注水井腐蚀原因分析及防护对策

胜利油田注水井腐蚀严重,结合注水水质,分析了腐蚀严重原因：注水井的腐蚀主要是回注污水中Cl含量高、细菌滋生严重、含较高的HCO3-及硫化物造成,且随着注水井温度的升高,腐蚀因素在不断变化。主要分析了东辛采油厂污水中高矿化度、高游离CO2对注水井造成的腐蚀;在现河采油厂注水井油套环空腐蚀主要是由于细菌滋生、繁殖造成的腐蚀。结合注水井实际现状,实施相对应的防护措施：在注水井管柱上应用渗氮油管,延长了管线使用寿命;在回注污水过程中有选择性地投加缓蚀剂、杀菌剂;在油套环空中实施环空保护技术,实施后取得较好的效果,对延长注水井有效寿命具有重要意义。     

循环流化床锅炉燃烧室边界层的实验研究

循环流化床锅炉燃烧室的物料浓度影响传热和燃烧,在75t/h循环流化床锅炉上对燃烧室物料浓度分布的测量结果发现,循环流化床锅炉燃烧室的下降流边界层中在接近壁面处存在气体边界层,气体边界层的厚度与距离布风板高度有关,据此给出了下降流边界层厚度和气体边界层厚度的计算公式,并提出了循环流化床燃烧室双环模型。     

Experimental study of natural convection heat transfer of air layers in vertical annuli under high rayleigh number conditions

In this paper experimental investigations of natural convection heat transfer of air layers in vertical annuli are presented. In these experiments, the surface of the inner cylinder is maintained at a constant heat flux condition and the outer cylinder is cooled in the atmosphere. In order to obtain the convective contribution, the overall heat transfer data are corrected for thermal radiation and axial conduction losses from the end plates in the annuli. Special emphasis, in these investigations, was placed on the high Rayleigh number region where no experimental data are available in the literature. Data were obtained for Rayleigh numbers greater than 10⁹. The radius ratios studied were 2.03 and 3.92, and the aspect ratios studied were 23.94 and 66.67. Heat transfer correlations for average Nusselt numbers were developed for different Rayleigh number regions. For the low Rayleigh number region the results of this paper agree with the correlations reported in the literature. Much needed data and correlations for the high Rayleigh number region are obtained for the first time. These results improve the predictive ability for the heat transfer characteristics in the high Rayleigh number region. ©1999 Scripta Technica, Heat Trans Asian Res, 28(1): 50–57, 1999     

哈萨克斯坦里海盆地M区块浅层气井控技术

浅层气难于防控的主要原因是气层埋藏浅,一旦打开气层,气体很快窜到井口,还没有来得及采取措施,已经发生井喷或井喷失控,即便是控制了井口,也容易憋破地层,气体窜至地面,造成财产损失、井眼报废和环境污染。哈萨克斯坦里海盆地的M区块,在270～510 m井段的不同层位埋藏着十分活跃的浅层气。钻井中为了做好浅层气防控工作和提高固井质量,对M区块前期发生的浅层气井喷情况采取了一系列行之有效的措施：①优化钻井设计;②第1次开钻井段,采用大排量循环固井,水泥浆返至地面,保证324 mm套管固井质量;③第2次开钻井段要注重1次井控;④第3次开钻井段采用设计钻井液密度和失水的下限,控制钻时,保证井眼清洁;⑤第4次开钻在碳酸盐岩地层钻进,注重硫化氢防护和防漏。推行上述配套技术,目前在该区块已经完井42口,避免了井喷失控,保障了钻井工程的安全、质量和速度,保护了资源和环境,为同类浅层气井的钻井施工提供了经验。     

煤层气井井底流压分析及计算

煤层气井井底流压的大小直接决定煤层气产量的大小,为了获得高产,必须清楚认识井底流压并精确计算其数值。根据垂直气液两相环空管流理论,首先描述了煤层气的环空流动特征及井底流压的组成部分;结合现场生产测试资料,采用Hasan-Kabir解析法和陈家琅实验回归两种方法计算了井底流压值,并分析了其与气体流量的关系。结论认为：①油套环空中流体由上而下分为纯气体段、混气液柱段（高含气泡沫段和普通液柱段）,井底流压为套压、纯气柱压力及混气液柱压力三者之和;②两种方法计算的井底流压值大体相同,与实测值误差小,精度高;③井底流压与气体流量呈负相关关系,而且随着井底流压下降,压降漏斗不断扩大,井底流压下降相同的数值能产出更多的煤层气。     

幂律流体偏心环空螺旋流压力梯度的数值计算

为合理设计钻井水力参数,对可视为幂律流体的钻井液偏心环空螺旋流动的压力梯度进行了研究。利用待定系数法对幂律流体偏心环空螺旋流的控制方程进行了变换,得到了压力梯度公式。以可视为幂律流体的CMC水溶液为例,利用有限差分法对该流动的压力梯度进行了数值计算,并分析了内管自转速度、环空偏心度和流量对其的影响。结果表明:环空偏心度和流量是其主要的影响因素。通过比较利用轴向速度数值解求得的压力梯度与利用轴向速度解析解求得的压力梯度,发现二者吻合效果较好,进一步说明文中给出的幂律流体偏心环空螺旋流的压力梯度公式和数值计算方法是正确的,可进一步推广应用。     

油套环空放空防止气井井筒生成水合物技术

基于气液两相流沿气井油管上升流动过程中质量和动量守恒及井筒传热机理,建立了压力和温度梯度耦合模型,并采用四阶龙格 库塔法数值求解。该模型中考虑了流体的焦耳 汤姆逊效应及环空介质和地层热物性沿井深的变化,分析了大牛地低渗低产D2-56气井环空介质换热系数和井筒总传热系数与套压的关系。计算结果表明：若井下安装封隔器,并将油套环空放空,可显著降低井筒总传热能力和油管内流体的热损失,提高油管内流体温度,可防止水合物在油管中生成。对于产量较高的气井,降低油套环空压力对防止水合物生成更具有实用性。     

煤层气直井井筒环空压力模型

为实现煤层气直井排采各阶段井筒环空压力分布的计算,为煤层气井的控压排采提供指导。结合国内煤层气井的生产实际,研究了以油管排水、环空产气为生产方式的煤层气直井,在排采各阶段的井筒内流体分布状态。提出了环空内的纯液流仅出现于煤层气解吸产出前;气液两相流阶段的环空内仅产生泡状流与段塞流;环空内气体上升不携液。基于此,采用水动力学方法,建立了3个井筒环空压力模型,分别为环空液体单相压力模型、环空气液两相压力模型以及环空气体单相压力模型,并给出了模型间的过渡条件及模型求解步骤,从而实现煤层气直井排采各阶段的环空压力分布计算。经41口井、共71组实测数据验证,所建立的3个环空压力模型,其计算结果与实测值的平均误差依次为:2. 70%,7. 96%及3. 80%,对煤层气直井井筒环空压力的计算具有一定准确性与实用性。     

22Y-F1型伞式流量仪的改进

本文简单介绍了22Y-F1型环空测井伞式流量仪的结构及缺点,并针对其缺点提出了两项改进:对流量传感器涡轮部件结构的改进和对布伞的改进,此设计的改进将为以后小直径仪器的设计和改进提供参考和借鉴。     

Investigation of Pre- and Post-Dryout Heat Transfer in Upward Steam-Water Two-Phase Flow at Low Flow Rate

A heat transfer experiment was performed on steam-water two-phase flow in an annular flow path with a uniformly heated rod under the conditions of the mass flow rates from 0.2xlO⁶ to l.Ox 10⁶ kg/m²-h, inlet qualities from 0.5 to 1.0, heat fluxes below 4.7x 10⁵ W/m² and pressure of 31 bar. Dryout of the heater rod surface was observed resulting in the sharp rise of the heater rod surface temperature. Measured heat transfer coefficients were compared with the several empirical and semi-empirical correlations with the emphasis on the applicability of the correlations to the present test conditions being important in the analysis of the thermal hydraulic behavior during a LOCA of a nuclear reactor. The measured heat transfer coefficient in the pre-dryout region is lower than the existing correlations. The cooling of the heat transfer surface by the liquid phase in the post-dryout region is significant, which is neglected in the existing correlations. The heat transfer coefficients calculated for the post-dryout region by the Groeneveld correlation show good agreement with the presently measured results within the accuracy of 0~27%.