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。

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.

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。

稠油油藏双水平井SAGD蒸汽腔上升阶段产量预测解析模型

蒸汽腔的上升阶段是双水平井蒸汽辅助重力泄油(Steam Assisted Gravity Drainage,简称SAGD)开发的关键阶段。蒸汽腔的上升速度、时间以及对应的产量是SAGD上升阶段需要关注的重要指标。解析模型是指导SAGD开发的重要理论方法,有利于实现现场SAGD项目的快速设计、评价及综合调整。然而,目前缺乏简单、准确的针对蒸汽腔上升阶段的产量预测解析模型。本文首先根据质量守恒原理和蒸汽腔发育规律,假设蒸汽腔上升阶段的斜坡角度为与油藏参数和操作参数相关的变量,同时考虑油藏渗透率受各向异性影响,建立了双水平井SAGD上升阶段的产量预测模型。然后,综合利用数值模拟方法和正交试验分析方法,确定了蒸汽腔上升阶段的初始斜坡角度和蒸汽腔有效泄油高度系数与油藏参数和操作参数的关系,修正和完善了蒸汽腔上升阶段的产量预测模型。进一步地,结合现场实际,将新模型预测结果与Butler模型预测结果以及现场实际生产数据进行了对比验证。研究结果表明,初始斜坡角度与蒸汽腔有效泄油高度不是常数,而是与油藏参数、操作参数相关的变量。初始斜坡角度越大,蒸汽腔上升至油层顶部所需的时间越短,蒸汽腔上升阶段的产量越大。油藏渗透率越大,渗透率纵横比越大,注汽压力越大,则初始斜坡角度越大,相同时刻的瞬时产油量越大。其影响大小排序为:渗透率纵横比>渗透率>注汽压力。另外,油层厚度越大,则初始斜坡角度越小,蒸汽腔上升至油层顶部所需的时间越短。新模型具有理论简单、计算快、计算结果准确的优势,可以为SAGD开发的快速优化提供理论指导。

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.

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.

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。