Beneficial effects of wettability altering surfactants in oil-wet fractured reservoirs

In fractured reservoirs, an effective matrix-fracture mass transfer is required for oil recovery. Surfactants have long been considered for oil recovery enhancement, mainly in terms of their ability to reduce oil–water interfacial tension. These surfactants are effective when the fractured formations are water-wet, where capillary imbibition of surfactants from the fracture into the matrix contributes to oil recovery. However, another beneficial aspect of surfactants, namely their ability to alter wettability, remains to be explored and exploited. Surfactants capable of altering wettability can be especially beneficial in oil-wet fractured formations, where the surfactant in the fracture diffuses into the matrix and alters the wettability, enabling imbibition of even more surfactant into the matrix. This sequential process of initial diffusion followed by imbibition continues well into the matrix yielding significant enhancements in oil recovery.In order to test this hypothesis of sequential diffusion–imbibition phenomenon, Dual-Drop Dual-Crystal (DDDC) contact angle experiments have been conducted using fractured Yates dolomite reservoir fluids, two types of surfactants (nonionic and anionic) and dolomite rock substrates. A new experimental procedure was developed in which crude oil equilibrated with reservoir brine has been exposed to surfactant to simulate the matrix-fracture interactions in fractured reservoirs. This procedure enables the measurements of dynamic contact angles and oil–water interfacial tensions, in addition to providing the visual observations of the dynamic behavior of crude oil trapped in the rock matrix as it encounters the diffusing surfactant from the fractures. Both the measurements and visual observations indicate wettability alterations of the matrix surface from oil-wet to less oil-wet or intermediate wet by the surfactants. Thus this study is of practical importance to oil-wet fractured formations where surfactant-induced wettability alterations can result in significant oil recovery enhancements. In addition, this study has also identified the need to include contact angle term in the dimensionless Bond number formulations for better quantitative interpretation of rock–fluids interactions.     

一种微透镜阵列的研制

介绍一种利用表面张力的作用、以光纤作材料、用分离的自聚焦透镜制作微透镜阵型的方法，这种方法具有制作工艺简单、无须昂贵设备等优点，用此方法实际制作了具有良好连续面型的微透镜阵列，并对制作的微透镜阵列进行了测试，效果较好。     

具有细小组织的高强度和高延性钢管的开发

介绍了日本川崎制铁公司技术研究所开发出的电焊钢管采用热张力减径工艺的特性 ,及这种钢管的高强度、高延性等基本特性。用这种钢管制造的汽车零部件 ,经弯曲、冲击和疲劳特性等实验 ,证明具有良好的机械加工性能 ,是制造汽车用零部件的优良材料。     

先张法预应力桥梁板施工工艺及应用实例

结合太原市向阳店桥梁板施工实例，介绍了采用先张法进行预应力桥梁板施工的过程。阐述了桥梁板的施工工艺，该工艺实现了整体张拉、整体放张，使钢绞线逐根受力均匀，施工速度快，能保证梁端的质量。指出拉杆系统的使用，降低了成本，增加了效益。     

十二酰胺丙基二甲基羟乙基氯化铵与十二烷基硫酸钠水溶液的表面吸附和胶束形成

利用十二酰胺丙基二甲胺和氯乙醇反应 ,合成了十二酰胺丙基二甲基羟乙基氯化铵 (DDHA)阳离子表面活性剂 ,将其与十二烷基硫酸钠 (SDS)以不同摩尔比进行混合 ,测定了混合系统的表面张力 ,计算了单一系统和混合系统的饱和吸附量、分子最小截面积 ,表面层和胶束中 DDHA的摩尔分率及分子间相互作用参数 ,目视观察了混合系统的浑浊情况。结果表明 :在降低γcmc和 cmc方面 ,DDHA SDS混合系统有协同效应 ,表面层和胶束的组成与二组分配比有关 ,但是非对称的 ,等物质的量混合物中 ,DDHA在胶束和表面层中具有较大的摩尔分数。DDHA与 SDS在实验测定的各混合系统中都不出现混浊     

The Influence of Surfactant on the Surface Characterization of Celestite in Spherical Oil Agglomeration

This study investigates the relationship between the critical surface tension of wetting of celestite and agglomeration recovery as well as the zeta potential in dependence of pH and amount of collector (Na‐Oleate). For this purpose, effects of pH and collector amount on the agglomeration recovery are investigated and zeta potential measurements and Fourier Transform Infrared Spectrophotometer (FTIR) analyses are carried out to determine the adsorption type of Na‐Oleate on celestite surface. The sessile drop technique is used for the measurement of contact angle and determination of the critical surface tension of wetting (Y_C) of celestite. The maximum agglomeration recovery is obtained at pH 7. The critical surface tension of wetting of celestite is very close to the surface tension of kerosene, which is 25.95 mN/m. Furthermore, at the optimum Na‐Oleate amount of 10 kg/ton, the critical surface tension of wetting of celestite is approximately equal to the surface tension of kerosene.     

链烷烃的表面张力与内压

对Ｄａｖｉｓ和Ｒｏｓｓｅｉｎｓｋｙ提出的关系检验表明，液体的表面张力σ与Ｐ１Ｖｍ１／３之比不仅取决于温度，还与液体的种类有关，据此，建立了一个能由链烷烃的分子结构准确预测其表面张力的方法。     

Best L1 Piecewise Monotonic Data Modelling

Let us consider n data measurements of a univariate process that have been altered by random errors. We assume that an underlying model function has a substantially smaller number of turning points than the observed ones. We propose algorithms that make least the sum of the moduli of the errors by requiring k monotonic sections, alternately increasing and decreasing, in the sequence of the smoothed values. The main difficulty in this calculation is that the optimal positions of the joins of the monotonic sections have to be found automatically among so many combinations that it is impossible to test each one separately. Moreover, the calculation seems to be very intractable to general optimization techniques because O(n^k) local minima can occur. It is shown that dynamic programming can be used for separating the data into optimal disjoint sections of adjacent data, where each section requires a single L₁ monotonic calculation. This procedure is highly efficient, requiring at most O(kn²) computer operations and O(n) best L₁ monotonic calculations to subranges of data for a global minimum.     

填料萃取塔液泛速度的计算

介绍了三种有代表性的填料萃取塔的液泛速度计算公式，并通过它们用于三种典型的液-液实验体系和两种不同填料的计算结果的比较，对这些公式的适用范围进行了讨论。     

用小尺寸R－CT试样研究核压力容器钢断裂韧性及与Charpy试样的比较

提出了一种用双边带深侧槽的小尺寸圆形紧凑拉伸试样评定核压力容器（ＲＰＶ）钢断裂韧性的单试作试验方法，给出了用该方法测定的两个厂家生产的核压力容器用Ａ５０８ＣＬ３钢的断裂韧性参数，还与Ｃｈａｒｐｙ试样的试验结果及大尺寸标准试样的试验结果进行了比较。研究结果表明：用双边带深侧槽的小尺寸Ｒ－ＣＴ试样测得的断裂韧性值比相同恻槽深度预制疲劳裂纹Ｃｈａｒｐｙ试样的测试值更接近有效断裂韧性值，所以，用于核压力容器断裂韧性的监测是可行的。