提高油田注汽锅炉热效率方法的研究与应用

辽河油田稠油资源非常丰富,稠油的开采以注入蒸汽的热采方法为主,占稠油产量80%以上的稠油,是以注入蒸汽的方法采出的。注汽系统是稠油开发的重要组成部分,也是最大耗能因素。为达到节能降耗、降低稠油开采成本的目的,近年来,不少高新配套技术在注汽系统上得到应用。本文通过从监测注汽锅炉烟气温度及氧含量和燃油(汽)节能器两个方面开展了提高注汽锅炉运行热效率研究。从理论分析、试验、设计、实际改造运行及节能效益等方面来看,均达到了预期效果。具有显著的经济效益和社会效益。     

稠油注蒸汽开采提干提效配套技术的开发

稠油油藏注蒸汽开发的复杂性主要体现在如何充分利用热能,而蒸汽干度是影响蒸汽热能利用效率的首要因素,是衡量蒸汽质量的重要指标。通过分析河南油田稠油注蒸汽开采在制汽系统、输汽系统、注入系统以及监测系统各个环节存在问题,进行提干提效技术研究,配套了地面高干注汽工艺、井筒全程保干技术、高效注汽工艺、以及热采井动态监测技术,通过加强地面和井筒一体化配套,从而保障热需求、控制热损失,从而提高蒸汽干度、提高热能利用效率,对改善稠油开发效果,提高稠油热采效益具有重要意义。     

海上稠油油藏水平井注蒸汽开发技术研究

为提高海上稠油油藏水平井注蒸汽开发效果,以渤海某油田明化镇组稠油油藏为实例,首兇分析了该稠油油藏注入蒸汽开采的经济和技术可行性,明确了该稠油油藏具有良好的注汽开发前景,通过油藏数值模拟方法,分别模拟了注蒸汽速度、关井时间、井底蒸汽干度、蒸汽温度和采液速度对周期内注汽开发效果的影响。结果表明:最佳注蒸汽参数设定为注蒸汽速度350 m~3/d、关井时间6 d、井底蒸汽干度0.8、蒸汽温度370℃、采液速度150 m~3/d,同时为迚一步提高注蒸汽开发效果,在设备条件允许的情况下,尽可能地提高注入蒸汽的温度来达到更好的注采效果。     

蒸汽驱等干度分配与计量技术

辽河油田是我国最大的稠油高凝油生产基地,稠油主要采用蒸汽吞吐和蒸汽驱的开采方式。稠油热采在蒸汽吞吐末期一般转蒸汽驱开发,蒸汽驱现场往往存在一台锅炉同时向2-3口井注汽,或多台注汽锅炉为整个注汽管网供汽的现象,存在干度分配的偏差,为此提出以下一种新的等干度分配技术,保证了一台或多台注汽锅炉在同时注多口井时的注汽干度相同、注汽速度相同。     

双涡街法测量饱和蒸汽干度研究

注汽热采是稠油油田开采的主要手段,此方法开采的效率主要取决于蒸汽干度的高低。经研究表明,在注入相同的蒸汽量的情况下,蒸汽的干度越大,采收率越大,油汽比越高。只有较高干度值的饱和蒸汽才能对稠油有很强的驱动效果。但是干度太高,会使注汽锅炉水中的盐份大量附着在炉墙壁上,致使锅炉结垢,降低锅炉的热效率,甚至危及锅炉的运行安全;干度太低,通过管道传送到井底后干度就更低了,无法有效驱动稠油层,达不到开采稠油目的。可见,对饱和蒸汽的干度值进行实时、准确测量具有重要意义。然而,现今国内外仍无工程上实用的干度仪,使其具有实时测量、准确度高、寿命长、造价低的性能,针对此问题提出了基于双涡街联合法测量湿饱和蒸汽干度的方法。     

空气辅助蒸汽驱室内实验研究

蒸汽驱是稠油油藏开发中使用较为普遍的提高采收率技术。目前大部分稠油开发区块进行蒸汽驱开发中后期,存在平面及层间矛盾,高温汽窜现象明显。蒸汽汽窜是制约提高稠油采收率的主要矛盾之一,此时如果不采取有效措施,蒸汽驱油效果会降低。针对此问题,为进一步提高稠油油藏蒸汽驱的开采效果,做了利用空气辅助蒸汽驱驱油的室内物理模拟实验,针对蒸汽空气注入比、段塞大小以及注入速率三个方面对空气辅助蒸汽驱油开发效果的影响进行了研究。研究结果表明:空气辅助蒸汽驱能够有效改善蒸汽驱效果,提高原油采收率。当空气与蒸汽的注入比为2∶1所取得的采收率最高,在此基础上空气与蒸汽的段塞大小为0.5 PV,注入速度为12～15 mL/h之间的汽驱效果最好。     

鲁克沁油田35兆帕超临界注汽的试验与应用

目前国内21MPa亚临界压力蒸汽开采超深层稠油效果不佳,为解决鲁克沁油田超深层稠油开发难题,吐哈油田提出超临界注汽热采方案,对鲁克沁油田超深层稠油进行了35MPa超临界蒸汽吞吐先导试验,结果表明,利用超临界注汽对超深层稠油开采效果明显,为有效开采鲁克沁油田提供有利技术支撑。     

提高陈家庄稠油水平井开采效果的技术及应用

陈家庄油田稠油资源丰富,但是具有层薄、油稠、出砂等特点,因此水平开采是有效的开采方式。水平井注蒸汽采油与常规竖直井注采相比,水平井射孔的井段长,油层打开程度大,因而可以用较低的驱动力提高采收率,目前在薄层稠油开采上得到了广泛的应用。针对陈家庄稠油水平井开采单油层注汽井段吸汽不均匀的问题,在理论研究与生产实践的基础上,除了对完井方式、注汽参数、生产管柱等进行优化完善,以适应热采开发的需要外,还重点研究和推广应用了热采防砂、降低注汽压力、气体辅助吞吐等三项保障薄层稠油热采的配套增效技术,使陈家庄稠油水平井热采达到了良好的开发效果。     

稠油井注汽增效技术的应用

本文针对油田稠油注汽过程中存在着注汽高压及低压井,影响了注汽效果,开展了提高稠油井注汽效果研究,研制引进了大功率井下震源振动解堵,小排量注入泵拌蒸汽注入化学药剂,氮气调剖等工艺,为油田稠油注汽质量提供了保证。     

稠油油藏混合气吞吐参数优化数模研究

CO_2吞吐可提高稠油开发效果,注N_2可使稠油控水增油,还能够补充地层能量。因此,采用N_2与CO_2混合注入的方式开采稠油将起到更加有效的开发效果。针对N_2与CO_2吞吐开发稠油如何能达到最佳的开发效果的问题,本研究采用数值模拟技术,从N_2和CO_2注入量、CO_2注气速度、焖井时间、周期生产时间和周期数等六个方面进行优化研究,确定最优的注气吞吐开发技术参数。该研究成果能够为类似稠油油藏的开发提供借鉴。     

注蒸汽热采技术研究进展

在研究大量文献的基础上,总结了注蒸汽采油的机理,概述了稠油注蒸汽热采的研究现状与发展趋势,着重探讨了稀油注蒸汽热采的应用前景、研究现状以及稀油注蒸汽热采还需要深入研究的课题。研究认为：稠油注蒸汽热采已是比较成熟的技术,在稠油开发中占有重要的地位,其发展趋势为利用天然气、溶剂、高温泡沫、聚合物等来改善注蒸汽热采效果;稀油油藏水驱、聚驱后转注蒸汽热采具有可行性,今后需重点解决的问题包括采用煤或核能生产蒸汽、采用水汽交注、蒸汽泡沫等方法提高稀油油藏注蒸汽热采的采收率。     

稠油复合吞吐中不同注入剂对比实验研究

稠油油藏在我国石油资源中占有重要地位,目前主要工业化开采方式是蒸汽吞吐和SGD技术等,但采收率一般在20%左右,这样大量资源无法有效采出,目前许多稠油区块开始使用注蒸汽过程中加入CO2和降粘剂等实现复合吞吐。本文在优选降粘剂的基础上,以中原油田油藏为基础开展复合吞吐过程中不同注入剂的配比优化研究。首先自主研发水平井吞吐的物理模拟实验装置,优化油溶性降粘剂+CO2+氮气+蒸汽的优化配比设计。实验结果表明,对于超稠油(粘度大于50 000 m Pa·S)复合吞吐效果不理想,这类油藏不适合,对于粘度小于50 000 m Pa·S的稠油复合吞吐可以提高单独蒸汽吞吐效果,同时得到注入剂的组合方式和具体组合参数值,对实际油藏开发有重要指导意义。     

Reducing heavy oil carbon footprint and enhancing production through CO2 injection

The world's dependence on heavy oil production is on the rise as the existing conventional oil reservoirs mature and their production decline. Compared to conventional oil, heavy oil is much more viscous and hence its production is much more difficult. Various thermal methods and particularly steam injection are applied in the field to heat up the oil and to help with its flow and production. However, the thermal recovery methods are very energy intensive with significant negative environmental impact including the production of large quantities of CO₂. Alternative non-thermal recovery methods are therefore needed to allow heavy oil production by more environmentally acceptable methods. Injection of CO₂ in heavy oil reservoirs increases oil recovery while eliminating negative impacts of thermal methods.In this paper we present the results of a series of micromodel and coreflood experiments carried out to investigate the performance of CO₂ injection in an extra-heavy crude oil as a method for enhancing heavy oil recovery and at the same time storing CO₂. We reveal the pore-scale interactions of CO₂-heavy oil-water and quantify the volume of CO₂ which can be stored in these reservoirs.The results demonstrate that CO₂ injection can provide an effective and environmentally friendly alternative method for heavy oil recovery. CO₂ injection can be used independently or in conjunction with thermal recovery methods to reduce their carbon footprint by injecting the CO₂ generated during steam generation in the reservoirs rather than releasing it in the atmosphere.     

稠油井分层稳恒注汽技术

注蒸汽吸汽不均问题是稠油非均质油藏蒸汽吞吐开发主要矛盾之一,多年来工艺技术人员研究应用选配注技术,通过分隔纵向油层,实施配汽,取得了较好的效。但是不能同时给两个油层注汽,只能先注下层,然后投球配注上层,蒸汽的热损失大,而且存在人为误差和蒸汽的浪费,同时在热采井口投球存在不安全隐患。针对这类问题,研制应用了分层稳恒注汽技术,将分层稳恒注汽管柱下入指定位置。注汽时,蒸汽通过稳恒注汽阀按设计注汽量进入油层,达到调整和改善油层的吸汽剖面,使油井各层位产能达到均衡动用,提高热采效果和采收率。     

稠油油藏蒸汽吞吐开发技术研究

自从20世纪50年代末注蒸汽技术首次投入工业应用以来,世界上的稠油产量迅速增长,在整个原油生产中占有重要的位置。热采方法是稠油油藏最主要的开采方法,而蒸汽吞吐为最常用的热采方法。通过阐述蒸汽吞吐的热采技术机理,了解和掌握基本的稠油油藏蒸汽吞吐开发技术。     

热采井抗高温长效水泥固井技术研究与现场应用

稠油油藏大多采用热力降粘的方式开采,主要是采用蒸汽热采的方法。注蒸汽热采一般为蒸汽吞吐,后期转为蒸汽驱,因此热采稠油井的固井必须适合和满足蒸汽吞吐和蒸汽驱开采方式。后期注蒸汽开采时,由于地层的保温效果很差,高温蒸汽在注入过程中能量通过水泥环很快耗散到地层中,导致稠油油藏达不到注蒸汽热采的效果,严重影响稠油油藏的开发效果。在注蒸汽开采过程中,水泥石在高温蒸汽环境中强度衰减严重,导致水泥环破裂损坏,使原本封固好的环空失效,引发油气水窜,严重缩短油井寿命。针对稠油油藏固井存在的问题,须研究开发一种适用于封固稠油热采井的长效固井技术,使该固井技术具有水泥浆热容高、保温效果好,可延缓蒸汽注入过程中能量损失;水泥浆具有良好的强胶结性能,大大改善固井第二界面胶结强度,有效防止油气水窜的发生,提高浅层水泥封固段长期封固效果;水泥石强度高,抗高温性能好,其强度在高温下衰减缓慢,可经受稠油热采高温蒸汽的侵蚀的优点。有效解决稠油热采井在高温驱替环境下固井质量差、油井寿命短的问题,为稠油油藏勘探开发提供有力的技术支撑。     

重18井区八道湾组超稠油油藏水平井开发效果影响因素分析

水平井蒸汽吞吐开采超稠油是一项非常有潜力、有优势的技术,相比直井开发,不仅能大幅度提高开发效果,而且能够进一步提高采收率。研究稠油油藏水平井蒸汽吞吐开发效果,分析地质参数及注汽参数对该类油藏开发效果的影响程度,并进行灰色关联分析。研究表明对周期产油量影响最大的因素是采注比,其次是原油粘度。     

SIMULTANEOUS HEAT AND FLUID FLOW IN POROUS MEDIA: CASE STUDY: STEAM INJECTION FOR TERTIARY OIL RECOVERY

Heat transfer and fluid flow in porous media occur simultaneously in thermal enhanced oil recovery and significantly increase the rate of energy transfer. The purpose of this investigation was to take advantage of such contemporary transfers and to study heavy oil recovery efficiency using hot-water flooding, cold-water flooding, and steam injection into porous media. A set of multistage laboratory tests was performed to find the temperature profile during steam injection as a means of tertiary oil recovery. Sand-packed models were utilized to investigate the oil recovery efficiency during cold and hot water injection as well as steam flooding for both secondary and tertiary oil production stages. An oil bank was formed in steam injection during the tertiary oil recovery from a vertical standing sand-packed model, resulting in very high oil recovery efficiency. Steam injection was found to be very effective, compared to cold- and hot-water flooding, for the recovery of heavy oil. Based on the principles of transport phenomena in porous media, a mathematical model was developed to predict the temperature profile during the steam injection process. Satisfactory agreement is achieved between the temperature profile predicted from the model and the experimental results.     

SIMULTANEOUS HEAT AND FLUID FLOW IN POROUS MEDIA: CASE STUDY: STEAM INJECTION FOR TERTIARY OIL RECOVERY

Heat transfer and fluid flow in porous media occur simultaneously in thermal enhanced oil recovery and significantly increase the rate of energy transfer. The purpose of this investigation was to take advantage of such contemporary transfers and to study heavy oil recovery efficiency using hot-water flooding, cold-water flooding, and steam injection into porous media. A set of multistage laboratory tests was performed to find the temperature profile during steam injection as a means of tertiary oil recovery. Sand-packed models were utilized to investigate the oil recovery efficiency during cold and hot water injection as well as steam flooding for both secondary and tertiary oil production stages. An oil bank was formed in steam injection during the tertiary oil recovery from a vertical standing sand-packed model, resulting in very high oil recovery efficiency. Steam injection was found to be very effective, compared to cold- and hot-water flooding, for the recovery of heavy oil. Based on the principles of transport phenomena in porous media, a mathematical model was developed to predict the temperature profile during the steam injection process. Satisfactory agreement is achieved between the temperature profile predicted from the model and the experimental results.     

Optimization strategies and impact of low oil price on long term SAGD projects

Steam assisted gravity drainage (SAGD) has been known as a commercially proven high ultimate recovery process for bitumen and heavy crudes. It is an energy intensive process, which is economical when oil price is above certain value. When the oil price goes below the economic threshold of project, steam injection can be decreased or completely stopped for a certain period of time, and can resume thereafter when the condition alters. The objective of this study is to provide comprehensive information about the effect of steam injection interruptions on thermal project performance. An optimization strategy for the SAGD process, in cases where steam injection interruption occurs, is discussed using actual reservoir models of different geological formations. An economical model is used to evaluate operating strategy effect on the net present value (NPV) of the project. The parameters, like shut-in period, initial steam injection period, etc, are optimized for Athabasca type oil sand reservoirs. The results show several key mechanisms exist in the life cycle of the SAGD process that must be included to reflect the field scale behaviour; otherwise, the mechanistic simplicity of the models could lead to directional and semi-quantitative conclusions. Among the mechanisms, temperature effect on basic petrophysical properties of reservoir rocks was found to have an important role in the oil recovery, and considerably impacts the results of optimization. When the steam injection is interrupted, an optimum shut-in period can be determined to maximize the oil recovery. The optimum length of steam injection interruption depends on the initial steam injection period.