Experimental Study on Polymer-enhanced Nitrogen Foam Flooding

In order to improve the traditional foam stability, a kind of polymer enhanced foam was proposed to enhance oil recovery in Gan’guyi oilfield. Based on experiments, the polymer concentration of 1,500 ppm was firstly determined by measuring the foam volume and half-life time. The investigation of the effect of polymer on foam plugging ability proved that polymer enhanced foam has excellent plugging capacity both with and without oil. The oil displacement experiments showed that polymer enhanced foam flooding increased oil recovery by 40.6% after waterflooding and the total recovery could reach 79.2%, which was 20.7% higher than that of traditional foam flooding, indicating polymer enhanced foam has excellent oil displacement performance.     

低渗透油层岩石启动压力梯度影响因素的试验研究

利用渗透率小于1×10-3μm2的油层岩样,试验研究了地层油通过岩石渗流启动压力梯度的影响。结果表明,粘度大于1·0mPa·s的地层油通过渗透率小于1×10-3μm2的地层岩石渗流时,均具有启动压力梯度,且启动压力梯度随岩石渗透率的减小和原油粘度的上升而增大;岩石的亲油性增强,启动压力梯度增大;含有束缚水的岩样的启动压力梯度大于不含有束缚水的岩样。     

超低渗储层单相油渗流特征试验研究

对长庆油田H区块长6超低渗储层岩心的单相油渗流试验的研究表明,流体在低速渗流时,非线性渗流特征明显,存在启动压力梯度;发生非线性流的渗流速度为0.136m/d。提出了一种新的低速非线性渗流的数学表达方式,能较好地拟合本次试验数据,相关系数大于0.99。从该方程得到的启动压力梯度值与相关文献同类岩心的启动压力梯度值接近,弥补了非线性渗流规律的一般性数学表达方式的不足。     

An Experimental Investigation of the Effect of Pressure Gradient on Gas-oil Relative Permeability in Iranian Carbonate Rocks

Abstract

The authors examine the effect of pressure gradient on gas-oil relative permeability in horizontal and vertical immiscible displacement. The experiments are conducted on a core from lower Dalan formation in the South Pars oilfield of Iran, in constant pressure, unsteady-state condition, and different pressure gradients. The Toth method is used for calculating the relative permeability and plotting proper curves. Data analysis and the effect of pressure gradient on gas-oil relative permeability are investigated. Results show that relative permeability curves are affected by pressure gradient and this effect is much prominent at low pressures due to end-effect phenomena. The dependence of relative permeability curves on pressure gradient is correlated as a function of dimensionless capillary number. The accuracy of this correlation for relative permeability prediction is examined and a new method is introduced to minimize the end-effect phenomena on relative permeability curves.     

Experimental Studies of the Effects of Permeability Variations on Immiscible Flow

Abstract

The properties of hydrocarbon reservoirs are generally derived from core experiments and use theories of fluid flow that normally assume homogeneous core properties. Reservoirs, however, are generally heterogeneous, and interpretations of the results of these experiments are likely to be unreliable if the core from which the data are derived is heterogeneous. This article examines experimentally immiscible displacement through well-defined permeability heterogeneities, modeled using 2-D visual models packed with clear beads of different permeabilities.

The results indicated that the displacement patterns were dominated by capillary pressure effects and that they were different from those found in miscible systems. This understanding is needed, since in reservoir simulators, the simulator codes must contain the correct physics, and in core analysis, the effluent profiles must be correctly interpreted for sensible predictions.     

泡沫钻井液动密度随井深变化关系模拟研究

提出了测定泡沫钻井液动密度与压力、温度关系的方法，根据现场实测温度、压力与井深的关系，测定和分析了泡沫钻井液密度随压力、温度的变化关系。结果表明，相同压力下泡沫钻井液动密度随温度的升高而降低；同一温度下随压力的升高，泡沫钻井液密度快速升高，大于一定压力后密度增加缓慢。泡沫钻井液动密度随井深的变化趋势可以分为三段：低压快速上升段、中间弯曲段和高压高温下降段。由于气泡内及气泡表面的各种力的综合影响，井深大于一定值后．温度升高引起的体积膨胀稍大于压力升高引起的体积缩小，泡沫钻井液的动密度会稍有下降，并且动密度始终是小于1．0kg／L的，能够满足现场欠平衡钻井的要求。     

The Shunt Effect and the Additive Effect of Foam

Abstract

To study the seepage characteristics of foam in the formation, combining the gas-liquid injection experiment and theoretical analysis to study the shunt effect and additive effect, the authors point out that in the nonhomogeneous strata, whether the gas or foaming agent is injected first, shunt effect of foam can be generated. After alternative multislug injection, the outflow fluid velocity in nonhomogeneous strata is the same, which in fact is the same fluidity. When the foam blocks effectively, the migration velocity of the gas-liquid slug in high- and low-permeability formation is subject to the pore. The ratio of high- and low-permeability formation is inversely proportional to the porosity. The foam additive effect should be further explored.     

低密度负压泡沫洗井用泡排剂的室内研究

以α烯烃磺酸盐(AOS)为主剂,选择泡沫基液和气源,考察起泡剂和稳泡剂对泡排剂泡沫性能的影响,确定了低密度负压泡沫洗井用泡排剂最佳配方:0.5%AOS发泡剂+0.6%W-1稳泡剂+清水+氮气,泡沫体系密度为0.92 g/cm3。室内评价结果表明,该泡排剂在负压泡沫洗井中具有较好的起泡、稳泡、耐高温和抗腐蚀能力,在低压高温洗井作业中具有良好的应用前景。     

The Investigation of Threshold Pressure Gradient of Foam Flooding in Porous Media

Abstract

Porous media were simplified as a series of constricted capillary tubes related to particle size and arrangement, and the distribution of pore diameter and pore volume factor in the pore cell was calculated. Based on mechanics theory, the models of threshold pressure gradient (TPG) for a pore cell and porous media were obtained that provided a comprehensive consideration of pore structure, gas–liquid ratio (GLR), gas–liquid interfacial tension, and the deformation characteristics of bubbles in throat and pore. Moreover, the experiments on the TPG of foams at steady state were investigated. The results showed that the TPG decreases sharply as the particle size increases up to 400 μm and then decreases slightly. The greater the interfacial tension, the higher the TPG, and there exists a approximate linear correlation between them. In addition when the GLR is lower than 20:1, the TPG increases rapidly as the GLR increases, and then the TPG remains almost steady.     

智能转向酸化的机理及试验研究

为了解决在常规酸化中高渗透层的指进、酸液的穿透深度小和残余伤害严重等问题,提出了一种新型的智能转向酸化技术,该酸液体系以粘弹性表面活性剂(visco-elastic surfactants简称VES)和盐酸或土酸为主体外加各种添加剂,在酸化过程中主要依赖于粘弹性表面活性剂的特殊性能实现转向、破胶、缓速降滤的功能,同时具...     

二氧化碳泡沫压裂液性能研究

对低压、低渗、水敏地层采用CO2泡沫压裂技术,起到增产增注效果。泡沫压裂由于具有地层伤害小、返排迅速、滤失低、粘度高、摩阻低以及携砂能力强等优点,因而在以上储层的改造中得到了广泛应用。研究了影响CO2泡沫压裂液性能的主要因素,如泡沫质量、温度、压力、稠化剂、酸性交联剂,并对CO2泡沫压裂液性能进行了评价。     

大庆特低渗砂岩单相水启动压力梯度实验研究

实验选取4块大庆低渗透砂岩岩心,渗透率分布0.1～110-3μm2,利用毛细管平衡法研究了岩样的非达西渗流过程。本实验周期长达3个月,精确度高,实验结果表明:低渗砂岩岩样存在启动压力梯度,流量-压力梯度曲线呈上凹变化,且随着气测渗透率的降低,曲线逐渐右移;流度越大,启动压力梯度越小,同时通过建立低渗岩样的启动压力梯度和流度的双对数坐标曲线,回归得到了启动压力梯度和流度的关系;实验后期表现出异常的渗吸现象,通过计算渗吸量与孔隙体积的比值(即渗吸度),得到平均渗吸度在13%左右,这对于提高低渗油藏的采收率有着重要意义。     

空气泡沫钻井流体的室内研究

通过对空气泡沫钻井流体用处理剂的优选,室内确定了阴离子型空气泡沫钻井流体的基础配方,对该泡沫流体性能进行了评价。结果表明,所研制的空气钻井泡沫流体具有良好的耐温性,耐温达90℃;良好的抗污染能力,耐NaCl量为6％,耐Ca^2＋浓度为500mg／L;较强的抑制性,能使泡沫在井壁形成保护膜,阻止水进入地层,有效防止井壁坍塌。并且,通过合理使用化学消泡剂,可达到泡沫基液循环利用的目的。     

泡沫发生器内部流场的数值模拟

泡沫流体广泛应用于酸化、冲砂洗井、堵水等作业中,泡沫发生器的结构直接影响泡沫流体的质量以及应用效果。通过对射流式和同心管式泡沫发生器内部流场的数值模拟,得到了泡沫发生器内部的速度分布、气液相分布和压力损失。由模拟结果知,射流式泡沫发生器的泡沫均匀程度要好于同心管式泡沫发生器;在一定范围内气液相入口的速度对出口泡沫流体的均匀程度影响不大,但对压降损失影响较大。在设计泡沫发生器时,应该根据泡沫产生速度的要求调整泡沫发生器入口尺寸,降低发生器的压降损失。     

冲砂泡沫流体室内携砂规律研究

为了解冲砂泡沫流体的携砂规律,在自制的试验装置上研究了冲砂时间与砂面高度的关系以及井筒倾角和砂粒直径对携砂率和停留时间的影响。试验结果表明,砂面高度首先快速下降,然后缓慢下降直至趋于平缓;直径小于0.5 mm的砂粒在泡沫中携砂率大于90%,此时井筒倾角对携砂率和停留时间基本没有影响;直径1.0～1.5 mm的砂粒,携砂率随倾角的增大先减小后增大,停留时间随倾角的增大而缩短,倾角在45°～60°时携砂率最小。对于相同的倾角,砂粒直径越大,携砂率越低且停留时间越长。垂直井筒中砂粒以均匀悬浮方式随泡沫流体一起运移;倾斜井筒中砂粒以跳跃方式运移,且明显滑向较低一侧。     

冷43块稠油油藏氮气泡沫调剖实验研究

在模拟辽河冷43块稠油油藏的烧结模型上进行了氮气泡沫调剖实验研究。起泡剂HL-1溶液与氮气质量比为1：1，驱替流量按相似条件求出，驱替程序包括：饱和地层水，水驱，氮气泡沫驱，后续水驱。常压下在均质模型中注入起泡剂溶液和氮气时，阻力因子随LH-1浓度增大而增大，随温度升高而略减小，在30、60、80℃下，0．5％LH-1浓度时分别为5．81，5．78，5．67；后续注水时残余阻力因子随温度升高略有减小，在以上3个温度下分别为1．83，1．78，1．68。在非均质模型上，在围压高于内压2MPa条件下，高渗低渗层流量比在水驱时为3．00～3．17。注入1．0％LH-1溶液和氮气时下降至1．44～1．67，后续水驱时回升至2．08～2．23；常压(0．1MPa)、60℃或80℃下该组流量比值相差不大；60℃、压力0．1、10、20MPa下的该流量比，注剂时分别为1．44，1．63，1．67，后续水驱时分别为2．08，2．08，2．13。两组实验结果表明：LH-1的浓度宜选择0．5％～0．6％；同时注入起泡剂溶液和氮气可在岩心中产生泡沫，泡沫先进入高渗层，起调剖和使后续泡沫流和水流转向的作用；在高压下泡沫仍具有这种调剖和使流体流转向能力，只是略有减弱。表2表4．     

The Validation of Methods to Calculate Gas-Oil Relative Permeability Using Capillary Pressure Data from South Pars Reservoir

Abstract

Gas-oil relative permeability is the most important parameter in the simulation of fluid flow in the gas condensate reservoirs. Experimental measurements of relative permeability need core samples with regular shape, which is costly and time consuming. On the other hand, experimental data of relative permeability may also have significant error and uncertainty in many cases. One source of uncertainty is that the input to numerical simulator is uncertain and inaccurate; it may be reduced if the number of input parameters is decreased, especially if the parameters with the greatest uncertainty are avoided. It is possible to impose only capillary pressure data, because relative permeability can be predicted consistently using specific models. The present methods, which are based on capillary pressure, considered the porous media as a bundle of capillary tubes; they indeed are mercury flow paths that are filled during the mercury injection capillary pressure test at the certain value of capillary pressure. The authors applied the existing capillary models for relative permeability calculations to a gas condensate reservoir. The tested samples have a wide range of liquid permeability from less than 1 to 18 md. The results of this study show that the Purcell model has the best fit with experimental data for wetting phase (oil), and the differences between measured and model data were almost negligible. The predictions of nonwetting phase (gas) relative permeability were a good agreement with experimental data except for Purcell model. Results reveal that the relative permeability could be computed by using accurate capillary pressure data.     

泡沫钻井液的静液柱压力分析与计算

讨论了泡沫质量和气体压缩性对泡沫密度的影响,推导出了泡沫钻井液静液柱压力计算式,可以方便地估算泡沫钻井时的静液柱压力。同时分析了在常压地层进行泡沫或充气欠平衡压力钻井时所需的气液比。     

油田深部液流转向技术

针对进入高含水阶段的油田,要稳产必须进行大幅度提液和大量注水。地层由于长期注水冲刷形成大孔道窜流,造成注入水严重低效循环,使得采油成本大幅度上升。堵水调剖技术在一定程度上改善了水驱开发效果,但由于其处理半径有限,不能解决油井水窜问题。因而,提出了利用深部液流转向剂改变注入水流场、遏制注入水通过高渗及强水洗部位无效循环的研究思路及作用机理,并结合机械器材使转向剂发挥作用。     

泡沫稳定性改进剂研究

对泡沫稳定机理及影响泡沫稳定性因素进行了研究,讨论了泡沫稳定性与泡沫体相粘度、膜强度、膜弹性及排液速度的关系,提出了改善泡沫稳定性的几类物质。通过泡沫稳定性实验,研究了不同种类的泡沫稳定性物质对几种泡沫剂稳定性的影响。利用Ross—Miles泡沫仪,测定了不同物质影响泡沫起泡体积及半衰期,研究了各种物质对泡沫稳定性影响程度及影响规律,初步确定了几种具有明显改进泡沫稳定性的物质。实验证明,NaCl、聚合物722、CMC、部分醇类、活性物质6501具有对驱油用泡沫活性剂不同程度的稳定作用,特别是聚合物及十二醇对泡沫剂具有良好的稳定性,能够提高泡沫剂AEO、ABS的泡沫稳定性50％以上。