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。     

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%。     

三维实验模拟垂直井和水平井降压开采水合物

为了研究降压法在不同井网布置条件下开采天然气水合物的机理,在水合物三维实验模拟平台中进行了垂直井和水平井降压开采实验,获得了两种布井方式的产气、产水、温度变化和三维温度空间分布情况。研究表明,在该实验条件下,利用水平井开采水合物的平均产气速率是垂直井的1.48倍,但水平井开采的产水量较大,垂直井开采的产水量则很小。三维温度分布图表明,开采过程中全釜的温度同步下降,水合物在反应釜内均匀分解,反应釜四周的温度比反应釜中心温度高,热量从边界向釜中心传递。     

An Investigation of WAG Process Using Horizontal Wells

In this study, a comprehensive laboratory investigation was conducted for the recovery of heavy oil from a three-dimensional (3-D) physical model, packed with 18°API gravity crude oil, brine and crushed limestone. A total of 15 experiments were conducted using the 3-D physical model with 30 cm × 30 cm × 6 cm dimensions. Basically, water-alternating gas (WAG) process was used for recovering heavy oil. Three groups of well configurations were mainly used: (i) vertical injection and vertical production wells, (ii) vertical injection and horizontal production wells, and (iii) horizontal injection and horizontal production wells. Base experiments were run with water only and carbondioxide alone and optimum rates for WAG process were determined. In CO₂ injection experiments, vertical injection and horizontal production well configuration supplied a higher recovery (15.06% OOIP) than that of the others. Horizontal injection and horizontal production well configuration gave poor recovery with the same gas rate, while vertical injection and vertical production was better off with a lower gas rate. The volumetric ratio of the water and CO₂ slugs (WAG ratio) was varied 1:3 to 1:10 in order to determine optimum conditions. For water alternating gas injection case at a WAG ratio 1:7, vertical injection and vertical production well configuration gave the highest recovery (21.04% OOIP). Waterflooding reached the best recovery (37.20% OOIP) in vertical injection and vertical production well configuration. Oil production from WAG injection is higher than that obtained from the injection of continuous CO₂ or waterflooding alone.     

天然气水合物开发的水平井控水控砂完井研究进展

2020年第二次南海水合物试采证明水平井是实现产业化的重要途径,计划在2030年南海天然气水合物商业开发中补齐粤港澳大湾区天然气供给的短板。但我国海洋水合物甜点多赋存在高含水、边底水丰富的非成岩泥质粉砂储层,水平井开发过程中储层水（排液）易携泥砂（出砂）脊进突入井筒导致产量降低,水平井控水控砂完井是产业化的瓶颈问题之一。针对第二次水平井开发水合物出现的新问题,分析了海洋天然气水合物储层开发过程中的水平井非均衡排液出砂情况,总结了国内外水平井控水控砂实验、模拟和现场的进展,提出了水平井开采水合物控水控砂的难点及我国面临的挑战。分析结果表明,天然气水合物储层开发的水平井控水控砂与常规油气开发存在共性问题,也有其自身分解特点及其赋存的非成岩储层有关的特性问题。针对我国海域天然气水合物储层间各向异性明显、潜在的“四气合采”和“碳封存”,对水合物水平井控水控砂抽取和注入提出了具体的研究思路及建议,以期推动海洋天然气水合物产业化开发进程。     

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。     

扶余油田蒸汽驱技术应用与评价

扶余油田扶北地区油品性质属于弱稠油,长期采用注水开发方式,效果差,资源没有得到充分动用。2007年,用热采方式成功动用探40区块的稠油资源,从第一阶段的蒸汽吞吐看,热采投产井的日产油量是常规投产井的2～3倍,效果较好。经过2～3个吞吐周期后,进入到蒸汽驱阶段试验,前期应用数值模拟技术,确定符合油藏特点的汽驱参数和注入方式:注汽压力8～11MPa,原则上注汽压力要求小于油层破裂压力;注汽速度50t/d;井底注汽干度大于40%;油藏压力1～3MPa。试验效果认识到,好的储层物性、合理的注汽参数、高的采注比和不发生汽窜,是取得蒸汽驱开发效果的关键因素。建议选择储层条件好,特别是油层的物性参数要好的区块,进一步扩大蒸汽驱试验范围,为扶余油田大规模蒸汽驱开发提供技术储备。并且,要具备完善的试验监测和评价手段。     

Immiscible CO2 Flooding through Horizontal Wells

Abstract

The CO₂ immiscible process is a potentially viable method of enhanced oil recovery (EOR) for heavy oil reservoirs. In an immiscible CO₂ process, part of the injected CO₂ is absorbed into the reservoir fluids and part forms a free-gas phase in the reservoir. Three groups of well configurations were mainly used: (1) vertical injection and vertical production wells, (2) vertical injection and horizontal production wells, and (3) horizontal injection and horizontal production wells. In immiscible CO₂ injection, highest recovery was obtained by vertical injection-horizontal production (VI-HP), followed by vertical injection-vertical production (VI-VP), and the least by horizontal injection-horizontal production (HI-HP). In VI-HP well configuration, the best recovery was obtained as 15.1% OOIP. In continuous CO₂ injection experiments, oil recovery for the VI-HP well configuration was higher than that of the other well configurations. The lowest ultimate recovery was obtained from HI-HP well configuration. The distance between the horizontal injector and horizontal producer was another important factor for the displacement of oil. In all runs, CO₂ breakthrough occurred very early, showing the dominance of viscous forces and relatively small effect of mass transfer between CO₂ and oil. The total oil recovery varied considerably because of the differences in injection rates and because of the unstable displacement. As a whole, oil recovery increased with an increase in the injection rate of CO₂. The cumulative gas-oil ratio (GOR) appeared to be sensitive to the gas injection rate for all well configurations. An increase in oil recovery with injection rate during initial stages of the runs was affected by the cumulative GOR.     

海上多元热流体热采工艺应用方法研究与实践

热力采油是稠油开发中最主要的开采方式,中国海上稠油储量大,稠油油田的合理高效开发,对海上油田的增产稳产具有重要意义。受海上特殊的自然环境、空间等条件限制,直到2008年,我国才在渤海湾南堡油区完成了海上第一口热采井的先导性试验项目,填补了国内海上稠油热采领域的空白,为多元热流体热采技术的发展和现场应用积累了经验。从多元热流体吞吐热采机理、多元热流体设备改造及作业流程设计、制氮设备在多元热流体吞吐热采中的应用、注入热流体管线的设计和预制、热采井口及井筒结构设计、多元热流体吞吐注采方案、多元热流体吞吐热采施工程序、多元热流体吞吐热采经济评价等方面,介绍了我国第一口海上多元热流体吞吐作业的工艺设计方法和实施方案。实施海上多元热流体吞吐热采工艺,对改善海上稠油开发效果、促进海上稠油高效开发具有指导作用。     

海洋天然气水合物开发产能及出砂研究

海洋天然气水合物多分布在深水非成岩储层,其开采过程中易出现泥砂运移（出砂）的情况且难以避免,然而出砂条件下的水合物产能估算偏差较大。本文通过室内海洋水合物降压开采出砂实验数据和海洋水合物试采公开资料,首次推导了出砂条件下现场尺度海洋水合物储层产能情况：在相当于1 200 m水深覆压、30.5 m厚的水合物细砂储层和7寸垂直井不防砂的情况下,得到最大产气速率4.63 ~ 14.1 m³/s,折合40.01×10⁴ ~ 121.84×10⁴ m³/d,综合出砂率0.16% ~ 10.74%;泥质储层在不防砂垂直井和水平井单个半径12 mm射孔下,其最大产气速率达到79.95×10⁴ m³/d和170 m³/d,但其综合出砂率是灾难性的。由于时空限制,产气速率、综合产能和出砂率还有很大提升空间,在平衡综合出砂率（控砂精度）和产气效率（产能）的情况下,有望达到产业化规模。本研究为合理估算出砂条件下的海洋天然气水合物产能提供支撑。     

电阻率测试技术在注水井中的应用

电阻率测试技术是一种地球物理探测方法。在石油天然气勘探中,用于解决油气藏边界探测、井周围油气藏探测、剩余油分布探测等问题。在采油工程中,该项技术用于解决水力压裂裂缝几何参数探测、酸化压裂裂缝几何参数探测、注水推进方向和波及范围探测、注水井调剖堵水效果探测等问题。对于注水井来说,了解和掌握注入水的运动方向和推进速度、注水前缘位置,了解和掌握不同油层或同一油层的不同部位的水淹特征,是合理部署注采井网、研究剩余油的分布规律、挖掘剩余油、提高最终采收率、提高注水开发水平的基本要求。因而,应用地球物理新方法和新技术,探测注水驱油前缘分布参数,意义重大。     

二次充填补砂技术在稠油热采井的应用

王庄油田坨82断块稠油热采井采用两步法防砂工艺,并实施区块蒸汽吞吐开发。注蒸汽过程中,高温、高压、高速的注入流体破坏了充填防砂形成的人工挡砂屏障,导致了筛套环空和近井地带严重亏空;油井投产后,地层砂及充填砂在产出液的携带下,经射孔炮眼高速喷出,刺破防砂筛管进入中心管及井筒,导致卡泵;同时,粒径较大的砂粒沉降至井底,掩埋地层,导致供液不足。在该断块40余口稠油热采井实施二次填补砂技术,注汽后将筛套环空和生产层段用充填砂充满填补,重新建立人工井壁,使流体通过径向渗流进入防砂中心管;而地层砂在经过充填砂形成的人工井壁时被阻挡下来,形成远离井筒的自然充填挡砂屏障。其中10口井的应用结果表明：补砂后,平均防砂有效期由146.9d提高到448.1d,平均日产油由2.28t/d提高至10.2t/d.     

Formation enhancement of methane hydrate for natural gas transport and storage

Methane hydrate is considered an excellent way of transporting and storing natural gas in large quantities. However, when methane hydrate is formed artificially, water/gas ratio is relatively low due to a slow reaction rate between water and methane gas. The major objective of this study is to investigate the mechanics of methane hydrate formation and to explore possible means for rapid production of hydrates and increasing its water/gas ratio. It is found that methane hydrate could be formed rapidly during pressurization if the subcooling is maintained at 8 K or above. In addition, water injection appears to be more effective in hydrate formation compared to gas injection or using a magnetic stirrer. It also gives higher water/gas ratios of 3–4 times for the methane hydrate through a nozzle at the same level of subcooling temperature, when compared to gas injection cases.     

水平气井靶点高差对排液的影响

随着川西低渗透致密气藏不断加大水平井开发力度,水平井气井逐渐增多,水平井井筒积液成为气藏水平井开发普遍存在的难题.如果井筒内产生积液,井底回压增大,井口压力下降,产量递减较快,气井携液能力减弱,将导致井筒附近储层的含水饱和度升高,气相渗透率下降,气井难以开采,甚至最终水淹停产.应用水平井筒内流体由分层流向非分层流转变判别式,对影响水平段井筒携液的因素进行分析表明:水平段井筒倾角越大、积液高度越高,水平井筒中气液两相流型更易从层流转向非层流,水平段中的液体也就更易被气流带出.虽然井筒倾角对气体临界流速的影响较小,但井筒倾角越大,井筒内A靶点附近的积液高度越高,液体就更易被气流携带出水平段.通过实例分析也证明,水平井A、B靶点高差对气井排液有影响,B靶点比A靶点越高,越有利于井底积液从水平段排出.     

塔河油田缝洞型油藏深井注气提高采收率配套工艺

塔河油田储层深(5500~7000m)、地层压力高(50~60MPa)、非均质性强、流体性质差异大;溶洞是最主要的储集空间,裂缝主要起连通通道作用,缝洞单元是基本开发单元。储集体类型复杂,导致剩余油分布认识不清,主要依靠弹性和水驱开发,采收率较低。对于单井缝洞单元而言,目前采取的主要手段是注水替油,前期取得良好效果。但随着注水替油轮次的增加,部分井组注采比逐步上升,替油效果逐渐变差,失效井数增加,导致大量剩余油无法采出。特别是钻遇缝洞储集体边部或相对低位置的油井,其剩余油主要分布在缝洞体的高部位,注水替油效果不明显。考虑到气体注入地层后,在重力作用下向高部位上升,会形成"气顶",排驱原油下移,可有效启动单纯注水无法驱动的"阁楼油"。所以,油田开发后期,采取注气提高采收率技术。在实施注气提高采收率过程中,完善了深井注气的配套工艺,形成了注气-采油一体化井口、注气-掺稀生产一体化管柱、掺稀气举阀、高压气密性封隔器、气水混注工艺设计方法、腐蚀结垢处理方法等一系列配套工艺。2013年1~8月,塔河油田累计实施注气69井次,累计产油5.49×104t。     

精细油藏描述技术在水平井轨迹设计中的应用

大庆油田萨中开发区自从2002年起进行水平井开发技术研究,经过几年的探索,形成了较为完善的挖潜厚油层顶部剩余油的水平井水驱挖潜技术。研究过程中,精细油藏描述技术在调整对象的确定、储层内部结构认识、水平井空间轨迹设计等方面发挥了重要作用,且该技术亦逐步得到完善。水平井的开发效果,取决于前期精细油藏描述的准备工作。如果在一定的油层条件下,选井过程中有较高的前期地质研究基础,对油藏认识比较清楚,构造、储层、流体特征刻画细致,并能够建立精细地质模型,则水平井就能得到较好的开发效果。大庆油田主力油层聚驱后设计的第一口水平井位于剩余油滞留区内,该井完钻井深1620m,完钻水平段长度563m,油层钻遇率达到67.1%。在深入研究剩余油分布状况、优化轨迹设计基础上,进行调整挖潜,该井初期投产日产液为134t/d,日产油为12.9t/d,含水为90.4%,含水较同类型直井低7个百分点以上,产能是直井的2倍以上,获得一定的开采效果。     

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。     

氮气泡沫改善蒸汽吞吐开发效果数值模拟技术研究

单家寺稠油油藏已进入高轮次、高含水、高采出程度开发后期,开发中的矛盾日益突出,蒸汽吞吐效果越来越差,水淹程度日益加剧,单2块和单10块大部分油井的综合含水达到90％以上.结合油藏实际,选取该区块单6-16-10井,利用油藏数值模拟技术,建立三维地质模型;在历史拟合的基础上,对氮气泡沫改善蒸汽吞吐开发效果进行了油藏适应性研究;并在此基础上,优化氮气泡沫在蒸汽吞吐过程中的注入时机、注入方式和注入参数,同时进行生产指标预测.研究结果表明,氮气泡沫在转注初期,以段塞式注入效果较好,最佳注入参数为:泡沫剂质量浓度为0.6％(质量分数),氮气总量为90000m3(标准)左右.自2006年来,该技术在胜利油田应用273井次,平均周期措施增油842t,油汽比提高0.3以上.本研究对氮气泡沫+蒸汽吞吐技术的推广应用具有理论和实践价值.     

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。     

Predicting the fracture initiation pressure for perforated water injection wells in fossil energy development

Water injection is widely performed to enhance oil recovery in fossil energy development. The fracture initiation pressure (FIP) is a key parameter for designing the reasonable injection pressure for micro-fracturing water injection (MFWI). In this work, a modified method was presented to accurately predict the FIP, in which the thermal effect and plugging effect were considered; moreover, the stress around perforations was analyzed. To validate our method, the field tests, including a step rate test (SRT) and a well test, were conducted to obtain the actual FIP for perforated water injection wells, and then the FIP calculated by our method was compared with a low relative error of about 1.7%. Results show that (i) a greater temperature difference between the injected water and the formation forms a greater thermal stress around perforations, resulting in a greater change in the FIP; (ii) a larger skin factor causes a greater pressure drop for the injected water flowing through a plugged area, resulting in a stronger effective stress reduction around perforations and further producing a larger FIP. Therefore, our present work illustrates a better understanding of the stress distribution around a perforated wellbore, and paves a path for a more accurate prediction of the FIP in perforated water injection wells.