海上低渗油藏注水水质关键参数界限研究——以涠洲11-4N油田流沙港组为例

doi:10.13809/j.cnki.cn32-1825/te.2021.05.007

摘要/Abstract

摘要：

针对海上低渗储层微观孔隙结构认识不清,影响注水水质关键参数界限确定的问题,以涠洲11-4N油田流沙港组为例,从室内实验角度出发,通过恒速压汞实验刻画各区块储层微观孔隙结构特征,在此基础上开展注水水质实验,评价水质关键参数对储层渗流能力的影响。研究结果表明：喉道大小及分布是决定储层渗流能力的主要影响因素,渗透率与主流喉道半径有较好的幂函数关系,流一段、流三段主流喉道半径主要分布在4 μm、1 μm左右,前者流动能力较强;注入水中悬浮物颗粒粒径、颗粒质量浓度、细菌含量增加会大幅度增加注水压力,降低岩心渗透率。以储层吸水指数伤害程度20 %为下限,建立了不同渗透率级别的注水水质关键参数界限,流一段储层推荐注入海水中悬浮物颗粒质量浓度小于等于2.0 mg/L、悬浮物颗粒直径中值小于等于3.0 μm、细菌小于等于100 个/mL。据此指导注水并配合海水软化处理技术,实现了涠洲11-4N油田主力层位的有效开发。

关键词: 低渗油藏, 水质关键参数界限, 主流喉道半径, 精细注水, 有效开发

Abstract:

The unclear understanding of the micro pore structure in the offshore low permeability reservoir affects the determination of the key parameter limits of water injection quality. Therefore, water injection quality evaluation experiment is carried out based on the characterization of reservoir micro pore structure in Liushagang Formation of WZ11-4N Oilfield studied by indoor constant velocity mercury injection experiment, then to evaluate the influence of the key parameters of water quality on the seepage capability. The results show that the throat size and distribution are the main factors that determine the seepage capability of reservoir. There is a good power function relation between permeability and mainstream throat radius. The throat radius of the first section in the Liushagang Formation is about 4 μm, while 1 μm for the third section, and the former has strong flow capacity. The increase of the particle size, particle concentration and bacterial content of the suspended solids in the injected water will greatly increase the injection pressure but decrease the core permeability. Taking the damage degree of water absorption index to reservoir, 20 %, as the lower limit, the key parameter limits of injected water quality of reservoirs with different permeability levels are established. For the first section of the Liushagang Formation, the water quality of the recommended injected seawater are of the concentration that the suspended solids particles is less than or equal to 2.0 mg/L, the median diameter of suspended solid particles is less than or equal to 3.0 μm, and the number of bacteria per milliliter is less than or equal to 100. According to the guidance of these above data, the effective development of the main formation in Weizhou 11-4N Oilfield is realized by the combination of water injection and seawater softening treatment technology.

Key words: low permeability reservoir, key parameter limits of injected water quality, mainstream throat radius, fine water injection, effective development

中图分类号:

TE327

汤明光,刘清华,薛国庆,张芨强,鲁瑞彬. 海上低渗油藏注水水质关键参数界限研究——以涠洲11-4N油田流沙港组为例[J]. 油气藏评价与开发, 2021, 11(5): 709-715.

TANG Mingguang,LIU Qinghua,XUE Guoqing,ZHANG Jiqiang,LU Ruibin. Key parameter limits of water injection quality in offshore low permeability reservoir: A case study of Liushagang Formation in Weizhou 11-4N Oilfield[J]. Petroleum Reservoir Evaluation and Development, 2021, 11(5): 709-715.

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区块	岩心编号	井号	层位	深度（m）	渗透率（10^-3μm²）	孔隙度（%）	最大喉道半径（μm）	平均喉道半径（μm）	主流喉道半径（μm）	相对分选系数	均质系数
WZ11-4N	17-2	WZ11-4N-6	L₁Ⅳ	2 211.6	2.77	12.5	5.0	1.629	1.288	0.534	0.279
	20-2	WZ11-4N-6	L₁Ⅴ	2 224.0	78.40	20.0	7.2	5.471	5.085	0.245	0.737
	5-1	WZ11-4N-6	L₁Ⅳ	2 220.5	30.28	14.7	7.1	2.735	2.455	0.509	0.335
WZ11-7	26-1	WZ11-7-1	L₁Ⅳ	2 508.0	0.46	12.2	3.0	1.134	0.975	0.377	0.351
	24-2	WZ11-7-2Sa	L₁Ⅴ	2 532.5	1.47	13.2	5.0	1.591	1.115	0.505	0.278
	22-2	WZ11-7-2Sa	L₁Ⅴ	2 537.3	296.60	23.9	14.6	11.419	10.395	0.255	0.757
WZ11-8	8-2	WZ11-8-2	L₃Ⅰ	2 985.0	1.67	10.3	3.6	1.524	1.284	0.474	0.376
	9-2	WZ11-8-2	L₃Ⅰ	2 987.5	0.14	9.8	1.5	0.781	0.651	0.345	0.490
	12-1	WZ11-8-2	L₃Ⅰ	3 003.4	0.80	10.1	3.0	0.923	0.692	0.536	0.263

区块	层位	孔隙度（%）	平均渗透率（10^-3μm²）	平均喉道半径（μm）	主流喉道半径（μm）	分级（常规方法）
WZ11-4N	流一段	15.7	104.30	6.88	5.36	粗
WZ11-7	流一段	14.7	47.14	5.94	4.04	粗
WZ11-7	流三段	10.7	0.84	1.18	0.96	细
WZ11-8	流三段	10.6	1.31	1.71	1.13	细

类型	区块	样品编号	井号	层位	深度（m）	渗透率（10^-3μm²）	孔隙度（%）
不同粒径	WZ11-4N	5-1	11-4N-6	L₁Ⅳ	2 220.5	30.28	14.7
	WZ11-7	22-2	11-7-2SA	L₁Ⅳ	2 537.3	296.62	23.9
	WZ11-8	8-2	11-8-2	L₃Ⅰ	2 985.0	1.67	10.3
不同质量浓度	WZ11-4N	20-2	11-4N-6	L₁Ⅴ	2 224.0	78.40	20.0
	WZ11-7	22-1	11-7-2SA	L₁Ⅳ	2 537.3	234.51	24.0
	WZ11-8	08-3	11-8-2	L₃Ⅰ	2 985.0	1.03	10.3

渗透率（10^-3μm²）	不同水质伤害数学模型		不同水质产能损失幅度数学模型
渗透率（10^-3μm²）	不同颗粒粒径	不同颗粒质量浓度	不同颗粒粒径	不同颗粒质量浓度
1	K = -2.210r² + 25.29r + 3.987	K= -1.130c² + 20.01c + 0.629	Q=f（k）,K=f（r）	Q=f（k）,K=f（c）
50	K= -1.838r² + 16.56r + 2.011	K= -0.737c² + 13.77c + 0.767	Q=f（k）,K=f（r）	Q=f（k）,K=f（c）
250	K= -0.555r² + 6.028r + 1.430	K= -0.395c² + 8.829c + 0.524	Q=f（k）,K=f（r）	Q=f（k）,K=f（c）

阳离子质量浓度（mg/L）				阴离子质量浓度（mg/L）			水型	矿化度（mg/L）	pH值	溶解氧 (mg/L)	细菌总数 (CFU/mL)	溶解CO₂ (mg/L)
K⁺+Na⁺	Ca²⁺	Mg²⁺		Cl^–	SO₄^2–	HCO₃^–	水型	矿化度（mg/L）	pH值	溶解氧 (mg/L)	细菌总数 (CFU/mL)	溶解CO₂ (mg/L)
10 500	333	1 280		18 538	2 353	165	MgCl₂	33 351	7.9	7.2	160	7.2