Preparation of Polymer Microsphere Feature Delayed Swelling and Its Channeling Sealing Performance in Natural Gas Flooding

doi:10.3969/j.issn.1006-396X.2022.04.009

Abstract

Abstract:

A block in Changqing oilfield has high heterogeneity,and there are high?capacity channels, microfractures and high?permeability zones in its formations. During the implementation of natural gas flooding, the high risk of gas channeling must be considered. The traditional polymer microspheres are characterized by fast water absorption and expansion rate.It is easy to shear and crush its plugging strength is low. In view of these shortages,a polymer microsphere featuring delayed swelling was thus synthesized by introducing and activating a crosslinker and adopting inverse emulsion polymerization to address those defects. Its structure was characterized by a laser particle size analyzer and a polarizing microscope. Laboratory experiments were conducted to systematically evaluate the performance of the polymer microsphere featuring delayed swelling in temperature resistance,salt resistance,swelling,stability,and plugging during natural gas flooding.The results show that with a temperature resistance of 85 ℃, a salt resistance of 100 000 mg/L, a swelling time delay of 7 days, a particle size enlargement factor of 5.5, long?term stability (more than 6 months), and a plugging rate of more than 92.0%, the proposed polymer microsphere featuring delayed swelling can be used for plugging deep microfractures and high?permeability zones in the formations.

Key words: Delay swelling, Polymer microspheres, Natural gas flooding, Channeling sealing

摘要：

长庆油田某区块非均质性较强，地层中有大孔道、微裂缝和高渗透条带，在实施天然气驱过程中气窜风险较高，而传统聚合物微球吸水膨胀速率快，易剪切破碎，封堵强度低。针对这些缺点，通过引入激活交联剂，采用反相乳液聚合法合成了一种延时膨胀聚合物微球，并采用激光粒度仪、偏光显微镜等手段对其进行了结构表征；通过室内实验，系统评价了延时膨胀聚合物微球的抗温性、抗盐性、溶胀性、稳定性和天然气封堵性。结果表明，延时膨胀聚合物微球抗温85 ℃，抗盐100 000 mg/L，延时7 d膨胀，粒径扩大倍数达到5.5，并长期保持稳定，稳定性大于6个月，封堵率大于92.0%，可用于地层深部微裂缝和高渗条带的封堵作业。

关键词: 延时膨胀, 聚合物微球, 天然气驱, 封窜

CLC Number:

TE357

Haifeng Zhao, Lü Wei, Xiaochun Liu, Sixian He, Shitou Wang, Weiyu Bi. Preparation of Polymer Microsphere Feature Delayed Swelling and Its Channeling Sealing Performance in Natural Gas Flooding[J]. Journal of Petrochemical Universities, 2022, 35(4): 60-65.

赵海峰, 吕伟, 刘笑春, 何思娴, 王石头, 毕卫宇. 延时膨胀聚合物微球制备及天然气驱封窜性能研究[J]. 石油化工高等学校学报, 2022, 35(4): 60-65.

Figures/Tables 10

Table 1 Relationship between reservoir permeability and average pore throat diameter

渗透率/ $μ$ m²	平均孔喉直径/ $μ$ m
0.000 5	0.38
0.000 1	0.53
0.002 0	0.75
0.005 0	1.19
0.010 0	1.68
0.050 0	3.76
0.100 0	5.31
1.000 0	16.80

Table 1 Relationship between reservoir permeability and average pore throat diameter

渗透率/ $μ$ m²	平均孔喉直径/ $μ$ m
0.000 5	0.38
0.000 1	0.53
0.002 0	0.75
0.005 0	1.19
0.010 0	1.68
0.050 0	3.76
0.100 0	5.31
1.000 0	16.80

Table 2 Composition of formation water quality in block

水样	$ρ$ （离子）/(mg $⋅$ L^-1)							矿化度/(mg $⋅$ L^-1)	水型
水样	Na⁺+K⁺	Ca²⁺	Mg²⁺	Cl^-	SO $4 2 -$	CO $3 2 -$	HCO $3 -$	矿化度/(mg $⋅$ L^-1)	水型
清水	2 019	164	20	372	4 083	0	129	7.00	Na₂SO₄
采出水	19 229	3 705	330	34 369	3 674	0	131	61.438	CaCl₂

Table 2 Composition of formation water quality in block

水样	$ρ$ （离子）/(mg $⋅$ L^-1)							矿化度/(mg $⋅$ L^-1)	水型
水样	Na⁺+K⁺	Ca²⁺	Mg²⁺	Cl^-	SO $4 2 -$	CO $3 2 -$	HCO $3 -$	矿化度/(mg $⋅$ L^-1)	水型
清水	2 019	164	20	372	4 083	0	129	7.00	Na₂SO₄
采出水	19 229	3 705	330	34 369	3 674	0	131	61.438	CaCl₂

Fig.1 Laser particle size analyzer analysis curve of original sample of time?delay expanded polymer microsphere system

Fig.2 The change of particle size expansion factor with time of delayed?expanding polymer microspheres

Fig.3 Comparison of particle size expansion ratio between 100 nm gel polymer microspheres and delayed?expansion polymer microspheres

Fig.4 Micrograph of the particle of the system of delayed?expansion polymer microspheres

Fig.5 The change of viscosity with aging time of the delayed?expansion polymer microspheres

Fig.6 The change of particle size expansion factor with time of the delayed?expansion polymer microsphere system

Table 3 Oil displacement effects of time?expanded polymer microspheres under different permeability conons

岩心编号	长度/cm	直径/cm	孔隙度/%	水测渗透率/（10^-3 $μ$ m²）	水驱采收率/%	气驱采收率/%	体系驱油采收率/%	封堵后气驱采收率/%	封堵率/%	总采收率/%
1	7.10	2.52	13.21	5.26	40.67	8.4	6.7	13.8	97.2	69.57
2	7.12	2.50	16.77	76.30	46.19	9.8	5.2	11.7	96.1	72.89
3	7.22	2.55	17.27	162.50	50.75	7.5	4.9	10.3	93.3	73.45
4	7.11	2.51	18.20	353.40	58.60	5.7	5.5	8.2	92.8	78.00

Table 3 Oil displacement effects of time?expanded polymer microspheres under different permeability conons

岩心编号	长度/cm	直径/cm	孔隙度/%	水测渗透率/（10^-3 $μ$ m²）	水驱采收率/%	气驱采收率/%	体系驱油采收率/%	封堵后气驱采收率/%	封堵率/%	总采收率/%
1	7.10	2.52	13.21	5.26	40.67	8.4	6.7	13.8	97.2	69.57
2	7.12	2.50	16.77	76.30	46.19	9.8	5.2	11.7	96.1	72.89
3	7.22	2.55	17.27	162.50	50.75	7.5	4.9	10.3	93.3	73.45
4	7.11	2.51	18.20	353.40	58.60	5.7	5.5	8.2	92.8	78.00

Table 4 Oil displacement experiments of time?delay expanded polymer microsphere system under different permeability levels

组别	长度/cm	直径/cm	孔隙度/%	渗透率/（10^-3 $μ$ m²）	渗透率级差	水驱采收率/%	气驱采收率/%	采收率增加值/%	封堵后气驱采收率/%
1	7.20	2.50	13.29	32.53	5.5	43.59	7.95	5.26	7.69
1	7.00	2.50	16.45	5.87	5.5	24.39	4.63	7.20	14.63
2	7.12	2.50	17.25	61.80	11.2	47.60	5.30	5.40	4.80
2	7.32	2.55	15.87	5.51	11.2	25.80	4.10	2.70	12.40
3	7.26	2.54	16.03	135.70	19.7	45.90	9.41	8.36	0
3	7.20	2.50	14.33	6.88	19.7	18.30	2.53	0.85	24.62

Table 4 Oil displacement experiments of time?delay expanded polymer microsphere system under different permeability levels

组别	长度/cm	直径/cm	孔隙度/%	渗透率/（10^-3 $μ$ m²）	渗透率级差	水驱采收率/%	气驱采收率/%	采收率增加值/%	封堵后气驱采收率/%
1	7.20	2.50	13.29	32.53	5.5	43.59	7.95	5.26	7.69
1	7.00	2.50	16.45	5.87	5.5	24.39	4.63	7.20	14.63
2	7.12	2.50	17.25	61.80	11.2	47.60	5.30	5.40	4.80
2	7.32	2.55	15.87	5.51	11.2	25.80	4.10	2.70	12.40
3	7.26	2.54	16.03	135.70	19.7	45.90	9.41	8.36	0
3	7.20	2.50	14.33	6.88	19.7	18.30	2.53	0.85	24.62

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