Remaining oil distribution characteristics in an oil reservoir with ultra-high water-cut

An accurate mapping and understanding of remaining oil distribution is very important for water control and stabilize oil production of mature oilfields in ultra-high water-cut stage.Currently,the Tuo-21 Fault Block of the Shengtuo Oilfield has entered the stage of ultra-high water cut(97.2%).Poor adaptability of the well pattern,ineffective water injection cycle and low efficiency of engineering measures(such as workover,re-perforation and utilization of high-capacity pumps)are the significant problems in the ultra-high water-cut reservoir.In order to accurately describe the oil and water flow characteristics,relative permeability curves at high water injection multiple(injected pore volume)and a semiquantitative method is applied to perform fine reservoir simulation of the Sand group 3e7 in the Block.An accurate reservoir model is built and history matching is performed.The distribution characteristics of remaining oil in lateral and vertical directions are quantitatively simulated and analyzed.The results show that the numerical simulation considering relative permeability at high injection multiple can reflect truly the remaining oil distribution characteristics after water flooding in an ultrahigh water-cut stage.The distribution of remaining oil saturation can be mapped more accurately and quantitatively by using the‘four-points and five-types’classification method,providing a basis for potential tapping of various remaining oil types of oil reservoirs in late-stage of development with high water-cut.

Development Strategies for Achieving High Production with Fewer Wells in Conventional Offshore Heavy Oil Fields in Bohai Bay,China

Development strategy for heavy-oil reservoirs is one of the important research interests in China National Offshore Oil Corp. （CNOOC） that plans a highly effective development for heavy oil fields in multilayered fluvial reservoirs because of their significant influence on marine oil and even on China＇s petroleum production. The characteristics analysis of multilayered fluvial reservoirs in the heavy oil fields in Bohai Bay indicates that large amounts ofoil were trapped in the channel, point bar and channel bar sands. The reserves distribution of 8 oilfields illustrates that the reserves trapped in the main sands, which is 20%-40% of all of the sand bodies, account for 70%-90% of total reserves of the heavy oil fields. The cumulative production from high productivity wells （50% of the total wells） was 75%-90% of the production of the overall oilfield, while only 3%-10% of the total production was from the low productivity wells （30% of the total wells）. And the high productivity wells were drilled in the sands with high reserves abundance. Based on the above information the development strategy was proposed, which includes reserves production planning, selection of well configuration, productivity design, and development modification at different stages.

Water-cut rising mechanism and optimized water injection technology for deepwater turbidite sandstone oilfield: A case study of AKPO Oilfield in Niger Delta Basin, West Africa

Through the analysis of the reservoir connection relationship and the water-cut rising rules after water breakthrough in the highly volatile oil AKPO oilfield, a new model of water-cut rising was established, and the timing and strategy of water injection were put forward. The water-cut rising shapes of producers after water breakthrough can be divided into three types, and their water-cut rising mechanism is mainly controlled by reservoir connectivity. For the producers which directly connect with injectors in the single-phase sand body of the single-phase channel or lobe with good reservoir connectivity, the water-cut rising curve is "sub-convex". For the producers which connect with injectors through sand bodies developed in multi-phases with good inner sand connectivity but poorer physical property and connectivity at the overlapping parts of sands, the response to water injection is slow and the water-cut rising curve is "sub-concave". For the producers which connect with injectors through multi-phase sand bodies with reservoir physical properties, connectivity in between the former two and characteristics of both direct connection and overlapping connection, the response to water injection is slightly slower and the water-cut rising curve is "sub-S". Based on ratio relationship of oil and water relative permeability, a new model of water cut rising was established. Through the fitting analysis of actual production data, the optimal timing and corresponding technology for water injection after water breakthrough were put forward. Composite channel and lobe reservoirs can adopt water injection strategies concentrating on improving the vertical sweep efficiency and areal sweep efficiency respectively. This technology has worked well in the AKPO oilfield and can guide the development of similar oilfields.

A New Method for Predicting Wall Sticking Occurrence Temperature of High Water Cut Crude Oil

In crude oil transportation, adhesion of oil on pipe wall can cause partial or total blockage of the pipe. This process is significantly affected by wall sticking occurrence temperature(WSOT). In this work, an efficient approach for estimating WSOT of high water-cut oil, which can agree well with the actual environment of multiphase transportation pipeline, is proposed. Based on the energy dissipation theory, it is possible to make comparison of average shear rates between the stirred vessel and the flow loop. The impacts of water content and shear rate on WSOT are investigated using the stirred vessel and the flow loop. Good agreement has been observed between the stirred vessel and the flow loop results with the maximum and the average absolute deviations equating to 3.30 °C and 2.18 °C, respectively. The development of gathering scheme can enjoy some benefits from this method.

Experimental study on surface-active polymer flooding for enhanced oil recovery: A case study of Daqing placanticline oilfield, NE China

Experiments on surface-active polymer flooding for enhanced oil recovery were carried out by detection analysis and modern physical simulation technique based on reservoirs and fluids in Daqing placanticline oilfield.The experimental results show that the surface-active polymer is different from other common polymers and polymer-surfactant systems in molecular aggregation,viscosity and flow capacity,and it has larger molecular coil size,higher viscosity and viscosifying capacity,and poorer mobility.The surface-active polymer solution has good performance of viscosity-increasing and viscosity retention,and has good performance of viscoelasticity and deformability to exert positive effects of viscosifying and viscoelastic properties.Surface-active polymer can change the chemical property of interface and reduce interfacial tension,making the reservoir rock turn water-wet,also it can emulsify the oil into relatively stable oil-in-water emulsion,and emulsification capacity is an important property to enhance oil washing efficiency under non-ultralow interfacial tension.The surface-active polymer flooding enlarges swept volume in two ways:Microscopically,the surface-active polymer has mobility control effect and can enter oil-bearing pores not swept by water to drive residual oil,and its mobility control effect has more contribution than oil washing capacity in enhancing oil recovery.Macroscopically,it has plugging capacity,and can emulsify and plug the dominant channels in layers with high permeability,forcing the injected fluid to enter the layer with medium or low permeability and low flow resistance,and thus enlarging swept volume.

桑托斯盆地盐下孤立碳酸盐台地沉积建造与深水大油田

针对桑托斯被动陆缘盆地深水盐下碳酸盐岩储层分布特征及大油田成藏规律不清的难题,综合利用地质、地震及岩心等数据资料,通过早白垩世原型盆地与岩相古地理恢复重建,提出盐下碳酸盐岩沉积建造受控于坳间断隆型和坳中断凸型两类孤立台地。坳间断隆型孤立台地分布于现今盐下坳间隆起带上,建造于早期陆内和陆间裂谷两个原型阶段继承性发育的单断式和双断式垒式断块上,早白垩世陆内裂谷晚期沉积的ITP组介壳灰岩和陆间裂谷早期沉积的BVE组微生物灰岩为连续建造;坳中断凸型孤立台地分布于现今盐下坳陷带中,建造于早期陆内裂谷原型阶段火山岩建隆所形成的凸起带上,发育BVE组微生物灰岩。两类孤立台地灰岩所形成礁滩体均具有储层厚度大、物性好的特点。结合盐下已发现大油田解剖,发现两类台地均可形成大型构造-岩性复合圈闭,周缘为优质湖相和潟湖相烃源岩环绕,上覆为巨厚的优质蒸发盐岩盖层高效封堵,形成了“下生中储上盖”式最佳生储盖组合关系,油气富集程度高。已发现大油田均为具有统一压力系统的底水块状油田,且均处于充满状态。未来勘探重点目标是西部隆起带和东部隆起带南段上的坳间断隆型孤立台地及中央坳陷带中的坳中断凸型孤立台地。该项研究成果为在桑托斯被动陆缘盆地超前选区选带、新项目评价及中标区块探区勘探部署提供了重要依据,也为今后在全球被动大陆边缘盆地深水勘探战略选区提供借鉴。

Theory and Application of Numerical Simulation of Chemical Flooding in High Temperature and High Salt Reservoirs

Applications, theoretical analysis and numerical methods are introduced for the simulation of mechanical models and principles of the porous flow in high temperature, high salt, complicated geology and large-scale reservoirs in this paper. Considering petroleum geology, geochemistry, computational permeation fluid mechanics and computer technology, we state the models of permeation fluid mechanics and put forward a sequence of implicit upwind difference iteration schemes based on refined fractional steps of the upstream, which can compute the pressures, the saturation and the concentrations of different chemistry components. A type of software applicable in major industries has been completed and carried out in numerical analysis and simulations of oil extraction in Shengli Oil-field, which brings huge economic benefits and social benefits. This software gives many characters: spatial steps are taken as ten meters, the number of nodes is up to hundreds of thousands and simulation time period can be tens of years and the high-order accuracy can be promised in numerical data. Precise analysis is present for simplified models of this type and that provides a tool to solve the international famous problem.

塔里木盆地顺北油气田少井高产地质工程一体化做法与关键技术

塔里木盆地顺北油气田埋藏深度为7300~9000m,脆性地层破碎形成的缝洞型储层沿高陡走滑断裂带发育,断裂破碎带内部非均质性极强,且流体性质差异大。面对这类超深复杂的断控缝洞型油气藏,高效成井面临世界级挑战,单井费用高,效益开发难度大,没有现成的经验、技术可借鉴。顺北油气田以项目管理为抓手,建立了独有的“五有五提升”地质工程一体化管理模式,创新形成了“少井高产”七要素关键技术。近几年,少井高产地质工程一体化实现了质的飞跃,落实了4号、8号断裂带2个亿吨级资源阵地,新增石油探明储量为1.53×10^(8)t、天然气探明储量为1620×10^(8)m^(3),4号断裂带共部署井位20口,两年建成了130×10^(4)t油当量产能阵地。与2016年开发动用的1号断裂带相比,高产井成功率提升了35%、单井产能提升了316%、单井发现探明储量提升了55%,实现了高效勘探,效益开发,其经验对其他同类型油藏开发具有较好的借鉴意义。

苏北页岩油二氧化碳强压质换技术

为了保持苏北页岩油藏能量,降低产量递减率,提高页岩油藏采收率,研究了苏北页岩油CO_(2)强压质换技术。采用苏北页岩油藏岩心进行了室内试验,分析了CO_(2)注入压力、焖井时间对原油采出程度的影响,CO_(2)注入量对原油采收率的影响;采用数值模拟软件,进行了SD1J井注入时机、注入量、注入速度及焖井时间的优化,并进行了SD1J井注超大量CO_(2)强压质换技术现场试验。SD1J井措施后自喷正常生产,产液量由38.6 t/d降至30.3 t/d,产油量由14.0 t/d升至29.2 t/d,含水率由63.8%降至3.5%。研究表明,CO_(2)强压质换技术能够提高页岩油藏地层能量和降低产量递减率,为提高页岩油藏开发效果提供了一种新的技术途径。

顺北油气田二叠系火成岩钻井技术研究与应用

塔里木盆地顺北区块二叠系火成岩地层厚度大、硬度高、裂缝发育、非均质性强,导致机械钻速低与堵漏耗时长,相比邻区平均钻井周期增加达1.5倍。近几年,通过持续强化钻井液堵漏技术与优选高效钻井工艺,漏失量与堵漏时间逐步缩短,钻井指标逐年提高。本文分析了影响堵漏时间长与机械钻速低的主控因素,提出堵漏浆中加入竹纤维、变形颗粒以改善堵漏工艺技术,明确了冲击工具的适用条件,优选攻击性与抗冲击性的PDC钻头,改进混合钻头结构以及配套大扭矩、长寿命螺杆等技术对策,提速降本成效显著,为加快顺北油气田的高效勘探开发提供了指导。

基于COMSOL仿真的终端电磁热场缺陷温度场分析

目的针对现有单一物理场模型及两两耦合模型对缺陷高压电缆终端整体温度场分布研究不够准确的问题。方法提出一种考虑负荷电流影响的电磁场、固体传热场及流体传热场多物理场有限元耦合模型,研究了110kV电缆终端漏油与硅油劣化缺陷时的温度场分布特性。结果据仿真研究显示随负荷电流增大,终端内部明显温升,从线芯到伞裙的温度逐渐降低。漏油缺陷会使得终端外表面温度产生空气域温度低于硅油域温度的分层现象,硅油劣化会产生终端局部发热而致使外表面应力锥附近最高温度升高。结论在实际应用中,模型结果与实际值误差约在1%之内,研究明确了利用整体温度分布特征监测终端常见缺陷在实际应用的可行性。

黏温黏压下径向柱塞泵滑靴副温度分布与泄漏量分析

针对高压大排量径向柱塞泵滑靴副摩擦失效和泄漏问题,以XDP1000型径向柱塞泵为例,对滑靴副温度分布与泄漏量进行了流场仿真和数值计算。首先,根据滑靴柱塞组件运动学特性分析,求解了滑靴偏转角变化规律,并通过建立滑靴副不同通道流量计算公式的方式,建立了滑靴副静压支承特性方程;然后,建立了滑靴副泄漏功率损失和摩擦功率损失模型,求解了滑靴副最佳油膜厚度,并分析了最佳油膜厚度的变化规律;最后,在考虑了油液黏温黏压特性的基础上,通过流场数值计算的方式,研究了滑靴副温度分布与泄漏量随径向柱塞泵工况参数的变化规律。研究结果表明:额定工况下,滑靴副最佳油膜厚度值约为14μm,滑靴副最佳油膜厚度值随着转子转角的增大而增大,随着工作压力和温度的增大而减小;滑靴运动方向侧油膜温度较另一侧高13 K,滑靴副温度值基本不受工作压力的影响,而随着转速的增大而升高;滑靴副阻尼孔泄漏量较滑靴边界泄漏量大0.02 kg/s,而且泄漏量随着压力、转速和油液温度的增大而增大。该研究结论可为高压大排量径向柱塞泵滑靴副设计及优化提供参考。

氮气泡沫辅助蒸汽驱技术研究及应用——以渤海油田稠油开发为例

受蒸汽超覆、蒸汽冲刷等因素影响,高孔高渗油藏开展蒸汽驱过程中容易出现窜流,造成蒸汽腔发育不均,生产井出现流温升高、含水率上升等问题,需要开展氮气泡沫辅助蒸汽驱,抑制蒸汽窜流,改善蒸汽驱开发效果。开展了高温起泡剂PH-F-H的耐温性和封堵性能评价研究,并确定了最佳注入体积分数,为氮气泡沫辅助蒸汽驱技术的应用奠定了基础。该技术在渤海A油田蒸汽驱井组成功应用,在实施高温泡沫堵调后,井组平均含水率下降5%~10%,井组日增油20~30 m^(3),段塞累计增油量841~2019 m^(3),有效期2~3月,有效实现流场调控,受效井优势通道得到明显抑制,扩大了热腔体积,与不调堵预测相比,热腔体积增大13.2×10^(4)m^(3),提高了蒸汽驱井组的开发效果。截至2023年8月底,蒸汽驱方案设计增油6.0万t,实际蒸汽驱增油达到9.8万t,超出预期。这表明泡沫辅助蒸汽驱是一种有效的蒸汽驱提质增效措施,可为蒸汽驱末期改善开发效果、提高油藏采收率、实现区块持续稳产提供有效的技术保障。

高重合度直齿圆柱齿轮温度场分析及试验验证

直升机传动系统中的高重合度直齿圆柱齿轮多采用喷油方式进行润滑冷却,其温度特性关系到齿轮的使用寿命。基于计算流体力学(Computational Fluid Dynamics,CFD),建立了高重合度直齿圆柱齿轮喷油润滑温度场数值计算模型;采用气液两相流(Volume of Fluid,VOF)、多重参考系(Multiple Reference Frame,MRF)法获得了齿轮表面的温度和对流换热系数大小及分布;使用控制变量法分析了润滑油参数、工况参数、齿轮参数对齿面温度及对流换热的影响规律;在CL-100型齿轮试验机上开展了齿轮温度试验。结果表明,齿轮温度随载荷增加而升高的趋势与CFD仿真计算结果一致,高重合度齿轮温度高于普通重合度齿轮,而且随着载荷的增大,这种现象越明显。

高含水原油在不同管材中的低温集输特性研究

目前,我国大部分油田已进入高含水期,采出液的流动特性发生变化,使降低集输温度成为可能。然而,关于管道材质对低温集输特性影响的研究相对较少。因此,利用现场实验装置对钢管与玻璃钢管中高含水原油低温集输特性进行了研究。结果表明,管线降低掺水量之后,井口回压上升,实验管道末点的油温缓慢下降;不同掺水量下井口回压上升过程不同,高掺水量下更容易实现低温集输;当掺水量相同时,玻璃钢管的黏壁温度低于钢管的黏壁温度,玻璃钢管低温集输的最低掺水量低于相同情况下钢管的掺水量。对黏壁温度实验数据进行拟合,得到了不同管材的黏壁温度计算模型,计算结果准确度较高,对高含水期油田实际生产中低温集输的可行性判断及其安全运行管理具有指导意义。

适用于套损井修复的高强度复合材料研究及应用

针对西部某特低渗透油田套损井采用机械封隔和水泥封堵修复技术成功率低以及有效期短的问题,以改性环氧树脂GE-1、缓凝剂柠檬酸、分散剂NNO、硅烷偶联剂KH-540、消泡剂SQ-XP105、固化剂GH-3和纳米二氧化硅为原料,制备了一种适用于套损井修复的高强度复合材料,并对其综合性能进行了评价。结果表明:高强度复合材料具有良好的稠化性能,在150℃下的稠化时间仍大于400 min;材料具有良好的力学性能,150℃下固化试件的抗压强度可达110.5 MPa,抗折强度可达32.4 MPa;材料的耐酸碱和耐盐性能较强,在强酸、强碱或者高矿化度水溶液中浸泡后的质量损失率较低;另外,材料还具有良好的封堵性能,填砂管中注入高强度复合材料后,水驱的突破压力可以达到42.6 MPa。现场应用结果表明:5口套损井采用高强度复合材料封堵修复均一次成功,成功率为100%,现场施工压力较高,套损井修复效果较好。

海上高含水油田用无机复合调驱剂实验研究

针对海上碳酸氢钠水型的高含水油田,以硅酸钠和氯化钙为主剂、聚羧酸分散剂和乳液聚合物为助剂制备了环保型无机复合调驱剂,并研究了聚羧酸分散剂类型和乳液聚合物质量浓度对调驱剂性能的影响规律。实验结果表明,当聚羧酸分散剂的酸醚比为3.7、分子量为23 800时,聚羧酸分散剂和无机颗粒表面的静电斥力和空间位阻作用相互促进,可达到有效分散效果。配合使用低质量浓度乳液聚合物(500 mg/L),形成的无机复合调驱体系可进一步增强体系的黏度和强度,初始黏度从1.1 mPa·s提升至5.4 mPa·s。封堵实验表明,无机复合调驱剂能够大幅度增加流动阻力,封堵率可达82.3%。该无机复合调驱剂可实现在线注入,具有快速分散、深部调驱和价格低廉等特点,在海上及其他作业空间受限的高含水油田中具有良好应用前景。

新型无困油齿轮泵齿轮副型线优化与工作过程模拟

齿轮泵齿轮副的型线对齿轮泵性能影响极大。传统的渐开线型齿轮泵齿轮存在困油现象,产生局部高压,对其运行产生极大的危害。通过型线设计,来解决齿轮泵困油现象。基于曲线啮合理论,采用圆弧和高次曲线,构建一种新型双圆弧-高次曲线齿轮副,消除了齿轮泵的困油现象。进而,建立其几何模型并推导出型线方程,通过数值模拟,分析新型无困油齿轮泵的流场变化规律,并与现有齿轮泵进行对比。结果表明:新型齿轮泵消除了困油现象,型线组成简单,便于优化设计;此外,新型齿轮泵的工作性能更佳,流场更均匀。

气相色谱-静电场轨道阱高分辨质谱测定植物油中57种持久性有机污染物

建立一种LPAS快速滤过净化柱结合气相色谱-静电场轨道阱高分辨质谱测定植物油中57种持久性有机污染物(POPs)残留量的方法。样品用乙腈-乙酸乙酯(体积比2:1)超声重复提取3次,提取液氮吹浓缩后经LPAS柱净化,用气相色谱-静电场轨道阱高分辨质谱在全扫描模式下检测。结果表明:57种POPs在0.4~100μg/L范围内线性关系良好,相关系数均大于0.9950;检出限为0.25~2.00μg/kg,定量限为0.8~6.0μg/kg;基质加标水平为0.8~60μg/kg时,平均回收率为62.4%~125.3%,相对标准偏差为1.2%~9.9%。利用该方法检测市售30例样品,其中8例检出多环芳烃,多氯联苯和有机氯农药均未检出。建立的方法简单、准确,适用于植物油中POPs残留的快速筛查。