Effect of CO_(2)flooding in an oil reservoir with strong bottom-water drive in the Tahe Oilfield,Tarim Basin,Northwest China

The dissolution and diffusion of CO_(2)in oil and water and its displacement mechanism were investigated by laboratory experiment and numerical simulation for Block 9 in the Tahe oilfield,a sandstone oil reservoir with strong bottom-water drive in Tarim Basin,Northwest China.Such parameters were analyzed as solubility ratio of CO_(2)in oil,gas and water,interfacial tension,in-situ oil viscosity distribution,remaining oil saturation distribution,and oil compositions.The results show that CO_(2)flooding could control water coning and increase oil production.In the early stage of the injection process,CO_(2)expanded vertically due to gravity differentiation,and extended laterally under the action of strong bottom water in the intermediate and late stages.The CO_(2)got enriched and extended at the oil-water interface,forming a high interfacial tension zone,which inhibited the coning of bottom water to some extent.A miscible region with low interfacial tension formed at the gas injection front,which reduced the in-situ oil viscosity by about 50%.The numerical simulation results show that enhanced oil recovery(EOR)is estimated at 5.72%and the oil exchange ratio of CO_(2)is 0.17 t/t.

Quantitative characterization of deep fault-karst carbonate reservoirs: A case study of the Yuejin block in the Tahe oilfield

The Ordovician reservoirs in the Tahe oilfield are dominated by fractured-vuggy carbonate reservoirs, of which fault-karst reservoirs are a hot topic in recent years. Fault-karst reservoirs feature high production, large burial depth, and strong heterogeneity under the control of faulting and karstification. Based on geological, logging, and seismic data, this study classified the Ordovician fault-karst reservoirs in the Yuejin block of the Tahe oilfield into three types, namely karst-cave, dissolved-vug, and fractured types, and established the integrated identification criteria of the three types of reservoirs. This study characterized karst caves, dissolved vugs, and multi-scale faults through seismic wave impedance inversion and frequency-domain detection of multi-scale faults. 3D geological models of different types of reservoirs were built using the combined deterministic and stochastic methods and characterized the spatial distribution of multi-scale faults, karst caves, dissolved vugs, and physical property parameters of reservoir. This study established the method for the geological modeling of fault-karst reservoirs, achieved the quantitative characterization and revealed the heterogeneity of fault-karst reservoirs. The karst-cave and dissolved-vug types are high in porosity and act as reservoirs, while the fractured type is high in permeability and act as flow pathway. This study lays the foundation for the development index prediction, well emplacement, and efficient development of the fault-karst carbonate reservoirs.

Production evolution patterns and development stage division of waterflooding oilfields

The continuous growth of recoverable reserves in a waterflooding oilfield has a significant impact on the patterns of production evolution. A new production evolution model is established by improving the Weng Cycle model. With the new model, the statistical correspondence between the production decline stage and the reserve-production imbalance is clarified,and the correlation of water cut with the recovery percent of recoverable reserves is discussed, providing quantitative basis of reservoir engineering for dividing development stages of oilfield and defining mature oilfields. According to the statistics of oilfields in eastern China, the time point corresponding to the reserve-production balance coefficient dropping to less than 1dramatically is well correlated the beginning point of production decline, thus the time when the reserve-production balance coefficient drops dramatically can be taken as the initiation point of production decline stage. The research results show that the water cut and the recovery percent of recoverable reserves have a good statistical match in the high water cut stage, and it is more rational to take both the start point of production decline stage and the water cut of 90%(or the recovery percent of recoverable reserves of 80%) as the critical criteria for defining a mature oilfield. Five production evolution patterns can be summarized as follows: growth–peak plateau–stepped decline, growth–stepped stabilizing–stepped decline, growth–stepped stabilizing–rapid decline, growth–peak plateau–rapid decline, and growth–continuous decline.

Development technologies for Triassic Chang 7 shale oil in Ordos Basin: A case study of Qingcheng Oilfield, NW China

The reservoirs in the seventh member of the Triassic Yanchang Formation (Chang 7 Member) in the Qingcheng Oilfield of the Ordos Basin are characterized by thin sandbody, tight rocks, high heterogeneity, low formation pressure coefficient, and complex geomorphology. Through the efforts in the stages of exploration, appraisal, pilot testing and development, a series of key technologies have been formed, including “sweet spot” optimization, differentiated three-dimensional well deployment, fast drilling and completion of large-cluster horizontal well, intensively-staged volume fracturing in long horizontal well, and optimization of rational production system. Furthermore, a production organization mode represented by factory-like operations on loess platform has been implemented. Application of these technologies has enabled to significantly improve the single-well production of the Qingcheng Oilfield, reduce the investment cost, and realize a large-scale and beneficial development at a full cost below $55 per barrel. In 2022, the annual production of Chang 7 shale oil in the Ordos Basin reached 221×10^(4) t, accounting for 70% of the annual shale oil production of China. The practice of development technologies in the Qingcheng Oilfield provides valuable references for efficient development of continental shale oil.

Origin of gas condensate reservoir in Fuman Oilfield, Tarim Basin, NW China

To understand the reservoir property and hydrocarbon accumulation conditions of the Middle and Upper Ordovician intraplatform shoal between ultra-deep main strike-slip faults in Fuman Oilfield of the Tarim Basin, China, the main strike-slip faults in and around well FD1 in the basin were analyzed in terms of sedimentary facies, sequence stratigraphy, intraplatform shoal reservoir property, and oil and gas origins, based on drilling data. The Yingshan Formation intraplatform shoal between the main strike-slip faults is superimposed with low-order faults to form a new type of hydrocarbon play. Firstly, hydrocarbons generated from the Lower Cambrian Yuertusi Formation source rocks vertically migrated into the second member of Yingshan Formation through the main strike-slip faults, and then migrated laterally until they were accumulated. A small amount of oil from Well FD1 came from the Yuertusi Formation source rocks in the mature stage, and a large amount of gas originated from oil cracking in the ultra-deep reservoirs. Therefore, the secondary gas condensate reservoir in Well FD1 is characterized by high gas to oil ratio, dry gas (dryness coefficient being 0.970) and hybrid origin. This new type of hydrocarbon play characterized by intraplatform shoal and low-order fault suggests a prospect of continuous hydrocarbon-bearing area in Fuman Oilfield, which will expand the ultrap-deep oil and gas exploration in the oilfield.

Evaluation of reservoir environment by chemical properties of reservoir water‒A case study of Chang 6 reservoir in Ansai oilfield,Ordos Basin,China

The Ordos Basin is the largest continental multi-energy mineral basin in China,which is rich in coal,oil and gas,and uranium resources.The exploitation of mineral resources is closely related to reservoir water.The chemical properties of reservoir water are very important for reservoir evaluation and are significant indicators of the sealing of reservoir oil and gas resources.Therefore,the caprock of the Chang 6 reservoir in the Yanchang Formation was evaluated.The authors tested and analyzed the chemical characteristics of water samples selected from 30 wells in the Chang 6 reservoir of Ansai Oilfield in the Ordos Basin.The results show that the Chang 6 reservoir water in Ansai Oilfield is dominated by calcium-chloride water type with a sodium chloride coefficient of generally less than 0.5.The chloride magnesium coefficients are between 33.7 and 925.5,most of which are greater than 200.The desulfurization coefficients range from 0.21 to 13.4,with an average of 2.227.The carbonate balance coefficients are mainly concentrated below 0.01,with an average of 0.008.The calcium and magnesium coefficients are between 0.08 and 0.003,with an average of 0.01.Combined with the characteristics of the four-corner layout of the reservoir water,the above results show that the graphics are basically consistent.The study indicates that the Chang 6 reservoir in Ansai Oilfield in the Ordos Basin is a favorable block for oil and gas storage with good sealing properties,great preservation conditions of oil and gas,and high pore connectivity.

滨里海盆地东缘北特鲁瓦油田石炭系层序地层与沉积演化特征

根据三维地震、测井及钻井取心等资料,结合Vail的层序划分方案,在滨里海盆地东缘北特鲁瓦油田石炭系碳酸盐岩台地内识别出7个地震层序界面及7个钻井层序界面,并将KT-Ⅰ油层组划分为3个半三级层序,KT-Ⅱ油层组划分为3个三级层序。纵向上层序格架内沉积环境由开阔台地、局限台地至蒸发台地演化。根据研究区层序格架内的古地貌恢复及沉积演化研究,将研究区古地貌—沉积演化划分为3个阶段:台地初始隆坳分异期(SQ2-SQ3层序)、差异抬升与沉积分异定型期(SQ4层序)及继承发育期(SQ5-SQ7层序)。进一步分析认为,层序格架控制下的隆坳格局分异控制了白云岩亚类在平面上的分布,低部位以泥晶云岩—膏盐岩组合和泥晶云岩—泥晶灰岩组合为主,主要为潟湖相沉积;而高部位则以泥粉晶云岩、细粉晶云岩和残余颗粒泥晶云岩为主,发育云坪相及云化颗粒滩相沉积。结果表明,区内KT-Ⅰ油层组沉积期并非前人认为的西高东低剥蚀后沉降充填,而是继承性差异沉降的结果,古地理格局总体具有“东台西槽、北高南低”特征,其始终控制着有利相带和优质储集层的发育展布。这一认识对滨里海地区油气勘探开发战略选区具有重要的指导作用。

基于“南阳实践”的云蒙湖水源地风险应急研究

借鉴河南省南阳市淇河水环境污染事故处置经验,大力推广“南阳实践”经验,是推动水源地风险应急能力建设的重要手段。以山东省蒙阴县云蒙湖水源地为例,对风险应急能力建设现状进行了分析。在云蒙湖主要风险源分析的基础上,提出了云蒙湖流域7个典型突发环境事故情景,针对每种情景,提出了风险应急预案。通过预见性地制定风险应急预案,事先构筑必要的工程设施,加强风险应急管理,可在污染事故一旦发生时变被动为主动,为应急处置赢得时间,最大程度地减轻或消除污染事故对云蒙湖的影响,保障临沂市城区饮用水供水安全。

渤海C油田馆陶组储层堵塞实验评价研究

为了分析明确渤海C油田导管架期间预钻井的12口生产井,在组块安装后投产产量达不到配产目标的原因,针对有机质沉积、原油乳化堵塞、流体配伍性、钻完井液漏失与返排等潜在储层伤害因素,开展了储层堵塞实验评价研究。实验结果表明:1)免破胶无固相钻开液(EZFLOW)漏失量越高渗透率伤害程度越大,同时考虑钻完井液漏失时,天然岩心的渗透率伤害程度为37%,伤害程度中等;2)有机质沉积对储层伤害较为明显,注入0.4 PV原油后渗透率伤害程度达到98%,且随有机质沉积量的增加,储层伤害越大;3)油包水型乳状液(W/O型)驱替对岩心渗透率伤害程度高达75.01%,水包油型乳状液(O/W型)驱替对岩心渗透率伤害程度为25.21%,低含水层受原油乳化堵塞影响较明显。综合分析认为,渤海C油田12口预钻井低产原因为导管架预钻井后待组块安装期间关井静置过程中有机质沉积和原油乳化伤害。同时,渤海C油田12口预钻井目的层馆陶组储层物性因子较小,产液指数较低是导致低产的原因之一。研究结论为后续增产措施以及方案提供了依据。

油田监测用密度可控同位素示踪微球的制备及应用

制备了用于油田监测的同位素示踪微球,分析了微球的形貌、抗压强度、热性能、耐溶剂性和加工性能,揭示了微球与同位素产率及加工性能的构效关系,提出了示踪微球密度计算方法。结果表明:示踪微球表面形貌主要为致密和松散两种,抗压强度的影响因素主要为黏合剂种类与加料方式;采用不同黏合剂制备的微球耐溶剂性差别较大,采用酚醛胺和聚酰胺制备的示踪微球抗压强度较高,耐热性较好;采用炭粉为原料获得的同位素产率较高;微球密度的调控可以通过一个经验系数来计算。

基于超音速膨胀凝结的油田伴生气脱二氧化碳研究

油田伴生气通常含有大量的二氧化碳等酸性气体,为了提升油田伴生气质量,必须对天然气进行脱二氧化碳处理;将超音速旋流分离技术用于伴生气脱除二氧化碳是一条全新路径,但二氧化碳在超音速流动条件下的冷凝特性有待进一步明晰。建立二氧化碳在喷管中的相变过程数学模型,讨论二氧化碳超音速凝结流动特性,分析入口温度和压力对二氧化碳超音速凝结特性的影响规律。结果表明:二氧化碳在喷管喉部之后的扩张段发生凝结,生成大量的二氧化碳液滴;随着喷管入口温度增加,尽管凝结的二氧化碳液滴数量增加,但喷管出口和中轴线上的液相质量分数减小,凝结位置越靠近喷管出口;随着喷管入口压力增加,混合气体在喷管出口的压力和温度升高、速度减小,二氧化碳在喷管内凝结产生的液滴数量减少,喷管出口和中心轴线上的液相质量分数越大。

南阳汉画所见汉代丧葬观念与宗教文化特征

南阳汉画中有大量涉及宗教信仰的题材内容,是反映汉代宗教文化最直观、最全面的资料。南阳汉画本身就是具有宗教色彩的丧葬艺术表达形式,是汉代丧葬观念意识的生动体现。它以追求长生不老、得道成仙为目的,展示了汉代人为死后世界臆造的一系列虚幻的宗教意象,是一种“天国的幻想”。其具备的多神崇拜和兼容并蓄的多元化特征,既反映了汉代宗教对原始宗教文化的继承与创新,又体现了鲜明的地域文化特色。南阳汉画对于了解汉代宗教文化的时代特点和发展演变以及汉代人的思维方式、文化观念提供了独特的视角。

长庆油田数智化油藏建设理论与实践

随着油气勘探认识和技术的不断进步,盆地边缘新层系非常规储层成为油气增储上产的重要领域,开采难度增加,工作量培增。然而,油田用工总量不增反降,如何提升油气藏研究的精细化水平,培育新质生产力,打造油田高质量发展新引擎,是油田急需解决的问题。长庆油田制定了“125”数智化油藏建设规划,通过数智化技术,助力资源勘探、油气开发和新能源3大主业的高质量发展。立足数智化油藏学科长远建设,结合地质研究、井位部署与随钻、产能建设、稳产提产等领域的数智化建设特点,总结出一套高效稳健的数智化油藏建设理论与方法,形成了“一体系四中台”基本建设思路,制定了勘探开发数智化整体解决方案。在该理论指导下,建成了数字油气藏研究与决策支持平台,有效推进了长庆油田的快速上产稳产,现已成为中国石油天然气集团有限公司的品牌产品,支撑着长庆油田向国际一流大油气田迈进。

准噶尔盆地永进油田侏罗系超深层致密砂岩储层成岩相识别及分布预测

深层致密砂岩储层非均质性强、分布规律复杂,地质甜点预测难度大。为实现高效勘探开发,如何准确识别与预测井间储层成岩相亟需深入研究。综合利用岩心、测井和三维地震资料,在准噶尔盆地永进油田侏罗系超深层储层成岩作用研究基础上,开展了成岩相识别及分布预测研究,认为储层成岩作用类型主要有压实作用、胶结作用及溶蚀与交代作用,可划分为强溶蚀+绿泥石包壳、中等溶蚀+自生高岭石、中等钙质胶结溶蚀、强钙质胶结及压实致密等5种成岩相。基于测井资料,利用岩石物理参数、物性参数对储层成岩相类型进行了综合识别,确定其垂向分布规律。研究发现强溶蚀+绿泥石包壳和中等溶蚀+自生高岭石这两种优势成岩相主要位于三角洲主干分流河道砂体内部,储层物性较好,是油层发育的主要部位。基于成岩相与地震纵波阻抗的对应关系分析,发现优势成岩相纵波阻抗相对较低,可通过纵波阻抗的数值分布特征预测优势成岩相分布。因此利用三维地震纵波阻抗反演成果开展了成岩相分布预测,根据纵波阻抗与不同类型成岩相对应关系落实了优势成岩相发育区。结果表明,优势成岩相主要位于研究区东北部的Y301—Y302井区以及西北部Y1井区,呈局部连片分布发育。储层成岩相识别可以为超深层地质甜点的分布预测研究提供重要依据。

大庆油田SEC储量折耗一体化评估模型

SEC储量是大庆油田有限责任公司经营决策的核心资产,是油气生产的物质基础。油气资产折耗和SEC储量相关,是完全成本中的重要构成部分,决定了油田经营效益。大庆油田进入双特高含水后期,开发对象变差导致增储能力变差、油气资产折耗上升,因此亟需开展SEC储量折耗一体化优化研究,使储量和折耗指标最优。结合折耗计算公式、ARPS递减模型和经济极限产量计算模型等公式,进行科学归纳和推导,建立了SEC储量折耗一体化增储模型,并且在量化分析各种影响因素的基础上,明确了储量和折耗的优化次序和参数,给油田开发经营提出建议。模型应用在大庆油田年度SEC储量评估中,使油田增储能力逐年提升,油气资产折耗得到有效控制。研究成果具有通用性和适应性,可以在国内其他油田推广应用。

大庆长垣油田水驱开发技术智能化实践与展望

数字化转型、智能化发展是老油田开发技术提档升级、提质增效的必要途径。全面总结了国内外油田开发技术智能化研究进展,介绍了人工智能技术在大庆长垣油田水驱开发中的应用进展及取得的重要成果,尤其强调了智能测井解释、智能井震结合储层预测、基于数据挖掘的注水优化调整以及措施井层智能优选等关键技术在提升油田开发效率、效果和经济效益方面的积极作用。通过技术创新,大庆长垣油田水驱自然递减率控制到7%以下,年含水上升值控制到0.2百分点以内,实现了特高含水后期油田的高水平、高质量开发。在此基础上,展望了水驱开发技术的智能化发展方向,指出应加快油气大语言模型的应用,加强实时动态监测技术的研发,并通过数字孪生模型、智能方案编制、注采智能优化等手段推动油田开发向更高水平的智能化转型。

金属有机框架MIL-101(Fe)用于增强光催化降解含油污水中的原油

利用溶剂热法合成了一种稳定的金属有机框架(MOF)MIL-101(Fe),并作为一种新型光催化剂提高了油田废水中原油的降解性能。通过对反应条件的优化,确定了以下最佳参数:暗反应时间为30 min,光反应时间为30 min,p H值为5.5,催化剂量为150 mg/L,反应温度为303.15 K。在这些反应条件下,去除率达到了94.73%。本研究是铁基MOFs在油田废水光催化降解中的应用。MIL-101(Fe)在温和的酸性条件下表现出良好的稳定性,并且可以有效地循环利用。这些发现为利用MIL-101(Fe)作为一种很有前途的工业应用材料,通过光催化降解从受油污染的水中去除原油提供了有价值的见解。

大庆油田萨中开发区二、三类油层同步挖潜补压结合射孔方法

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西周时期南阳地区的封国和方国

西周时期,今南阳地区内分布有不同类别和不同规模的国家。然而,迄今尚未见有对此进行探讨的专文。将文献记载同考古发现结合起来并相互参验,对西周时期今南阳境内众多的国家进行系统研究,可以发现西周时期南阳地区的封国和方国有楚国、申国、谢国、吕国、蓼国、唐国、鄀国、鄂国、养国等。

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塔里木盆地哈拉哈塘油田奥陶系碳酸盐岩储层非均质性复杂,亟需开展评价预测研究。本文基于哈拉哈塘油田地质及地震资料,开展了碳酸盐岩缝洞储层归位、储层空间展布、储层与断裂的匹配关系、井间连通性研究。在此基础上,依据实钻、测录井资料及生产动态分析,开展了断控区碳酸盐岩储层缝洞雕刻。研究结果表明:哈拉哈塘油田断裂系统发育包括加里东早-中时期、加里东晚期-海西早期、海西晚期、燕山期4个阶段;断裂走向和断裂发育的多期次性是断裂系统的通源性的主控因素;断块水平滑移的增大将使走滑断裂具有较好的连通性;断裂的平面扩溶宽度受断裂活动强度以及深部通源分支断层发育程度控制。此外,为明确潜山岩溶区、层间岩溶区、断控岩溶区碳酸盐岩储层的空间形态与分布特征,开展了针对性的储层预测,以反演成果为主,结合属性、沉积、钻井等资料,对储层进行多属性综合预测。预测结果显示,哈拉哈塘油田塔河北区块的潜山岩溶区断裂带的通源性、连通性及扩溶性整体较好,有利于大型溶蚀孔-缝-洞储集体的形成,储层平面展布呈连片特征,储层质量最优,是未来油气勘探开发的重点区域。研究认识揭示了哈拉哈塘油田塔河北区块奥陶系断裂发育特征及断控区有利储层的分布区域,以期为有效指导深层-超深层断控区碳酸盐岩油气勘探与开发工作提供依据。