Heavy oil recovery efficiency using SAGD,SAGD with propane co-injection and STRIP-SAGD

Primary oil recovery methods in heavy oil basins generally extract 5–10% of the available resource, with the vast majority left in the ground and recoverable only through Enhanced Oil Recovery (EOR) methods. Traditional EOR methods, such as SAGD and solvent-assisted SAGD, generate steam in surface facilities and inject it underground to mobilize the oil for production. However, these methods can have considerable energy losses that significantly impact process performance. In contrast, the Solvent Thermal Resource Innovation Process (STRIP) technology, which uses down hole combustion of methane to produce CO₂ and steam, reduces the operating and capital costs of surface facilities, saving more than 50% of the energy typically required for thermal production. In this work, simulations of conventional SAGD, SAGD with a non-condensing solvent (propane), and STRIP-SAGD for a typical bitumen reservoir in the Fort McMurray region in Alberta, Canada were performed using the combined software system ADGPRS/GFLASH. SAGD simulations used steam injection with a quality of 0.8 while STRIP simulations injected a vapor–liquid mixture with a quality of 0.8. Furthermore, both solvent-based EOR methods required longer operation periods than conventional SAGD to recover a similar amount of oil. However, when compared on the basis of cumulative oil produced for the same overall energy input, it is shown that STRIP-SAGD recovered more oil per kJ of energy input to the reservoir than either SAGD or SAGD with propane co-injection.     

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。     

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。     

Design,construction and operation of lab scale cylindrical steam assisted gravity drainage model for heavy oil recovery

Based on a theoretical background [1,2], a lab scale cylindrical SAGD (steam assisted gravity drainage) model was designed, constructed and operated. There are six different parts in the apparatus: (1) water supplier, (2) steam generator, (3) SAGD cylindrical model, (4) cooling system, (5) constant pressure maintaining system and (6) production system. Temperature, pressure and steam injection rate were controlled by computer, and product (mixture of oil and water) was collected/separated manually. Extra heavy oil (<10 cp at 200 °C) and glass bead (diameter 1.5 mm) were mixed homogeneously for making porosity of 0.3 and applied for simulating oil sand. For obtaining optimum operation conditions of SAGD apparatus, several attempts were made. When the steam at high temperature (160–180 °C), high pressure (8–9 atm) was injected with 20–25 cc/min, cSOR (cumulative steam to oil ratio) of about 5 was obtained with oil recovery of 78.8%.     

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。     

风城油田重18井区超稠油油藏注气方式优化选择研究

水平井热采模式一直是改善特、超稠油油藏开发效果的有效手段。在热采中后期,常规同采同注的注气方式存在着蒸汽热利用率低、蒸汽波及范围小和剩余油量大等问题。研究不同注气方式对该类油藏开发效果和经济效益的影响,研究表明,水平井组一注多采和直平井组合吞吐方式均能很大程度提高蒸汽利用率,有效驱替井间的剩余油。     

Stability of the edge of a SAGD steam chamber in a bitumen reservoir

Steam-Assisted Gravity Drainage (SAGD) is a key in-situ recovery process being used today to extract oil from bitumen reservoirs. In SAGD, an oil-depleted chamber of steam grows within the oil sands formation along a pair of horizontal wells and heats bitumen-laden oil sands at its edge. The viscosity of bitumen drops by up to five orders of magnitude when heated to above 200 °C and mobilized bitumen at the chamber edge flows under gravity to a production well located at the base of the chamber. If the steam chamber does not grow uniformly along the wellpair, then bitumen recovery is less than ideal. To raise the thermal efficiency, and consequently the economics, of the process, efficient heat transfer from chamber to the oil sands must occur and the chamber must grow uniformly along the entire length of the wellpair. If steam fingers develop at the edge of the chamber, then the heat transfer area enlarges and raises the thermal efficiency of the process since more heat is directed to the oil sands. In this research, the stability of the interface between the steam chamber and oil sands is examined by using linear stability theory. The results show that the stability is controlled by the difference between the energy content-weighted Darcy–Rayleigh numbers of the steam/water phases (displacing fluid) and the oil phase (displaced fluid). Also, the results show that at typical SAGD steam saturation temperatures, the chamber edge is unstable providing the steam quality at the edge exceeds about 50%.     

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。     

Multiphase flow at the edge of a steam chamber

The use of steam‐assisted gravity drainage (SAGD) to recover bitumen from Athabasca deposits in Alberta has been growing. Butler [Butler, J. Can. Pet. Tech. 1985;24:42–51] derived a simple theory to calculate the production rate of oil during SAGD in an ideal reservoir. This simple and useful theory made several assumptions about the properties of the reservoir and operating conditions of the process. The theory also assumed that the highest mobility oil is at the edge of the steam chamber and that the oil phase velocity is highest at the chamber edge and reduces with distance into the oil sand. This research examines flow conditions at the edge of the steam chamber. Specifically, a new theory is derived that takes into account the impact of oil saturation and relative permeability on the oil mobility profile at the edge of a steam chamber. It is shown that the flow behaviour at the edge of a steam chamber is more complex and is not fully represented by Butler's theory. Contrary to Butler's theory, the oil mobility has its maximum some distance away from the edge of the steam chamber. The results reveal that the higher the thermal diffusivity of the oil sand, the deeper the location where the oil phase velocity is maximum. The developed model has been validated against published experimental and field data.     

稠油油藏蒸汽辅助重力泄油参数优化研究

在SAGD开采过程中,蒸汽腔的形成与发育直接影响着最终开发效果的好坏,在泄油过程中,蒸汽腔的大小、泄油能力不断在改变,蒸汽—油界面不断在移动,为防止蒸汽突破进入生产井或者热油积聚在蒸汽腔底部压迫蒸汽腔,必须对蒸汽腔的扩展状况以及油层温度场、压力场以及含油饱和度场进行动态模拟。本文应用STARTS数值模拟软件,对注采井间进行局部加密,精细模拟井间温度、压力场,对直井—水平井组合的SAGD技术的布井参数、注采参数等进行了优化设计,并对开发效果进行了预测。验证了运用数值模拟方法研究蒸汽辅助重力泄油技术开发效果的可行性和蒸汽辅助重力泄油技术开发超稠油油藏的可行性。     

薄层稠油油藏SAGD物理模拟研究

紧密围绕杜84块兴Ⅰ组油藏的地质特点与开发现状,依据相似原理设计建立了比例物理模型,开展SAGD比例物理模拟实验,探讨了薄层稠油双水平井SAGD开采中蒸汽腔的形成和发育过程,生产特征和开发效果,预测了盖层的热损失,可为开发方案编制提供借鉴。     

注蒸汽稠油油藏汽窜防治技术

对稠油油藏注蒸汽过程中的汽窜现象、危害及产生原因等进行了调研,对注蒸汽油藏汽防治技术进行了深入探讨。分析指出,汽窜井的补救措施只能延长生产井的寿命,对汽窜的控制效果不大,不能提高蒸汽波及体积;为控制注蒸汽油藏的汽窜,应采用低廉的高温调剖剂进行中、深部调驱,以提高蒸汽驱动的纵向、平面波及系数,继而提高注蒸汽采收率。     

稠油蒸汽吞吐后期增产技术现状与前景

目前,国内外许多油藏已处于蒸汽吞吐的后期。此时的油藏油气比低、含水量高、地层压力低、井况差、周期注气量大、操作成本高,产油更加困难。改善蒸汽吞吐后期的采油技术,可以最大限度的提高油藏的采收率。如今,应用于蒸汽吞吐后期增产的方法有:应用助剂改善吞吐效果、间歇注汽技术、"一注多采"技术、多井整体吞吐技术、注采参数优化技术、侧钻水平井技术、蒸汽驱技术、蒸汽辅助重力泄油技术和火烧油层技术等。然而,现在我国还在尝试发展一些新的技术,如水平压裂辅助蒸汽驱和多井组整体优化蒸汽驱等等。这使得蒸汽吞吐后期的增产技术拥有更为广阔的前景。     

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。     

Steam fingering at the edge of a steam chamber in a heavy oil reservoir

The steam‐assisted gravity drainage (SAGD) process is one of the key in situ recovery processes being used today to recover heavy oil and bitumen. In this process, steam injected through a horizontal well, flows convectively towards the outer edges of a depletion chamber. At the edges of the depletion chamber, the steam releases its latent heat to the cool oil sand and raises its temperature. The heated oil is mobile and flows under the action of gravity to a horizontal production well located several metres below the injection well. It remains unclear what is the exact mechanism of chamber growth. Some have suggested that in addition to heat conduction, it is by convective steam flow in the form of pointed fingers at the edges of the chamber which penetrate the oil sand. In theory published by Butler [Butler, J. Can. Petroleum Technol. 1987;26(3):70–75], it was determined that the fingers can be as long as 6 m for Athabasca bitumen reservoirs. In this research, a new theory is derived and provides predictions of the rise rate which compare better to estimates derived from field thermocouple data and physical model experimental observations than values obtained from Butler's theory. The results suggest that in the absence of mobile water, heat conduction rather than steam fingers at the chamber edge is the dominant heat transfer mechanism.     

Steam flow law in horizontal wells when considering reservoir heterogeneity

Steam injection in horizontal wells for thermal recovery of heavy oil is a complex and changeable process. The prediction of thermal properties of steam along horizontal wells is critical to the uniform production of reservoirs. In this paper, considering the mutual coupling effects of reservoir permeability, confining pressure, and steam phase transition, a comprehensive mathematical model for predicting steam injection flow in horizontal wells was established. Compared with the on-site logging data, the accuracy of the model was verified. The simulation results show that under a single variable condition, the larger the steam injection pressure at the heel, the faster the mass flow and steam dryness decrease. When the steam injection pressure drops from 11 MPa to 8.5 MPa, the steam distribution distance doubles. At the same position, the higher the steam dryness at the heel, the greater the mass flow in the steam injection well, and the faster the steam pressure decrease. Double the steam injection dryness, the pressure drop is almost doubled, but the longer steam injection distance. The larger the steam injection flow at the heel, the faster the steam pressure decreases, and the decrease in the steam dryness in the tube slows down. When the steam injection flow increases by 1.75 times, the pressure drop increases by 5.3 times. The higher the reservoir permeability, the faster the steam dryness decreases. By obtaining the general rules of steam distribution in horizontal wells to provide theoretical support for on-site steam injection, the steam distribution effect can be effectively improved to increase production and reduce consumption.     

考虑储层非均质时注汽井内蒸汽流动规律

稠油热采水平井注蒸汽是一个复杂多变的过程,水平井沿程蒸汽热物性的预测对于储层的均匀动用十分关键。考虑储层渗透率、围压和蒸汽相变等条件的相互耦合影响,建立了预测水平井注汽流动的综合数学模型。与现场测井数据进行对比分析,验证了模型的准确度。模拟结果表明,单一变量条件下,水平井跟部注汽压力越大,注汽井内质量流量和蒸汽干度下降越快,当注汽压力由11 MPa降为8.5 MPa时,配汽距离增加1倍;在水平井相同位置处,跟部注汽干度越高,注汽井内质量流量越大,且蒸汽压力下降越快,注汽干度提高1倍时,压降也几乎增加1倍;跟部注汽流量越大,蒸汽压力下降越快,注汽流量提高1.75倍时压降提高了5.3倍,但管内蒸汽干度下降趋缓;储层渗透率越高,注汽井内的蒸汽干度下降越快。该模型可以为现场注汽提供理论支撑,有效提高配汽效果达到增产降耗。     

高盐高硬稠油污水淡化工艺方案优选

针对高盐高硬稠油污水回用需求,结合注汽锅炉用水标准,比选出蒸馏法作为污水脱盐首选方案。根据同一水性和产水规模,分别采用机械压缩、热力压缩、多效蒸发等蒸馏工艺进行脱盐装置设计,从装置规模、公用需求、产品能耗等方面进行对比,并从投资和运行成本角度进行综合评价。结果表明,在蒸汽昂贵,电价便宜地区,采用机械压缩占绝对优势;废蒸汽场合采用多效蒸发较为经济;廉价高压蒸汽场合,宜采用热力压缩。     

CO_2辅助蒸汽驱驱油效率实验研究

稠油开发是世界性的大难题。在中国能源紧缺的今天,稠油资源无疑是中国不可忽视的能源之一。传统的稠油开采方法采用的是单一注蒸汽的热力开采方式,但单一的注蒸汽会带来很多的问题,如汽窜、产量递减过快等问题。随着稠油开采技术的进步,发现在蒸汽中加入CO_2会改善注汽效果。本文进行了CO_2辅助蒸汽驱驱油进行了室内研究,通过改变CO_2与蒸汽的注入比、注入段塞的大小、注入速度来确定最优的注入参数。     

萨中油田聚驱后蒸汽吞吐工艺技术研究

大庆油田萨中开发区主力油层聚驱后,油层含水高,剩余油分布零散,但丰度仍然很高,开采难度大。为探索聚驱后进一步提高采收率的新途径,应用蒸汽吞吐可以改善原油流动性能、提高驱油效率的技术特性,着重进行了聚驱后油井蒸汽吞吐技术的矿场试验,并以北一区断东中块萨中开发区北部的北1-4-P37井进行现场应用与分析,探索出合理的注气参数、注入方式,掌握吞吐后油井的动态变化规律,为进一步取得聚驱后蒸汽吞吐后开采效果提供依据。