稠油油藏蒸汽驱中后期剩余油分布特征及提高采收率方式研究

doi:10.19657/j.geoscience.1000-8527.2022.224

摘要/Abstract

摘要：

针对中国浅层及中深层稠油油藏,利用数值模拟研究方法,研究了不同稠油油藏的蒸汽驱开发规律和蒸汽驱中后期的剩余油分布特征,明确了稠油油藏蒸汽驱中后期的提高采收率方式。研究结果表明:浅层稠油油藏与中深层稠油油藏蒸汽驱的开发规律基本一致。驱替阶段生产效果好、产量高且稳定、油汽比高、含水率低;蒸汽突破后的开发阶段也是蒸汽驱开发的重要阶段,但是该阶段油汽比明显低于驱替阶段,表明该阶段蒸汽热效率明显降低。不同稠油油藏的剩余油分布特征类似,均表现出明显的垂向动用差异特征,即油层上部动用程度高,剩余油饱和度低,油层下部动用程度低,剩余油饱和度高,下部油层是剩余油挖潜的主要对象。从下到上逐层上返开发和多介质辅助是提高蒸汽驱中后期采收率的有效方式。研究结果对同类油藏开发具有重要意义。

关键词: 蒸汽驱, 中后期, 剩余油, 多介质, 提高采收率

Abstract:

Aiming at shallow and medium-deep heavy oil reservoirs in China, numerical simulation is used to reveal the steam flooding development pattern in different types of heavy oil reservoirs, and the distribution characteristics of the residual oil in the mid-late stages of steam flooding. Besides, the enhanced oil recovery method of mid-late-stage steam flooding of heavy oil reservoirs is elucidated. The results show that the steam flooding development pattern in the shallow heavy oil reservoirs is basically the same as that in the medium-deep heavy oil reservoirs. In the displacement stage, the performance is good with high and stable oil rate, high oil steam ratio (OSR), and low water cut. The development stage (after steam breakthrough) is also important for steam flooding development, but the oil steam ratio is obviously lower than that in the displacement stage, indicating that the steam thermal efficiency is markedly lower in this stage. Distribution characteristics of the residual oil in different heavy oil reservoirs are similar, showing clear vertical differences, i.e., the development degree of the upper pay zone is high with low residual oil saturation, while that of the lower pay zone is low with high residual oil saturation. The lower pay zone is the main target zone for residual oil extraction. Layer by layer reverse development (from bottom to top) and multi-component assistance are effective tools for the enhanced oil recovery (EOR) of mid-late-stage steam flooding. Our finding is of great significance to the development of similar reservoirs.

Key words: steam flooding, mid-late stage, residual oil, multi-component, enhanced oil recovery (EOR)

中图分类号:

TE341

石兰香, 李秀峦, 王宏远, 罗池辉, 刘鹏程. 稠油油藏蒸汽驱中后期剩余油分布特征及提高采收率方式研究[J]. 现代地质, 2022, 36(06): 1585-1593.

SHI Lanxiang, LI Xiuluan, WANG Hongyuan, LUO Chihui, LIU Pengcheng. Residual Oil Distribution Characteristics and Enhanced Oil Recovery Methods in Mid-late Stages of Steam Flooding of Heavy Oil Reservoirs[J]. Geoscience, 2022, 36(06): 1585-1593.

图/表 18

表1 模拟区块油藏参数表

Table 1 Reservoir parameters of numerical simulations

类型/值	浅层稠油	中深层稠油
目标油藏埋深/m	200	806
初始地层压力/MPa	2.0	8.06
初始油藏温度/℃	18	40
有效厚度/m	21	24.2
渗透率/10^-3 μm²	2 500	2 100
饱和度/%	75	75
孔隙度/%	30	31
地下脱气原油黏度/(mPa·s)	23 848@20 ℃	5 819@40 ℃

图1 浅层稠油油藏数值模拟渗透率剖面

Fig.1 Vertical permeability profile of the shallow heavy oil reservoir by numerical simulation

图2 中深层稠油油藏数值模拟渗透率剖面

Fig.2 Vertical permeability profile of the medium-deep heavy oil reservoir by numerical simulation

图3 不同稠油油藏原油黏度曲线

Fig.3 Oil viscosity vs. temperature curve for the different heavy oil reservoirs

图4 中深层稠油油藏蒸汽驱生产全过程生产指标变化曲线

Fig.4 Production indicator variation curve throughout the steam flooding process in the medium-deep heavy oil reservoirs

图5 浅层稠油蒸汽驱生产全过程生产指标变化曲线

Fig.5 Production indicator variation curve throughout the steam flooding process in the shallow heavy oil reservoirs

表2 不同蒸汽驱油藏阶段生产指标对比

Table 2 Comparison of production indicators at different steam flooding stages in the different reservoirs

阶段	生产指标	新疆浅层	辽河中深层
热连通阶段 (吞吐阶段)	采出程度/%	21.50	24.8
	油汽比/(m³/sm³)	0.29	0.43
	含水率/%	77.7	69.2
	采油速度/%	2.09	2.41
驱替阶段 (上产+ 稳产阶段)	采出程度/%	18.44	19.0
	油汽比/(m³/sm³)	0.08	0.13
	含水率/%	91.8	88.3
	采油速度/%	1.82	2.31
	稳产时间/年	10	8
突破+ 剥蚀阶段 (递减阶段)	采出程度/%	16.53	15.9
	油汽比/(m³/sm³)	0.08	0.09
	含水率/%	92.6	91.9
	采油速度/%	1.70	1.64
合计	采出程度/%	56.46	59.7
	油汽比/(m³/sm³)	0.11	0.16
	含水率/%	89.6	86.4
	采油速度/%	1.87	2.12

图6 浅层稠油油藏不同生产阶段温度、含油饱和度以及气体饱和度纵向剖面

Fig.6 Vertical profiles of the temperature, oil saturation and gas saturation of the shallow heavy oil reservoir in the different steam flooding stages

图7 中深层稠油油藏不同生产阶段温度、含油饱和度以及气体饱和度纵向剖面

Fig.7 Vertical profiles of the temperature, oil saturation and gas saturation of the medium-deep heavy oil reservoir in the different steam flooding stages

表3 不同蒸汽驱油藏阶段温度、压力、饱和度对比

Table 3 Comparison of temperature, pressure, and oil saturation at different steam flooding stages in the different reservoirs

阶段	参数	新疆浅层	辽河中深层
热连通阶段 (吞吐阶段)	温度/℃	44.0	69.9
	压力/MPa	0.30	0.90
	剩余油饱和度/小数	0.64	0.67
驱替阶段 (上产+ 稳产阶段)	温度/℃	102.5	156.3
	压力/MPa	1.2	2.8
	剩余油饱和度/小数	0.48	0.48
突破+ 剥蚀阶段 (递减阶段)	温度/℃	132.0	183.9
	压力/MPa	1.1	2.1
	剩余油饱和度/小数	0.35	0.36

表4 正交试验方案设计表(L45(25))

Table 4 Design of orthogonal experiments (L45(25))

水平/ 因素	原油黏度 @50 ℃/(mPa·s)	渗透率/ 10^-3μm²	有效厚度 /m	转驱时含油饱和度
1	500	500	8	0.45
2	1 000	1 000	10	0.50
3	2 500	1 500	12	0.55
4	5 000	2 000	14	0.60
5	6 500	2 500	16	0.65

表5 正交实验统计结果表——最终采收率(%)

Table 5 Statistics of orthogonal experiment—Final recovery factor (%)

水平/ 因素	原油黏度 @50 ℃/(mPa·s)	渗透率 /10^-3μm²	有效厚度 /m	转驱时含油饱和度
k1	45.3	28.8	28.7	50.1
k2	38.6	33.9	35.0	44.5
k3	35.4	38.4	39.7	37.3
k4	35.2	47.5	43.5	36.9
k5	35.6	41.7	43.3	21.4
级差	10.1	18.7	14.9	28.7
主次顺序	转驱时含油饱和度>渗透率>有效厚度>原油黏度

图8 典型生产井产液剖面

Fig.8 Typical production profile of producing wells

图9 目标区垂向剩余油饱和度剖面

Fig.9 Vertical profile of the residual oil saturation in the target block

表6 多介质复合蒸汽驱效果实验结果对比(砂岩油藏@200℃)

Table 6 Comparison of experimental results of multi-component-assisted steam Flooding (sandstone reservoir@200℃)

驱替方式	纯蒸汽驱	CO₂辅助蒸汽驱	N₂辅助蒸汽驱	尿素辅助蒸汽驱
累积注水量(CWE)	521	446	454	454
累产油量/g	34.59	36.32	35.44	39.16
采收率/%	68.5	72.62	70.20	77.66
残余油饱和度/%	24.74	21.57	23.42	17.54

图10 不同提高采收率方式的日产油变化曲线

Fig.10 Daily oil production rate curves for the different EOR methods

表7 不同提高采收率方式的生产指标统计表

Table 7 Statistics of production indicators for the different EOR methods

指标/方式	笼统注汽	逐层上返	尿素辅助	CO₂辅助
阶段采收率/%	3.41	27.96	38.81	33.28
最终采收率/%	46.3	70.9	81.8	76.2
阶段油汽比/(m³/sm³)	0.13	0.22	0.19	0.22
继续生产时间/d	735	6 956	7 320	7 320
区块平均日产油/(t/d)	65.1	56.5	74.5	63.9

表8 不同提高采收率方式投入产出统计表

Table 8 Statistics of input and output from the different EOR methods

指标/方式	笼统注汽	逐层上返	尿素辅助	CO₂辅助
产出/万元	10 401	85 383	118 517	101 629
投入/万元	7 923	38 446	91 943	50 381
产出/投入比	1.31	2.22	1.29	2.02

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