蒸汽辅助重力泄油技术在超稠油开发中的应用_张方礼

收稿日期:2007-01-20;改回日期:2007-02-02 作者简介:张方礼(1961-),男,教授级高级工程师,1983年毕业于大庆石油学院油藏工程专业,现任中油辽河油田公司副总地质师兼勘探开发研究院院长、《特种油气藏》主编。

文章编号:1006-6535(2007)02-0070-03蒸汽辅助重力泄油技术在超稠油开发中的应用张方礼,张丽萍,鲍君刚,张　晖(中油辽河油田公司,辽宁　盘锦　124010)摘要:对国外超稠油开发方式进行调研,利用数值模拟技术对辽河油区超稠油油藏进行了蒸汽辅助重力泄油(SAGD )开发可行性及油藏工程研究,确定了在杜84块馆陶组开展4个井组的直井与水平井组合SAGD 试验。

通过2a 的现场应用,馆陶油层SAGD 试验获得成功,目前处在蒸汽腔扩展阶段,井组日产油较蒸汽吞吐阶段上升了72t ,预测SAGD 开发可提高采收率27%。

SAGD 技术已成为超稠油油藏蒸汽吞吐后期的重要开发方式,可为类似油藏的开发提供依据。

关键词:蒸汽辅助重力泄油;超稠油;蒸汽吞吐;蒸汽腔;数值模拟;采收率;辽河油区中图分类号:TE345 文献标识码:A前　言目前,国外重油开采在现场试验成功并得到工业化应用的技术主要是蒸汽辅助重力泄油技术(SAGD ),其理论首先是由R .M .Butler 博士[1,2]于1978年提出的、最初是基于注水采盐的原理,将这一原理应用于注蒸汽热采过程就产生了重力泄油的概念。

蒸汽辅助重力泄油必须通过注汽井和采油井来实现(注汽井位于采油井的上部)。

对于在地层原始条件下无流动能力的高粘度原油,首先要实现注采井之间的热连通(油层温度达到原油可流动温度),该阶段为油层预热阶段。

形成热连通后,由注汽井连续不断地向油层注入高干度蒸汽,使其在地层中形成蒸汽腔,通过蒸汽腔向上及侧面移动,与油层中的原油发生热交换,加热的原油和蒸汽冷凝水依靠重力作用泄流至下部的生产井中产出。

加拿大不同类型的重油油田已开展了10多个SAGD 试验区,并建成了7个商业化开采油田,SAGD 开采方式最终采收率超过50%,最高可达70%以上。

为了探索辽河油区超稠油油藏蒸汽吞吐后的转换方式,1997年杜84块兴隆台油层兴VI 组开展了双水平井蒸汽辅助重力泄油试验,由于受工艺设备等方面的限制,该试验于1998年底停止。

随着SAGD 工艺技术的不断成熟以及配套设备的完善,结合大量的室内物理模拟实验以及数值模拟研究,2005年首次在馆陶组油层开展了直井与水平井SAGD 先导试验,获得成功,为超稠油油藏蒸汽吞吐后期转换开发方式、实现产量接替提供了依据。

1　试验区概况曙一区杜84块馆陶组油藏埋深530～640m 。

整体构造形态为向南东倾没的单斜构造,地层倾角为2～3°。

SAGD 先导试验区位于杜84块西北部,含油面积为0.15km 2,石油地质储量为249×104t 。

该区油层为湿型沉积扇沉积体系,储层岩性主要为中粗砂岩和不等粒砂岩,其次为砾岩、砾状砂岩和细砂岩等[3]。

馆陶油层粒度中值平均为0.42mm 。

平均单层解释厚度为107m ,油层有效厚度为60～90m ,为巨厚块状油藏。

平均孔隙度为36.3%,平均渗透率为5.54μm 2。

20℃地面原油密度平均为1.001g /cm 3,50℃地面脱气原油粘度为231910mPa ·s ,胶质和沥青质含量为52.9%。

馆陶油藏是一个被水包围的边顶底水油藏,试验区内无底水,单井有效厚度在88～94m 之间,平均为91.7m 。

原始地层温度为28～32℃,原始油层压力为6.0～6.5MPa 。

截至目前,试验区有9口注汽井,4口水平井和4口直井采油。

日注汽量为1255t /d ,日产液为1013t /d ,日产油为2489t /d ,含水率为75.4%。

SAGD 阶段累计注汽45.11×104t ,累计产油9.16×第14卷第2期2007年4月 特种油气藏Special Oil and Gas Reservoirs Vol .14No .2Apr .2007104t,累计产水29.92×104t,累计油汽比为0.20,累计采注比为0.87,采出程度为3.7%。

2　超稠油蒸汽吞吐生产存在的问题超稠油油品性质决定了超稠油的生产特点,主要表现在:蒸汽吞吐周期生产时间短,周期产油量低,油汽比低,蒸汽吞吐生产阶段周期产量变化呈不对称“抛物线”型。

由于油品性质的不同,周期产油量高峰出现的时间也不同:原油粘度低,周期产油量、油汽比的高峰期为3～5周期;原油粘度高,周期产油量、油汽比的高峰期为4～6周期。

超稠油蒸汽吞吐生产中存在的主要问题有以下5方面:(1)油井进入高周期吞吐生产后,产量递减快,周期产量低,油汽比低,单位操作成本高[4]。

(2)蒸汽吞吐阶段平面动用半径有限[5],井间剩余油饱和度依然较高,井底附近含油饱和度为35%左右,井间剩余油饱和度为50%～65%。

(3)由于生产周期短,注汽频繁,油井井下技术状况变差,套管损坏严重,油井间歇吞吐生产造成开井率低[6]。

据统计,发生套管变形和损坏的井占投产井数的37%。

(4)蒸汽吞吐生产稳产时间短,产量递减快,稳产时间只有2a,年综合递减率平均为20%左右。

(5)数值模拟研究表明,馆陶油层蒸汽吞吐阶段采收率低,预测采收率为29%[7]。

3　蒸汽辅助重力泄油试验方案设计要点蒸汽辅助重力泄油试验方案设计要点如下:(1)井组4个。

(2)井距:直井与水平井的侧向水平距离为30～40m,直井射孔底界距水平井段的垂直距离为3～7m。

(3)水平段长度为368～418m。

(4)水平段垂深为648.0～661.3m。

(5)转SAGD时机:直井平均吞吐7.6个周期,水平井平均吞吐2个周期,直井与水平井之间已形成热连通,地层压力降至3～4MPa。

(6)蒸汽干度:井口大于97%,井底大于80%。

(7)注汽压力为4～6MPa。

(8)注汽速度:单直井为120～200t/d。

(9)产出液温度为115～140℃。

(10)生产井排液速度为注汽速度的0.8～1.0倍。

4　SAGD现场试验及效果评价4.1　实施情况根据生产特征及监测资料分析,试验区经历了3个开发阶段:第1阶段为注采井间温度、压力连通阶段,第2阶段为弥补地下亏空和蒸汽驱阶段,第3阶段为蒸汽腔形成及向上扩展阶段。

2005年2月24日～2005年5月中旬为热连通阶段。

水平生产井井底压力较低,只有1.0MPa;注汽井井底压力相对较高,为4～5MPa;注采井间温度为100℃左右。

该阶段以蒸汽吞吐生产为主,生产特征表现为产液量下降、含水及动液面下降、水平井井底温度下降。

2005年5月下旬～2006年3月初为弥补地下亏空和蒸汽驱阶段。

蒸汽吞吐造成单井平均地下亏空0.95×104m3,注入的蒸汽及冷凝水用于弥补地下亏空,水平井产油主要以蒸汽驱方式为主,生产特征表现为产液量、动液面、水平段温度及压力稳定。

2006年3月至今为蒸汽腔形成及向上扩展阶段。

馆平11、馆平12两个井组形成了蒸汽腔,由蒸汽驱替为主开发逐渐转向重力泄油为主开发。

生产井井底压力回升至3.0MPa,注汽井的井底压力为3.5～4.0MPa。

该阶段生产特征表现为产液量、产油量明显提高,相对稳定,含水率下降较为突出,由80%左右下降到70%左右,与蒸汽驱明显不同。

4.2　效果评价4.2.1　油井产量明显提高转入SAGD初期,注入蒸汽用于祢补地下亏空,连续注汽0.5a后,注采井间的压力趋于平衡,基本稳定在3.5MPa,生产井日产液量由140t/d上升为300～400t/d,日产油量由30t/d上升为70t/ d左右(图1)。

4.2.2　蒸汽腔向上扩展阶段油井含水率稳定转入SAGD初期,油井含水率较高,达到了95%以上。

当蒸汽腔开始形成还不发育时,以蒸汽驱替为主,含水率逐渐上升至80%左右。

随着蒸汽腔的不断扩大,逐渐转为以重力泄油为主,蒸汽驱替作用逐渐减弱,含水逐渐下降,并趋于稳定,随着蒸汽腔的向上扩展,含水率将进一步下降并稳定在65%～70%。

71第2期 张方礼等:蒸汽辅助重力泄油技术在超稠油开发中的应用图1　馆平12井SAGD阶段产量变化曲线4.2.3　SAGD开发初期蒸汽腔以单井点形式存在数值模拟跟踪表明,垂直水平井段方向蒸汽腔发育较好,而沿水平段方向,蒸汽腔只是在注汽井与水平段最近处形成,形成多个独立的蒸汽腔,相互之间没有连通。

目前,馆平12井发育4个蒸汽腔,位于水平井中段的3个蒸汽腔的上部出现逐渐联通的趋势;馆平11井主要发育3个蒸汽腔,3个腔相距较远,短期内很难连通。

根据数值模拟研究并结合动态资料可知,蒸汽腔数量的多少决定产量的高低。

初步计算馆陶油层每个蒸汽腔日产油量30t左右。

馆平12井目前日产油为128t/d,馆平11井日产油为84.5t/d。

4.2.4　试验方案达到设计要求目前,馆平11、馆平12井单井日产液水平达到300t以上,日产油为70～100t左右,含水率稳定在65%～70%,井底压力上升至3.0MPa,温度上升至180～220℃,采注比达到1.0,各项生产指标均达到方案设计要求。

从泄油状况看,馆平11井有3个泄油点,馆平12井有4个泄油点,且均进入稳定泄油阶段,随着蒸汽腔的扩展和泄油通道的扩大,各项指标会继续朝着更好的方向发展。

4.2.5　最终采收率得到有效提高物理模拟SAGD阶段采收率接近60%,最终采收率达到75%以上;数值模拟研究表明,馆陶油层蒸汽吞吐后转SAGD阶段采出程度为36.1%,最终采收率为56.1%;馆观4井取心资料证实,SAGD开发蒸汽驱扫带内驱油效率达到83%[8],计算最终采收率可达58%。

5　结　论(1)直井与水平井组合SAGD开发方式符合油藏实际,可以利用多井点注汽抑制蒸汽腔的单点突破。

(2)SAGD试验初步获得成功,井组产量递减得到遏制,试验区日产油由转SAGD前的176t/d 上升到目前的290t/d,产量呈现逐渐上升趋势。

(3)多种方式预测馆陶油层蒸汽吞吐后转SAGD开发采收率可以达到55%以上。

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Key words:data quality;seis mic data;large scale processing;signal-to-noise ratio;Liaohe west tidal zoneMemory technique for large scale seismic data processing systemZHANG Guo-jun,FU Zheng-xiu,SUN Kai,WANG Yan-hua,ZHENG Li-he(Lia ohe Oilfield Co mpany,PetroChina,Panj in,Liaoning124010,China)A bstract:As the popularization of prestack migration processing technique,large scale PC group has replaced traditional parallel cluster and become a high performance computer system for seismic data processing.In accordance with the I/O bottleneck problem in PC group stor-age,conventional storage technique used in recent years has been studied.Shared document s ystem SAN,high-speed disc array and stripe document s ystem have been used in new PC groups of seis mic data processing s ystem in Liaohe oilfield,thus solved the I/O bottleneck prob-lem and provided good computing environment for application of prestack processing technique.Key words:seismic data processing;PC group;I/O;SAN;equilibriu m load;storage techniqueC haracteristics of Cretaceous volcanics in the western depression of Liaohe fault depressio nSONG Bai-rong,BIAN Shao-zhi,WANG Ren-hou,WANG Yan-fang(Lia ohe Oilfield Co mpany,PetroChina,Panj in,Liaoning124010,China)A bstract:This paper studies Cretaceous volcanics distribution,rock types,tectonic settin g and reservoir characteristics in the western de-pression of Liaohe fault depression through statistics of compound logging data,core observation,thin section identification,cathodelu mi-nescence,scanning electron microscope,X-ray diffraction analysis,image analysis,rock chemical anal y s is,isotope age testing,and in-clusions temperature testing.The study s hows that Cretaceous volcanics mainly consist of mediu m acidic volcanic lava and volcanoclastic rocks,with locally developed basic lava;med ium acidic volcanics mainly consists of calc-alkalic series,was formed in compressive oro-genic environment,and has good reservoir property,while Cretaceous bas is lava mainly consists of alkalic series,was formed in rift environ-ment,and has poor reservoir property.Understanding of volcanic rock characteristics is of guiding importance to the exploration and develop-ment in this area.Key words:volcanic rock characteristics;reservoir space;Cretaceous;reservoir;Liaohe fault depressionNew recognition of geo logic age of the middle section of the buried hill in the westerndepression of Liaohe fault depression and its geologic im plicationWANG Ren-hou,WEI Xi,SHI Dun-jiu,CUI Xiang-dong,SONG Bai-rong(Lia ohe Oilfield Co mpany,PetroChina,Panj in,Liaoning124010,China)A bstract:This study uses multi-type micropaleontology,petrostratigraphy,isotope stratigraphy and geophysical logging data to re-recog-nize the geologic age on the top of the buried hill in the study area to be mid-late Cambrian to early Ordovician,while Mesoprotozoic and Neoprotozoic only locally appear in the top of the buried hill.This has changed the traditional understanding in the past30years that the buried hill in this area totally belonged to Mes oprotozoic and Neoprotozoic,and has provided valuable proof for re-establishing stratigraphic sequence,understanding inner buried hill structure,reservoir distribution and lithofacies palaeogeograph y.Key words:palaeontologic foss il association;geologic age;Paleozoic-Mesoprotozoic and Neoprotozoic;buried hill;the middle section of the western depression;Liaohe fault depressionApplicatio n of SAGD in ultra heavy oil developmentZHANG Fang-li,ZH ANG Li-pin g,BAO Jun-gang,ZHANG Hui(Lia ohe Oilfield Co mpany,PetroChina,Panj in,Liaoning124010,China)A bstract:SAGD feasibility and reservoir engineering have been studied through investigation of ultra heavy oil development in foreign coun-tries as well as nu merical simulation for ultra heavy oil reservoirs in Liaohe oil province.It had been determined to cond uct SAGD test in4 well groups involvin g vertical and horizontal wells in Guantao formation of Block Du84.After two years of field application,the SAGD test in Guantao reservoir is s uccessful.The steam chamber is expanding at present,and daily oil production of the well groups has increased72t than that in cyclic steam stimulation stage.It is predicted that SAGD can improve the recovery factor b y27%.SAGD technology is an effec-tive way of converting development scheme of ultra heavy oil reservoir and realizing production substitution in the late stage of cyclic steamstimulation.Key words:SAGD;ultra heavy oil;cyclic steam stimulation;steam chamber;numerical simulation;recovery factor;Liaohe oil provinceStudy on botto m/edge water control in heavy oil reservoirs of Liaohe oil provinceZH ANG Ji-chang,ZHANG Ying,JIANG You-wei,WANG Zhong-yuan,LI Pei-wu(Lia ohe Oilfield Co mpany,PetroChina,Panj in,Liaoning124010,China)A bstract:Heavy oil reservoirs with bottom/ed ge water in Liaohe oil province have a large amount of reserves and distribute widely.This pa-per studies water in vasion rule in heavy oil reservoirs with bottom/ed ge water and summarizes bottom/ed ge water control technology for vari-ous reservoirs.During develop ment process,the energy of bottom/edge water has been utilized,water breakthrough time has been post-poned,and good develop ment resp onse is achieved.Key words:heavy oil reservoir;bottom/edge water invasion;perforation;infill adjustment;side tracking;water plugging;Liaohe oil provinceStudy and application of shallow gas potential tappingMIN Zhong-shun,PAN Hong-hao,MA Quan-hua,ZHAO Ai-ting,ZUO Yue(Lia ohe Oilfield Co mpany,PetroChina,Panj in,Liaoning124010,China)A bstract:Taking Hon gxing area as an example,this paper analyzes the geological conditions of forming shallow gas reservoirs,and the re-sult shows that Liaohe Basin had the favourable conditions of forming shallow gas.Gas layers can be identified accurately b y using shallow gas identification standard and recognition chart.48new gas wells have been discovered by using shallow gas potential tapping technology, with cumulative increased gas volume of4.0×108m3,showing good exploration and develop ment result.Mean while,man y valuable explo-ration targets have been discovered,which will contribute to gas production capacity construction in Liaohe oil province.This stud y has de-veloped a set of techniques for progressive exploration of shallow gas.Key words:shallow gas;reservoir forming condition;neutron-gamma logging;neutron lifetime log;pulse neutron log;potential tapping; Hongxing areaCalculate technical recovera ble reserves of ultra heavy oil reservoirs in cyclic steamstimulation stage by using viscosity-temperature modelYU Jun,ZHENG Hong-ying,HUANG Xian g-guang,CHEN Shu-feng,WANG Fei-yu(Lia ohe Oilfield Co mpany,PetroChina,Panj in,Liaoning124010,China)A bstract:A viscosity-temperature model of cumulative steam injection rate and cumulative oil production has been establis hed for cyclic steam stimulation stage accordin g to the standard viscosity-temperature curve of American Material Experiment Society.The technical re-coverable reserve of developed ultra heavy oil reservoir is obtained by using iterative method and mathematical model.This model provides theoretical basis for rational development of similar reservoirs and improved the calculation method of technical recoverable reserves of heavy oil reservoirs in Liaohe oil province.Key words:viscosity-temperature model;ultra heavy oil reservoir;cyclic steam stimulation;technical recoverable reserve;Block Du84; Block Wa59Comprehensive assessment of block grade of undeveloped reserves in Liaohe oil provinceJIANG Guang-yi,ZENG Xian-hong,TANG Zhi,DONG Liang,LU Hai-bin(Lia ohe Oilfield Co mpany,PetroChina,Panj in,Liaoning124010,China)A bstract:Undeveloped reserves in Liaohe oil province are characterized by scattering,low abundance,low oil saturation,poor petrophysical property,deeply buried and low productivity,and both static and dynamic data are incomplete.This paper uses comprehensive assess ment method of block grade to determine the appraisal factors,and uses comparison method to determine the weight of each factor,and finall y de-termine the grade and order of undeveloped reserves.Blocks with higher grade are selected as next develop ment blocks,thus guiding effec-tive and ordered development of undeveloped reserves in Liaohe oil province.Key words:undeveloped reserves;comprehensive assessment method of block grade;appraisal factor;weight value;Liaohe oil provinceFine reservoir description study on low permeability reservoirs in Dujiatai of HuanbeiYAO Wei-ying(Lia ohe Oilfield Co mpany,PetroChina,Panj in,Liaoning124010,China)。