计算油、气、水物理性质参数的新公式

本文介绍了计算油、气、水物理性质参数(如地面脱气原油粘度、饱和原油粘度、不饱和原油粘度、溶解油气比和原油体积系数等)的较新公式,并给出了计算水的粘度、原油-天然气和水-天然气的表面张力公式,可供油田开发、采油工艺和油气集输工作者使用.     

稠油注天然气混合密度变化规律研究及模型建立

稠油注气后的密度改变直接影响举升效率,为了提高塔河稠油开采效益,针对塔河油田超稠油开展了稠油注天然气混合密度研究。结果表明:稠油注天然气后混合密度随温度升高、注气比增加而降低,近似呈线性关系。在实验基础上,对应用较广泛的原油注气密度计算Obomanu模型进行了修正,建立了塔河原油注天然气密度模型;Obomanu模型的相关系数R²为0.670 3~0.769 2,修正模型的相关系数R²为0.985 2~0.998 9,修正后的密度模型拟合度提升了30%左右,适用于低压和高压环境;建立了原油注天然气平衡压力-原油密度-平衡气油比关系图版,可指导稠油注天然气开采。      

饱和溶气原油溶解度与黏度预测模型的建立

以长庆饱和溶气原油为研究对象,在研究长庆脱气原油基本物性(密度和析蜡特性)、溶气原油溶气特性(溶解气组成和溶解度)和流变特性(黏度)的基础上,对已有饱和溶气原油溶解度模型、黏度预测模型进行改进,得到了适用于长庆饱和溶气原油的溶解度模型、黏度预测模型。以McCaln溶解度模型为基础,将脱气原油的析蜡参数引入该模型,得到了改进的McCaln溶解度模型;以Chew-Connaly黏度模型为基础,将脱气原油的黏度模型代入,得到了不依赖脱气原油黏度的新Chew-Connaly黏度模型。实验结果与模型预测结果表明,新的饱和溶气原油溶解度模型、黏度模型预测精度高,能够满足油田工程需要。     

确定凝析气偏差因子的新方法

天然气偏差因子是气藏工程计算中的重要参数,确定天然气偏差因子的方法主要分为:实验法、图版法及经验公式法。针对凝析气的特殊性,利用凝析气生产过程中分离器所得干气的相对密度、凝析油的相对密度及原始生产气油比GOR,确定凝析气的视相对分子质量,在凝析气视相对分子质量确定的基础之上,根据相关方法计算凝析气的拟临界压力与拟临界温度,最终利用经典的DAK法即可确定凝析气的偏差因子。实例计算表明,该方法计算所需参数易获取,计算过程相对简单,计算结果准确,实用性强。     

多参数找水在油气水分析中的应用

由于地面与井下的流体环境不同,井下流体产状与地面产状又有不同,多相流体间存在滑脱等影响,因此,找水录取到的产液及含水率值在两相分析的情况下与实际状况存在差距;引入流体力学理论建立滑脱速度模型,把多参数找水测得产液及含水通过气-液和油-水滑脱进行叠加校正,得到井下实际流体体积流量和含水值;把多参数找水测得井下状态的压力、温度等数据用于气液密度及溶解油气比的计算,再通过气态方程和气体压缩因子计算井下各测量点原油体积系数,建立各找水测量点的井下状态与地面标准状态的气-液流量及含水关系模型.从而,通过多参数找水的压力、温度、流量、含水等参数得到地面脱气原油、伴生气、溶解气、水的体积流量,克服了两相分析的不足.通过实际应用,收到较好效果.     

塔中地区奥陶系油气充注特征及运移方向

油气充注特征及运移方向对于确认塔中地区奥陶系有利富集区至关重要。通过现有油气勘探成果、断裂体系特征等资料,利用常规测井、地震及地球化学等多种方法,对研究区目的层油气充注特征及运移方向开展深入研究。结果表明,塔中地区多期充注的原油与天然气均通过11个油气充注点注入奥陶系储层,进而沿NW-SE向发生局部运移,11个油气充注点均位于NW向逆冲断裂与NE向走滑断裂纵切形成的断裂交汇部位。油气点状充注特征及NW-SE向局部运移控制了原油与天然气相关参数的分布：靠近油气充注点,油气性质出现异常分布,自NW-SE向异常逐渐减弱,表现为随着距油气充注点距离的增大,油气充注强度变小,原油密度逐渐增大,原油Ts/（Ts+Tm）指数、金刚烷指数（MDI）、TMNr指数、TeMNr指数逐渐减小,天然气干燥系数、气油比、油气产能逐渐减小,天然气甲烷碳同位素逐渐变轻。塔中地区奥陶系油气充注特征及运移方向研究表明,研究区目的层下一步油气勘探应更多聚焦于北部斜坡带西部,尤其是断裂交汇部位的上倾构造部位。     

SIMULATING METHOD OF THE PETROLEUM MOLE FRACTION FIELD IN CHEMICAL FLOODING FOR CONVENTIONAL HEAVY OIL

化学驱模拟器CMG提供的由黑油模型向化学驱模型自动转换工具由于不能转换多套PVT,存在转换后模型中油气摩尔分数场为常数而无法体现原油性质分布差异的问题.应用Lasater公式,建立了溶解气油比、原油相对密度、摩尔质量分布与油气组分摩尔分数场之间的关系,从而获取化学驱模拟器中所需的油气组分摩尔分数分布场,再根据获取的摩尔分数场准确表征地下原油性质的分布.经过渤海某油田实际模型验证,计算结果准确可靠,能有效避免模型转换后流体性质非均质性表征不准的问题.     

泡沫油油藏冷采后期注气吞吐开采实验

以脱气原油与活油为参照,利用非常规PVT实验方法开展了泡沫油溶气特性实验,揭示了泡沫油溶气特性,明确了天然气在泡沫油中的溶解能力以及地层压力对其溶解的影响规律,并通过岩心驱替实验研究了天然气吞吐提高采收率的可行性以及注气时机、注气轮次对泡沫油天然气吞吐开发效果的影响。泡沫油溶气特性实验表明,天然气溶解过程分为快速溶解、波动下降和稳定3个阶段。注气前期天然气溶解速度较大,累积溶气量增加迅速;天然气溶解能力随深度的增加逐渐减小,垂向上可形成一定的混相区域;增大地层压力有利于增加天然气溶解速度和累积溶气量;各压力下泡沫油溶气能力小于活油及脱气原油,但同一深度处其含气量最多,黏度最小。泡沫油天然气吞吐实验表明,天然气吞吐比冷采开发提高采收率7.8%,注气时机应在泡点压力与拟泡点压力之间,且焖井时间不宜过长,并应最大限度地提高地层压力。     

测井方法识别南八仙油气田N22-N1储层的油气

柴达木盆地南八仙油气田N₂²-N₁油气藏储层分布不稳定,横向上岩性变化大,进行地层对比和细分层工作存在着很大的困难;油气藏无统一的油气水界面和统一的压力系统,油气性质及油气比也存在较大差异,用常规的处理手段和处理程序无法计算和预测储层的产油气比例,导致解释结果符合率低。为此,采用CONGAS凝析油气藏解释评价软件,根据三孔隙测井曲线对天然气的响应特征,通过计算三孔隙测井响应方程,计算出地面条件下的气油比和可动油气密度等参数,将计算的油气饱和度与气油比进行交绘,形成综合测井解释图版。通过对该图版的综合分析,结合储层物性,得到N₂²-N₁油气藏储层油、气、水层的综合定量区分解释标准。应用该标准的综合解释符合率达到94.8%。     

往复式油气混输泵组合阀流场数值模拟

建立了往复式油气混输泵组合阀的三维流场几何模型。根据泵速、活塞行程和活塞直径等工作参数,给定组合阀的边界条件。利用Fluent软件对不同最大开启高度、不同介质气液比下组合阀内流场进行数值模拟,获得了最大开启高度、介质气液比与组合阀进出口压差、流量系数之间的定量关系。结果表明:当最大开启高度一定时,随着介质气液比的增大,阀进出口压差减小,而流量系数基本保持不变;当介质气液比一定时,随着最大开启高度的增大,进出口压差减小,流量系数减小。为往复式油气混输泵组合阀的设计计算提供参考。     

利用测录井资料定量计算复杂油气水系统的气油比——以柴达木盆地英东油气田为例

柴达木盆地英东油气田多套油气水系统纵向上相互叠置,油层、气层难以准确区分,气油比计算非常困难。为此,结合油气测试、生产资料,分别利用常规测井、核磁共振测井、气测录井来定性区分油气进而定量计算气油比。在区分油气方面,常规测井主要是利用补偿中子测井的挖掘效应;核磁共振测井依据的是轻质油与天然气在岩石大孔隙中不同的弛豫机制;气测录井则是在考察现有图版法和数理统计方法的基础上,提出气体组分星型图版。在气油比定量计算方面,首次提出以气体组分星型图面积比来计算气油比。研究结果表明:1受地层压力、含氢指数、泥质含量、井眼条件、钻井液侵入等因素的影响,常规测井定性区分油气效果一般;2核磁共振测井区分油气效果较好,但受昂贵价格的制约难以广泛使用;3气体组分星型图区分油气效果最好;4根据气体组分星型图面积比计算的气油比得到了油气测试、生产、产液剖面资料的验证。所得成果为该油气田的勘探开发提供了技术支撑。     

天然气偏差因子计算新方法

天然气偏差因子是油气藏工程相关领域中的重要参数,它在采油采气、气体计量、管线设计、地质储量和最终采收率的估计等油气勘探、开发、化工的诸多工程应用中都不可或缺,快速准确地确定该参数尤为关键。为此,基于Nishiumi-Saito状态方程结合多元非线性回归分析,提出了一种新的偏差因子关系式,相应形成新的计算偏差因子的方法,利用该方法可准确计算整个压力范围内的气体偏差因子。利用偏差因子标准数据对该方法及油气藏工程中常用的DPR、HY、DAK方法进行了对比。误差分析表明,该方法在常用压力范围和高压下的平均绝对误差分别为0.357%、0.066%,其计算精度比DPR、HY和DAK方法高。     

补偿中子测井估计油气流体密度

用补偿中子含氢指数测井方法估计地层油气流体密度是其应用的新领域.提出油气流体密度与它的含氢指数的新方程、给出冲洗带含水饱和度、流体密度、地层孔隙度对补偿中子测井响应的影响,指出用补偿中子测井响应识别流体性质有它的灵敏区和盲区,提倡在下套管后测量补偿中子测井以提高它的识别油气层的能力.提出补偿中子测井对油气层有特别的附加效应,利用它在定性识别油气层、定量计算油气流体密度等方面的应用见到好的效果;计算油气层流体密度发现在块状厚油层内油气密度分布是不均的,往往在厚油层底部或在油水界面附近有高密度的原油分布.     

凝析气顶油藏开发过程中原油性质变化

让纳若尔油田是一个带凝析气顶的大型碳酸盐岩油藏,原油为弱挥发性原油,储集层为低孔低渗生物碎屑灰岩.由于早期衰竭式开发和碳酸盐岩储集层的强非均质性,在注水开发过程中,油藏地层压力逐渐下降.随着地层压力的下降,凝析气顶向外扩大,导致油气界面附近的生产井发生气窜,气油比上升,原油密度降低;同时,在远离油气界面的油环内部,由于...     

Depletion oil recovery for systems with widely varying initial composition

The principal depletion drive mechanism is the expansion of oil and gas initially in the reservoir—neglecting water influx. The main factors in depletion drive reservoir performance are total cumulative compressibility, determined mostly by initial composition (gas–oil ratio), saturation pressure, PVT properties, and relative permeability. In this paper, we systematically study the effect of initial composition on oil recovery, all other parameters held constant. We also evaluate other aspects of reservoir performance, but the main emphasis is surface oil recovery including condensate.To analyze the effect of initial composition, a series of fluid systems was selected by a recombination of separator samples at varying gas–oil ratios. The systems ranged from low-GOR oils to high-GOR gas condensates, with a continuous transition from gas to oil through a critical mixture.Black oil and compositional material balance calculations, 2D fine-grid, and 3D coarse-grid models have been used to investigate the effect of initial fluid composition on reservoir depletion performance. Systematic variation of relative permeabilities was also used to map the range of fluid systems, which were most sensitive to relative permeability.For reservoir oils, the depletion recovery of surface oil initially increases with increasing initial gas–oil ratio. Oil recovery reaches a maximum for moderate-GOR oil reservoirs, followed by decreasing oil recoveries with increasing initial solution GOR. A minimum oil recovery is reached at a near-critical oil. For gas reservoirs, depletion drive condensate recovery increases monotonically from a near-critical gas towards near 100% condensate recovery for very-high GOR systems.STO recovery from oil reservoirs depends increasingly on gas–oil relative permeabilities as initial solution GOR increases, up to a point. At higher initial solution GORs, oil recovery becomes less dependent on relative permeability and, as the fluid system transitions to a gas at the critical point, relative permeability dependence rapidly diminishes. Condensate recovery from gas condensate systems is more or less independent of gas–oil relative permeabilities, with only slight dependence for near-critical gases.     

凝析气水合物生成条件的测定及计算

利用全透明蓝宝石水合物静力学实验装置,采用“压力搜索法”,分别测定了5种凝析气的水合物生成条件,实验体系包括纯水、地层水以及含醇的水溶液和地层水溶液,共9个体系,58个数据点.考察了气油比对凝析气水合物生成条件的影响以及电解质和醇类抑制剂对凝析气水合物生成的抑制作用.实验温度范围为273.35～293.75K,压力范围为0.6～12MPa.并利用Chen和Guo提出的水合物生成条件预测模型对所测数据进行了计算,结果与实验数据吻合得较好,表明该模型能够较好地预测凝析气水合物的生成条件.     

Variation of Crude Oil Physical Properties and Oil Recovery of Natural Gas Flood Under Different Pressures

For the gas flood process, crude oil physical properties including oil volume and viscosity would be greatly changed resulting from gas solution and extraction. First, solubility of natural gas in oil and brine was measured and compared. Meanwhile, the resulting oil expansion and viscosity reduction were experimentally tested. Second, oil viscosity increase due to extraction was studied by extraction experiments. Finally, oil recovery of natural gas and propane-enriched natural gas flood was studied under different pressures. Results show that solubility of natural gas in oil is dozens of times of that in brine. Variation of crude oil physical properties during natural gas injection mainly includes the remarkable volume expansion and viscosity reduction caused by gas dissolution into oil, and the oil volume shrinkage and viscosity increase caused by extraction are not so significant. The oil recovery of natural gas flood grows linearly with increased injection pressure and gas solubility in oil, but is still less than 90% even at 55 MPa, which indicates immiscible flood at 55 MPa. Addition of propane to natural gas is proved to be helpful for enhancing oil recovery and achieving miscibility.     

黑油模型在凝析油气多相集输管流工艺计算中的应用

采用黑油模型计算凝析油气的热物性参数,并采用经验或半经验关系式计算集输管路的压力、温度,计算精度能够满足要求。在输送压力高于凝析油气露点压力的情况下,首先应考虑采用黑油模型进行工艺计算。     

Diffusion coefficients of natural gas in foamy oil systemsunder high pressures

The diffusion coefficient of natural gas in foamy oil is one of the key parameters to evaluate the feasibility of gas injection for enhanced oil recovery in foamy oil reservoirs.In this paper,a PVT cell was used to measure diffusion coefficients of natural gas in Venezuela foamy oil at high pressures,and a new method for determining the diffusion coefficient in the foamy oil was developed on the basis of experimental data.The effects of pressure and the types of the liquid phase on the diffusion coefficient of the natural gas were discussed.The results indicate that the diffusion coefficients of natural gas in foamy oil,saturated oil,and dead oil increase linearly with increasing pressure.The diffusion coefficient of natural gas in the foamy oil at 20 MPa was 2.93 times larger than that at 8.65 MPa.The diffusion coefficient of the natural gas in dead oil was 3.02 and 4.02 times than that of the natural gas in saturated oil and foamy oil when the pressure was20 MPa.However,the gas content of foamy oil was 16.9times higher than that of dead oil when the dissolution time and pressure were 20 MPa and 35.22 h,respectively.