ASP复合驱油体系瞬时界面张力的研究

以胜利油田孤岛试验区原油为油相,用正交试验筛选了碱/天然混合羧酸盐/聚合物驱油体系,讨论了各组分对ASP复合驱油体系油水瞬时界面张力的影响,并探讨了各组分间的相互作用机理及其在油水界面的吸附机理。     

Application of response surface methodology for optimization of the stability of asphaltene particles in crude oil by TiO2/SiO2 nanofluids under static and dynamic conditions

In this work, the onset of asphaltene flocculation for an Iranian crude oil by titration of samples with heptane in the presence and absence of the TiO₂/SiO₂ nanofluids was obtained by Near-IR spectroscopy. Nanoparticles and nanocomposites were characterized by BET, FESEM, EDX, XRD, and XRF analysis. Modeling and optimization of inhibition of asphaltene flocculation process by TiO₂/SiO₂ nanofluids were conducted by response surface methodology (RSM). Under optimum conditions (nanocomposite composition = 0.04 wt% (80%TiO₂:20%SiO₂), salinity = 4.01 wt%, and pH = 3.42), the onset point increased. For nanofluids stability analysis, the optimum nanofluid was compared with the two other nanofluids (SiO₂ and TiO₂) by visual observation method. The results indicated that high stability and surface area of the 80%TiO₂ nanocomposites increase asphaltene adsorption on the particles surface that subsequently increases the onset point. In addition, the optimum nanofluid performance on the carbonate rocks was evaluated by contact angle and core flooding experiments. The 80% TiO₂ nanofluid changed the wettability of carbonate rocks from strongly oil-wet to strongly water-wet condition and also decreased the residual oil saturation and enhanced the oil recovery with an increase in the recovery factor of about 15%.     

基于阴性选择的网络限制洪泛算法

为使网络在洪泛故障信息时洪泛时延和业务质量两方面性能都能够得到改善,提出了一种基于阴性选择的限制洪泛算法.该算法根据网络环境对洪泛时延和业务损失的侧重程度,分别给出了洪泛时延与业务损失两方面代价函数以及综合两方面因素的优化目标函数,利用阴性选择算法进行寻优,计算出能够最大程度适应网络需求的限制洪泛范围,通过对故障的洪泛范围进行限制,将故障洪泛对网络造成的影响降低到最小.实验结果表明该算法能够改善网络的性能.     

车载自组织网络RBVT-R协议的改进

分析了基于地理位置的路由协议RBVT-R.针对RBVT-R协议在路由建立过程及分组转发过程中的缺陷,提出了一种RBVT-R协议的改进算法.该算法在路由建立过程中,根据自主获取的道路车辆密度改进了RBVT-R协议的洪泛机制;在分组转发过程中采用基于方向和位置预测的转发方法,解决了分组在同一路段重复传输的问题.仿真结果表明,提出的改进策略有效地提升了分组的交付率与端到端平均时延.     

Emergence of relativistic effect in probabilistic flooding of Mobile Ad hoc Networks

Broadcasting is a fundamental operation in Mobile Ad hoc Networks (MANETs) whereby a source node transmits a message that is to be disseminated to all the nodes in the network. This paper shows that for several classes of MANETs with distinct topologies, the broadcasting behavior of probabilistic flooding in a network and that of blind flooding in the network possess a single mathematical form of equation under certain conditions. That is, the principle of relativity can be observed in MANETs.     

New insights into the mechanism of wettability alteration during low salinity water flooding in carbonate rocks

There is not a consistent view about the mechanism of wettability alteration during low salinity water flooding. This paper highlights extensive wettability studies to investigate the wettability alteration on mineralogically different carbonates. Contact angle measurements were conducted to characterize wettability changes quantitatively. The results clearly revealed that wettability of carbonate rock surfaces can be altered to a more water-wet condition by lowering water salinity. The trend of the maximum change of contact angle (MCCA) variation with dolomite/calcite content in the rock is fairly linear under the same salinity, which demonstrates that carbonate minerals can affect rock wettability in a way. Also, the higher calcite content in the rock, the greater MCCA, i.e. the stronger effect of LSWF. Besides, the sensitivity of rock wettability to minerals is different under different salinity conditions. When the salinity is in the range of 2384.6?～?4769.2?mg/L, rock wettability is most sensitive to minerals. The analysis of the effect of ion composition showed that the effect of Ca²⁺ on wettability alteration is greater than that of Mg²⁺ at room temperature, and with the increase of the content of calcite in the rock, the effect of Ca²⁺ is more pronounced than that of Mg²⁺.     

Variable density bore interaction with block obstacles

A horizontally variable density flow model is used to simulate hydraulic bore interactions with idealised urban obstacles. The 2D non-linear shallow water equations are solved using a second-order Monotonic Upstream-centered Schemes for Conservation Laws-Hancock Godunov-type HLLC approximate Riemann scheme. Validation test results are reported for wave propagation over a hump, a constant-density circular dam break and two 1D dam breaks involving different spatial distributions of solute concentration. Detailed parameter studies are then considered for hydraulic bore interactions with single and multiple-square obstacles under subcritical, critical and supercritical flow conditions. In all cases, reflected and diffracted wave patterns are generated immediately after the bore impacts the obstacle(s). Later, the incident bore reconstitutes itself downstream of the obstacle(s). Variable density flows are also considered, with the upstream volumetric concentrations set to values corresponding to water–sediment mixture densities of 1165 and 1495 kg/m³. It is found that the upstream Froude number, gap spacing between obstacles and upstream to downstream density difference influence the strength of the bore–structure interaction, run-up at the front face of the obstacle(s), and subsequent wave–wave interactions.     

聚驱后油田剩余油潜力分布规律研究

综合考虑剩余油饱和度、厚度、渗透率、孔隙度、相带、原始含油饱和度、注水井距离等7个因素,利用模糊综合评价方法,以大庆油田北一二排西块为例,计算了该区块8个沉积聚驱后剩余油潜力,并分析聚驱后剩余油潜力分布特征.结果表明,聚驱后仍有比较大的剩余油潜力;聚驱后剩余油潜力主要集中在高渗透、厚度较大、剩余油饱和度较高、河道砂等高级别沉积相带的区域;聚驱后在潜力值为0～0.2区间内的剩余油储量很小,潜力值为0.4～0.6区间内的剩余油储量最大,而潜力值为0.6～0.8区间内剩余油储量次之.     

基于离散裂缝模型的裂缝性油藏注水开发数值模拟

针对目前裂缝性油藏数值模拟方法存在的问题,基于单裂缝等效的概念,建立离散裂缝模型.对宏观大裂缝进行显式降维处理,在保证高计算效率的同时能够真实地反映裂缝对整个油藏流体流动的影响.详细阐述模型的基本原理,基于Galerkin加权残量法推导有限元数值计算格式,实现二维问题的数值模拟,通过算例验证模型和算法的正确性.以此为基础,分析裂缝对注水开发效果的影响.计算结果表明,对于裂缝发育程度不高尤其是当油藏中存在数条控制着流体流动方向的大裂缝时,离散裂缝模型具有很好的适用性.     

Reducing Latency and Overhead of Route Repair with Controlled Flooding

Ad hoc routing protocols that use broadcast for route discovery may be inefficient if the path between any source–destination pair is frequently broken. We propose and evaluate a simple mechanism that allows fast route repair in on demand ad hoc routing protocols. We apply our proposal to the Ad hoc On-demand Distance Vector (AODV) routing protocol. The proposed system is based on the Controlled Flooding (CF) framework, where alternative routes are established around the main original path between source–destination pairs. With alternative routing, data packets are forwarded through a secondary path without requiring the source to re-flood the whole network, as may be the case in AODV. We are interested in one-level alternative routing. We show that our proposal reduces the connection disruption probability as well as the frequency of broadcasts.