Research progress and potential of new enhanced oil recovery methods in oilfield development

This paper reviews the basic research means for oilfield development and also the researches and tests of enhanced oil recovery(EOR)methods for mature oilfields and continental shale oil development,analyzes the problems of EOR methods,and proposes the relevant research prospects.The basic research means for oilfield development include in-situ acquisition of formation rock/fluid samples and non-destructive testing.The EOR methods for conventional and shale oil development are classified as improved water flooding(e.g.nano-water flooding),chemical flooding(e.g.low-concentration middle-phase micro-emulsion flooding),gas flooding(e.g.micro/nano bubble flooding),thermal recovery(e.g.air injection thermal-aided miscible flooding),and multi-cluster uniform fracturing/water-free fracturing,which are discussed in this paper for their mechanisms,approaches,and key technique researches and field tests.These methods have been studied with remarkable progress,and some achieved ideal results in field tests.Nonetheless,some problems still exist,such as inadequate research on mechanisms,imperfect matching technologies,and incomplete industrial chains.It is proposed to further strengthen the basic researches and expand the field tests,thereby driving the formation,promotion and application of new technologies.

Performance Evaluation of the Halophilic Crude Oildegrading Bacterial Consortium XH-1 for Oilfield Wastewater Treatment

A total of 14 halophilic hydrocarbon-degrading strains were isolated from crude oil-contaminated sites,using petroleum as the sole carbon and energy source.Among these,four highly efficient strains were selected to create the mixed bacterial agent XH-1.These four strains were identified through 16S rRNA gene-based sequencing as belonging to Acinetobacter,Bacillus paramycoides,Rhodococcus sp.,and Enterobacter sp.,respectively.The optimal cultivation time for the mixed consortium XH-1 was found to be 48 h,and a nitrogen-phosphorus molar ratio of 10:1 was determined to be beneficial for crude oil degradation.XH-1 showed notable crude oil degradation even at a salinity of up to 30 g/L,with little inhibition observed at sulfide concentrations as high as 150 mg/L and initial oil concentrations of 500 mg/L.Gas chromatography analysis revealed that XH-1 was able to efficiently degrade C9–C29 n-alkanes.Moreover,a bio-contact oxidation reactor enhanced by XH-1 showed promising results in treating oilfield wastewater.These findings suggest that XH-1 can be applied for the treatment of oilfield wastewater.

Oilfield analogy and productivity prediction based on machine learning: Field cases in PL oilfield, China

In the early time of oilfield development, insufficient production data and unclear understanding of oil production presented a challenge to reservoir engineers in devising effective development plans. To address this challenge, this study proposes a method using data mining technology to search for similar oil fields and predict well productivity. A query system of 135 analogy parameters is established based on geological and reservoir engineering research, and the weight values of these parameters are calculated using a data algorithm to establish an analogy system. The fuzzy matter-element algorithm is then used to calculate the similarity between oil fields, with fields having similarity greater than 70% identified as similar oil fields. Using similar oil fields as sample data, 8 important factors affecting well productivity are identified using the Pearson coefficient and mean decrease impurity(MDI) method. To establish productivity prediction models, linear regression(LR), random forest regression(RF), support vector regression(SVR), backpropagation(BP), extreme gradient boosting(XGBoost), and light gradient boosting machine(Light GBM) algorithms are used. Their performance is evaluated using the coefficient of determination(R^(2)), explained variance score(EV), mean squared error(MSE), and mean absolute error(MAE) metrics. The Light GBM model is selected to predict the productivity of 30 wells in the PL field with an average error of only 6.31%, which significantly improves the accuracy of the productivity prediction and meets the application requirements in the field. Finally, a software platform integrating data query,oil field analogy, productivity prediction, and knowledge base is established to identify patterns in massive reservoir development data and provide valuable technical references for new reservoir development.

Effect of CO_(2)flooding in an oil reservoir with strong bottom-water drive in the Tahe Oilfield,Tarim Basin,Northwest China

The dissolution and diffusion of CO_(2)in oil and water and its displacement mechanism were investigated by laboratory experiment and numerical simulation for Block 9 in the Tahe oilfield,a sandstone oil reservoir with strong bottom-water drive in Tarim Basin,Northwest China.Such parameters were analyzed as solubility ratio of CO_(2)in oil,gas and water,interfacial tension,in-situ oil viscosity distribution,remaining oil saturation distribution,and oil compositions.The results show that CO_(2)flooding could control water coning and increase oil production.In the early stage of the injection process,CO_(2)expanded vertically due to gravity differentiation,and extended laterally under the action of strong bottom water in the intermediate and late stages.The CO_(2)got enriched and extended at the oil-water interface,forming a high interfacial tension zone,which inhibited the coning of bottom water to some extent.A miscible region with low interfacial tension formed at the gas injection front,which reduced the in-situ oil viscosity by about 50%.The numerical simulation results show that enhanced oil recovery(EOR)is estimated at 5.72%and the oil exchange ratio of CO_(2)is 0.17 t/t.

Dynamic simulation of differential accumulation history of deep marine oil and gas in superimposed basin:A case study of Lower Paleozoic petroleum system of Tahe Oilfield,Tarim Basin,NW China

According to the complex differential accumulation history of deep marine oil and gas in superimposed basins,the Lower Paleozoic petroleum system in Tahe Oilfield of Tarim Basin is selected as a typical case,and the process of hydrocarbon generation and expulsion,migration and accumulation,adjustment and transformation of deep oil and gas is restored by means of reservoine-forming dynamics simulation.The thermal evolution history of the Lower Cambrian source rocks in Tahe Oilfield reflects the obvious differences in hydrocarbon generation and expulsion process and intensity in different tectonic zones,which is the main reason controlling the differences in deep oil and gas phases.The complex transport system composed of strike-slip fault and unconformity,etc.controlled early migration and accumulation and late adjustment of deep oil and gas,while the Middle Cambrian gypsum-salt rock in inner carbonate platform prevented vertical migration and accumulation of deep oil and gas,resulting in an obvious"fault-controlled"feature of deep oil and gas,in which the low potential area superimposed by the NE-strike-slip fault zone and deep oil and gas migration was conducive to accumulation,and it is mainly beaded along the strike-slip fault zone in the northeast direction.The dynamic simulation of reservoir formation reveals that the spatio-temporal configuration of"source-fault-fracture-gypsum-preservation"controls the differential accumulation of deep oil and gas in Tahe Oilfield.The Ordovician has experienced the accumulation history of multiple periods of charging,vertical migration and accumulation,and lateral adjustment and transformation,and deep oil and gas have always been in the dynamic equilibrium of migration,accumulation and escape.The statistics of residual oil and gas show that the deep stratum of Tahe Oilfield still has exploration and development potential in the Ordovician Yingshan Formation and Penglaiba Formation,and the Middle and Upper Cambrian ultra-deep stratum has a certain oil and gas resource prospect.This study provides a reference for the dynamic quantitative evaluation of deep oil and gas in the Tarim Basin,and also provides a reference for the study of reservoir formation and evolution in carbonate reservoir of paleo-craton basin.

胜利油田污水对微球调驱性能影响实验研究

微球调驱技术因其能够有效封堵高渗透通道、改善油层流动性能而备受关注。通过核心驱替实验和流变性能测试,系统分析了微球在不同浓度及pH值胜利油田污水中的分散性、驱油性能、长期稳定性及作用机理。结果表明:随着油田污水质量分数从0增加至50%,微球的平均粒径从1.2µm增至2.0µm,分散性显著变差。在不同pH值条件下,微球在pH值为4的油田污水中的平均粒径为2.2µm,而在pH值为9时降至1.3µm,分散性较好。核心驱替实验结果显示,在高有机物成分的油田污水中,微球的驱油效率最高,达到50.3%。微球在质量分数为30%的油田污水中的长期稳定性较差,28 d后平均粒径增至2.1µm。流变实验结果表明,微球悬浮液具有剪切增稠特性,剪切速率为1000 s-1时剪切应力为9.1 Pa。机理分析表明,微球通过静电吸附、物理吸附和化学吸附与污水中的杂质和悬浮颗粒发生相互作用,显著影响其分散性和驱油效果。

Petroleum Accumulation Associated with Volcanic Activity in the Tarim Basin —— Taking Tazhong-47 Oilfield as an Example

The discovery of the Tazhong-47 oilfield confirmed that it is realistic to explore oil and gas fields around igneous rocks in the Tarim basin. The favorable conditions for petroleum accumulation due to volcanic activity and igneous rocks formed during the activity show in two aspects. A) The contact surface of igneous rocks and the surrounding sedimentary rocks, like a vertical unconformity surface, formed the conduit of petroleum migration. Petroleum would accumulate once it encountered a trap in which the reservoir had fine porosity and permeability. B) It formed a trap barriered by igneous rocks, or changed or cut the original trap. In addition, volcanic rocks are a kind of potential reservoir, there are many such examples in the world, and oil also shows in the Permian igneous rocks in well Zhong-1 on Tazhong uplift. Petroleum accumulation associated with volcanic activity will be a new exploring field in the Tarim basin.

Application of Comprehensive Geophysical Techniques to Predict Carbonate Fractured Reservoirs inQingxi Oilfield

Inter-crystalline pores, cavities, and fractures created from diagenetic shrinkage of dolomite are inter-connected each other, forming fine oil- and gas-bearing reservoirs. It is hard to predict these complex fracture-cavity reservoirs because of their random distribution, different growth timing, and so on. Taking the lacustrine dolomite fracture-pore reservoir in the Lower Cretaceous Xiagou Formation in the Qingxi oilfield within the Jiuquan basin as an example, we put forward a comprehensive geophysical method to predict carbonate fractures.

顺北4号断裂带凝析气藏相态特征及差异富集主控因素

顺北4号断裂带位于顺托果勒低隆起中部,该条带油气藏类型为受断裂带控制的凝析气藏,内部凝析气藏相态特征具有明显的南北分异性,国内外同类型的油气藏较少,因此,对该条带的相态特征及造成其差异性分布的主控因素进行深入研究能为同类型凝析气藏的勘探开发提供借鉴。研究利用PVT(压力—容积—温度)高压物性实验分析、有机地球化学分析、流体包裹体分析测试等技术手段,综合研究得出相关认识。研究结果表明:顺北4号断裂带原油整体为低凝固点、低含硫、中—高含蜡的轻质油;天然气甲烷摩尔分数、气油比、天然气干燥系数、CO_(2)摩尔分数在段内呈现差异性分布特征;通过PVT实验分析油气藏类型为凝析气藏,地露压差较大,属于未饱和油藏,北段的临界温度、临界压力明显高于中、南段,由北向南存在递减趋势;从烃源岩和成藏的角度分析,认为顺北4号断裂带凝析气藏差异富集的主控因素为多源供烃和多期成藏。

气浮旋流中油滴与气泡的运动规律

微气泡气浮旋流技术是将气浮分离与旋流分离相结合的一种新型高效分离方法。利用微气泡气浮旋流技术进行油水分离,探究了溶气水微气泡、旋流场、絮凝剂3种因素对油水分离效果的影响,并用高速成像技术考察了微气泡与油滴、微气泡与絮体的结合过程。结果表明,溶气水微气泡可大幅缩短油水分离时间,相比纯水静置缩短了50%。在油水混合物初始质量浓度为400 mg/L时,气浮+旋流+絮凝剂组合工艺的最佳实验条件为油水混合物与溶气水的体积比1∶4、旋流速度370 r/min、复合絮凝剂(PAC∶CPAM)的复配比2∶1,此条件下污水最终含油质量浓度低于10 mg/L,满足《污水综合排放标准》(GB 8978—1996)。静水条件下,微气泡-絮体结合体的平均投影面积约为微气泡-油滴结合体的6倍,投加絮凝剂有利于提升油水分离效果。交互实验证明,相比纯水静置处理,经微气泡气浮、气浮+旋流以及气浮+旋流+絮凝剂3种工艺处理后,污水含油率分别降低38.7%、71.4%、76.5%。就最终油水分离效果来说,3因素组合>溶气水微气泡+旋流场>溶气水微气泡。

砂质辫状河储集层构型表征——以孤东油田七区西馆陶组为例

孤东油田七区西馆陶组N1g45小层—N1g16小层为辫状河沉积,砂体内部构型复杂,需精细解剖储集层结构,揭示其对油气开发的影响。采用Miall构型要素分析法,以现代辫状河规模作为约束,进行砂体储集层构型表征,采用动静结合手段检验研究成果,总结储集层构型对注水开发和剩余油分布的影响。结果表明:研究区为砂质辫状河沉积,主要发育辫状河道、心滩、溢岸以及泛滥平原4种构型单元;辫流带宽度为150~750 m,宽厚比为47~74;在辫流带内,有辫状河道-辫状河道、心滩-心滩、辫状河道-心滩-辫状河道和心滩-辫状河道-心滩4类构型模式;心滩平均长度为250~350 m,平均宽度为110~140 m,长宽比为2.20~2.50,心滩与河道平面面积比为0.36~0.51;心滩内一般发育2~4个落淤层,落淤层延伸长度为70~150 m,产状近水平,背水面夹层倾角为0.9°~2.3°;生产动态揭示由于构型单元边部物性变差,构型拼接部位油气流动受阻,成为局部剩余油富集区;在构型单元主体部位,油藏连通性好,开发效果好。

翻译四步骤理论指导下石油科技文本的机译问题与对策--以Oilfield Review的节译为例

随着待翻译文本涉及的领域越来越广、翻译量越来越大,机器翻译因其具有速度快、价格低廉的特点逐渐成为重要的翻译手段。此后,机器翻译与译者的关系一直受到学者们的关注。文章以乔治斯坦纳提出的翻译四步骤作为指导,将Oilfield Review中的部分内容作为源文本,使用谷歌翻译将原内容转换成中文,后从理论内容中信赖、侵入、吸收、补偿的四个方面分析机器翻译后的石油科技文本出现的问题,并提供解决方案。

注入生产水对储层岩心的堵塞机理及配伍性评价

以中国南海西部某油田为例,综合考察了生产水中悬浮颗粒、油、化学离子等因素对油田储层岩心堵塞的影响。结果表明,注入水驱替体积越多,级别越低的岩心渗透率伤害程度越高。随着岩心级别的增加,化学堵塞对岩心的伤害程度逐级递减,100 m D以下级别的岩心伤害率均超过20%。10~50 mD、50~100 mD、100~300 mD三种级别的岩心在不同平台中物理因素对岩心堵塞贡献分别是化学因素贡献占比的6.45、14.89、6.67、3.15倍。两块相同级别的天然岩心与人造岩心在经过驱替后渗透率保留率相差不大,说明了注入流体与岩石配伍性良好,但长期水驱对岩心(尤其是低渗岩心)的伤害较大。

Using a support vector machine method to predict the development indices of very high water cut oilfields

Because the oilfields in eastern China are in the very high water cut development stage, accurate forecast of oilfield development indices is important for exploiting the oilfields efficiently. Regarding the problems of the small number of samples collected for oilfield development indices, a new support vector regression prediction method for development indices is proposed in this paper. This method uses the principle of functional simulation to determine the input-output of a support vector machine prediction system based on historical oilfield development data. It chooses the kernel function of the support vector machine by analyzing time series characteristics of the development index; trains and tests the support vector machine network with historical data to construct the support vector regression prediction model of oilfield development indices; and predicts the development index. The case study shows that the proposed method is feasible, and predicted development indices agree well with the development performance of very high water cut oilfields.

Burial Dissolution of Ordovician Granule Limestone in the Tahe Oilfield of the Tarim Basin,NW China,and Its Geological Significance

With a comprehensive study on the petrology, geology and geochemistry of some Ordovician granule limestone samples in the Tahe Oiifieid of the Tarim Basin, two stages of burial dissolution were put forward as an in-source dissolution and out-source dissolution based on macro-microcosmic petrology and geochemistry features. The main differences in the two stages are in the origin and moving pass of acid fluids. Geochemical evidence indicates that burial dissolution fluids might be ingredients of organic acids, CO2 and H2S associated with organic matter maturation and hydrocarbon decomposition, and the in-source fluid came from organic matter in the granule limestone itself, but the out-source was mainly from other argillaceous carbonate rocks far away. So, the forming of a burial dissolution reservoir resulted from both in-source and the out-source dissolutions. The granule limestone firstly formed unattached pinholes under in-source dissolution in situ, and afterwards suffered wider dissolution with out-source fluids moving along unconformities, seams, faults and associate fissures. The second stage was much more important, and the mineral composition in the stratum and heat convection of the fluid were also important in forming favorable reservoirs.

A Study of the Genesis of Karst-type Subtle Reservoir in Tahe Oilfield

The genesis of the Ordovician karst in the Tahe Oilfield is hypothesized on the basis of many analyses of the geo-chemical data and the sporopollen. Ordovician carbonate rocks experienced multistage karst reconstructions under the condition of low-temperature oxidation meteoric water on the surface or near-surface. The karst occurred mainly in the early Hercynian, which has undergone three stages of karst cycle and developed three sets of cave reservoirs under the influence of the tectonic uplift, and the upper of the cave was formed earlier. The evidence of karst was found in the Caledonian. On the above basis, the genetic prediction pattern of the Ordovician palaeokarst reservoir in this region was set up.

Distribution and treatment of harmful gas from heavy oil production in the Liaohe Oilfield, Northeast China

The distribution and treatment of harmful gas （H2S） in the Liaohe Oilfield, Northeast China, were investigated in this study. It was found that abundant toxic gas （H2S） is generated in thermal recovery of heavy oil. The H2S gas is mainly formed during thermochemical sulfate reduction （TSR） occurring in oil reservoirs or the thermal decomposition of sulfocompounds （TDS） in crude oil. H2S generation is controlled by thermal recovery time, temperature and the injected chemical compounds. The quantity of SO4^2- in the injected compounds is the most influencing factor for the rate of TSR reaction. Therefore, for prevention of H2S formation, periodic and effective monitoring should be undertaken and adequate H2S absorbent should also be provided during thermal recovery of heavy oil. The result suggests that great efforts should be made to reduce the SO4^2- source in heavy oil recovery, so as to restrain H2S generation in reservoirs. In situ burning or desulfurizer adsorption are suggested to reduce H2S levels. Prediction and prevention of H2S are important in heavy oil production. This will minimize environmental and human health risks, as well as equipment corrosion.

Types of Karst-fractured and Porous Reservoirs in China's Carbonates and the Nature of the Tahe Oilfield in the Tarim Basin

Almost all the oil and gas reservoirs developed in marine sedimentary strata of China have undergone processes of multi-phase reservoir formation and later modification. The irregular reservoirs are classified into three types as the Naxi, Tahe and Renqiu ones, increasing successively in the development degree of karstificated pores and fissures and the connection degree of independent reservoirs. In these reservoirs, the unity in the fluid feature, pressure and oil-gas-water interface also increases successively from the Naxi to the Renqiu type. The main body of Ordovician reservoirs of the Tahe Oilfield in the Tarim Basin is a network pool rather than a stratified, massive, stratigraphically-unconformed or weathering-crust one. The fluid nature of oil, gas and water, the interface positions and the pressures, as well as the dynamic conditions of fluids within the reservoirs during the production are all different from those in stratified or massive oil and gas reservoirs. Carbonates in the Akekule uplift and the Tahe Oilfield are assemblages of various types of reservoirs, which have an overall oil-bearing potential and obvious uneven distribution. Testing and producing tests are the major means to evaluate this type of reservoirs and acid fracturing improvement is a key link in petroleum exploration and development.

Influences of water treatment agents on oil-water interfacial properties of oilfield produced water

The emulsion stability of oilfield produced water is related to the oil-water interfacial film strength and the zeta potential of the oil droplets. We investigated the effects of water treatment agents （corrosion inhibitor SL-2, scale inhibitor HEDP, germicide 1227, and flocculant polyaluminium chloride PAC） on the stability of oilfield produced water. The influence of these treatment agents on oil-water interfacial properties and the mechanism of these agents acting on the oilfield produced water were studied by measuring the interfacial shear viscosity, interfacial tension and zeta electric potential. The results indicated that the scale inhibitor HEDP could increase the oil-water interfacial film strength, and it could also increase the absolute value of the zeta potential of oil droplets. HEDP played an important role in the stability of the emulsion. Polyaluminum chloride （PAC） reduced the stability of the emulsion by considerably decreasing the absolute value of the zeta potential of oil droplets. Corrosion inhibitor SL-2 and germicide 1227 could decrease the oil-water interfacial tension, whereas they had little influence on oil-water interfacial shear viscosity and oil-water interfacial electricity properties.

延长油田数字化转型探索与发展

延长油田紧跟国家数字化发展趋势,积极推进数字化转型,通过自主研发,组建数字化团队,打造数字化研发培训基地,通过物联网自主研发、建设、自主维护化,以及软件定制化,实现数字化转型的全面发展。促进延长油田组织模式优化和业务流程创新,不断助推油田减员、降本、增效、提安,创建具有延长特色DNA的数字油田。2023年被国家工业和信息化部授予物联网赋能行业典型案例称号。