Experimental Investigation of Capillarity and Drainage Height Roles in the Vapor Extraction Process

The authors present the results of a novel comprehensive experimental program to investigate the roles of capillary pressure and drainage height on the performance of the VAPEX process. Measured stabilized drainage rates at lower permeability range (5.1–6.4 D) in this study show no linear relationship with square root of permeability, as reported for experiments at high permeabilities (>200 D). In these tests stabilized drainage rates are a function of drainage height to the power of 1.1–1.3.     

The Vapor Extraction Process: Review

The high viscosity of Canadian crude oil is a serious challenge for the recovery efficiency of this resource by conventional methods. Since 1991, the vapor extraction process (VAPEX) has emerged as a promising technology that has gained considerable attention within the oil industry. This article presents a current review of this process and its variations, as well as describing important factors affecting the process such as solvent requirements, mass transfer, asphaltene precipitation, oil rate, and wettability. Recent research has shown that VAPEX is an efficient alternative for the recovery of heavy oil.     

The Vapor Extraction Process: Review

Abstract

The high viscosity of Canadian crude oil is a serious challenge for the recovery efficiency of this resource by conventional methods. Since 1991, the vapor extraction process (VAPEX) has emerged as a promising technology that has gained considerable attention within the oil industry. This article presents a current review of this process and its variations, as well as describing important factors affecting the process such as solvent requirements, mass transfer, asphaltene precipitation, oil rate, and wettability. Recent research has shown that VAPEX is an efficient alternative for the recovery of heavy oil.     

Feasibility study on application of the recent enhanced heavy oil recovery methods (VAPEX,SAGD, CAGD and THAI) in an Iranian heavy oil reservoir

Enhanced oil recovery (EOR) methods assisted by gravity drainage mechanism and application of sophisticated horizontal wells bring new hope for heavy oil extraction. Variety of thermal and non-thermal EOR techniques inject an external source of energy and materials such as steam, solvent vapor, or gas through a horizontal well at the top of the reservoir to reduce in-situ heavy oil viscosity. So, the diluted oil becomes mobile and flows downwards by gravity drainage to a horizontal producer located at the bottom of the reservoir.

In this paper, a sector model of an Iranian fractured carbonate heavy oil reservoir was provided to simulate and evaluate capability of some EOR techniques such as Vapor Extraction (VAPEX), Steam Assisted Gravity Drainage (SAGD), Combustion Assisted Gravity Drainage (CAGD), and Toe to Heel Air Injection (THAI) at its reservoir conditions and fluid properties. The simulation results demonstrated that wet CAGD in comparison with other nominated methods could improve heavy oil recovery factor to around 19% much more than each of SAGD, THAI, and VAPEX techniques. It could also reduce the total energy to produced oil ratio index up to 82% with respect to SAGD process in a year.

Although lower oil recovery has been gained by VAPEX process, but using a proper vaporized solvent could produce a kind of de-asphalted and upgraded oil with increased API gravity up to 29°API with no considerable solvent loss.     

加油站油气回收综合治理的工艺设计

详细阐述了加油站卸油油气回收、加油油气回收和油气排放处理系统的工艺设计,分析了现有工艺存在的问题,提出了加油站油气回收系统的改进方向。     

酯类化合物降低原油与二氧化碳体系最小混相压力实验

针对试验区近井地带达到混相驱、远井地带尚未达到混相驱的问题,通过注入油溶性表面活性剂(柠檬酸异丁酯或柠檬酸异戊酯)来降低原油与二氧化碳体系的最小混相压力,该表面活性剂既能够溶于原油中降低原油黏度,又能够溶解在超临界二氧化碳中降低原油与二氧化碳之间的界面张力,从而降低原油与二氧化碳之间的最小混相压力。采用长细管驱替实验的方法,测定了2种油溶性表面活性剂对试验区原油与二氧化碳体系的最小混相压力的影响。实验表明,注入的油溶性表面活性剂能够明显降低试验区原油与二氧化碳体系的最小混相压力,2种表面活性剂降低的最小混相压力值分别为7.2 MPa和6.6 MPa,并且随着表面活性剂注入段塞的增大,测得的原油与二氧化碳体系的最小混相压力逐渐降低,但是降低幅度越来越小,结合表面活性剂制备价格,得到最经济的表面活性剂注入段塞量为0.003 PV,并建议选择柠檬酸异丁酯作为试验区降低最小混相压力的化学试剂。     

The Effect of Fractures' Geometrical Properties on the Recovery Mechanism of the Top-down In Situ Combustion Process

Abstract

The top-down in situ combustion (ISC) involves the stable propagation of the combustion front from the top vertical injector to the bottom horizontal producer. Apart from laboratory studies in conventional sandstones, no application of the process in fractured carbonates has been addressed yet. The authors modified a successful combustion tube history matched model of an Iranian low-permeable heavy oil reservoir called Kuh-E-Mond to investigate the feasibility of ISC in fractured carbonate reservoirs mimicking block-scale combustion cells. Effects of fractured geometrical properties such as orientation, location, extension, density, spacing, and dispersion were considered. Results confirmed a higher outcome in the case of optimum vertical or horizontal fracture density and spacing. Vertical fractures located at the lateral sides of the cell enhanced the process in terms of ultimate oil recovery and oxygen sweep efficiency. The longer vertical fractures and higher dispersion through the reservoir improved the recoveries compared with the lower efficiency in the case of extended horizontal fractures and raised their dispersion through the reservoir. Simulation analysis confirmed that top-down ISC has higher feasibility in the case of highly networked fractures through reservoirs such as those in the Persian Gulf coast.     

Investigation of the Effect of Geometrical Properties of Networked Fractures on the Efficiency of Steam-Assisted Gravity Drainage Process

Abstract

Various fracture geometrical properties such as orientation, extension, discontinuity, dispersion, location, and networking were investigated. Results indicate improved oil recovery and sweep efficiency in the presence of vertical fractures. Longer vertical fractures seemed to have even more beneficial effects. Horizontal fractures revealed detrimental effects on oil recovery and the performance became worse for longer horizontal fractures. Discontinuous horizontal fractures caused a better performance especially when combined with continuous vertical fractures (networking). Vertical fractures helped the growth of the steam chamber in the vertical direction, which resulted in higher oil recovery. However, horizontal fractures seemed to inhibit growth of the steam chamber in the vertical direction, hence retarding oil recovery.     

吸收法回收油气工艺研究

对吸收法回收汽油挥发的油气进行了研究,试验考察了影响油气吸收的因素。结果表明,采用柴油作为吸收剂可以有效回收油气,油气回收率可达85％以上,具有一定的工业应用前景。     

正理庄高89-1区块CO2混相驱参数优化数值模拟研究

为了确保高89-1区块CO2混相驱项目的顺利实施,依据该区块的精细油藏描述成果,在优化适于CO2混相驱模型基础上,建立了符合油藏地质特点的三维地质模型。在此基础上对开发指标进行计算,对五个参数(井网、开发方式、压力水平、注入量和采油速度)进行优化,并提出了推荐方案,预测采收率可达23.10%,比弹性开采方式提高15.16%。     

An Investigation of and Comparison Between the Simulation of Miscible and Immiscible Gas Injection in an Undersaturated Fractured Reservoir in the South of Iran

M-Reservoir is a dual porosity fractured reservoir having active aquifer and heterogenous production zones. It had had only a total oil recovery of 8.4% with the total production of 240 MMSTB up to 2008. By simulation of slime tube experiment using Eclipse 300 software, minimum miscibility pressure of 3700 psia was obtained, which was below its average pressure. Production optimization and final recovery increment were performed via analyzing and matching of fluid reservoir, history matching of past reservoir performance, and investigating on different location of gas injected well. The best location of injected well was selected based on the recovery coefficient and gas injection method of miscible and immiscible at various rates and were compared with natural depletion in selected locations. The results represent that the miscible gas injection has more recovery coefficient than natural depletion and there is somewhat recovery coefficient in comparison with immiscible gas injection.     

Prediction of Oil Production Rate Using Vapor-extraction Technique in Heavy Oil Recovery Operations

Heavy oil and bitumen are major parts of the petroleum reserves in north of America. Owning to this fact and produce this type of oils various methods could be considered. Vapor extraction (VAPEX) method is one of the promising methods that have been executed successfully through North America, specifically in Canada, and is a solvent-based approach. The authors present the implication of the new type of network approach with low parameters called least square support vector machine (LSSVM) in prediction of the oil production rate via VAPEX method. To evaluate and examine the accuracy and effectiveness of both developed models in estimation oil production rate via VAPEX method, extensive experimental VAPEX data were faced to the two addressed models. Moreover, statistical analysis of the output results of the LSSVM was conducted. Based on the determined statistical parameters, the outcomes of the LSSVM model has lower deviation from relevant actual value. Knowledge about oil production via enhanced oil recovery (EOR) methods could help to select and design more proper EOR approach for production purposes. Outcomes of this research communication could improve precision of the commercial reservoir simulators for heavy oil recovery specifically in thermal techniques.     

原油油气冷凝回收工艺模拟与优化

我国每年都会进口大量原油作为战略储备,主要采用地下水封石油洞库进行原油储存。具有量大、种类多、高含硫等特点的原油在我国进行周转和储存,会产生大量油气。油气回收是防火防爆、保护环境的最优方法,而冷凝法为最常见的油气回收方法之一。通过Aspen Plus模拟软件对原油油气冷凝回收工艺模拟可知,加压后回收率明显提高,且出口浓度降低;高浓度油气回收率不一定高于低浓度油气回收率。冷凝温度达到-10℃,油气回收率出现上升趋势;冷凝温度为-110℃时,出口浓度低于1 g/m³的排放要求,再降低冷凝温度已不具有经济性,可采取加压冷凝或集成工艺后续进一步处理。随着气量的增大,能耗增加;在相同冷凝温度及压力下,相同气量、不同浓度的油气所需的压缩机功率相近。     

Design and Numerical Study of a New Hybrid CSS-SAGD Process Using Horizontal Wells for Recovering Heavy Oil

Abstract

The cyclic steam stimulation (CSS) and steam-assisted gravity drainage (SAGD) processes have extensively been applied as standard methods for Canadian oil sands extraction. Recently, many studies have been concentrated on CSS with horizontal wells and hybrid CSS-SAGD processes. In this article, a new hybrid CSS-SAGD process with two CSS horizontal wells and a single SAGD well is developed and investigated for shallow reservoirs by using the fourth SPE Comparative Solution Project adapted for oil sands reservoirs. Compared with the conventional CSS process, it is shown from simulation results that this new hybrid CSS-SAGD process is a more efficient recovery process.     

注水开发稠油油藏转蒸汽驱提高采收率

分析了水驱稠油油藏剩余油分布特征、水驱开发过程中原油性质的变化情况以及引起原油性质变化的主要原因。论述了蒸汽驱提高采收率的开采机理、水驱转蒸汽驱时机及注汽参数对开采效果的影响,阐明了稠油油藏水驱后期转蒸汽驱开采的技术策略。     

海上强边底水油帽稠油油藏注CO2提高采收率

A油田馆陶组是受断层切割的低幅构造“水上漂”稠油油藏,其油层厚度薄、油柱高度低,边底水能量强.用Eclipse数值模拟技术进行了稠油油藏注CO2混相能力评价、注CO2流体相态模拟实验,以及不同开发方式注采参数优化、合理开发方式优选,形成了一套强底水稠油油藏高效开发模式.结果表明:在原始地层压力条件下,CO2无法与地层原油混相,同时由于油藏构造平缓,也无法实施重力稳定驱,因此只能实施CO2非混相采油;CO2具有很强的溶解能力和膨胀能力,对地层原油有很好降黏效果;注CO2单并吞吐开发效果好于CO2非混相平面驱,衰竭开发效果最差;CO2吞吐有利于降低油水流度比、降低生产压差,抑制底水上窜,是海上底水稠油油藏提高采收率一种较为合适的方法.     

二次加工重油对炼油工艺过程的影响

基于国内外大量文献资料的研究表明，二次加工重油对常压蒸馏、减压蒸馏、催化裂化、溶剂脱沥青、延迟焦化、重油加氢处理、烷基化等炼油工艺过程有重要影响，可使液体产品经提高，质量明显改善，同时也解决了二次加工重油的有效利用问题，经济效益显著，具有很好的开发和应用前景。     

A Post–Cold Production Solvent Vapor Extraction (SVX) Process Performance Evaluation by Numerical Simulation

Solvent vapor extraction (SVX) process has been proposed as an approach to improve heavy oil production after cold production. The wormholes formed during cold production can be utilized as conduits available to produce diluted oil in SVX process. Through numerical simulation, the authors studied the effects of wormhole characteristics (length, permeability and water saturation, direction, and wormhole branch number) and fluid and formation uncertainties (dispersion coefficients, relative permeability curves, and reservoir heterogeneity) on the production performance of SVX process. The conclusions drawn can be used as guidance for designing post-cold SVX processes.     

海上油田稠油热采井注采一体化工艺技术研究

渤海油田稠油资源丰富,多元热流体吞吐与蒸汽吞吐等热采技术试验效果较好,但需采用注采两趟管柱予以实现,导致热采开发成本较高。鉴于此,通过举升工艺优选、管柱设计、井下关键工具设计、专用井口装置设计及地面配套工艺优选等研究,形成了海上油田稠油热采井注采一体化工艺技术,实现了海上油田稠油注采一体化领域从0到1的突破。现场试验结果表明:该技术所用工具耐温性好,工作筒与机械式安全阀配合良好,打开灵活;工作筒下入顺利,内泵筒插入密封耐压20 MPa,符合技术要求。一体化工艺技术实施的总费用相比目前工艺降低幅度达60%,有助于实现海上稠油油田的规模化热采开发,经济效益与社会效益显著。     

非离子低分子表面活性剂优选及驱油效率研究

目前国内外对低渗透油藏开发的主要趋势为注气开发,又以CO2混相驱居多。我国低渗油藏以陆上沉积为主,储量大且非均质性严重,油质较重黏度高一般不易达到CO2混相。为了降低驱油混相压力,在尽量少增加成本的情况下提高驱油效率,找到了一类不溶于水但溶于超临界CO2及原油中的非离子低分子表面活性剂,通过研制复配及溶解性与降黏评价实验,找到了2种表活剂CAE、CAF。以细管实验为载体,采用高温高压配样器配置地层油进行驱油效率评价,筛选确定了一种表活剂CAE。进行溶解式驱替及段塞式驱替以确定表活剂CAE的最佳注入方式;进行不同浓度的驱替实验确定表活剂CAE的最佳注入浓度。研究表明:段塞式驱替为该活性剂的最佳注入方式,最佳浓度为0.2%;表活剂CAE在最佳驱替方式下与纯CO2相比可以提高驱油效率约13.13百分点。该研究为国内低渗透油藏相对有效地降低混相压力、提高驱油效率找到了途径,是我国低渗油藏注气开发研究中值得探索和尝试的方法之一。