超深高温高盐油藏注天然气提高采收率评价与应用

塔里木油田碎屑岩油藏进入“双高一低”开发中后期阶段,受超深、高温、高盐条件影响,国内成熟应用的提高采收率技术难以适应。从地质特征、开发特征、开发矛盾、潜力评价出发,开展了提高采收率室内实验,认为注气不受高温高盐条件限制,超深油藏注气容易实现混相驱；结合天然气气源充足条件,明确注天然气驱是塔里木超深高温高盐碎屑岩油藏最现实的三次采油技术方向。编制完成东河塘油田注天然气辅助重力驱试验方案,现场实施见到明显效果。     

哈得逊油田东河砂岩油藏水驱采收率预测

哈得逊东河砂岩油藏目前采出程度低,含水上升较快,需要明确水驱剩余可采储量,指导该区块后期合理开发。采用室内实验、水驱曲线法及油藏数值模拟法3种方法对哈得逊油田东河砂岩油藏水驱采收率进行了预测。室内水驱实验表明,在注入2倍孔隙体积水体时驱油效率为50.14%,利用谢尔卡乔夫公式计算目前井网水驱采收率为33.56%；水驱曲线法分析认为丁型水驱曲线与该区块实际生产数据符合程度最好,预测水驱开发采收率为31.47%；数值模拟法预测目前井网水驱采收率为33.76%。推荐丁型水驱曲线预测该区块采收率。目前哈得逊东河砂岩油藏的采出程度为27.15%,水驱剩余可采储量相对较小,建议对于剩余油富集区域完善注采井网,提高储量控制程度和动用程度,进一步提高水驱采收率。     

轮南油田2井区高温高盐油藏整体调驱先导试验油井受效差异

轮南油田2井区TI油组是典型的高温高盐油藏,经过注水实现高效开发,但长期注水导致层间、层内矛盾凸显,注水开发效率不断降低。为改善水驱开发效果,采用高温改性“微米微球+颗粒+凝胶/冻胶”调驱体系,在该油组东部开展了4井组的整体深部调驱矿场先导试验。试验实施后整体增油效果明显,但不同井组和油井增油差异很大。研究认为,油井控制储量、储层物性和注采对应关系是影响调驱油井增油效果的关键因素;注采井组控制剩余可采储量越大越有利于调驱、储层物性越好越利于调驱受效,注水一线受效油井调驱增油好于二线井。     

轮古油田氮气水混注采油技术实践

轮古潜山油藏储层埋藏深(5000～6000m),油气藏成藏复杂,油井生产表现出“一井一藏”特征,油井生产经历自喷、停喷转机采、注水替油、关井压锥等几个阶段,井底附近油水界面逐步抬升,目前轮古油田整体处于高含水开发阶段。为了挖潜油井井底周围构造高点剩余油,2013年在大量调研和室内试验的基础上,提出开展气水混注采油技术试验,逐步完善并形成了单井潜力评价、注入介质优选、注气工艺优化等配套技术。截至目前成功完成了3井次的矿场试验,该研究为轮古碳酸盐岩油藏及类似油气藏的开发提供了技术借鉴。     

哈得油田超深超薄油藏高效开发特色技术

哈得油田石炭系中泥岩段薄砂层油藏开发面临埋藏超深、油层超薄、储量丰度及品位超低、开发难度大等 诸多世界性难题。构造、储层及流体分布规律难以预测, 直井单井控制储量低且产吸能力差, 提高水平井油层钻遇率及 双台阶水平井动态监测、稳油控水难度大。通过开展动、静结合研究, 针对这种埋深超过5000m、厚度小于2m 的超深 超薄油藏, 提出适应油藏地质特征的储层预测、水平井钻井及轨迹调整优化、复杂井动态监测及综合治理3 项集成创新 技术对策, 在国内首次整体采用双台阶、双分支、超长水平井复合高效井网全面注水开发, 取得了良好的经济效益, 该 油藏自2003 年起年产规模25×104 t 以上已稳产12a, 预计水驱采收率可达44. 72%, 形成多项配套特色技术, 实现了边 际油田的高效开发并成为中国石油高效开发油田的典范。     

轮南油田JⅢ6+7近临界凝析气藏注水实例分析

轮南油田JⅢ⁶⁺⁷凝析气藏因储量较小一直未进行系统开发,仅以过路井上返为主,受气藏认识局限性影响,开发方式多次改变。为确定轮南油田JⅢ⁶⁺⁷凝析气藏合理开发方式,首先根据相图、气油比、₁及四组合参数经验判别法,确定其气藏类型为高含凝析油的近临界凝析气藏;其次,在对该凝析气藏一个注水井组的连通性及生产动态分析基础上,明确了井组注采对应关系,认为注水试验取得了较好效果,有效地遏制产量递减及含水率上升,指出注水开发时采气井必须严格控制压差延长气井无水采油期。此外,结合相态理论及该气藏水驱实验对注水见效机理进行探讨,认为轮南油田JⅢ⁶⁺⁷近临界凝析气藏注水开发时,地层压力已明显小于露点压力,储层中已发生多相流动,注水见效原因与注入水的保压、驱替作用及油套环空中的重力分异作用有关。     

轮南油田三叠系储层非均质性及剩余油分布研究

轮南油田经历20余年开发,受储层非均质性的影响,剩余油在油藏内的流动和分布特征日渐复杂,油田开发矛盾日益突出。通过精细分析轮南油田三叠系储层的层内、层间、平面、微观非均质性,探讨了储层非均质性对剩余油的控制作用。研究结果表明,轮南油田三叠系各小层主要表现为复合正韵律,层内非均质程度总体上为中等—强,夹层不稳定分布;层间物性差异大,隔层发育,非均质严重;平面上三叠系砂体为多期河道叠置而成,横向变化快,储层物性受沉积相带控制,平面非均质性较强;储层微观孔隙类型以粒间孔为主,中—粗孔喉,分布欠均一,峰态属于缓峰型。受储层非均质性影响,剩余油主要分布在物性较差的小层和正韵律的顶部以及平面上河道两侧及其末端的砂体内。该研究为下一步勘探开发提供了依据。     

动态监测技术在塔里木油田套损井诊断中的应用

塔里木油田砂岩油藏深井、超深井近年来套损井数量增加,套损诊断和找漏采用了油藏工程法、生产测井法、井下作业坐封打压综合分析法,应用了产量和含水变化、压力温度梯度及动静液面监测、产吸剖面测井、工程测井、地层流体分析、井下液性液量等资料,较好地指导了快速准确判断套损位置及有效补救措施。截至2011年底,及时指导套损油井、注水井补救,修复率分别达到71.6%、76.9%,减少了油水井生产综合时率损失,对油田平稳高效开发发挥了积极作用。     

高压充填覆膜砂防砂工艺在超深砂岩储层的应用

D 油田由于井深、压力系数低、高含水, 防砂难度增大, 且部分油水井由于出砂严重导致套管变形, 严重影响油 田正常开发。根据D 油田油藏地质情况, 提出采用高压充填覆膜砂防砂工艺, 通过向目的层高压充填覆膜砂, 阻挡地层流砂的 运移, 改善地层岩体骨架受力状态, 同时疏通地层, 提高油层的渗透率和供液能力。在D1 井应用后, 油产量增产1.84 倍, 含 水率并未提高, 累计有效期达到19mon。该井的成功应用对超深砂岩老井防砂、油气增产具有较好的借鉴意义。     

轮古油田缝洞型油藏注气吞吐数值模拟研究

轮古油田奥陶系油藏非均质性强, 储集体类型及油水关系复杂, 开发难度大。前期主要依靠弹性驱动和注 水补充能量提高油藏采收率, 但注水难以动用溢出口以上顶部阁楼油。针对井周高部位大量剩余油无法采出的难题, 论 述注气开发机理和适用性, 并在注N2 吞吐现场试验基础上, 运用数值模拟方法系统研究原油黏度、水体能量等因素对 单井注气吞吐开发效果的影响, 优化轮次注气量、注气速度、焖井时间等注气参数, 进一步优化轮古油田碳酸盐岩缝洞 型油藏的单井注气开发技术政策。     

塔中碳酸盐岩凝析气藏注水注气提高采收率数值模拟研究

塔中Ⅰ号气田缝洞型碳酸盐岩凝析气藏在衰竭式开发下采收率低,需要采取注水注气方式来提高采收率。首先,运用离散裂缝方法针对不同储层类型的理想模型建立了相应概念的地质模型;其次,根据不同储层类型及不同油气藏特征而采取注水或注气开采方式下的采收率进行了数值模拟;最后进行综合对比,得出适用于不同凝析油含量和不同储层类型情况下的合理开发方式。     

塔中Ⅰ号气田缝洞型碳酸盐岩凝析气藏相态特征与开发对策

塔中Ⅰ号气田缝洞型碳酸盐岩凝析气藏开发中存在复杂相态特征,为此将这种特殊的凝析气藏分为Ⅰ、Ⅱ、Ⅲ类,分别对应带底油凝析气藏、无底油中高含凝析油凝析气藏、无底油低含凝析油凝析气藏。其中,Ⅰ类为饱和凝析气藏,开发过程中相图由凝析气逐渐过渡到原油；Ⅱ类为未饱和凝析气藏,开发过程中随着反凝析的发生相图逐渐收缩,井流物反凝析油饱和度降低,但整个试采期间均呈凝析气藏特征；Ⅲ类为低饱和凝析气藏,在开发过程中会发生轻微反凝析,后期相图逐渐过渡到干气。基于相态分类研究提出了适合缝洞型碳酸盐岩凝析气藏的开发对策:Ⅰ类控制合理生产压差,衰竭式开发后优先考虑注水开发；Ⅱ类优先考虑进行注水保压提高凝析油采收率,分为单井注水保压和单元注水保压；而Ⅲ类则可直接采用衰竭式开发。     

哈拉哈塘油田缝洞型挥发性油藏注水保压开采实践与认识——以热瓦普区块为例

哈拉哈塘油田南部热瓦普区块奥陶系缝洞型油藏部分试采井为弱挥发油生产特征,当油藏压力低于饱和压力后,原油急剧收缩脱气,油层内气饱和度增加,生产气油比持续攀升,日产油能力迅速下降,导致天然能量过快衰竭,造成油藏最终采收率偏低。针对该区油藏地质特征,借鉴国内外此类油藏开发实践和经验,首次在热普3-5井实施超深缝洞型挥发油注水保压开采现场试验。通过多轮次注水补充能量,将油藏压力恢复至饱和压力以上,生产气油比显著下降,单井日产油量升高,有效遏制住由于地层脱气造成天然能量过快衰竭的不利形势。     

大宛齐油田薄互层油藏提高采收率对策研究

大宛齐油田属于复杂断块油藏,纵向多套油层发育,含油砂体面积小且厚度薄,注采井距仅为50~70m,油田开发过程中采用多层合采和合注的方式,层间矛盾突出。基于大量的产液剖面、吸水剖面等资料对井区层间矛盾进行系统分析,同时建立油藏数学模型,采用正交实验设计方法对含油单砂体采收率的主控因素和层间矛盾进行了系统研究,明确砂体规模、水体大小是影响砂体采收率的关键因素,基于研究成果对井区提出了砂体分类、分级动用、对应精细注水等开发调整对策并取得了良好的应用效果,对井区的下步调整和同类油田开发具有一定的指导意义。     

A mechanistic investigation of low salinity water flooding coupled with ion tuning for enhanced oil recovery

Oil recovery by low salinity water flooding (LSWF) from carbonate reservoirs has gained tremendous attention in recent years due to its cost-effectiveness and environment-friendly nature. The mechanisms of low salinity water flooding for enhanced oil recovery are very complex and depend on the mineralogy of the formation rock, properties of injection brine and reservoir fluids. The present work aimed at the optimization of salinity and concentration of potential determining ions (PDIs) in injection water for enhanced oil recovery from carbonate reservoirs. Initially, we conducted a series of experiments on the dilution effect of seawater (SW) with the help of rock/fluid and fluid/fluid interactions via interfacial tension (IFT), zeta potential and contact angle measurements. This offered an optimum salinity (20dSW) with an 11% increase in recovery of the original oil in place (OOIP) over the SW injection in secondary flooding mode. Then, the ion tuning was done on the optimum salinity (20dSW) by manipulating the PDIs (Ca²⁺, SO₄²⁻ and Mg²⁺) while keeping ionic strength constant. The properties of ion tuned brine were optimized by zeta potential and contact angle measurements. The core flooding experiments performed with the injection of designed ion tuned water obtained by dilution and ion tuning of SW showed more than 20% OOIP as incremental recovery over the SW injection. Effluent analysis after the flooding confirms that the main mechanisms for enhanced oil recovery include calcite dissolution and wettability alteration due to interplay of PDIs.

The combined effects of dilution and ion tuning of seawater for enhanced oil recovery from carbonate reservoirs. Dominating mechanisms are calcite dissolution and the interplay of potential determining ions that lead to wettability alteration of rock surface.     

Linearly descending viscosity for alkaline–surfactant–polymer flooding mobility modification in multilayer heterogeneous reservoirs

Alkaline–surfactant–polymer (ASP) flooding is considered to be one of the most promising tertiary oil recovery techniques. Nevertheless, its low sweep efficiency in a multilayer heterogeneous reservoir limits field applications. In this work, linearly descending viscosity, a novel injection pattern of ASP flooding, was used for mobility control. Three-dimensional multilayer heterogeneous core models were designed and fabricated. ASP flooding experiments were conducted in the laboratory, and the remaining oil distribution was measured during flooding. Fluid samples obtained from production wells were used for the viscosity measurement. Contrast experiments were made using another two injection patterns including constant viscosity fluid injection and linearly ascending viscosity fluid injection. The results indicated that ASP flooding with linearly descending viscosity improved oil recovery by over 25%, which was a better performance than that obtained using the other two injection patterns. As the different injection patterns presented a similar recovery in the high permeability layer, the sweep efficiency of ASP fluid in the middle and low permeability layers contributed to the difference in the ultimate oil recoveries. In addition, the initial viscosity of the ASP slug had the greatest effect on the mobility modification. Linearly descending viscosity had the highest initial viscosity, leading to the highest fluid distribution rate in the middle and low permeability layers. In addition, higher effluent viscosity was obtained and an earlier viscosity peak occurred in ASP flooding with linearly descending viscosity. Therefore, the sweep efficiency in middle and low permeability layers was remarkably enlarged by using linearly descending viscosity. Thus, increasing the viscosity of the displacement agent as early as possible was found to be significantly in a multilayer heterogeneous reservoir. This study provides an insight into ASP flooding in multilayer heterogeneous reservoirs.

Descending viscosity gradient presented a remarkable performance for improving sweep efficiency of the layers with middle and low permeability.     

牙哈凝析气藏注气提高采收率相态特征实验研究

以牙哈凝析气藏为研究对象,开展不同深度地层流体相态实验测试,得到不同深度目前地层流体相态特征、凝析油含量、气油比等变化规律;通过地层凝析油、气注干气膨胀实验,得到相态、蒸发量等随注气量变化规律;对重力分异现象有了清晰认识,对注气层位优选等开发技术政策的制定,提高凝析油采收率具有重要意义。     

塔中碳酸盐岩凝析气藏储集空间类型判别及开发对策

塔中地区奥陶系碳酸盐岩由于构造作用和岩溶作用等复杂的地质作用而缝洞发育,形成种类多样的储集空间,如何提高塔中地区奥陶系碳酸盐岩不同储集空间类型凝析气藏采收率是目前塔中凝析气藏高效开发面临的主要难题。综合钻井、录井、测井静态资料和完井酸压改造、试井、试采动态等资料制定了一套碳酸盐岩储层储集类型综合判别技术及标准。借助室内实验和现场试验相结合的方法,论证了不同储集空间类型的凝析气藏提高采收率对策。研究表明,对于洞穴型储层适宜注水替气开采,对于裂缝孔洞型或孔洞型凝析气藏采用早期注气保压的开发方式。提出的碳酸盐岩凝析气藏储集空间类型判别方法及其对应的开发对策,有效地指导了碳酸盐岩凝析气藏高效开发。     

Molecular selectivity in the water flooding heavy oil process from porous rocks

Water flooding increases the recovery factor of crude oil and has been proven to be an economical and viable technique for enhancing the oil recovery of oil fields. The process has been systematically studied previously, in which the oil was considered a substance of constant composition. However, the molecular selectivity during the water flooding process has rarely been addressed, especially for heavy oil. Herein, the properties and compositional changes of heavy oil have been investigated in a simulated water flooding process at 60 °C and 85 °C. The crude oil and produced oils from different water flooding stages were characterized by gas chromatography, gas chromatography-mass spectrometry, and Fourier transform ion cyclotron resonance mass spectrometry. The results show that with the increase in temperature, the content of resins in the produced oils from different water flooding stages decreases, and the content of asphaltenes increases slightly. The viscosity of the produced oils increases at low temperatures and decreases at high temperatures as the water cut increases. The composition of the produced oils from different water flooding stages is different. Compared with the no water cut and high water cut stages, the changes in the produced oils of the low water cut stages are significant at different temperatures. The molecular selectivity of heteroatoms is higher than that of hydrocarbons in the water flooding process. Water flooding preferentially extracts small-molecule low-carbon hydrocarbons and small-molecule heteroatoms with low condensation degrees. The compositional differences between the produced oils were characterized by the double bond equivalent versus carbon number distribution of the S, N, and O-containing compounds. This study can not only provide some explanations on the viscosity-forming mechanism of heavy oil but also explains the watered-out phenomena in the development of oilfields.

The composition of heavy oil changes during the water flooding process. Water flooding preferentially extracts small-molecular components with the increase in temperature.