Oxidization characteristics and thermal miscible flooding of high pressure air injection in light oil reservoirs

Physical modeling,numerical simulation and field case analysis were carried out to find out the subsurface thermal oxidation state,thermal oxidation front characteristics and production dynamic characteristics of high pressure air injection thermal oxidation miscible flooding technology.The lighter the composition and the lower the viscosity of the crude oil,the lower the fuel consumption and the combustion temperature are.The thermal oxidation front of light oil and volatile oil can advance stably,and a medium-temperature thermal oxidation stable displacement state can be formed in the light oil reservoir under high pressure conditions.With strong thermal gasification and distillation,light oil and volatile oil are likely to form a single phase zone of gasification and distillation with thermal flue gas at the high-temperature and high-pressure heat front,finally,an air-injection thermal miscible front.In light oil reservoirs,the development process of high-pressure air-injection thermal miscible flooding can be divided into three stages:boosting pressure stage,low gas-oil ratio and high-efficiency stable production stage and high gas-oil ratio production stage.Approximately 70%of crude oil is produced during the boosting pressure stage and low gas-oil ratio high-efficiency and stable production stage.

油田开发提高采收率新方法研究进展与展望

总结近年来油田开发基础研究手段方法方面的进展,以及老油田和陆相页岩油开发提高采收率新方法的研究和试验进展,分析各类方法存在的问题、提出下一步研究方向与建议。阐述了原位获取地下岩石/流体样品与无损检测分析等基础研究手段的进展,综述了“纳米水”驱等改善水驱,低浓度中相微乳液驱等化学驱,微纳米气泡驱等气驱,注空气热辅助混相驱等热采,以及密切割均匀压裂/无水压裂等常规油和页岩油提高采收率新方法的驱油机理、技术路线、关键技术研究与矿场试验进展。油田开发提高采收率新方法研究已取得了显著的进展,有些已在矿场试验中取得了良好的初步效果,但仍然面临机理研究欠深入、方法和配套工艺待完善、产业链不完整等问题,建议持续加强基础研究、加大现场试验规模,进而促进新技术系列的形成和推广应用。

热作用条件下烟道气与轻质原油混相规律

通过细长管混相驱替实验开展高温高压条件下烟道气与不同类型轻质原油的热混相规律研究。在高温高压条件下烟道气可以与轻质原油实现混相驱替;相同温度条件下,烟道气驱油效率与压力呈近线性关系;相同压力条件下,随温度增加驱油效率先平缓增加,然后急速增加,驱油效率快速达到90%以上,实现混相驱,驱油效率急速增加过程与稀油轻质组分随温度增加发生蒸馏相变有着密切关系;相同压力条件下,原油越轻,烟道气与原油的最小混相温度越低,越容易实现混相,注空气热混相驱替开发效果越好;高温高压条件下轻质原油与烟道气的混相更多体现的是超临界状态的高温相变特征,与常规高压条件下CO_(2)的接触抽提混相存在较大差异。

不同气介质-原油热辅助混相实验

利用“界面消失法”开展高温高压可视化PVT(压力-容积-温度)筒实验,研究不同气介质-原油热混相规律。实验表明:恒压升温过程中CO_(2)-原油混相存在两个混相温度域,实验压力为15 MPa时,温度低于140℃,混相带呈液相特征,温度对混相过程起抑制作用;温度高于230℃,混相带趋向气相特征,提高温度有利于形成混相。恒压条件下,温度足够高时,烟道气、N_(2)与原油可以实现混相;温度较低时,CO_(2)促混效果明显,混相温度以N_(2)最高,烟道气居中,CO_(2)最低;温度较高时,CO_(2)促混效果逐渐下降,N_(2)、烟道气与原油混相温度值逐渐接近,混相过程以原油轻组分蒸馏挥发混相为主,相平衡时气相中存在大量轻烃组分,混相带呈气相特征。

Miscibility of light oil and flue gas under thermal action

The miscibility of flue gas and different types of light oils is investigated through slender-tube miscible displacement experiment at high temperature and high pressure.Under the conditions of high temperature and high pressure,the miscible displacement of flue gas and light oil is possible.At the same temperature,there is a linear relationship between oil displacement efficiency and pressure.At the same pressure,the oil displacement efficiency increases gently and then rapidly to more than 90% to achieve miscible displacement with the increase of temperature.The rapid increase of oil displacement efficiency is closely related to the process that the light components of oil transit in phase state due to distillation with the rise of temperature.Moreover,at the same pressure,the lighter the oil,the lower the minimum miscibility temperature between flue gas and oil,which allows easier miscibility and ultimately better performance of thermal miscible flooding by air injection.The miscibility between flue gas and light oil at high temperature and high pressure is more typically characterized by phase transition at high temperature in supercritical state,and it is different from the contact extraction miscibility of CO_(2) under conventional high pressure conditions.

Research progress and potential of new enhanced oil recovery methods in oilfield development

This paper reviews the basic research means for oilfield development and also the researches and tests of enhanced oil recovery(EOR)methods for mature oilfields and continental shale oil development,analyzes the problems of EOR methods,and proposes the relevant research prospects.The basic research means for oilfield development include in-situ acquisition of formation rock/fluid samples and non-destructive testing.The EOR methods for conventional and shale oil development are classified as improved water flooding(e.g.nano-water flooding),chemical flooding(e.g.low-concentration middle-phase micro-emulsion flooding),gas flooding(e.g.micro/nano bubble flooding),thermal recovery(e.g.air injection thermal-aided miscible flooding),and multi-cluster uniform fracturing/water-free fracturing,which are discussed in this paper for their mechanisms,approaches,and key technique researches and field tests.These methods have been studied with remarkable progress,and some achieved ideal results in field tests.Nonetheless,some problems still exist,such as inadequate research on mechanisms,imperfect matching technologies,and incomplete industrial chains.It is proposed to further strengthen the basic researches and expand the field tests,thereby driving the formation,promotion and application of new technologies.

稠油油藏蒸汽驱后期CO2辅助蒸汽驱技术

为了进一步提高稠油油藏蒸汽驱后期采收率和开发效益,以新疆油田J6区块为研究对象,通过室内三维物理模拟实验,分别对全射孔条件下蒸汽驱、CO2辅助蒸汽驱、CO2泡沫辅助蒸汽驱和射开下部油层下半部分条件下蒸汽驱、CO2辅助蒸汽驱进行了实验研究,提出了蒸汽驱后期CO2辅助蒸汽驱开发技术。室内实验表明:蒸汽驱后期调整射孔后的CO2辅助蒸汽驱形成了注汽井中下部蒸汽腔侧向扩展、生产井顶层蒸汽腔超覆重力泄油的开发模式,高温水、油、CO2能够形成稳定的低黏拟单相乳化流体,且CO2在顶部的蒸汽腔起到隔热作用,在蒸汽腔内部降低了蒸汽分压,有效提高了注入蒸汽热效率。根据新疆油田J6区块CO2辅助蒸汽驱设计和应用效果,调整射孔后,与蒸汽驱相比,CO2辅助蒸汽驱将油汽比从0.12提高到0.16,增长34.0%,阶段采出程度从16.1%提高到21.5%,最终采收率可以达到66.5%。

轻质油藏高压注空气氧化特征与热混相驱技术

通过物理模拟实验、数值模拟和现场实例分析,综合研究轻质油藏高压注空气热混相驱的地下热氧化状态、热氧化前缘稳定性及生产动态特征。研究结果表明,原油组分越轻、黏度越低,热氧化燃料消耗量越低,氧化生热温度越低。稀油和挥发油热氧化前缘能够稳定推进,形成高压条件下的轻质油藏中温热氧化稳定驱替状态。稀油和挥发油的热气化和蒸馏作用强,容易在高压高温热氧化前缘与热烟道气一起形成气化和蒸馏单相区带,形成注空气热混相前缘。轻质油藏高压注空气热混相驱开发过程可分为增压见效、低气油比高效稳产、高气油比生产等3个阶段,增压见效阶段和低气油比高效稳产阶段产出70%以上的原油。

稠油油藏火驱驱替特征实验研究

火驱驱替特征是火驱的复杂物化过程和油藏地质条件综合作用的结果,是火驱方案设计和跟踪调控的重要基础。利用一维热跟踪补偿燃烧管实验装置,对比分析了不同性质稠油线性火驱的驱替特征,并与烟道气驱驱替特征进行对比。结果表明:原油黏度对火驱产液速率影响较大,黏度较低时火驱初期产液速率较高,大部分原油在中前期采出;黏度较大时,初期产液速率较小,甚至不产液,大部分原油在火驱中后期产出。火驱阶段含水率主要由地层初始含水饱和度(火驱前含水饱和度)决定。当地层初始含水饱和度高于束缚水饱和度时,火驱初期含水率较高,之后逐渐降低并趋于稳定。火驱初期(注气量小于1 PV)的生产动态特征与烟道气驱相近。在持续开发过程中,火驱仍保持稳定的采油速度,而烟道气驱采出程度增幅放缓。火驱开发的原油采出程度与累积注气量呈近似线性的关系,表明要保证火驱开发的效果则需保证相应的注气量。

稠油油藏火驱燃烧关键参数的计算及应用——以克拉玛依油田H1井区为例

以克拉玛依油田H1井区火驱试验为例,从物质和能量守恒出发,推导了高温燃烧条件下地下燃烧参数的平衡关系式,分析了火驱过程中原油、岩石骨架、次生水体等的热量分配,对H1井区地下燃烧温度、空气消耗量、空气油比等参数进行了计算,结果表明,在实际生产过程中油层空气消耗量为350~400 m^3/m^3,地下燃烧温度约为550℃,对实验室数据进行了重新标定。在此基础上,为了进一步提高火驱开发效果,对湿烧注入方案进行计算,当空气消耗量为350 m3/m3时,湿烧水空气比为0.000779 m^3/m^3,日注冷水量为49.9 m^3。

CO2 assisted steam flooding in late steam flooding in heavy oil reservoirs

To improve the oil recovery and economic efficiency in heavy oil reservoirs in late steam flooding,taking J6 Block of Xinjiang Oilfield as the research object,3D physical modeling experiments of steam flooding,CO2-foam assisted steam flooding,and CO2 assisted steam flooding under different perforation conditions are conducted,and CO2-assisted steam flooding is proposed for reservoirs in the late stage of steam flooding.The experimental results show that after adjusting the perforation in late steam flooding,the CO2 assisted steam flooding formed a lateral expansion of the steam chamber in the middle and lower parts of the injection well and a development mode for the production of overriding gravity oil drainage in the top chamber of the production well;high temperature water,oil,and CO2 formed stable low-viscosity quasi-single-phase emulsified fluid;and CO2 acted as a thermal insulation in the steam chamber at the top,reduced the steam partial pressure inside the steam chamber,and effectively improved the heat efficiency of injected steam.Based on the three-dimensional physical experiments and the developed situation of the J6 block in Xinjiang Oilfield,the CO2 assisted steam flooding for the J6 block was designed.The application showed that the CO2 assisted steam flooding made the oil vapor ratio increase from 0.12 to 0.16 by 34.0%,the oil recovery increase from 16.1%to 21.5%,and the final oil recovery goes up to 66.5%compared to steam flooding after perforation adjustment.

丙烷与二甲醚辅助SAGD开采规律二维物理模拟实验

蒸汽辅助重力泄油技术(SAGD)是一种成熟的稠油热采技术,但其开采后期,随着蒸汽腔与盖层接触面积进一步增大,散热量增加,驱油效率降低,累计油汽比下降。在SAGD中、后期采用转轻烃溶剂辅助的接替技术,选择二甲醚作为辅助溶剂,并选取丙烷作为对照,进行了3组二维可视化实验,全程监测产油和产液速率、产出液含水率、原油采收率、累计油汽比和溶剂回收率,并揭示了温度场和蒸汽腔的变化规律。实验结果表明,SAGD开采主要分为蒸汽腔向上发育、蒸汽腔横向扩展以及蒸汽腔向下发育3个阶段。蒸汽腔扩展到盖层边界,即达到SAGD开采中-后期,产油速率下降明显。在SAGD中-后期加入溶剂后,产油、产液速率均有明显上升。SAGD的采收率为53.67%,累计油汽比为0.141,相比之下丙烷辅助SAGD采收率提高了11.91%,累计油汽比提高了0.012;二甲醚辅助SAGD采收率提高了19.26%,累计油汽比提高了0.027。二甲醚的回收率为86.6%,比丙烷回收率高出6.9%。