Comparison of oil displacement mechanisms and performances between continuous and dispersed phase flooding agents

To compare the oil displacement mechanisms and performances of continuous phase flooding agent(traditional polymer solution) and dispersed phase flooding agent(particle-type polymer SMG dispersion), the particle phase separation of SMG dispersion migrating in pores was simulated by using the microfluidic technology. Theoretically guided by the tree fork concentration distribution of red cells in biological fluid mechanics, the concentration distribution mathematical model of SMG in different pores is established. Furthermore, the micro and macro physical simulation experiments of continuous and dispersed phase flooding agents were carried out. The results show that the continuous flooding agent enters all the swept zones and increases the flow resistance in both larger and small pores. On the contrary, the particle phase separation phenomenon occurs during the injection process of dispersed flooding agent. The SMG particles gather in the larger pore to form bridge blinding, and the carrier fluid displace oil in the small pore. Working in cooperation, the SMG particle and carrier fluid drive the residual oil in the low permeability layers step by step and achieve the goal of enhanced oil recovery. The laboratory experimental results indicate that, the oil increment and water reduction effect of dispersed flooding agent is much better than that of continuous flooding agent, which is consistent with the field test results.

A WEAKLY NONLINEAR WATER WAVE MODEL TAKING INTO ACCOUNT DISPERSION OF WAVE PHASE VELOCITY

This paper presents a weakly nonlinear water wave model using a mild slope equation and a new explicit formulation which takes into account dispersion of wave phase velocity, approximates Hedges’ (1987) nonlinear dispersion relationship, and accords well with the original empirical formula. Comparison of the calculating results with those obtained from the experimental data and those obtained from linear wave theory showed that the present water wave model considering the dispersion of phase velocity is rational and in good agreement with experiment data.

Attractor comparison analysis for characterizing vertical upward oil gas water three-phase flow

We investigate the dynamic characteristics of oil-gas-water three-phase flow in terms of chaotic attractor comparison. In particular, we extract a statistic to characterize the dynamical difference in attractor probability distribution. We first take time series from Logistic chaotic system with different parameters as examples to demonstrate the effectiveness of the method. Then we use this method to investigate the experimental signals from oil-gas-water three-phase flow. The results indicate that the extracted statistic is very sensitive to the change of flow parameters and can gain a quantitatively insight into the dynamic characteristics of different flow patterns.

Crude oil wax:A review on formation,experimentation,prediction,and remediation techniques

Wax deposition during crude oil production,transportation,and processing has been a headache since the early days of oil utilization.It may lead to low mobility ratios,blockage of production tubing/pipelines as well as fouling of surface and processing facilities,among others.These snags cause massive financial constraints increasing projects’turnover.Decades of meticulous research have been dedicated to this problem that is worth a review.Thus,this paper reviews the mechanisms,experimentation,thermodynamic and kinetic modeling,prediction,and remediation techniques of wax deposition.An overall assessment suggests that available models are more accurate for single than multi-phase flows while the kind of remediation and deployment depend on the environment and severity level.In severe cases,both chemical and mechanical are synergistically deployed.Moreover,future prospective research areas that require attention are proposed.Generally,this review could be a valuable tool for novice researchers as well as a foundation for further research on this topic.

Preparation of Microcapsules with Liquid Droplet Coalescence Method Followed by Phase Separation

Novel preparation method of microencapsules was developed on the basis of the liquid coalescence method followed by phase separation. Oil droplets of limonene dissolving expanded polystyrene as a shell material were forced to collide and coalesce with the Isopar oil droplets of core material in the continuous wates phase. When two kinds of oil droplets are collided and coalesced with each other, expanded polystyrene dissolved in the limonene oil may be phase-separated in the oil droplets newly formed to form the microcapsule shell, because the Isopar oil was a poor solvent for expanded polystyrene but a good solvent for the limonene oil. In the experiment, the diameter (or number) of limonene oil droplets dissolving expanded polystyrene was mainly changed, because the coalescence frequency between the droplets is strongly dependent on the number of droplets. Favorable core shell types of microcapsules with the shell thickness from 1.0 to 5.0 μm were able to be prepared under all the experimental conditions adopted here.

Experimental investigation of the effects of various parameters on viscosity reduction of heavy crude by oil-water emulsion

The effects of water content, shear rate, temperature, and solid particle concentration on viscosity reduction （VR） caused by forming stable emulsions were investigated using Omani heavy crude oil. The viscosity of the crude oil was initially measured with respect to shear rates at different temperatures from 20 to 70℃. The crude oil exhibited a shear thinning behavior at all the temperatures. The strongest shear thinning was observed at 20℃. A non-ionic water soluble surfactant （Triton X-100） was used to form and stabilize crude oil emulsions. The emulsification process has significantly reduced the crude oil viscosity. The degree of VR was found to increase with an increase in water content and reach its maximum value at 50 % water content. The phase inversion from oil- oil emulsion occurred at 30 in-water emulsion to water-in- % water content. The results indicated that the VR was inversely proportional to temperature and concentration of silica nanoparticles. For water-in-oil emulsions, VR increased with shear rate and eventually reached a plateau at a shear rate of around 350 s^-1. This was attributed to the thinning behavior of the continuous phase. The VR of oil-in-water emulsions remained almost constant as the shear rate increased due to the Newtonian behavior of water, the continuous phase.

Multi-scale complexity entropy causality plane: An intrinsic measure for indicating two-phase flow structures

We extend the complexity entropy causality plane（CECP） to propose a multi-scale complexity entropy causality plane（MS-CECP） and further use the proposed method to discriminate the deterministic characteristics of different oil-in-water flows. We first take several typical time series for example to investigate the characteristic of the MS-CECP and find that the MS-CECP not only describes the continuous loss of dynamical structure with the increase of scale, but also reflects the determinacy of the system. Then we calculate the MS-CECP for the conductance fluctuating signals measured from oil–water two-phase flow loop test facility. The results indicate that the MS-CECP could be an intrinsic measure for indicating oil-in-water two-phase flow structures.

Multifractal analysis of inclined oil-water countercurrent flow

Characterizing countercurrent flow structures in an inclined oil-water two-phase flow from one-dimensional measurement is of great importance for model building and sensor design.Firstly,we conducted oil-water two-phase flow experiments in an inclined pipe to measure the conductance signals of three typical water-dominated oil-water flow patterns in inclined flow,i.e.,dispersion oil-in-water pseudo-slug flow （PS）,dispersion oil-in-water countercurrent flow （CT）,and transitional flow （TF）.In pseudo-slug flow,countercurrent flow and transitional flow,oil is completely dispersed in water.Then we used magnitude and sign decomposition analysis and multifractal analysis to reveal levels of complexity in different flow patterns.We found that the PS and CT flow patterns both exhibited high complexity and obvious multifractal dynamic behavior,but the magnitude scaling exponent and singularity of the CT flow pattern were less than those of the PS flow pattern; and the TF flow pattern exhibited low complexity and almost monofractal behavior,and its magnitude scaling was close to random behavior.Meanwhile,at short time scales,all sign series of two-phase flow patterns exhibited very similar strong positive correlation; at high time scales,the scaling analysis of sign series showed different anti-correlated behavior.Furthermore,with an increase in oil flow rate,the flow structure became regular,which could be reflected by the decrease in the width of spectrum and the difference in dimensions.The results suggested that different oil-water flow patterns exhibited different nonlinear features,and the varying levels of complexity could well characterize the fluid dynamics underlying different oil-water flow patterns.

碳酸盐岩缝洞型油藏流固耦合下的油水两相流动特征

为提高缝洞型碳酸盐岩油藏采收率,探究其流固耦合下的油水两相流动特性,根据不同介质中的流体流动规律,建立了Stokes-Darcy两相流体流动模型;基于有效应力原理和广义胡克定律,建立了适用于缝洞型碳酸盐岩油藏的油水两相Stokes-Darcy流固耦合数学模型;分别针对有无流固耦合的缝洞型碳酸盐岩油藏,进行了宏观和细观的油水两相流体流动模拟。研究结果表明:油藏有无流固耦合作用,其油水两相流体流动特性在基质区差异较大,在溶洞内差异较小,注水速度对缝洞型碳酸盐岩油藏的油水流动影响较大。

纳米石杉碱甲脂质体的热稳定性及分配系数

采用薄膜旋蒸-超声法制备了纳米石杉碱甲脂质体(Hup-A-Lip),并对其微观形貌、包封率、相变温度、分配系数及生物利用度等进行了研究.结果表明:Hup-A-Lip呈粒径约40 nm的球形结构;包封率为(82.74±2.68)%;相变温度为67℃,在25~60℃具有较好的热力学稳定性;Hup-A-Lip中药物与脂质体膜之间的作用力以静电相互作用和氢键为主;石杉碱甲(Hup-A)经脂质体包封后,明显提高了游离药物的生物利用度.

T型管油水分离效率的正交数值试验研究

T型管广泛应用于油田的油水分离,影响其分离效率的因素较多。运用正交试验方法对T型管的管径、垂直管间距、垂直管数等三个几何参数和含油率、进口速度和分流比等三个操作参数共计6因素3水平设计了18组试验方案,并运用计算流体力学数值模拟方法对其进行了数值试验研究,结果表明:各因素对T型管分离效率的影响大小为垂直管数>垂直管间距>分流比>含油率>入口流速>管径。管径60 mm、垂直管数3、垂直管间距1000 mm、含油率40%、入口流速0.35 m/s、分流比0.4为T型管的最优结构组合,此时T型管的分离效率达到99.99%。分离效率随垂直管数、垂直管间距的增加先降低再升高,随分流比、含油率的增加先升高再降低。管径和入口速度对分离效率的影响较小,其大小可视需要而定。

SIMULATION OF OIL-WATER TWO PHASE FLOW AND SEPARATION BEHAVIORS IN COMBINED T JUNCTIONS

The combined T junctions used for the oil-water separation have the advantages of compactness in structure, consistency in effects and economy in cost. The mixture k- ε turbulence model and the Eulerian multi-fluid model are used to simulate the flow and phase distribution in the combined T junctions. The effects of structural parameters such as the branched pipe interval and height on the flow distribution and the separation behaviors are studied. The results show that the combined T junctions under fixed inlet and outlet boundary conditions form a single hydraulic equilibrium system in which the fluid energy distributes freely till a balance is achieved. The split-flow promotes the separation of the immiscible oil and the water. The separation efficiency increases with the increase of the branched pipe interval and changes slightly with the increase of the branched pipe height. The structural change of the combined T junctions may change the flow direction in the branched pipes. Simulation results can provide some guidance for the design of the combined T junctions as one kind of oil-water separator.

基于两相流的水封油库油气泄漏运移规律及控制措施

地下水封油库运行的关键是保持一定的水封厚度,为确定合适的水封厚度,基于气液两相流理论,采用有限元数值模拟方法,以我国某石油储备地下水封洞库为依托,模拟了地下水封石油洞库储油运行期油气的泄漏运移演变过程。结果表明:施工期不设置水幕系统情况下,洞室顶部出现了大面积的疏干区,造成后期无法储油;设置水幕系统情况下,洞库上方能够维持一定水封厚度,洞库周围岩层油气泄漏范围和泄漏量均与储油运行时间呈正幂函数关系;水封厚度越大油气泄漏范围和泄漏量越小,但过大的水封厚度会大大增加工程成本,所对应的案例在水封厚度为30 m时对油气泄漏控制最为经济合理,《地下水封石洞油库设计标准》推荐的水封厚度合理且有一定安全裕度。研究成果可为水封油库工程的设计及油气泄漏控制提供一定理论参考。

稠油冷采用冻胶分散体调驱体系的相互作用机制

目的旨在有效解决稠油化学冷采过程中降黏剂窜流现象严重、油藏动用效率低的问题,支撑稠油绿色高效开发。方法基于稠油冷采降黏剂高效降黏洗油与冻胶分散体调剖剂储层调控的协同效应,采用复配方式构建了稠油冷采用冻胶分散体调驱体系,测试其基本性能,并使用界面扩张流变仪以及流变仪,考查了体系的界面流变特性和剪切应力特性。结果体系由质量分数为0.06%~0.12%的冻胶分散体和质量分数为0.05%~0.15%的降黏剂组成,为粒径均一的低黏流体,能够降低界面张力并乳化稠油,降黏率达到95%以上。体系中降黏剂在油水界面的吸附行为决定了体系的乳化降黏能力,降黏剂通过吸附在冻胶分散体的表面提高了体系的聚结稳定性,并考查了组分含量及油藏条件对以上过程的影响。结论构建了一种兼具储层调控和高效降黏能力稠油冷采用冻胶分散体调驱体系,探明了体系中各组分间的相互作用机制,为稠油化学冷采提供了技术支持。

水相循环对乙醇-水体系液化蜈蚣草产油特性和砷富集影响

砷富集植物的生态友好处置是实现植物修复产业化发展的关键环节,对土壤重金属污染治理高质量发展起到了制约作用。该研究以蜈蚣草为原料,采用乙醇-水作为反应共溶剂体系,考察了乙醇占比和水相循环次数对蜈蚣草水热产油及重金属砷分布的影响。研究结果显示:在乙醇浓度60%、水相循环3次的条件下,蜈蚣草液化生物油产率最高可达51.08%,其热值为29.15 MJ/kg。生物油主要由酯(>80%)、酚、醇、酮、烃等组成。随水相循环次数的增加,生物油中的酯类和酚类物质增加,高沸点化合物会减少,生物油产率和能量回收率分别提高了58%和32.23%;经过水相循环液化后,超过80%的重金属砷主要分布在水相,且砷的浓度增加至215.05 mg/kg,该结果可为砷富集植物无害化后处置提供参考。因此,水相循环利用是砷富集植物液化处置制取高产率生物油与砷富集的有效途径,为富集植物生态友好处置提供了新的思路。

油水混相泡沫的稳定化研究进展

油水混相泡沫是一种特殊的泡沫体系,由于其在化工、食品、药品等领域的广泛应用,因此对其稳定化机制的研究变得越来越重要。基于最新研究进展,研究了影响油水混相泡沫稳定性的因素,包括表面活性物质、油相以及一些其他因素,以探究其对泡沫的发泡性能和稳定性的作用机制,并着重论述了油相的种类、含量对泡沫稳定化的影响,最后探究了温度、矿化度以及不同表面活性剂和颗粒或者油相的耦合对泡沫稳定性的影响。文章还提出了一些未来的研究方向以及利用新型材料和纳米颗粒技术开发更有效的泡沫稳定化方法,对于深入理解油水混相泡沫的稳定化机制、优化泡沫性能、开发新的应用和解决相关领域的问题具有重要意义。

相关式油井液相计量系统研究与设计

针对现有油井计量方式自动化程度低,误差较大等问题,利用同轴线相位法含水率计设计了一种相关式油井液相计量系统,该系统以同轴线相位法含水率计为传感器构建了相关流量计,基于互相关法建立了计量模型,实现了流量与含水率的同步测量。通过对不同情况下上、下游含水率计信号的分析可知,两路信号之间具有相关性,满足相关流量计的使用条件。该系统在现场试验的测量结果与涡轮流量计相比,平均误差为11.36%。试验结果证明了相关式油井液相计量系统在实际应用中的可行性。

低含水油水两相流等效介电常数模型

电容法测油水两相流含水率在油田的地面油水计量及井中的产出剖面分层测试中都得到广泛应用。持水率(水相体积分数)的测量需要建立油水两相流持水率与传感器电容的关系,为此需要建立混相等效介电常数与持水率的理论模型或经验模型。由于油井采出的地层水以及地面实验室标定所用的自来水在低频和中频时均具有良好导电性,因此,单纯考虑介电性而不考虑导电性会对持水率测量的准确性产生显著影响。基于电介质极化的有效电场理论,在低含水且油水状态为精细泡状流条件下,将水视为良导体,建立了油水两相流等效介电常数模型。按此模型,油水两相流的等效介电常数只取决于持水率和油相介电常数,与水相介电常数以及水相电导率无关,初步实验验证了模型正确。该研究对于油为连续相时油水两相流的含水率传感器的设计和现场应用具有重要意义。

页岩油水相中油含量的测定

本文采用紫外分光光度法,对页岩油水相中的油含量进行分析。对比并筛选了溶剂,优选120号溶剂油萃取水相中的油品,以页岩油为标准油,配制了标准油+120号溶剂油体系,在紫外检验波长228nm条件下,测定并得到了标准曲线。油含量C与吸光度A在50~500mg·L^(-1)范围内具有良好的线性关系,线性方程为:C=652.69A+8.4091,相关系数R^(2)=0.9993。对方法的准确度和精密度进行了实验分析,对不同浓度的页岩油标样进行测定,相对标准偏差为0.6%~1.15%。配制了模拟乳化液,采用超声提取法进行了验证实验,结果一致,表明本方法测定的数据准确可靠。

油水环状流截面相含率超声衰减法测量

为研究超声衰减法测量油水环状流截面相含率问题,采用COMSOL仿真软件建立油水环状流模型,选择超声传感器结构尺寸6mm和超声发射频率1MHz进行研究,通过分析油水环状流超声衰减特性,确定油水环状流的超声衰减系数与截面含油率关系,并获得线性关系的测量范围。在此基础上进一步研究非理想环状流相关参数对超声衰减特性的影响,并提出将非理想环状流差别阈限用于定量评价非理想环状流因素对于理想环状流超声衰减法的影响,获得非理想环状流差别阈限±10%以内同心度和椭圆度的变化范围。最后开展了油水环状流静态验证实验。研究结果表明:油水环状流截面相含率在5%~30%范围内,与超声衰减系数呈线性关系,同时在此范围内,非理想环状流差别阈限在±10%以内的同心度和椭圆度变化范围分别为0.75~1和0~5%,实验结果和仿真模拟结果具有近似的上升趋势。