提高高凝油油藏水驱效率实验研究

采用胜利油田王131区块高凝油油样,研究了水驱不同阶段储层流体流变曲线变化规律,利用王斜区块岩心,研究了温度对高凝油水驱相渗曲线影响和高低渗岩心渗流能力变化,通过两组驱替实验对比研究了温度与水驱驱油效率的关系,揭示了王斜区块高凝油油藏“冷伤害”机理和体系独特的相态变化,结论认为差热分析法适用于测定胶质和沥青质含量多的高凝油黏温曲线,水驱开发期间混合液黏度会不断上升,原油乳化影响使黏温曲线与含水率同向变化,岩心流动能力在注入1PV时下降较为迅速,低温水驱低渗区域渗透率会出现大规模降低现象,建议该区块开发初期驱替介质选为60℃热水,注入单倍孔隙体积后,驱替介质转换为45℃左右冷水,可基本消除“冷伤害”对高凝油油藏开发效果的影响.     

前3-沈12块注热水开发前期研究

前3-沈12块是低渗高凝油油藏,油藏开发受温度的影响比较大.大量的测试资料和生产数据证明,长期注冷水开发后油藏冷伤害比较严重.运用热力学原理和油藏渗流力学原理对高凝油油藏的渗流机理进行研究,通过岩心高压物性实验,证明了温度对原油的粘度变化及相渗透率变化的影响,从而揭示了温度是影响高凝油油藏开发效果的重要因素,只有提高油藏温度--注热水驱开发,才能够改善油藏的开发效果.     

高凝油／水相对渗透率的确定

高凝油／水相对渗透率是研究高凝油多相渗流规律和进行油田动态预测的重要依据。由于高凝油在低于其析蜡点的某一温度下，呈非牛顿流体的流动特征，故常规的确定油／水相对渗透率的方法不完全适合于高凝油／水体系。文中以辽河油沈北高凝油为样品，采用加压式细管流变仪，确定了高凝油在不同温度下的流变性。证明沈北高凝油在低于析蜡点某一温度下，是幂律流体，推导了关于蜡沉积所产生的岩石渗透率降低系数的计算公式，依据高凝油流     

CO2驱酸化溶蚀作用对原油采收率的影响机理

CO₂驱酸化溶蚀作用对储层会产生一定程度的伤害。为揭示这种伤害作用对原油采收率的影响机理，选取6块同级别渗透率的岩心样品，在地层温度、压力条件下进行物理模拟实验，通过核磁共振技术评价酸化溶蚀作用对原油采收率的影响机理。实验结果显示，驱替产出流体的pH值低于原始地层水，且通过离子浓度变化发现驱替过程中有长石和碳酸盐矿物发生溶蚀；岩心的渗透率在驱替结束后出现一定程度降低，且反应时间越长，渗透率的降幅越大；岩心样品的最终采收率与反应时间呈反比，反应时间为240 h的岩心样品相比反应时间为0 h的岩心样品，其最终采收率降幅达到27.31%。综合分析认为，CO₂驱长时间的酸化溶蚀反应产物及脱落的黏土颗粒会堵塞孔喉，导致储层渗流能力下降，进而影响CO₂驱的驱油效率及最终采收率。     

高凝油油藏水驱油效率影响因素

高凝油油藏普遍采用注水开发方式,但冷水驱替会对储层产生伤害,影响水驱油效率。为完全模拟实际储层条件,采用含气原油进行水驱油室内实验,分别研究温度、渗透率、注水倍数、注水速率和润湿性对高凝油油藏水驱油效率的影响。研究发现:温度主要通过改变原油黏度和析蜡来影响驱油效率,驱油效率随温度的变化曲线具有明显的3个阶段;渗透率在原油析蜡前对驱油效率影响较大,但随着温度降低,析出的蜡质形成具有一定强度的空间网状结构堵塞渗流通道,导致渗透率的影响逐渐减小;随着注水倍数的增加,驱油效率呈上升趋势,但注水后期上升缓慢;相同注水倍数下,注水速率在析蜡前后对高凝油油藏的影响规律不同,针对不同储层温度合理选择注水速率对提高驱油效率十分关键。     

微波对高凝油作用规律的实验研究

高凝油即为含蜡较多的高凝点原油，如大庆、胜利、任丘和南阳等原油。此类原油在油温高于析蜡温度时，粘度较低，且随温度变化不大，属于牛顿流体；当温度接近凝点时，粘度急增，具有非牛顿流体的特性。高含蜡原油集输过程中，由于石蜡析出并不断沉积于地面集输管线、阀门、分离器和储罐等的金属表面，减小了油流通道，增     

稠油油藏聚合物驱相对渗透率曲线及驱油效率影响因素

针对目的海上稠油油藏地质特征、流体性质和现场施工工艺,通过岩心驱替实验、岩心CT扫描和理论分析,开展了岩心渗透率、水冲刷作用及原油黏度对聚合物驱相对渗透率和驱油效率影响研究。结果表明,随岩心渗透率增加,油相相对渗透率降低,驱替相渗流阻力减小,水相相对渗透率增高,波及区域面积增大,两相流跨度带增大,最终采收率增加;水冲刷对岩心孔隙结构的“携屑”和 “剥蚀”作用会扩大孔喉半径,增大岩心渗透率,其对相渗透率曲线和驱油效率的影响与岩心渗透率增大造成的影响相同;随原油黏度增加,油水两相相对渗透率降低,驱替相黏性指进现象加剧,渗流阻力增加,波及区域面积减小,两相流跨度带减小,最终采收率降低。     

大庆榆树林油田扶杨油层CO2驱油试验

为了探索大庆榆树林油田扶杨油层有效动用方法,在Y101区块进行了CO2驱油试验.通过物理模拟实验和岩心驱替实验等研究了原油与CO2作用后的参数变化情况,分析了CO2驱与水驱的渗流特征和驱油效率.结果表明:由于CO2与原油容易混相,因此降低了界面张力;CO2能够提高原油的泡点压力、降低原油的黏度;CO2驱的注入能力和渗流能力都比水驱强,其驱油效率比水驱高17％～35％,水气交替驱的驱油效率比连续CO2驱高.现场试验效果证实CO2驱油技术值得推广应用.     

低渗透轻质油油藏热采室内模拟实验研究

针对大庆肇源油田低渗透轻质油油藏特征，采用该油藏油层岩心及原油进行了热采室内模拟实验研究。通过实验分析了热水驱、蒸汽驱对驱油效率的影响，并与常规水驱进行对比。实验结果表明，蒸汽驱开采方式优于热水驱，而热水驱又优于常规水驱；热水驱驱油效率随着注水温度的升高而增加；注汽速度过高将影响驱油效率，而蒸汽温度及干度对驱油效率的影响不明显。     

微生物+化学复合驱提高高凝油油藏采收率室内实验

针对高凝油油藏析蜡冷伤害、水驱采收率低的问题，运用微生物高通量测序分析、化学驱实验评价方法，利用岩心物理模拟与CT扫描等手段，提出了微生物+化学复合驱组合提高高凝油采收率技术，研制了微生物化学复合驱配方，该体系兼有化学驱大幅度提高驱油效率及微生物降低原油蜡质组分双重优点，最后通过物模实验优化了微生物与化学驱配方段塞组合。实验结果表明：微生物+化学复合驱较水驱提高驱油效率35.19个百分点，较单一化学复合驱可提高驱油效率7.27个百分点，单位质量聚合物增油量提高了1.16 t/t。该研究为高凝油油藏开发后期方式转换、提高采收率提供有效接替技术。     

沈阳油田高含蜡高凝固点油藏注热水开发可行性研究

本文通过沈阳油田高含蜡高凝固点原油的实验,观察原油在不同温度下的渗流规律,分析了原油在析蜡前后的渗流特征和差别以及产生差别的原因,得到了高含蜡高凝固点原油在低于析蜡温度条件下的渗流,造成析蜡和伤害油层孔隙的结论,建立了反映高含蜡高凝固点油析蜡影响的两维(R,Z)两相油藏数值模型,并研究了析蜡影响的处理及析蜡量的计算.通过模拟计算还得出对高含蜡高凝固点油藏早期注冷水会在油层中近井地带发生析蜡伤害的结论.对这种油藏,本文提出了采用先注热水后注冷水的开发方法,并对温度的选择,热水段塞的大小提出了确定的方法和依据.最后提出了热电联产联供,与原油热力开采一体化,实现能量综合利用开发油田的建议.     

The Effect of Commercial Additives as Pour Point Depressants for Fuel Oils

When the crude oil temperature goes below the pour point value wax crystals will come out of solution and tend to plug lines and filters. Additionally, the wax deposited in tanks decreases the storage capacity. In general, wax deposition can cause problems in production, storage, transportation, and consumption. Pretreatment of the crude oil with flow improver or pour point depressants has received the greatest acceptance due to its simplicity and economy. Four commercial additives were evaluated as pour point depressant for fuel oils. The structures of the commercial additives were confirmed by FTIR spectra. The results indicate that the n-alkanes carbon distributions display an obvious normal distribution in fuel oils. The distributions of high carbon n-alkanes are all broad so that wax crystals not precipitate in fuel oil at low temperatures is good. These commercial additives were tested as pour point depressants for fuel oil. The obtained data revealed that the prepared compounds depress the pour point of the fuel oil successfully. Comparison of structures of wax crystals in untreated and treated fuel oil was also done by photomicrographic analysis.     

LOW TEMPERATURE FLOW CHARACTERISTICS OF SOME WAXY CRUDE OILS IN RELATION TO THEIR COMPOSITION : PART I WITH AND WITHOUT POUR POINT DEPRESSANT ADDITIVES

ABSTRACT

The yield stress, plastic viscosity and apparent viscosity and the dependence of the latter on the shear rate have been studied at different temperatures below pour point of Lingala (Krishna-Godavari basin, Eastern coast), Duliajan (Eastern region of Assam), Rava (Godavari basin) and Bombay-High (off-shore western region) indigenous crude oils

Four different commercial pour point depressant additives have been used to study their effects on the pour point, yield stress and plastic viscosity

From this study it has been found that wax concentration and its composition are primarily responsible for the variation in the pour point, and crude base composition has a small effect. However, the response of the pour point depressant additive in effecting the change in the pour point is primarily governed by the liquid matrix. As the temperature is lowered both the yield stress and plastic viscosity increase in case of each crude oil. However, the magnitude is dependent on the nature of the crude oil. With pour point depressant additives, the yield stress and plastic viscosity are decreased and this decrease is a function of nature of the liquid matrix of the crude oil and concentration of the additive     

LOW TEMPERATURE FLOW CHARACTERISTICS OF SOME WAXY CRUDE OILS IN RELATION TO THEIR COMPOSITION : PART I WITH AND WITHOUT POUR POINT DEPRESSANT ADDITIVES

The yield stress, plastic viscosity and apparent viscosity and the dependence of the latter on the shear rate have been studied at different temperatures below pour point of Lingala (Krishna-Godavari basin, Eastern coast), Duliajan (Eastern region of Assam), Rava (Godavari basin) and Bombay-High (off-shore western region) indigenous crude oils

Four different commercial pour point depressant additives have been used to study their effects on the pour point, yield stress and plastic viscosity

From this study it has been found that wax concentration and its composition are primarily responsible for the variation in the pour point, and crude base composition has a small effect. However, the response of the pour point depressant additive in effecting the change in the pour point is primarily governed by the liquid matrix. As the temperature is lowered both the yield stress and plastic viscosity increase in case of each crude oil. However, the magnitude is dependent on the nature of the crude oil. With pour point depressant additives, the yield stress and plastic viscosity are decreased and this decrease is a function of nature of the liquid matrix of the crude oil and concentration of the additive     

胺解聚合物型原油降凝剂的合成及应用

通过丙烯酸高碳酯与马来酸酐、醋酸乙烯酯、苯乙烯共聚后进行不同系列胺解得到一系列新型高蜡原油降凝剂。考察了该类降凝剂对大庆高蜡原油和尼尔阿曼混合原油的降凝效果。结果表明，胺解聚合物型原油降凝剂具有较好的原油降凝性能，降凝幅度最高达到27℃；同时，测定了加剂温度对降凝剂降凝效果的影响，结果发现，当加剂温度高于原油析蜡温度时，降凝剂的降凝效果才能充分显现出来。     

Poly(ethylene-co-vinyl acetate) (EVA) as wax inhibitor of a Brazilian crude oil: oil viscosity, pour point and phase behavior of organic solutions

Several techniques have been used to minimize the problems caused by the wax deposition, and the continuous addition of polymeric inhibitors is considered an attractive technological alternative. The addition of copolymers like polyacrylates, polymethacrylates or poly(ethylene-co-vinyl acetate) (EVA) permit to inhibit the deposition phenomenon; nonetheless, this effect is specific, i.e. similar copolymers present different performance depending on their physical–chemical properties in solution. In this work, the influence of the EVA vinyl acetate content on the viscosity and the pour point of a Brazilian crude oil were evaluated. A correlation between both results was also obtained. The phase behavior and the solubility parameter of EVA copolymers, with different vinyl acetate contents, were investigated in various solvents together with an evaluation of the efficiency of these copolymers as pour point depressants for two different samples of crude oil. EVA copolymers containing 20, 30, 40 and 80 wt.% of vinyl acetate were used and tests with the crude oil were carried out using 50, 500, 1000 and 5000 ppm of EVA as additive. The results obtained from viscosity measurements showed that only below the temperature at which wax crystals start forming did the copolymer exhibit a strong influence in the reduction of oil viscosity, at an optimum concentration. The pour point results revealed EVA 30 to be the most efficient. The results obtained from both experiments showed that the viscosity and the pour point behaviors do not show good correlation. Not only the solubility parameter and the vinyl acetate content, but also the molecular weight and polydispersity have an important influence on both phase behavior and pour point depression. Furthermore, it was confirmed that the additive must present a reduced solubility at a temperature close to the crude oil cloud point. This, however, is not the only factor that determines the efficiency of the additive as paraffin/wax deposition inhibitor.     

含蜡原油热处理工艺的研究

本文在室内试验研究的基础上认为:以凝固点,屈服值和表观粘度作为评价含蜡原油热处理效果的指标;我国含蜡原油热处理的较好蜡胶比范围为0.8～1.5;以各段最高不大于1.5℃/分的低冷却速率分段冷却,可得较好的热处理效果;以及简易的失流点,反常点温度区间划分法,并以此法得出我国含蜡原油的失流点高于凝固点6℃,失流点到反常点温度区间只有6～8℃,高于凝固点10～13℃即为牛顿液体。     

Characteristic Temperatures of Waxy Crude Oils

Gel point or pour point is widely used to evaluate the low temperature flowability of crude oil. However, it is not adequate to describe the gelling properties of waxy crude oils under flow conditions with gel point or pour point, since the rheological behavior of crude oils is dependent on shear history. Waxy crude oils tend to gel at a low temperature. Based on gelation theory, the characteristic temperature of waxy crude oil was determined by analyzing viscosity-temperature data. Two mathematical models were developed for calculating characteristic temperatures of virgin crude oils and pour point depressants (PPD) beneficiated crude oils, respectively. By using these two models, the characteristic temperatures of crude oils that have experienced shearing and thermal histories can be predicted. The model for predicting the characteristic temperature of virgin crude oils has an average relative deviation of 4.5%, and all predicted values have a deviation within 2 ℃. Tested by 42 sets of data, the prediction model for crude oil treated with PPD has a high accuracy, with an average relative deviation of 4.2%, and 95.2 percent of predicted values have a deviation within 2 ℃. These two models provide useful ways for predicting the flowability of crude oils in pipelines when only wax content, wax appearance point and gel point are available.     

论“三高”原油不加热集油的影响因素

以大庆萨南油田室内和现场试验研究结果及矿场生产实际为论据，对油井出油温度，油井生产状况，原油流变特性，原油含水率四个影响“三高”（高含蜡，高凝点，高粘度）原油不加热集油的主要因素及其相关问题进行了论述。给出了油井实施不加热集油的可行性及其工艺方法；提出了在低温不加热集同条件下，“三高”原油生产井出油管道结蜡轻微或基本不结蜡，井口回压高的主要原因是“三高”原油的低温高粘特性所致，低温集油基本不影响油     

The action mechanism of wax inhibitors (WI) on pour point and viscosity of mixed waxy oil

Several methods had been used to minimize the problems caused by wax deposition in crude oil pipelines during the production and transportation of waxy crude oil; among them, the continuous addition of wax inhibitor (Abbreviation for WI) is considered as the most efficient one. This study uses two kinds of polymeric compounds as wax inhibitors with different solvents on the pour point and viscosity of mixed waxy oils evaluated. These four wax inhibitors defined as WI-1, WI-2, WI-3, WI-4, respectively. Five types of mixed waxy oil have the same wax content but different resin contents. Meanwhile, different resin contents affect the pour point and viscosity of mixed oils. Under different processing temperature, the viscosity of mixed oil measured when the temperature changes among 20 to 60°С. In this work, the results were that the effect of WI-1 and WI-3 relied on the resin content, processing temperature and dosing concentration. For mixed waxy oils, the pour point reductions contacted with dosing concentration and the resin content. The wax inhibitor shows good efficiency when the resin content was between 1.01 and 4.03 wt %. When the WI-1 added, the pour point of mixed oil-1 reduced 30°С at most and viscosity of mixed waxy oil greatly reduced. In sum, toluene as solvent shows better performance of wax inhibitors.