Prediction of curved oil–water interface in horizontal pipes using modified model with dynamic contact angle

In this study,interface shapes of horizontal oil–water two-phase flow are predicted by using Young-Laplace equation model and minimum energy model.Meanwhile,the interface shapes of horizontal oil–water twophase flow in a 20 mm inner diameter pipe are measured by a novel conductance parallel-wire array probe(CPAP).It is found that,for flow conditions with low water holdup,there is a large deviation between the model-predicted interface shape and the experimentally measured one.Since the variation of pipe wetting characteristics in the process of fluid flow can lead to the changes of the contact angle between the fluid and the pipe wall,the models mentioned above are modified by considering dynamic contact angle.The results indicate that the interface shapes predicted by the modified models present a good consistence with the ones measured by CPAP.

A Review of Formation Mechanism Study on Reservoirs with Tilted Oil-water Contacts

The distribution characteristics of the oil-water contact are the basis for the reservoir exploration and development and reserves evaluation. The reservoir with a tilted oil-water contact has a unique formation mechanism, and the understanding of its distribution and formation mechanism will directly affect the evaluations for the reservoir type, well deployment, selection of well pattern and type, determination of test section, and reserves evaluation. Based on the analysis of reservoir characteristics, petrophysical properties and geological structure in 40 reservoirs worldwide with tilted oil-water contacts, the progress of the research on the formation mechanisms of titled oil-water contacts is summarized in terms of the hydrodynamic conditions, reservoir heterogeneity, neotectonic movement and oil-gas exploitation. According to the formation mechanism of tilted oil-water contacts and the needs of exploration research, different aspects of research methods are summarized and classified, such as the calculation of equipotential surfaces for oil and water in the formation, analysis of formation pressure and analysis of reservoir physical properties and so on. Based upon statistical analysis, it is suggested that the degree of the inclination of the oil-water contact be divided based on the dip of oil-water contact（DipTOWC）. The tilted oil-water contact is divided into three categories： large dip（DipTOWC≥55 m/km）, medium dip（4 m/km≤DipTOWC55 m/km）, and small dip（DipTOWC4 m/km）. The classification and evaluation method can be combined with structure amplitude and reservoir property. The formation mechanism of domestic and international reservoirs with tilted oil-water contacts are summarized in this paper, which have important significance in guiding the exploration and development of the oilfield with tilted oil-water contacts, reserves evaluation, and well deployment.

Wettability alteration analysis of smart water/novel functionalized nanocomposites for enhanced oil recovery

Smart water flooding,as a popular method to change the wettability of carbonate rocks,is one of the interesting and challenging issues in reservoir engineering.In addition,the recent studies show that nanoparticles have a great potential for application in EOR processes.However,little research has been conducted on the use of smart water with nanoparticles in enhanced oil recovery.In this study,stability,contact angle and IFT measurements and multi-step core flooding tests were designed to investigate the effect of the ionic composition of smart water containing SO4^2- and Ca^2+ ions in the presence of nanofluid on EOR processes.The amine/organosiloxane@Al2O3/SiO2(AOAS) nanocomposite previously synthesized using co-precipitation-hydrothermal method has been used here.However,for the first time the application of this nanocomposite along with smart water has been studied in this research.Results show that by increasing the concentrations of calcium and sulfate ions in smart water,oil recovery is improved by 9% and 10%,respectively,compared to seawater.In addition,the use of smart water and nanofluids simultaneously is very effective on increasing oil recovery.Finally,the best performance was observed in smart water containing two times of sulfate ions concentration(SW2 S) with nanofluids,showing increased efficiency of about 7.5%.

A Study on Water Repellent Effectiveness of Natural Oil-Applied Soil as a Building Material

This study was performed to investigate the water repellent effectiveness of natural oil-applied soil when it is used as a building material. Natural oil types such as olive oil, bean oil, perilla oil and linseed oil, which are being used for producing water repellent timber, are selected for the experiments. It is expected that perilla oil and in seed oil, which are drying oil types will have better water repellent effectiveness than the other types. For the evaluation of water repellence of natural oil-applied soil, a contact angle test was performed. A contact angle of water drop on various surface conditions were tested, and large differences were seen between the natural oil-applied soil and untreated soil. As a result, it is showed that all natural oil types have water repellent effectiveness. However, linseed oil, which is a drying oil type, shows an outstanding water repellent effectiveness value, while perila oil, which is also a drying oil type, shows the lowest value. Additionally, results show that there is no link between water repellent effectiveness and the number of applications of natural oil. Nevertheless, existing commercial water repellents show better performance than natural oil, and it is anticipated that the results of this study will provide essential information for further research to enhance the water repellent effectiveness of soil as a building material.

Donghe Sandstone Subtle Reservoir Exploration and Development Technology in Hade 4 Oilfield

Hade 4 oilfield is located on the Hadexun tectonic belt north of the Manjiaer depression in the Tarim basin, whose main target layer is the Donghe sandstone reservoir, with a burial depth over 5,000m and an amplitude below 34m, at the bottom of the Carboniferous. The Donghe sandstone reservoir consists of littoral facies deposited quartz sandstones of the transgressive system tract, overlapping northward and pinching out. Exploration and development confirms that water-oil contact tilts from the southeast to the northwest with a drop height of nearly 80m. The reservoir, under the control of both the stratigraphic overlap pinch-out and tectonism, is a typical subtle reservoir. The Donghe sandstone reservoir in Hade 4 oilfield also has the feature of a large oil-bearing area (over 130 km2 proved), a small thickness (average efficient thickness below 6m) and a low abundance (below 50 × 104t/km2). Moreover, above the target layer developed a set of igneous rocks with an uneven thickness in the Permian formation, thus causing a great difficulty in research of the velocity field. Considering these features, an combination mode of exploration and development is adopted, namely by way of whole deployment, step-by-step enforcement and rolling development with key problems to be tackled, in order to further deepen the understanding and enlarge the fruits of exploration and development. The paper technically focuses its study on the following four aspects concerning problem tackling. First, to strengthen the collecting, processing and explanation of seismic data, improve the resolution, accurately recognize the pinch-out line of the Donghe sandstone reservoir by combining the drilling materials in order to make sure its distribution law; second, to strengthen the research on velocity field, improve the accuracy of variable speed mapping, make corrections by the data from newly- drilled key wells and, as a result, the precision of tectonic description is greatly improved; third, to strengthen the research on sequence stratigraphy and make sure the distribution law of the Donghe sandstone; and fourth, with a step- by-step extrapolation method, to deepen the cognition of the leaning water-oil contact, and by combining the tectonic description and drilling results, to make sure little by little the law of change of the water-oil contact. The exploration and development of the Donghe sandstone subtle reservoir in Hade 4 oilfield is a gradually perfected process. From 1998 when it was discovered till now, the reservoir has managed to make a benign circle of exploration and development, in which its reserve has gradually been enlarged, its production scale increased, and, in a word, it has used techniques necessary for this subtle reservoir in the Tarim basin.

The Role of Seal and Source Rocks in Fluid-rock Interactions and their Reservoir Effects within the Carbonate Deep Burial Realm

Discoveries of deep high-quality carbonate reservoirs challenged the general understanding on the evolution of porosity decreasing with depth.New mechanisms of pore generation and preservation in the deep realm require to be proposed.Dolostones in the Feixianguan and Dengying Formations experienced maximum depths in excess of 8000 m,but still retained high porosity.Petrographic observation and homogenization temperatures help to identify products of deep fluid-rock interactions,visual and experimental porosity were used to quantify reservoir effects,the distribution of products finally being plotted to unravel the mechanisms.Th data reveal that thermochemical sulfate reduction(TSR),burial dissolution and quartz cementation are typical deep fluid-rock interactions.The SO_(4)^(2-)of residual porewater sourced from the evaporative dolomitizing fluid was supplied for TSR in the hydrocarbon column,the TSR-inducing calcite cements were homogeneously dispersed in the hydrocarbon column.Quartz cementation was caused by the increasing acidity and Si-rich residual porewater in the oil column.Burial dissolution is forced by organic acid and limited in oil-water contact.This study suggests that seal and source rocks not only play important roles in hydrocarbon accumulation,but also have a general control on the deep fluid-rock interactions and porosity evolution in the deep burial realm.

Automatic measurement of three-phase contact angles in pore throats based on digital images

With the help of digital image processing technology, an automatic measurement method for the three-phase contact angles in the pore throats of the microfluidic model was established using the microfluidic water flooding experiment videos as the data source. The results of the new method were verified through comparing with the manual measurement data.On this basis, the dynamic changes of the three-phase contact angles under flow conditions were clarified by the contact angles probability density curve and mean value change curve. The results show that, for water-wetting rocks, the mean value of the contact angles is acute angle during the early stage of the water flooding process, and it increases with the displacement time and becomes obtuse angle in the middle-late stage of displacement as the dominant force of oil phase gradually changes from viscous force to capillary force. The droplet flow in the remaining oil occurs in the central part of the pore throats, without three-phase contact angle. The contact angles for the porous flow and the columnar flow change slightly during the displacement and present as obtuse angles in view of mean values, which makes the remaining oil poorly movable and thus hard to be recovered. The mean value of the contact angle for the cluster flow tends to increase in the flooding process, which makes the remaining oil more difficult to be recovered. The contact angles for the membrane flow are mainly obtuse angles and reach the highest mean value in the late stage of displacement, which makes the remaining oil most difficult to be recovered. After displacement, the remaining oils under different flow regimes are just subjected to capillary force, with obtuse contact angles, and the wettability of the pore throat walls in the microfluidic model tends to be oil-wet under the action of crude oil.

Ideal Failure Curve of Rolling Contact Bearings

The prevailing cumulative failure curves of Rolling Contact Bearings (RCB) have two main drawbacks: they begin at the origin and have a large dispersion. The purpose of this study is to develop an ideal failure curve and overcome the present drawbacks. The ideal failure curve of RC bearings is obtained by applying a water-free lubricant to the tested bearings. This eliminates the cavitation erosion from the Bimodal failure mechanism and the synergistic effect with the mechanical failure mode. This new concept considers the fatigue process involved in the failure mechanism and suggests decreasing the dispersion of bearing life.

Analysis of air adsorptive on solid surfaces by AFM and XPS

Solid surfaces of HOPG, pure copper, chromium, zinc, copper and SUS304 steel were observed in ambient air with an a.c. non-contact mode of atomic force microscope(AFM). A type of film-like-domains (adsorptive) was detected on the above surfaces. The thickness of the adsorptive was about 1.2-2.4 nm in this case. The film-like-adsorptive was confirmed to be a liquid layer by the static contact-mode scanning, the measurement of the elasticity and viscosity images, and the detection of the condensation/ evaporation phenomena when the relative humidity changed. The liquid layer is considered to be condensed water covered with organic contaminant.

Paleo-oil-Water Contact and Present-Day Gas-Water Contact:Implication for Evolution History of Puguang Gas Field, Sichuan Basin, China

The Puguang （普光） gas field is the largest gas field found in marine carbonate in China. The Puguang gas field experienced complicated evolution history from paleo-oil pool to gas pool. The purpose of this article is to reveal the evolution history of Puguang gas field through systematic study on the relationship between paleo-oil-water contact （POWC） and present-day gas-water contact （PGWC）. POWC was recognized by observing the change of relative content of residual solid bitumen in the cores, and PGWC was observed using log and drilling stem test data. Two types of relationship between POWC and PGWC were observed in the Puguang gas field： POWC is above PGWC, and POWC is below PGWC. The former is normal as oil cracking may cause gas-water contact to move downward. The latter can be interpreted by lateral gas re-migration and re-accumulation caused by changes in structural configuration. The relationship between POWC and PGWC suggests that during oil charge, the southwestern and northwestern parts of the Puguang gas field were structurally lower than the northeastern and southeastern parts. Thrusting from Xuefengshan （雪峰山） since Yanshanian movement and from Dabashan （大巴山） since Himalayan movement resulted in the relative uplift of the southwestern and northwestern parts of the Puguang structure, which significantly changed the structural configuration. Based on the paleo-structure discussed in this article, the most probable migration directions of paleo-oil were from the northwest to the southeast and from the southwest to the northeast. Consequently, the evolution history of the Puguang gas field can be divided into three stages, namely,oil charging （200-170 Ma）, cracking oil to gas （155-120 Ma）, and gas pool adjustment （12-0 Ma）.

应用测井资料小波变换与伪成像技术精细划分深部隔夹层

隔夹层影响流体渗流,控制油水及剩余油分布,深层取心成本高,常规测井曲线分辨率低且薄互层信号模糊,深部隔夹层识别难度大。通过对关键井岩心研究,得出了隔夹层敏感测井曲线及其响应特征,采用小波分解和重构,对常规敏感测井曲线进行了高分辨率处理,降低了邻层平滑效应,突出了薄层界面测井响应特征,薄层识别分辨率提高了近1倍。综合利用隔夹层地层倾角矢量模式和伪成像特征,确立了深部隔夹层判识划分方法,应用实例表明,该方法可精细识别隔夹层,相比常规方法,隔夹层辨识能力显著提升,井间小层对比精度提高38%,解释了油水界面倾斜问题,得出了剩余油分布规律。

大庆SN油田东部过渡带油水边界综合确定

为确定大庆SN油田东部过渡带油水界面,综合钻井、测井、地震资料,结合岩心含油产状分析和老井油水层二次解释,基于双相介质理论的叠后属性油气检测以及基于叠前地震波形指示反演的流体识别等技术,探讨构造油气藏外扩区油水边界的综合确定方法。研究区油水边界具有以下特征:岩心含油产状为油斑以上;测井解释外推为油层或油水同层;叠后属性低高频能量比大于0.85;叠前反演预测含水饱和度小于75%。因此,以“井点定深度、地震定边界、动态来验证”为原则,从“点—线—面—空”,经过综合分析,确定最终油水边界位置。研究成果有效指导了研究区外扩评价部署,对同类型构造油田油水边界研究具有参考意义。

聚丙烯织物表面超亲水涂层构筑及其油水分离性能

[目的]为得到具有优秀耐久性和高油水分离效率的超亲水性聚丙烯(PP)分离材料。[方法]通过将天然来源的羧甲基纤维素(CMC)与聚丙烯织物共价结合,制备出一种具有超亲水-水下超疏油性能涂层的改性PP织物。通过扫描电镜(SEM)、红外光谱(IR)、X射线光电子能谱(XPS)等手段对改性后的样品进行分析,利用接触角测量仪和自建油水分离装置测试了改性PP织物的润湿性及油水分离性能。[结果]改性PP织物在空气中的水接触角低至0°,在水下对不同油(包括正己烷、甲苯、煤油、柴油、汽油和石油醚)的接触角都不低于150°,对油水混合物的分离效率都可达到98%以上,分离时的水通量高达69449 L/(m^(2)·h)以上。经过50次循环分离、酸碱盐溶液腐蚀浸泡8 h、砂纸刮擦30次、高含沙量水冲刷2 h等多项测试后,改性PP织物均保持优异的水下疏油性和大于97%的油水分离效率。从微观结构与化学组成的角度揭示了是表面粗糙度与亲水基团的协同作用使PP织物由最初的疏水亲油转变为超亲水-水下超疏油。[结论]通过化学键连接的方式可以在PP织物表面成功构筑牢固结合的超亲水涂层。该改性过程绿色、简便、低成本,能赋予PP织物优异、耐久的油水分离性能。改性后的PP织物有望在复杂水体环境下的油水分离场景中应用。

三聚氰胺基疏水海绵的制备及其吸油性能

采用单宁酸(TA)/Fe^(3+)复合物(TA/Fe^(3+))对三聚氰胺海绵(MS)进行预处理,然后通过生物蜡乳液浸渍法对三聚氰胺海绵进行疏水改性,制备了高吸油倍率的疏水三聚氰胺海绵(MS-TA/Fe^(3+)-Wax)。采用扫描电子显微镜、傅里叶变换红外光谱和接触角测试等手段对三聚氰胺海绵改性前后样品进行微观形貌、结构组成和表面润湿性表征,并考察其对不同油品的吸油性能。结果表明:MS-TA/Fe^(3+)-Wax具有高度疏水性,水接触角可达141.5°;在常温常压条件下,MS-TA/Fe^(3+)-Wax对正辛烷、二氯甲烷、甲苯、柴油、泵油和菜籽油的吸油量为54.91~97.46 g/g,吸油过程符合拟二级动力学。疏水改性的三聚氰胺海绵材料通过挤压解吸附可实现循环使用,在处理油-水污染物方面具有潜在的应用前景。

大口径锥头弹体高速倾斜入水偏转规律数值模拟

结合某大口径锥头弹体高速倾斜入水试验,采用任意拉格朗日-欧拉(arbitrary Lagrange-Euler,ALE)流固耦合方法对弹体倾斜入水偏转行为进行数值模拟,研究了弹体以500 m/s高速倾斜入水过程中不同受力模式、载荷变化特征以及弹体发生偏转的力学机理,分析了入水角度对弹体偏转规律的影响。结果表明:在俯仰力矩作用下,弹体均发生抬头方向偏转,且偏转速度呈现先增大后减小的趋势,偏转程度在不同入水角度范围内呈现不同的变化趋势。当入水角度小于15°时,弹体会发生“跳弹”现象;当入水角度为30°~60°时,弹体偏转趋势基本一致,均由初始倾斜状态逐渐转动至水平状态、竖直状态并最终以弹头入水反方向的“出水”姿态向水下运动;当入水角度为75°时,弹体转动至水平状态后,并未继续偏转至竖直状态,弹头以朝斜上方的姿态向水下运动;弹体的入水侵深随入水角度的增大而增大,且增大趋势近似满足指数函数关系。

金属网基油水分离材料的制备与应用

特异性润湿材料为处理含油污水的新型材料。在各种润湿性材料中,聚合物材料存在表面活性剂污染及降解等缺陷,而金属网基材料具有较好的自清洁性能,并且,具有较高的力学强度及分离效率,两者均被广泛应用于含油废水的油水分离处理。文章叙述了含油污水的主要来源及传统油水分离技术存在的问题,介绍了表面润湿性的基本原理,包括空气中接触角(弹性模型、Wenzel模型及Cassie-Baxter模型)、滚动角等,然后,分别对超疏水/亲油、超亲水/水下超疏油材料的制备方法及特点进行介绍,并且,重点分析了材料表面微观结构及表面能对油水分离效果的影响,最后,结合工业生产中存在的问题及实际需求对未来金属网基油水分离材料的发展进行了展望。

微量油辅助水润滑成膜特性的研究

由于水的润滑膜建立能力较差,本文中研究了微量环保型润滑油辅助水润滑的润滑膜建立机制.利用滚子-盘接触润滑膜测量仪,研究了水环境下2种黏度的环保型润滑油作为第二介质的辅助润滑特性,并通过荧光标记对油的流动进行了观测.结果表明,水环境下滚子-盘接触区的润滑油主要来源于入口油池和侧油脊.与在空气中不同,水环境使油在固体表面的润湿性变低,接触区供油易受外界干扰,膜厚易发生波动.低速下侧油脊更容易向接触区回流,从而改善供油;在高速下水的逆流推动侧油脊回流的油远离接触区,导致入口供油变差.此外,环块试验机结果表明微量环保型润滑油辅助水润滑具备良好的减摩抗磨能力.

渤海曹妃甸低幅底水稠油油田特高含水期开发模式研究与实践

曹妃甸油田群为渤海规模最大的底水稠油油田,构造幅度低、油柱高度低、地层原油黏度大,经过十多年开发进入了特高含水期,目前采油速度低、水驱采收率低,亟需综合调整。通过室内实验与水驱模型推导,研究了底水稠油油藏水平井水脊特征与水驱波及系数变化规律。结果表明,水平井开采过程中单区脊进严重、沿程驱替不均衡;水平井水驱波及系数“早期缓慢上升、后期持续增大”,这说明提高产液量可以提高水驱波及系数。在此基础上,提出了基于水脊演化规律的水平井网加密调整技术、融合构造与储层描述的水平井精准布井技术、基于孔隙有效动用的水平井大排量提液技术等关键技术,进而建立了特高含水期老区与新区并举、老井与新井交错、纵向分带、平面分区的水平井整体加密调整模式。按照本文模式调整后,油田储量动用程度提高了21.3个百分点,采油速度提高了1.3倍,水驱采收率提高了10.9个百分点,实现了特高含水期快速上产并持续稳产,为海上油田中长期持续稳产和高效开发提供借鉴。

春风油田沙湾组稠油油藏倾斜油水界面成因

春风油田新近系沙湾组一段稠油油藏油水关系复杂,运用传统油水界面观点难以解释,影响该油田勘探开发进程。以油水关系矛盾突出的P601-20区块为例,开展地震-地质综合研究及成藏动力学研究,结合油藏开发动态资料,分析春风油田沙湾组一段稠油油藏油水关系及其成因。研究认为:该油田油水关系复杂是由于油藏存在倾斜油水界面,其油藏类型仍然为构造-岩性油藏,并且存在边底水;储集层物性、断层、地层压力、构造运动等方面,形成倾斜油水界面的主要原因是构造运动导致油藏调整,原油稠化和地层构造平缓加剧了油水界面调整滞后,该油藏属于非稳态油气藏。

KGM/CNF-不锈钢网油水分离材料的制备及其油水分离性能研究

目的在KGM/CNF包覆不锈钢网表面制备超亲水、水下超疏油功能材料,实现油水体系的分离。方法采用溶液浸泡法在不锈钢网上沉积魔芋葡甘聚糖(Konjac Gluco Mannan,KGM)/纤维素纳米纤维(CelluloseNanoFiber,CNF),构造超亲水/水下超疏油表面。通过加热使KGM脱乙酰化、KGM/CNF分子间氢键重构、CNF在材料表面重新排布,制备了KGM/CNF-不锈钢网油水分离材料;利用扫描电镜、傅里叶变换红外光谱仪、X射线衍射仪和界面接触角对油水分离材料的表面形貌及物化性质进行了表征和研究,采用红外测油仪研究了油水分离性能。结果KGM/CNF-不锈钢网油水分离材料在空气中具有优异的超亲水性(WCA=0°)和水下超疏油性能(OCA≥151°)。通过油水分离性能研究发现,KGM/CNF-不锈钢网油水分离材料在自身重力下可以对大豆油、汽油等不同油水混合物进行高效分离,对油水混合物的分离效率可达97.40%,分离通量为1236.75L/(m^(2)·h)。结论KGM/CNF-不锈钢网油水分离材料以不锈钢网为载体,弥补了力学强度差的缺点,具有优异的油水分离性能以及良好的耐腐蚀性和循环使用性;该材料制备方法简单,制备过程绿色环保、成本低,在油水体系的分离中具有较好的潜在应用前景。