimental carbonation environment to produce K₂CO₃•1.5H₂O,which was unfavorable to carbonation reaction.When K₂CO₃was loaded on Al₂O₃,the surface area and porosity of the sorbent was improved greatly.So the carbonation properties of the K₂CO₃/Al₂O₃ supported sorbent was also improved.     

中间完全冷却CO_2跨临界双级压缩节流循环

双级压缩是提高CO2跨临界制冷循环性能系数COP的有效途径,且中间完全冷却形式的性能优于中间不完全冷却形式。对于中间完全冷却CO2跨临界双级压缩节流循环,节流形式有一次节流(STDC循环)和两次节流(DTDC循环)。分析了高压压力和气体冷却器出口温度对STDC循环和DTDC循环的性能影响,并与CO2跨临界单级压缩(STSC)节流循环进行了比较。结果表明:在给定条件下,DTDC循环的COP值最大、STDC循环的最优高压压力值最高;随着气体冷却器出口温度的升高,3个循环的最大COP均减小,最优高压压力均升高,压缩机的等熵效率均降低。对于DTDC和STDC循环,最优中间压力值偏离高压压力与低压压力的几何平均值,但是对系统的性能系数影响不大。     

CO2捕集的吸收溶解度计算和过程模拟

为了降低CO2吸收法捕集技术的能耗和成本,以目前常用的单乙醇胺(MEA)溶液吸收CO2为例,采用电解质非随机双流体热力学模型(E-NRTL),对溶液中的CO2气体溶解度进行计算,计算过程包含了化学反应平衡和汽液平衡,计算结果和文献数据相吻合。在此基础上,建立了CO2吸收过程模拟程序和包括解吸能耗、气体压缩能耗以及液体输送能耗的过程总体能耗的计算方法,继而通过过程模拟分析了吸收塔和解吸塔压力、溶液浓度和流量等因素对吸收捕集过程的总体能耗的影响,获取了最优的工艺条件,为以后新CO2吸收捕集过程提供能耗分析方法基础。     

沉淀法SiO2包覆纳米CaCO3吸附剂性能

以CO₂为沉淀剂,Na₂SiO₃为硅源,制备了SiO₂包覆纳米CaCO₃吸附剂。TEM测试证实纳米CaCO₃表面包覆一层SiO₂膜, 用SEM & EDX 测试5个包硅样品Si含量为0.67%～4.93%。采用TGA考察吸附剂的分解温度及600℃、20% CO₂条件下的吸附性能。结果表明：采用CO₂沉淀法包覆SiO₂后,与未包硅的纳米CaCO₃相比,分解温度降低9～42℃。纳米SiO₂/CaCO₃吸附剂的循环吸附率、吸附容量、吸附速率均随Si含量的减小先增加后降低。Si含量为1.05%的纳米SiO₂/CaCO₃吸附剂显示最佳吸附性能,第1、5次循环吸附容量分别为8.9、6.0 mol·kg^-1,与未包覆SiO2的纳米CaCO₃相比,分别提高11%、50%,同时在第5次循环快反应段吸附速率较纳米CaCO₃提高10%。与纳米CaCO₃相比,包硅后的吸附剂具有较高的吸附容量和循环吸附率,循环稳定性较好。     

Effect of operating pressure, matrix permeability and connate water saturation on performance of CO2 huff-and-puff process in matrix-fracture experimental model

The main objective of study is to examine the performance and efficiency of CO₂ huff-and-puff process for improving oil recovery and subsequent storage of CO₂ in light-oil fractured porous media through designing and conducting targeted experiments.The experimental set-up consisted of a high-pressure stainless steel cell made specially to hold a cylindrical core with spacing around it, simulating a matrix and its surrounding fracture environment. The matrix was saturated with normal decane, which was used as oil during the experiments. A total of six separate sets of huff-and-puff experiments, using CO₂ as solvent, were conducted under operating pressures of 250, 500, 750, 1000, 1250, and 1500 psi. The temperature was kept constant (35 °C) during all tests. Each set of the huff-and-puff experiments was conducted by injecting CO₂ in the fracture system surrounding the core (injection step). Then, the system was shut-in for a period of 24 h to allow CO₂ to diffuse from fracture into the oil in matrix (soaking period step). At the end of the soaking period, the pressure was released and the oil production was measured (production step). The above cycle was repeated until no more oil was produced.The results obtained show that when CO₂ was injected at 1500 psi through a huff-and-puff process, it recovers more than 95% of oil from a fracture-matrix experimental model saturated with normal decane. Also indicates that at such a pressure, 45% of initial oil-in-place can be recovered during the first cycle. However, when CO₂ was injected at pressures below CO₂-nC₁₀ minimum miscibility pressure (MMP), the maximum recovery factor achieved was less than 50%. Similarly, recovery factor of the first cycles performed at pressures below MMP were much lower (less than 30%) compare to those conducted at miscible condition. This indicates that miscible huff-and-puff process is a viable option for fractured porous media.As part of this study, effects of matrix permeability, and connate water saturation on the performance of huff-and-puff process in fracture-matrix core set-up at both immiscible and miscible conditions were studied. Results indicate that presence of connate water saturation is beneficial to immiscible CO₂ huff-and-puff process while it has almost negligible effect on the performance of this process when performed at miscible conditions. In presence of connate water saturation more than 70% of oil-in-place was recovered at immiscible condition compare to a maximum of 45% recovered when matrix was 100% saturated with normal decane. Results of the tests performed in a core with permeability about 10 times higher than the original core shows similar production trends. However, recovery factor in the high permeable core was slightly less than twice of that in low permeable core at immiscible condition. According to this study, effect of core permeability was less pronounced when CO₂ was injected at miscible conditions.