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.     

渗透率级差对空气泡沫驱油效果的影响

在华北油田文120区块油藏条件下(温度87℃、矿化度28291 mg/L),用不同目数的石英砂制成4组渗透率级差分别为2.8、6.8、8.9、10.7的填砂管物理模型,研究渗透率级差对空气泡沫驱油效果的影响。结果表明,随着渗透率级差的增大,高、低渗管及双管采收率增幅先增大后减小。渗透率级差由2.8增至8.9时,高渗管采收率增幅由15.13%增至18.56%,低渗管由19.45%增至29.81%,双管由17.24%增至23.43%,泡沫体系对高、低渗层的封堵调剖能力增强,驱油效果变好;渗透率级差为10.7时,高渗管、低渗管、双管采收率增幅分别为13.55%、9.00%、11.74%,泡沫体系对高、低渗层的封堵调剖能力降低,驱油效果变差。     

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.     

蓄能液气泡钻井液的制备

针对普通泡沫流体抗压能力弱的缺点,研究了蓄能液气泡的制备原理,并设计研制出了蓄能液气泡钻井液发生装置,其可提供在0.1~20 MPa不同压力下产生的蓄能液气泡钻井液。蓄能液气泡内部是黏膜包裹的独立内气核,外部是由表面活性包裹水分子构成的双层膜结构,平均粒径约为0.29 mm,累计体积分布最多的气泡直径在0.25~0.33mm之间。研究表明:与常规泡沫相比,蓄能液气泡表现出很强的抗压能力,例如成泡气核压力为0.5 MPa的蓄能液气泡,其直径随压力的增加而下降,当压力增加到5 MPa时气泡直径分布在0.29 mm左右,压力大于7 MPa后气泡体积不再发生较大变化,趋于稳定,而且仍然能够有效降低钻井液密度。蓄能液气泡钻井液是对泡沫流体认识的一次飞跃。     

The Calculation of Oil-water Relative Permeability From Capillary Pressure Data in an Oil-wet Porous Media: Case Study in a Dolomite Reservoir

Estimating relative permeability curves from capillary pressure data is a well-known technique and the reliability of these techniques for approximation of liquid-gas relative permeability curves had thoroughly investigated. However, there is not enough information to conclude which method is the standard one for calculating oil-water relative permeability curves. The authors utilized various capillary pressure techniques such as the Corey, Brooks-Corey, Li-Purcell, and Li-Burdine methods to calculate oil-water relative permeabilities using the measured oil-water capillary pressure data in drainage process in an oil-wet Dolomite reservoir. Despite wide popularity of Purcell and Burdine methods for calculating relative permeability, the authors used new Li-Purcell and Li-Burdine methods. The calculated results were compared to the experimental data of oil-water relative permeabilities measured in a Dolomite reservoir. The Corey and Brooks-Corey models show an acceptable and nearly exact match with the measured oil relative permeability values. However, the Li-Purcell and Li-Burdine models underestimate the values for wetting phase in most cases. It is also worth mentioning that, except Li-Purcell method, the results of all other methods for calculating nonwetting phase relative permeability are almost the same and they are in good agreement with the measured data. Results of this work reveal that calculation of oil-water relative permeability using the capillary pressure data is also a reliable technique in oil-wet systems.     

断块油藏层系组合与液流转向措施对开发效果的影响

利用现代油藏工程理论、仪器检测和物理模拟方法,研究了合层模型渗透率级差、小层数和液流转向措施对开发效果的影响。转向剂最佳配方为:1.2 g/L部分水解聚丙烯酰胺、聚铬质量比180∶1、6 g/L氯化钠、污水;驱油剂为弱碱三元复合体系,由1.2 g/L部分水解聚丙烯酰胺、2 g/L重烷基苯磺酸盐、8 g/L Na2CO3、污水组成。结果表明,合层模型渗透率级差和小层数对水驱开发效果的影响较大。当渗透率级差由3倍增至30倍时,模型水驱采收率从40.4%降至35.4%;采取液流转向措施后,采收率增幅从5.3%增至8.5%。当模型小层数为2、3、4、5时,模型水驱采收率分别为37.5%、32.1%、33.2%和36.0%;采取液流转向措施后,采收率增幅分别为5.8%、7.2%、5.5%和4.7%。渗透率级差愈大,低渗透层分流率愈小。在渗透率级差和转向剂注入量相同时,随转向剂的不断注入,高渗透层分流率逐渐下降,中、低渗透层分流率逐渐增加。图10表5参15     

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。     

低渗透砂岩渗吸驱油规律实验研究

低渗透油田的开发比较复杂,其生产能力和注水能力很差,水的自发渗吸对原油的开采十分有利。文中采用自行研制的实验装置,通过大量的室内实验研究了低渗透砂岩常温常压以及脉冲压力条件下的渗吸规律及其影响因素。结果表明:常温常压渗吸实验中基质岩块的渗吸规律满足r=rmax(1-e-λt);常压或脉冲压力条件下,最终渗吸采收率均随着岩心渗透率、孔隙度的增大而增加,这与常规认识不符,主要与实验岩心的特低孔低渗性质有关;脉冲渗吸驱油效果优于常压渗吸驱油效果,随着脉冲次数及脉冲压力的增加,渗吸采收率会有不同程度的提高。     

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。     

多相泡沫体系调剖优化实验研究

利用均匀设计实验方法,对多相泡沫体系调剖效果的影响因素进行了实验研究;运用逐步回归分析方法得到了分流系数与聚合物浓度、聚合物微球浓度、多相泡沫注入量、渗透率级差等四个因素的经验公式,并对多相泡沫体系的注入方式进行了优化。结果表明,分流系数主要受渗透率级差、多相泡沫注入量和聚合物微球浓度影响。渗透率级差越大,分流效果越明显;多相泡沫注入量存在一个与聚合物浓度有关的最大值;聚合物微球的浓度与渗透率级差、多相泡沫注入量存在交互作用;多相泡沫体系中段塞注入方式的分流效果要稍好于连续注入方式。     

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。