注采单元地层结垢机理及数值模拟研究

摘要/Abstract

摘要：

注水开发是确保油田持续稳产,提高原油采收率最经济、有效的措施之一。然而长期的注水开发过程中地层结垢不可避免,严重影响和制约油田开发效果。以注采单元为研究对象,基于热力学及溶度积规则等理论,考虑地层温度、压力、成垢离子浓度以及流速等因素的影响,建立了注采单元地层结垢数值模型,包括压力场模型、温度场模型、孔隙度与渗透率分布模型以及地层结垢模型,并根据油田实际生产数据,运用MATLAB数学模拟软件进行实例模拟,分析各因素对注采单元内结垢总量、结垢范围、结垢量分布以及地层结垢对视吸水指数和渗透率的影响。结果表明,注水井近井地带温度较低,溶解平衡常数较小且流速大,难以结垢;径向往外,地层温度升高,注入水的流速大幅减缓,最易成垢;继续往外,成垢离子浓度低于最小结垢浓度时,不再结垢。

关键词: 注采单元, 注水井, 结垢模型, 阻垢率, 数值模拟

Abstract:

Water flooding is one of the most economical and effective measures for the sustainable and stable production of oil field and EOR（enhance oil recovery）. However, formation scaling is inevitable in the process of long-term water flooding, which seriously affects and restricts the effect of oil field development. Taking injection-production unit as the research object, based on thermodynamic theory and solubility product rule, and considering the influence of formation temperature, pressure, scaling ion concentration and flow rate, the numerical models of formation scaling in injection-production unit was established, including pressure field model, temperature field model, porosity and permeability distribution model and formation scaling model. Meanwhile, according to the actual production data of oil field, mathematical simulation software—MATLAB—was used to carry out the case to analyze the influence of each factor on the total scaling amount, scaling range, distribution of scaling quantity and formation scaling on apparent water absorption index and permeability in injection-production unit. The results showed that the temperature of the immediate vicinity of the injection wells was low, the dissolution equilibrium constant was small and the flow rate was high, so that scaling was difficult. When in radial outward direction, the formation temperature increased, and the flow rate decreased greatly, which made it the most easy condition for scaling. Continue outward, when the scaling ion concentration was lower than the minimum scaling concentration, scale would no longer form.

Key words: injection-production unit, injection well, scaling model, scale inhibition rate, numerical simulation

中图分类号:

TE357

李年银,康佳,张昊天,陶卫东,任屹. 注采单元地层结垢机理及数值模拟研究[J]. 油气藏评价与开发, 2019, 9(4): 19-25.

LI Nianyin,KANG Jia,ZHANG Haotian,TAO Weidong,REN Yi. Study on mechanism and numerical simulation of formation scaling in injection-production unit[J]. Reservoir Evaluation and Development, 2019, 9(4): 19-25.

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地层水离子浓度/（mg·L^-1）							注入水离子浓度/（mg·L^-1）
Ca²⁺	Na⁺、K⁺	Mg²⁺	Cl^-	HCO₃^-	SO₄^2-		Ca²⁺	Na⁺、K⁺	Mg²⁺	Cl^-	HCO₃^-	SO₄^2-
140	2 680	61	2 570	3 051	288		560	2 716	45	3 962	640	225

井号		产量/（m³·d^-1）	注水量/（m³·d^-1）
采油井	X1030	15
	X1036	25
	X1022	30
注水井	X1007		100