大尺度串联双缝洞碳酸盐岩油藏的压力响应分析

摘要/Abstract

摘要：

针对以裂缝—溶蚀洞穴为储集空间的大尺度非连续介质缝洞型油气藏,大量的井基本上都是独立的缝洞系统,多为通过井眼沟通大裂缝,然后由裂缝串联起1至2个大型溶蚀洞穴系统的独立缝—洞单元,采用连续介质理论解释所获得的结果难以和储层实际流动过程相对应.提出的数学模型把井—洞之间和洞与洞之间的裂缝考虑为一维裂缝,远井洞外围存在裂缝沟通流动,从而形成裂缝沟通两个溶蚀洞穴系统的线性串联试井数学模型,模型中引入了瞬态流动概念和多重介质中窜流的概念.利用瞬态传导原理和拉普拉斯变换逐步求解数学模型,在拉普拉斯空间下无因次井底压力的解析解进行改进的Stehfest数值反演绘制典型曲线,通过敏感性分析讨论发现该模型可正确反映流动控制因素与地质因素之间的关系.实例解释对比表明:用该模型可正确解释井筒储集系数,表皮效应,裂缝系统渗透率,溶洞系统等效渗透率,缝长和溶洞大小等几何参数.

关键词: 缝洞型油藏, 钻遇裂缝, 双缝洞串联, 数学模型, 典型曲线分析

Abstract:

The fracture-cavity carbonate reservoir has large scale and discontinuous medium, and its main reservoir space is composed of fractures and caverns. Many wells are independent fractured-cavity systems, and most of them connect macrofractures to the wellbore. These wells are separate fracture-cavity cells which connect with one or two big cavities in series by fracture network, so the actual flow process of the reservoir does not match the result obtained by adopting traditional continuum theory. An analytical mathematic model is presented by considering the fracture network between well-cavity and cavity-cavity as one dimensional linear fracture, and other fracture communication flow exist in the periphery of the cavity(away from wellbore). Accordingly, the linear-in-series well test mathematic model with fracture connecting two cavity systems is established, and the model introduces the conception of transient flow and channeling flow of multiple media. The Transient conduction principle and Laplace transform are used to solve the mathematical model, and the dimensionless bottom hole pressure type curves are plotted in real space by using the improved Stehfest numerical inversion. The analysis of the sensitivity of cave parameters shows that the model can correctly reflect the relation between flow control factor and geological factor. Application examples indicate that this model can correctly explain wellbore storage factor, skin effect, the permeability of fracture system and cavity system, and the geometric parameters of fracture and cavity.

Key words: fracture-cavity reservoir, drilling fracture, double fractured-cavity in series, mathematical model, type curves analysis

中图分类号:

TE372

熊钰,叶海峰,蔡明金等. 大尺度串联双缝洞碳酸盐岩油藏的压力响应分析[J]. 油气藏评价与开发, 2018, 8(2): 22-29.

Yu Xiong,Haifeng Ye,Mingjin Cai, et al. Pressure response analysis of large scale series double fracture-cavity carbonate reservoir[J]. Reservoir Evaluation and Development, 2018, 8(2): 22-29.

图/表 10

图1

图2

图3

图4

图5

图6

图7

图8

表1

无因次参数主要拟合参数"

$ω f$ ,f	$ω R$ ,f	$ω L$ ,f	$K$ ,f	$L 2 D$ ,f	$W D$ ,f	$R RD$ ,f	$R LD$ ,f	$C D$ ,f
0.212	0.451	0.337	0.238	4 780.65	0.360	607.42	359.96	0.854

表1

表2

使用不同方法的解释结果"

本文方法
$ω f$ ,f	$ω R$ ,f		$ω L$ ,f	$K$ ,f	$L 2$ /m	W/m	$R R$ /m	$R L$ /m	$C D$ ,f	$V R + L$ /10⁴m³
0.212	0.451		0.337	0.238	425	0.032	54	32	0.854	80
Saphir 软件
$K 1$ /10^-3μm²		$R 1$ /m	$K 2$ /10^-3μm²	$R 2$ /m	$K 3$ /10^-3μm²	$R 3$ /m	$K 4$ /10^-3μm²	$S$ ,f	$C D$ ,f	$V cavity$ /10⁴m³
11.42		48.1	1.05	121.22	10.48	130.3	1.46	0.085	49.5	30

表2

参考文献 19

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