凝析气藏开采中的几个问题

指出传统凝析气藏油气分布模型存在的问题,推荐三区渗流模型,并提出凝析气藏多区多相油气分布的概念。分析了不同开采阶段气藏露点压力和油气相渗变化特征,并将油气相渗进行性变化的思想引入凝析气藏的试井分析中,提出基于多区多相油气分布模型的凝析气藏不稳定试井和产能试井分析方法。指出目前凝析气藏生产压差确定存在的问题,强调了合理确定生产压差的原则与方法。     

凝析气藏反凝析规律与生产制度关系优化研究

大多数以衰竭方式开采的凝析气藏在地层压力降到露点以下时，在储层中会产生反凝析，并不断堆积，造成气相渗透率急剧下降，产量大幅度递减，甚至导致井筒大量积液。针对这一生产现象，分析了不同开采阶段气藏露点压力和油气相渗透率的变化规律与特征，指出，优化凝析气井生产制度必须有效地监测凝析气井积液和地层压力，采用节点分析方法确定合理的生产制度参数。     

变形介质中毛细管压力对凝析气藏相态的影响

低渗凝析气藏在开采过程中,随着地层压力的降低,储集层会发生变形,孔隙半径会随有效应力的增大而减小,毛细管压力效应会随孔隙半径的改变而发生变化.为研究毛细管压力对凝析气藏相态的影响,定量分析了储集层变形对平均孔隙半径的影响,建立了同时考虑储集层变形和毛细管压力影响的相平衡数学模型,模拟了一个凝析气藏露点和等组成膨胀过程的相态特征,研究结果表明,变形介质中毛细管压力对凝析油气相态特征的影响比无变形多孔介质中的影响更强,应当考虑变形介质中毛细管压力对液相压力、反凝析液饱和度、液相摩尔含量等产生的影响（对液相压力的影响尤为明显）.在相态特征分析和组成分析的基础上,剖析了毛细管压力对凝析油气相平衡过程的作用机理.     

凝析气试井技术现状

从凝析气渗流机理、物性数据处理、试井分析方法、凝析气藏污染评价等几个方面总结了当前凝析气试井的研究现状，并提出了当前凝析气试井所面临的几个问题。     

Investigating the Effect of Capillary Number on Performance Prediction of an Iranian Fractured Gas Condensate Reservoir

Abstract

Gas condensate reservoirs are one of the most complicated reservoirs in which the special thermodynamic behavior of reservoir fluid leads to condensate buildup instead of gas expansion, when the reservoir pressure drops below dew point pressure. To justify the phase behavior of such reservoirs, several models have been proposed. One of the models is a capillary number model that has a considerable effect on the shape of relative permeability curves. Taking account of capillary number is shown to improve the performance prediction of gas condensate reservoirs that otherwise is poorly predicted. In pressures below dew point pressure, velocity and surface tension between gas and oil increases more rapidly in the vicinity of the well compared with other parts of the reservoir, which results in condensate saturation reduction and gas relative permeability improvement. The authors model a fractured gas condensate reservoir with and without taking capillary number into consideration; the performance prediction results are compared to the actual results. The model with capillary number included is shown to be able to predict the performance with a greater accuracy than the case without capillary number.     

毛细管压力对凝析气相态的影响

凝析油气体系和储层多孔介质是一个相互作用的系统,考虑多孔介质界面现象对凝析气相态规律和渗流规律的影响,能更真实地反映凝析气在储层多孔介质中的相态特征和渗流特征,特别是低渗透凝析气藏,更不能忽略毛细管压力对凝析气相态的影响。建立了考虑毛管力的凝析气相态计算模型,利用SPE 21428的流体组成研究了毛管力对凝析气露点及反凝析进程的影响。研究认为,毛管力和界面张力决定毛管力对凝析气相态影响的强弱,当孔隙半径达到10-8m数量级时,毛管力对凝析气露点及反凝析进程的影响十分显著。     

低渗透凝析气藏反凝析水锁伤害解除方法现状

低渗透凝析气藏的反凝析污染、水锁伤害对气井生产、气藏采收率等产生严重影响,因此研究解除凝析气藏近井地层反凝析、反渗吸地层伤害,提高气井产能的技术方法,具有重要的实际意义。调研了国内外文献,详细阐述了反凝析和水锁效应机理,提出了各种解除此两种伤害的方法,并提出在注气吞吐之前先注入一个有限尺寸的甲醇溶液前置段塞来解除反凝析油和水锁产生的地层堵塞,以改善注气吞吐,提高凝析气井产能的效果,该方法在现场得到了成功应用。     

凝析气井停喷产量及停喷压力研究与应用

利用板桥凝析气藏丰富的矿场资料,对凝析气井的停喷压力、停喷产量以及二者间的关系进行了研究,归纳出适用性较强的经验公式。利用这些公式可对凝析气井(藏)废弃产量、废弃压力进行预测,进而较准确地预测凝析气藏油气的可采储量,为凝析气藏的高效开发、储量管理及制定开发规划提供依据。     

利用试井数据确定凝析气藏气水界面位置

地层中气水界面位置 ,对圈定气藏的含气面积 ,确定气藏厚度 ,计算储量极为重要。当地层被完全钻开时 ,气水界面的位置除了可以通过测井解释和试气资料确定外 ,还可以通过试井所测的静压和压力梯度来确定。为动态掌握凝析气田气水界面位置提供一种方便、快捷的方法 ,指导凝析气田合理开发、控制采气速度具有深远的影响。应用该方法确定牙哈凝析气田油水界面位置与实际情况较为吻合     

考虑气液两相流的凝析气井生产动态研究

凝析气藏开发中,反凝析液析出常 常不可避免,由此造成储集层渗流表现出与干气或常规溶解气驱流动不同的特性。目前大多采用单相气或折算方法来进行凝析气井的流入动态预测,理论和现场应用表明,这类方法会带来较大的误差,因其忽略了凝析液析出对气相相对渗透率的影响。尽管众多学者对此进行了大量的理论研究,但由于模型过于复杂或是缺乏严格、全面的理论描述,均限制了其应用。以油气两相渗流的基本理论为基础,可以给出拟稳态形式的流入动态方程,同时还可以对储集层参数分布计算进行严格理论证明。实例应用表明,采用提出的油气两相流入动态方程有助于正确评估凝析气井产能,准确把握储集层动态。     

The Effect of Nitrogen Injection on Production Improvement in an Iranian Rich Gas Condensate Reservoir

In gas condensate reservoirs, after a decrease in pressure below the dew point pressure, condensate formation would occur. One of the common and practical methods for prohibiting the rapid pressure drop in the reservoir and reduction of liquid dropout is gas injection. In this study, experimental measurement, the full field reservoir model and an economical evaluation have been performed to investigate the effect of nitrogen injection on an Iranian Southwestern gas condensate reservoir. At first, swelling and CVD tests were carried out to determine the swelling factor and changing the saturation pressure by nitrogen. Then, the full field simulation (history matching and prediction) was performed and finally an economical evaluation has been made. The results show that injecting more volumes of nitrogen cause to decrease the liquid dropout, increase the dew point pressure, and condensate ultimate recovery, but this process is not an economical project.     

大张坨凝析气藏循环注气的动态监测

对于循环注气开发的凝析气藏，全过程动态监测工作十分重要，但目前国内还没有可借鉴的方法。以大张坨凝析气藏为例，建立了一套适合于凝析气藏循环注气开发的动态监测体系和监测结果的分析方法。监测对象包括开发过程中的地层压力、示踪剂运移规律和井流物组分变化。监测数据和分析结果为大张坨凝析气藏合理开发及动态调整提供了依据，从而达到提高采收率之目的。     

Long-Term Performance of Hydraulically Fractured Layered Rich Gas Condensate Reservoir

Abstract

Compositional simulator has been used to investigate the effect of hydraulic fracture on the performance of a layered rich gas condensate reservoir in Saudi Arabia. The reservoir consists of five layers having permeabilities ranging from 0.08 to 115 md with about 68% of the gas reserve located in the lowest permeability layer. The fracture is assumed to penetrate all layers. The results of this investigation showed that hydraulic fracturing of such a reservoir is effective in improving the productivity of the gas condensate wells. The productivity index (PI) of the cases investigated was found to increase by as much as 3.6 folds. Hydraulic fractures were also found to delay the onset of the dew point pressure and consequently extend the production plateau above the dew point pressure. The production plateau above the dew point pressure was found to increase with increasing the dimensionless fracture conductivity. The results of this study also showed that once the dew point pressure is reached, the flowing bottom hole pressure was found to drop sharply to the specified minimum flowing bottom hole pressure in the fractured and nonfractured cases. However, the drop is less severe in the fractured case. This sharp drop in the flowing bottom hole pressure results in dropping the productivity of the gas condensate wells. Condensate build up along the fracture faces was found to be more significant in the high permeability layers. At early times after reaching the dew point pressure, the highest condensate saturation was found to be in the highest permeability layer. However, at late times (after reaching pseudo steady state) it decreased to a certain level above the critical condensate saturation. Finally, formation cross-flow is found to improve the productivity of the fractured and the nonfractured gas condensate wells. However, the improvement is more pronounced in the fractured cases.     

广安凝析气藏水平井携水采气工艺技术探讨

川中地区小口径连续油管携自由水采气工艺技术,首次成功地在水平井中先导试验,提高了低产气井开采效果。然而工艺技术水平的提高,又受到了许多技术性挑战。在剖析了气井产自由水地质特征和水患危害,小口径连续油管携水采气工艺技术进展的基础上,提出了发展战略和技术思路,有助于技术攻关及科学决策。     

凝析气藏中替代相渗和真实相渗曲线差别对油气采收率的影响

时至今日 ,获得凝析油气相对渗透率曲线的方法仍旧是常规的实验手段 ,即采用模拟油 (如煤油 )和模拟气 (如氮气 )。模拟流体典型的界面张力值约为 3 0mN/m ,这与凝析油气的界面张力范围相比高出数十倍 ,在应用该实验曲线时通常采用经验的界面张力校正方法。文章采用实际凝析气体系在真实长岩心上采用稳态法测量了真实凝析油气相对渗透率曲线。而后 ,用常规的煤油和氮气体系测量了目前用于数模和试井输入曲线的代凝析油气相渗曲线。比较两者的区别 ,并采用CMG单井径向一维数模比较了采用不同相渗曲线作为输入曲线时的地下径向凝析油饱和度分布 ,油气采收率。结果表明 ,凝析油气相对渗透率与常规的煤油 -氮气体系相渗差别很大且凝析油气相渗具有明显速敏性 ,两个不同的相对渗透率曲线对凝析油气的最终采收率影响差别很大。凝析气田开发时应用真实的现场凝析气流体和储层岩心作真实凝析油气相渗曲线来作为指导开发方案设计的基础数据。     

Long-Term Performance of Hydraulically Fractured Layered Rich Gas Condensate Reservoir

Compositional simulator has been used to investigate the effect of hydraulic fracture on the performance of a layered rich gas condensate reservoir in Saudi Arabia. The reservoir consists of five layers having permeabilities ranging from 0.08 to 115 md with about 68% of the gas reserve located in the lowest permeability layer. The fracture is assumed to penetrate all layers. The results of this investigation showed that hydraulic fracturing of such a reservoir is effective in improving the productivity of the gas condensate wells. The productivity index (PI) of the cases investigated was found to increase by as much as 3.6 folds. Hydraulic fractures were also found to delay the onset of the dew point pressure and consequently extend the production plateau above the dew point pressure. The production plateau above the dew point pressure was found to increase with increasing the dimensionless fracture conductivity. The results of this study also showed that once the dew point pressure is reached, the flowing bottom hole pressure was found to drop sharply to the specified minimum flowing bottom hole pressure in the fractured and nonfractured cases. However, the drop is less severe in the fractured case. This sharp drop in the flowing bottom hole pressure results in dropping the productivity of the gas condensate wells. Condensate build up along the fracture faces was found to be more significant in the high permeability layers. At early times after reaching the dew point pressure, the highest condensate saturation was found to be in the highest permeability layer. However, at late times (after reaching pseudo steady state) it decreased to a certain level above the critical condensate saturation. Finally, formation cross-flow is found to improve the productivity of the fractured and the nonfractured gas condensate wells. However, the improvement is more pronounced in the fractured cases.     

濮城油田濮67块低渗凝析气藏配套采气工艺技术的应用

濮城油田濮 6 7块是一个低渗凝析气藏 ,针对该气藏的特点 ,开展了配套工艺技术研究 ,主要应用了压裂改造工艺技术、泡沫排液采气技术、优选管柱排液采气技术、机抽排液采气技术、液氮和撬装式氮气举排液采气技术、柱塞排液采气技术以及防止井口油嘴被“冰堵”的井下节流器技术。并介绍这些技术的应用效果 ,同时指出了这些技术的优点和不足。这些配套技术的应用 ,满足了濮 6 7块凝析气藏开发的需要。     

凝析气藏气液相变引起的压力恢复特征研究

为揭示凝析气藏气液相变对压力恢复响应的影响,建立了油气两相流定解问题,得到压力恢复响应解析解。通过描述压力恢复特征,提出压力响应分析应根据关井时刻井底压力和初始地层压力分别考虑。对实例井分析表明,单相流与两相流在压力恢复曲线上存在明显差别。同时,不同恢复井底压力下,凝析油含量径向分布在不断变化。     

凝析气藏工业气流量计算方法

国土资源部颁发的《DZ/T 0217-2005 石油天然气储量计算规范》给出了我国东部地区气藏不同埋藏深度下估算的工业气流标准,但该标准没有考虑气藏储渗条件的影响,也没有明显体现凝析油成分对工业气流的影响,不适合凝析气藏的对照使用。根据投入产出平衡原理,提出了凝析气藏工业气流计算模型,以我国西部凝析气藏为例,根据目前各项参数测算了相应的工业气流,绘制了工业气流图版。提出的方法也适用于含硫化氢等其他复杂成分气藏工业气流的计算。     

基于注气井刻度法凝析油气产出剖面解释方法

通过对循环注气XY凝析油气田注产剖面测井特性的研究,提出并建立注气井刻度法产出剖面测井解释方法和模型。研究分析23口井注气井干气密度值与温度、压力数据关系,拟合出干气密度值与温度、压力的关系式,应用Standing公式计算的凝析油地层体积系数推算出井下凝析油的密度值。干气的体积系数利用地面干气密度值与计算出井下干气密度值的比值确定。在1口凝析油气井产出剖面测井解释实例中计算出的油、气单相误差在9%以内。该方法为循环注气凝析油气田产出剖面测井解释提出新的解释方法,取得了较好的应用效果。