Oil Base Mud. Part I: Synthesis of Some Local Surfactants Used as Primary Emulsifiers for Oil Base Mud and Evaluation of Their Rheology Properties

Six oil soluble nonionic surfactants with different HLBs have been prepared. Their HLBs situate between 3.9 and 6.7. Transesterification was carried out for glycerol and triethanol amine with oleic acid at different moles to obtain six emusilifiers. They named glycerol momooleate (I), glycerol diooleate (II), glycerol trioleate (III), triethanol amine mono-, di- and tri-oleate (IV), (V,) and (VI). The chemical structure was confirmed using; the elemental analysis, FTIR and ¹HNMR. They were evaluated as a primary emulsifiers (PE) for thdrilling fluids (oil base mud) comparing with a currently used primary emulsifier (Fc). The water in oil base mud (w/o emulsions) was prepared. The concentration of emulsifiers and their HLB exhibited interesting rheology properties including shear-thinning behavior, yield value, viscoelastic effects, thixtropy, gel strength, and filtration loss. The rheology properties of such emulsions strongly depended on the average size distribution of the dispersed droplets that could be varied both with the bulk concentration and HLB value of the emulsifiers. The interfacial and surface properties of these emulsifiers suggest that the droplet size of the dispersed phase and bulk concentration are strongly related to the HLB value of emulsifiers. The w/o emulsion (mud formulation) stability is sensitive to the droplet size of the dispersed phase and HLB value of the used emulsifier. The results were discussed on the light the chemical structure of the primary emulsifiers and the emulsion ingredients.     

CFD Simulation of Rheological Model Effect on Cuttings Transport

Foam, as a non-Newtonian fluid, plays an important role in the underbalanced drilling technique in oil field development. The rheological properties of drilling fluids, such as foam, have a direct effect on flow characteristics and hydraulic performance. Two rheological models—the Herschel–Bulkley model and power law—were fitted to two foam systems in this study. Computational fluid dynamics (CFD) was used to simulate the effect of the rheological models on solid–liquid (cuttings transport) hydraulics in concentric and eccentric annulus during the foam drilling operation. The simulation results are compared to the experimental data from previous studies. The results of CFD using the power law model are in good agreement with experimental results in horizontal annulus with respect to the Herschel–Bulkley model with relative error less than 8%. Thus, for CFD cuttings transport for simulations in inclined and horizontal annulus, it is best to use the power law's rheological model parameters.     

羟甲基化木质素磺酸盐添加剂对钻井液性能的影响

为了进一步优化木质素磺酸盐作为钻井液处理剂的效能,利用其与甲醛的羟甲基化反应制备了羟甲基化木质素磺酸盐;采用红外光谱仪、X射线粉末衍射仪、扫描电镜等分析了其结构;测定了改性前后的木质素磺酸盐对钻井液流变性、降滤失性、黏土水化膨胀抑制性等性能的影响.结果显示,改性后的羟甲基化木质素磺酸盐的整体结构变化不大,但羟基数量增加,与水的相溶性增强.与木质素磺酸盐相比,羟甲基化木质素磺酸盐在室温下对基浆有较强的提黏作用,经180℃高温老化后降黏、降滤失作用有所增强,形成的泥饼厚度降低,对黏土水化膨胀的抑制作用增强.     

隔水管弯曲对钻柱振动影响的计算与分析

海洋油气资源钻探中隔水管的弯曲对钻柱振动以及钻进特性有特别的影响。为得到隔水管弯曲对钻柱振动的影响规律,对南海已钻深水井使用非线性有限元软件建立全井钻井数值计算模型,研究获得了不同垂深时隔水管弯曲对钻柱振动特性的影响规律。研究表明:隔水管弯曲会加剧钻柱的振动,钻柱振动加剧会导致钻井能耗上升、钻头切削能力下降并且会加快钻柱疲劳;当隔水管的弯曲达到某临界值,钻柱与隔水管间的接触力会陡增;井口的钩载越大,隔水管弯曲带来的井口钩载波动量越大;井越深,隔水管弯曲对全井钻柱最大弯矩和钻头切削能力的影响越小。     

膨胀管残余应力测试

膨胀管残余应力是影响膨胀管抗外挤、内压强度的重要因素之一。确定膨胀管的残余应力,测试方法至关重要。在常用测试方法中,机械测量法中的盲孔法体现出测试的优越性。应用盲孔法测试J55、K55两种规格膨胀管的残余应力,并根据实际测试的应力水平和实验误差,采用应变释放系数分级法对试验结果进行修正,以提高测试结果的精度。实验结果表明,膨胀管膨胀后存在环向、轴向的残余应力,且外表面总是压残余应力。将实验结果与仿真结果对比,误差满足工程要求,说明盲孔法测试膨胀管残余应力方便、快捷、准确、有效。     

Laser drilling of stainless steel with nanosecond double-pulse

Nanosecond double-pulse laser drilling is reported in this paper. The double-pulse herein represents two closely conjoint pulses with 21 ns pulse duration and about 52 ns interpulse separation, which are acquired by temporal pulse shaping. Percussion drilling with such double-pulse is performed in stainless steel samples with different laser fluences, sample's thickness, repetition rates and ambient pressures. The experimental results show that the drilling rates of double-pulse drilling are more than one order of magnitude higher than that of conventional single-pulse drilling in air. Differences in the processing results between single-pulse and double-pulse with various processing parameters are investigated. In addition the ablation mechanisms of the double-pulse drilling are discussed.     

Combined implementing the hole-drilling method and reflection hologram interferometry for residual stresses determination in cylindrical shells and tubes

Main features inherent in simplified approach to residual stresses determination in cylindrical shells and tubes, external diameter of which is not less than 60 mm, by combing the hole-drilling method and reflection hologram interferometry are discussed in detail. Initial experimental information in a form of hole diameter increments in principal stress directions is derived from high-quality reflection holograms recorded near cylindrical objects of intermediate curvature value. Converting measured parameters into required stress values is based on the transition model that corresponds to plane stress conditions of pure membrane type. The technique developed is capable of determining residual stress component values within 5% accuracy in an absence of stress gradients over the probe hole diameter when a type of residual stress field corresponds to the transition model adopted. The accuracy analysis involved is based on matrix formulation of conventionally direct problem and an assumption on a pure membrane character of residual stress field under study for thin-walled shell. Required error estimations in a case of inspecting thick-walled cylindrical tube are obtained by combining the above-mentioned approach and an analogy of reconstructed fringe patterns with actual and artificial interferograms, which follow from drilling blind hole of the same geometrical parameters in thick-walled plates. Experimental verification of the developed approach is founded upon a determination of actual stresses in thin-walled cylindrical shell and obtaining residual stress distributions at the proximity of welded joint in thick-walled cylindrical tube.     

Analysis of laser micro drilled holes through aluminium for micro-manufacturing applications

Conventional laser machining of aluminium with long wavelength lasers has its inherent problems due to the high reflectivity of aluminium to laser radiation (Handbook of Optics, vol 1, 2nd ed. New York: McGraw-Hill; 1995). Laser processing at shorter wavelengths reduces the reflectivity of the workpiece to the incident laser radiation and can also reduce the dimensions of the obtainable machining geometries. This paper reviews the limiting factors in the micro machining of aluminium using a diode pumped solid state (DPSS) Nd:YAG laser operated at 1064, 532, and 355 nm. The geometries of the laser-machined samples were investigated using interferometric, and optical methods to assess how the processing fluence and wavelength will affect the obtainable precision for successful integration of the laser in a micromachining CAD/CAM system.     

Coupled boundary element method and finite difference method for the heat conduction in laser processing

This paper is presented as a way to model transient heat conduction in a 3-D axisymmetric case where large rates of heat fluxes are applied on the surfaces as done in the case of laser processing. This would result in large temperature gradients in a small area irradiated by the laser on the incident surface that could also reach melting and subsequent vaporization. BEM can handle large fluxes very easily and it also can be formulated if needed to incorporate the moving boundary problem in a unique manner while on the other hand FDM is a fast and efficient method. For these reasons a coupled BEM–FDM method is formulated to simulate the heat conduction process. In the BEM method linear elements for the boundary and quadratic elements for the domain were used. The integrals in BEM were integrated in time using the asymptotic expansion for the modified Bessel functions in the Green’s function. To further improve the accuracy, special techniques were employed in the spatial integration. As for the FDM formulation, a flux conservation scheme with a 4th order formula for the fluxes was used. The FDM and BEM were coupled at the interface by the temperature from the FDM formulation being imposed on the BEM and the flux from the BEM being utilized by the FDM elements near to the interface. To advance in time, the Crank–Nicholson scheme was used on the FDM directly and due to coupling indirectly on the BEM. The relative errors for the simulation of constant and variable flux cases demonstrate the successful nature of the numerical model.     

钻孔法测量残余应力过程中钻孔附加应变的研究（Ⅱ）

本文应用弹塑性理论研究了被测试样的屈服强度、应力场对钻孔法测量残余应力过程中钻孔附加应变的影响,使用简化的理论模型推导了低速旋转钻头钻孔产生附加应变的一般表达式.结果表明钻孔引入的附加应变与被测试样的原始残余应力状态有关,随应力水平增加而增大,在压应力减小到某一临界值σ时,钻孔附加应变为零。在 Ly12铝合金上的实验测量结果与理论结果一致。