中深层稠油蒸汽驱注采剖面调整工艺技术研究

从1997年开始,辽河油田进行了中深层稠油蒸汽驱先导试验,目前已进入蒸汽驱先导试验的后期调整阶段,先导试验区的稠油采出程度由试验前的24%提高到57%,基本达到方案设计指标,先导试验获得成功。然而,在蒸汽驱先导试验及随后的扩大试验中,存在着纵向动用程度不均、平面动用程度差等问题,影响蒸汽驱先导试验效果。为此,从2004年开始,辽河油田钻采工艺研究院开展了中深层稠油蒸汽驱注采剖面调整工艺技术研究工作,形成了中深层稠油蒸汽驱注采剖面调整系列技术,主要包括耐高温化学调堵技术与机械封堵技术,并应用于现场,有效解决了蒸汽驱层间、层内动用不均的问题,提高了中深层稠油的采收率。下一步仍需加大高温调剖剂的深入研究,研制高效、经济的高温调剖剂;对生产井机械封堵工艺技术的研究重点,是加快对耐高温胶筒的选优,满足现场生产需求。     

超稠油蒸汽驱先导试验效果分析

杜229块兴隆台油藏为中厚互层状超稠油油藏,单层厚度薄、储层物性好、原油黏度高,已进入蒸汽吞吐末期,综合含水率快速上升,产量递减严重,亟需实施开发方式转换。针对该区块蒸汽吞吐后期的特点,运用开发机理研究、数值模拟研究等方法,论证了超稠油蒸汽驱的可行性,并于2007年规划了7个70m井距"反九点"井组,开展蒸汽驱先导试验。经过8年的探索与实践,先导试验取得成功,井组年产油由转驱前的4.1×104t上升至5×104t左右,油汽比为0.17,采注比为1.09,采出程度达到53.8%,各项指标达到国际先进水平。通过对历史生产资料及监测资料分析研究,初步形成了超稠油蒸汽驱"先连通、再驱替"的驱油机理,掌握了影响生产效果的各项主要因素,总结了汽驱阶段的动态调控理念及方法。该试验的成功实施,突破了超稠油不能实施蒸汽驱的认识禁区。     

蒸汽热力采油中抗高温调剖堵剂的应用与展望

稠油油藏开发过程中,受油藏层间非均质性、渗透率变化、原油性质差异、不利的流度比、重力分离、井距和油藏倾斜,以及原油黏度大、密度大、流动性差等因素的影响和制约,降低了蒸汽利用率和体积波及系数,导致油井吸汽剖面不均匀,含水率高、采出程度低,影响稠油油藏的高效开发.为解决这一问题,目前主要采取调剖堵水的方法来控制油井含水上升,进而提高原油采收率.稠油油藏主要采用热力采油方式,要求所使用的堵剂必须同时具备长期耐蒸汽温度和蒸汽冲刷的特性,以实现深度调剖和封堵汽窜通道的作用.本文所指的抗高温调剖剂,主要针对油藏温度高达250℃以上的稠油油田.分析固体颗粒型调剖剂、抗高温凝胶类调剖剂、高温泡沫调剖剂的原理及其在国内外的发展和应用状况,并对抗高温堵剂的发展方向进行展望.     

改善薄层稠油油藏蒸汽吞吐效果的技术探讨

江37区块作为采油九厂第一个稠油开发试验区,已经进行了3年的蒸汽吞吐热采试验,目前油井已进入第四轮蒸汽吞吐开采阶段。随着热采试验的不断深入,试验区的含水上升快、井间干扰严重,油层平面和纵向动用不均、储量动用差等问题日益显现,严重影响了试验区的稠油开发。针对这些问题和矛盾,在研究稠油蒸汽吞吐开发模式和递减规律的基础上,提出了改善蒸汽吞吐阶段开发效果的有效方法和途径,为下步试验区的稠油热采试验提供一定的借鉴。通过现场试验证实,提高蒸汽干度、多井整体吞吐和水平井试验,是改善薄层稠油油藏蒸汽吞吐效果的有效途径,其中提高蒸汽干度可以降低单位注入热量的注水当量,减少近井地带的冷凝水饱和度;多井整体吞吐可以有效解决油井之间因注汽而相互干扰的问题;水平井由于其吸汽能力强,开发效果远好于普通直井。     

The numerical simulation and wellbore modelling of steam injection and stored heat recovery from light oil reservoir

ABSTRACT

Steam injection and thermal recovery of oil from the reservoir are increasing day by day. However, the recovery of the heat remained stored in the steam-flooded oil reservoir is nor in practice neither researched previously. A novel concept of steam injection and energy recovery from a light oil reservoir is presented in this paper. Reservoir numerical model of an actual oil field was generated and simulated with steam injection. Different parameters of thermal properties of geologic formations were discussed and adopted as per actual geology of the study area for more realistic simulation of heat storage, dissipation, and losses. After the optimum oil recovery, water was circulated through the same injection well into the reservoir to extract the energy in the form of heat, stored during the steam injection phase. The effects of different completion schemes of injection well were also simulated, discussed and pointed out for optimum oil recovery. Oil recovery factor is the most important parameter from both research and field development point of views. The comparative analysis was also carried out with the oil production without steam injection and found that steam flooding increased oil recovery factor up to more than 15% by decreasing the production time period up to 40% as compared to without steam injection oil production. The transmission of heat through conduction and convection mechanisms in the porous media, and through advective, dispersive and diffusive processes in the fluid was modeled. To fully investigate the feasibility of the concept presented in this paper, the production wellbore modeling was also carried out and temperature profile of recovered heat energy at the wellhead was obtained by acknowledging the thermal losses and found to be very useful for any direct and indirect utilization of heat throughout the energy recovery period of the reservoir.     

重力泄水辅助蒸汽驱采油工艺技术研究与试验

洼59块为深层中厚层状特超稠油油藏。区块已进入高轮次吞吐阶段,吞吐效果逐轮变差,采油速度急剧递减。采用重力泄水辅助蒸汽驱技术,探索深层特超稠油油藏蒸汽吞吐开发后期开发方式的转换。该技术采用直井、水平井组合开发模式,上叠置水平井注汽,下叠置水平井辅助排液,周围直井产油。针对工艺技术难点,通过汽水分离器、高效隔热管柱和环空注氮隔热的综合应用,实现了深层稠油油藏井底干度大于45%的目标;采用双管注汽技术使水平段得到高效动用;通过电加热降黏和防偏磨技术的成功应用,解决了试验初期黏度大、水平井杆管偏磨的问题;利用越层深抽和高温大排量举升解决了提液降压、深层高温大排量举升的难题。井组整体效果明显,产液量由179t/d增大到最高值526.9t/d,产油量由31.0t/d增大到最高值96.5t/d,含水由91.1%下降到平均值84.69%。     

稠油油藏注空气改善开发效果研究与试验

杜80块油藏属超稠油油藏,含油面积为1.68km2,石油地质储量为1012×104t,采用注蒸汽吞吐开发,累积产油89.69×104t,累积注汽254.7×104t,累积油汽比0.38,阶段采出程度7.4%,采油速度0.62。伴随着多轮次蒸汽吞吐开发,油层低压力、低油气比矛盾越来越突出,周期递减逐渐加大,效果越来越差,汽窜呈逐渐加剧趋势,严重影响区块油井产量。提出应用注空气辅助蒸汽吞吐技术改善开发效果。对于稠油油藏,注空气驱油机理主要是燃烧产生的热和蒸汽,使原油降黏。与热力采油和化学采油技术相比,注空气技术在操作成本、采收率、经济效益等方面具有明显优势。理论研究及现场先导试验显示,注空气辅助蒸汽吞吐技术适合于井间气窜不严重、油层温度高(100℃)、油层动用不均衡、地层有倾角、地层压力低、胶质和沥青质含量相对较高的井,可以改善普通稠油、超稠油低产低能问题,恢复地层压力,改善稠油蒸汽吞吐效果。同时,通过合理监测及细化生产管理,亦可保证现场操作安全可靠。     

杜84断块馆陶油藏双水平SAGD优化设计

辽河油田曙一区杜84块馆陶油层为一顶部和四周被水包围的特殊油藏．开发初期按70m井距正方形井网部署直井蒸汽吞吐开发,在油井蒸汽吞吐过程中,射孔井段下部油层动用差,蒸汽超覆现象随周期延长而加剧．带来顶水突破的隐患,同时油藏递减逐渐加大,油藏开发效果逐渐变差。为提高杜84块馆陶超稠油油藏剩余油动用程度．决定采用SAGD开发技术。本文以油藏特点和开发现状为基础,应用STARTS数值模拟软件,采用变深度、不均匀网格进行油藏数值模拟,对双水平井组合的SAGD技术布井方式、水平段长度、水平段在油层中的位置、注采参数等进行了优化设计。实施效果表明,采用双水平井组合SAGD技术,提高超稠油原油采收率是经济可行的。     

Experimental study on blocking mechanism of nitrogen foam for enhancing oil recovery in heavy oil reservoirs

Foam flooding is one of the effective techniques during thermal recovery process in heavy oil reservoir. Nitrogen is generally co-injection with the foaming agent for the generation of foam. However, the mechanism has not been totally understood, thereby requiring further discussion. In this study, a series of sand pack experiments for nitrogen foam steam flooding were designed and conducted. A comparison of influencing factors, including gas-liquid (foaming agent) ratio, permeability, injection scheme, and oil saturation was used to evaluate the stability and blocking mechanisms of foam. The results show that the blocking capacity of the gas-liquid ratio of 1:1 is the greatest in all cases under high-temperature condition. The blocking mechanism of foam is analyzed, which indicates that foam is selective to block larger pores and throats in porous media with high-permeability. And also, the stability of foam becomes worse while meeting oil. This characteristic is favorable for improving the sweep efficiency to enhance oil recovery in developing heavy oil reservoir.     

Effect of initial water saturation on crude oil recovery and water cut in water‐wet reservoirs

Crude oil recovery and water cut are key parameters in petroleum industry. Note that ‘crude oil’ was reduced to ‘oil’ for simplicity in many cases in the rest of this article. Both theoretical prediction and experimental results have shown that oil recovery could increase or decrease with initial water saturation at a core scale. However, there have been few studies on this once‐considered peculiar phenomenon at a reservoir scale. Initial water saturation and its distribution in oil reservoirs depend upon oil‐water capillary pressures. In this study, effect of initial water saturation on oil production, oil recovery, and water cut in reservoirs with bottom water was investigated numerically in horizontal wells. Distribution of initial water saturation as a function of reservoir height was either calculated using the oil‐water capillary pressure or determined as constant values. The numerical simulation results were compared with experimental data. The results demonstrated that some of the numerical simulation results at a reservoir scale were consistent with the theoretical results from models derived at a core scale as well as the experimental data in the core samples, but the others were not. Experiments conducted in small core samples were often doubted because of the small size compared with the reservoir scale and the poor representation of large‐scale reservoirs. The consistence of the results at both core and reservoir scales implies the importance of core analysis experiments and is of great significance in petroleum industry. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of minerals on steam distillation during thermal heavy-oil recovery: An experimental investigation

An experimental study was carried out to investigate the role of various clay and non-clay minerals present in reservoir formations on steam distillation process. Dead oil samples (100 g) of two heavy oil reservoirs with 30 g of water and 10 g of crushed rock mixed with different clay minerals were kept under steam pressure with 150, 200, and 250°C in a batch autoclave reactor for a period of 40 hours, and the results were compared with respect to the changes in the density, viscosity and chemical composition of remaining heavy oil. Three different clay minerals (bentonite, kaolinite, and sepiolite) were added to the crushed rock to observe their effects. Among these clay minerals, kaolinite had the greatest effect on steam distillation. Kaolinite has an inert surface compared to other clay minerals which can be considered as an catalytic effect to make easier the evaporation of the volatile components of heavy oil during steam distillation. On the other hand, bentonite which has a swelling property in the presence of water may not allow the entrance of oil molecules because of its low permeability has retard/decrease the evaporation of volatile components. In case of kaolinite addition, density and viscosity of remaining oil are the greatest comparing with the two other minerals added. In addition, the asphaltene content of the remaining oil after distillation increased compared to original oil sample for all added clay minerals.     

过热蒸汽装置-提高稠油开发效果的有效设备

本文介绍的过热蒸汽装置技术首次将普通锅炉软化水产生的湿饱和蒸汽直接过热,根据稠油热采工艺需要生产出蒸汽温度（320～400）℃,过热度（30～100）℃的过热蒸汽,用于稠油油田注过热蒸汽吞吐开采,试图对传统注湿饱和蒸汽稠油热采进行技术革命,为稠油油田高效开发提供了新途径。哈萨克斯坦肯基亚克盐上稠油实验区现场运行表明：注过热蒸汽较普通热采的驱油效率提高6％～12％以上,单井稠油产量相对第一轮常规湿饱和蒸汽吞吐平均日增油量达1～8t,并普遍延长了注过热蒸汽井的生产周期,是一项可提高稠油开发效果的有效措施,对实现稠油热采领域节能降耗具有重要意义。     

稠油油藏蒸汽吞吐开采参数优化

通过查阅稠油相关物性及特种油藏相关参数,利用数值模拟方法对蒸汽吞吐的过程进行了数值模拟,得到相关参数的数据,通过对数据的分析以达到注气参数最优化.并对其中主要的注气参数分别进行分析比对,如周期注气量、注气压力和速度等.只有在各参数达到最佳值时才能产生较高的经济效益,此研究对特种油藏的开采提供了依据.     

超稠油水平井蒸汽吞吐开发实践

在跟踪研究现场水平井生产情况的基础上,总结分析了浅层超稠油水平井开发特征,提出了提高开发效果的技术措施。通过优化注汽参数和注汽方式,扩大了蒸汽波及体积,提高了油层的动用程度,从而提高水平井开发的最终采收率。目前,实施了三种均匀布汽方式:步进式注汽、分流式注汽、均点式注汽。工业规模试验结果表明,单一水平井步进式注汽技术能够使得水平段油层逐步得到动用,实施后生产效果良好;分流式注汽方式打孔段油层吸汽效果有所改善,二、三轮产油和油汽比相比第一轮均有所提高;均点式注汽方式使得水平段油层吸汽相对均匀了些,从实施前后的生产效果对比来看,措施后日产液、日产油水平也有明显增加。本文各项措施和手段,对于改善水平井开发效果,指导后续超稠油油藏的开发,以及其他地区此类油藏的开发,具有一定的指导意义。     

Assessment of reservoir heterogeneity by using produced water chemistry in SAGD

The key challenge of extracting oil from oil sand reservoirs is the viscosity of the oil which is typically between 100 000 and several million cP. To reduce the viscosity of the oil, high pressure, high temperature steam, typically between about 185 and 250 °C, is injected into the reservoir by using recovery processes such as the steam‐assisted gravity drainage (SAGD) process. In this process, steam heats the bitumen and as a consequence, its viscosity drops to about 5 cP and it readily flows under gravity within the reservoir. One key issue that has not gained much attention with respect to SAGD process evolution are steam–rock reactions, water geochemistry, and how the produced water composition varies as the process evolves. Here, we examine how the produced water composition varies in SAGD operations. For the first time, we show that the produced water composition can be used to detect shale barriers and contact of the steam chamber with the overburden. As yet, the produced water composition is not used to understand in situ process development but as we show here, this could be a rich data source for understanding process dynamics. Copyright © 2016 John Wiley & Sons, Ltd.     

Advanced mathematical model for reservoir heat efficiency with liquid in steam-injection wellbore

The accurate determination of reservoir heat efficiency of steam injection in heavy oil reservoirs is very important for heating radius calculation and production dynamic prediction. In conventional calculation methods of reservoir heat efficiency, the steam-injection wellbore is assumed as taking steam over the entire height. In fact, a liquid level in steam-injection wellbore is a very significant observation with respect to the steam override. Aiming at the actual situation that the steam-injection wellbore always has a liquid level, combined with the formation temperature distribution, the new mathematical model for reservoir heat efficiency with the consideration of liquid in steam-injection wellbore was established based on the Van Lookeren steam override theory and the energy conservation principle. The established mathematical model was used to calculate and analyze the reservoir heat efficiency of steam injection in heavy oil reservoirs. The results show that because the new mathematical model considers the liquid in the steam-injection wellbore, the predicted results are more reasonable, thus verifying the correctness of the new model. According to the influential factors analysis based on the new model, it is observed that although increasing the steam quality can effectively increase the steam-taking degree of the steam-injection wellbore, it has limited impact on reservoir heat efficiency. Moreover, the larger the steam-injection rate, the higher the steam-taking degree and reservoir heat efficiency. The reservoir heat efficiency decreases with the pay-zone thickness when the steam-injection wellbore has liquid.     

双水平井SAGD循环预热工艺研究与应用

蒸汽辅助重力泄油(SAGD)技术是开发超稠油的一项前沿技术,具有驱油效率高、采收率高的特点。该技术应用分为启动阶段和生产阶段。SAGD启动阶段应用的技术主要有蒸汽吞吐预热启动和循环预热启动。相对于蒸汽吞吐预热启动,注蒸汽循环预热启动加热均匀,启动平稳,有利于蒸汽腔的均匀扩散,蒸汽腔发育体积大,转入SAGD生产以后,生产效果好,采收率高。但配套循环预热管柱结构复杂、预热参数优化困难、循环预热机理仍需进一步研究,尤其在工艺配套上,尚无满足循环预热试验要求的同注同采工艺技术,且国内尚无成功实施循环预热的先例可资借鉴。对循环预热工艺机理、注采参数设计、管柱结构进行研究,完成了为循环预热工艺配套的井下双管柱结构、无接箍长冲程抽油泵、注采一体双管井口等多项关键技术设备,现场应用表明,完全满足循环预热工艺要求。同时,得到合理的循环预热注汽量、注汽速度、注汽压力、采注比等预热参数,为下步SAGD试验的规模实施奠定了基础。     

超稠油水平井分段注汽配合调剖技术研究与应用

辽河油田超稠油水平井蒸汽吞吐进入中后期开采阶段，逐渐暴露出水平段动用不均、吞吐效果差等开发矛盾。分析认为，由于蒸汽超覆作用，水平段各井段区域储层非均质性差异大，吸汽强度不均，井间汽窜严重；近井地带地层存水增多，含油饱和度下降；油层亏空加大，地层压力下降，油层供液能力不足。依据水平井温度监测资料，合理判断水平段剖面动用状况，采用分段注汽工艺技术，独立分隔水平段注汽腔，灵活分配注汽量，实现对水平段不同区域分段均匀注汽。并通过注入高温复合调剖剂，辅助分段注汽进行蒸汽吞吐，有效封堵水平井段局部大孔道高渗透区域，补充地层能量，抑制汽窜发生，提高蒸汽波及半径，调整水平段动用剖面，实现水平段均匀吸汽，近而起到降黏、驱油助排和提高动用程度的作用，达到改善开采效果的目的，为油田开发持续稳产提供技术依据。     

欢喜岭油田提高稠油采收率技术应用实践

欢喜岭油田稠油油藏经过20多年开发已进入“两高一低”,即高含水、高采出程度和低油汽比的开采阶段,常规蒸汽吞吐开发方式面临诸多矛盾,进一步提高采收率难度大。为此,开展了稠油蒸汽吞吐转换为蒸汽驱、利用水平井技术实现老油田“二次开发”及提高稠油吞吐井开发效果配套技术（包括分层注汽、组合注汽、水平井多点注汽、水平井双管注汽、化学辅助吞吐等）的研究与应用。措施实施后,累计增产原油110.6×104t,创经济效益11.7亿元。     

关于吸汽剖面测试中油层吸汽量计算方法研究

在蒸汽吞吐或蒸汽驱开发方式中,为了分析稠油井注蒸汽效果,通常需要在井筒中进行吸汽剖面测试,并利用测得的数据进行油层吸汽量计算、油层动用程度等分析解释工作.为了减少人工因素、仪器操作等对测试数据可靠性的影响,通常要求按照不同的仪器下入(上提)速度做多次测试,在数据进行分析解释时,综合考虑多次测试数据.为此,对在实际工作中常年使用的油层吸汽量计算方法进行了总结,并推导出了详细的计算方法:使用盖层、隔层段获取的流量测试数据的算术平均值来计算每个油层的相对流量,同时应用多套测试数据的算术平均值来精确每个油层的吸汽量;给出了计算公式.结合200余口1注汽井的吸汽剖面测试数据,利用该方法进行了试算.结果表明,计算结果与油层的实际吸汽情况非常接近,证明该方法有效可行.