﻿ 油藏流场定量表征方法及应用
 西南石油大学学报(自然科学版)  2020, Vol. 42 Issue (4): 111-120

Quantitative Characterization Method and Application of Reservoir Flow Field
LU Fengming, WU Xi, ZHU Hongyun, ZHANG Yang, WANG Rui
Dagang Oilfield Company, PetroChina, Binhai New Area, Tianjin 300280, China
Abstract: Due to long term washing of water injection in the complex fault block reservoirs, the distribution of reservoir flow field would be more and more complicated and it results in forming different types of reservoir flow field with different intensities. In regions of high intensity of reservoir flow field, invalid water injection is very serious. But water injection cannot reached the regions of low intensity easily. It results in a poor efficiency of reservoir development and makes it hard to adjust reservoir development. Due to the above reasons, taking a case Block Zao Z of the first member of the Kongnan, Cangdong Sag, south of Huanghua Depression, the simulation model was modeled to study quantitatively reservoir flow field at high water cut stage. According to the influence on reservoir flow field, the primary characterization parameters were selected from some static and dynamic parameters, including permeability, pressure gradient, oil saturation and surface flux. A calculation model of intensity of reservoir flow field was proposed by the theory of fuzzy mathematics. The ranges of different types of reservoir flow field were determined on the study reservoir. And then technical strategies of reservoir flow field adjustment were given in different types of reservoir flow field. The implement results of flow field adjustment of the study reservoir show that the characterization method of reservoir flow field could be applied to a correct understanding of the characteristic of reservoir flow filed at high water cut stage. It is helpful to guide to adjust layer series and well groups and to improve effect of reservoir development.
Keywords: reservoir flow field    quantitative characterization    flow field intensity    flow field adjustment    Huanghua Depression

1 基于真实油藏的概念模型建立

 图1 油藏渗透率概念模型 Fig. 1 Theoretical reservoir permeability model

2 油藏流场表征方法

2.1 主要影响参数筛选

(1) 渗透率

(2) 地层压力梯度

 图2 第2层含水率90%时地层压力、流线分布、地层压力梯度分布 Fig. 2 Distribution of pressure, streamline distribution and pressure gradient at 90% water cut in the 2$^{\rm nd}$ layer

(3) 含油饱和度

 图3 含水率90%时单层含油饱和度和流线分布 Fig. 3 Distribution of oil saturation and streamline distribution of different layers at 90% water cut

(4) 面通量

2.2 主要表征参数影响关系的确定

 $\pmb{C} = [K(i), M(i), {S_{\rm o}}(i), \Delta p(i)$ (1)
2.2.1 利用隶属函数实现参数标准化

 $\Delta {p'}(i) = \dfrac{{\lg \Delta p(i)}}{{\lg \Delta {p_{\rm max}}}}$ (2)
 ${K'}(i) = \dfrac{{\lg K(i)}}{{\lg {K_{\rm max}}}}$ (3)
 图4 ZV3-3层压力梯度和渗透率的概率分布图 Fig. 4 Probability distribution of pressure gradient and permeability in layer ZV3-3
 图5 ZV3-3层平面网格压力梯度、渗透率分布曲线 Fig. 5 Pressure gradient and permeability distribution curve of layer ZV3-3 plane grid

ZV3-3层含油饱和度概率和平面网格含油饱和度分布见图 6。从图 6可以看出，含油饱和度主要分布在24%$\sim$68%，且各区间段分布大体一致。因含油饱和度越高，被驱替程度越低，为负相关，且含油饱和度为0$\sim$100$\%$，所以，可以采用线性负相关隶属函数处理。标准化含油饱和度公式为

 图6 ZV3-3层含油饱和度概率分布图和平面网格含油饱和度分布曲线 Fig. 6 Probability distribution of oil saturation and oil saturation distribution curve in plane grid in layer ZV3-3
 ${S'_{\rm o}}(i) = 1 - {S_{\rm o}}(i)$ (4)

 图7 ZV3-3层面通量概率分布图和平面网格面通量分布曲线 Fig. 7 Probability distribution chart of surface flux and oil saturation distribution curve of plane grid in layer ZV3-3

 ${M'}(i) = \dfrac{1}{{1 + 1.3727 M{{(i)}^{ - 0.5279}}}}$ (5)

 $\mathit{\boldsymbol{A}} = [{K'}(i), {M'}(i), {S'}_{\rm o}(i), \Delta {p'}(i)]$ (6)
2.2.2 确定权重

 $\mathit{\boldsymbol{B}} = {(0.0844, 0.4742, 0.1632, 0.2782)^{\rm T}}$ (7)
2.2.3 流场表征

 $F_{\rm s}=aK' +bM' +cS'_{\rm o} +d \Delta p'$ (8)

 $F_{\rm s}\!=\!0.0844K'\!+\!0.4742M'\!+\!0.1632S'_{\rm o}\!+\!0.2782 \Delta p'$ (9)
3 油藏流场强度分级评价

 图8 流场强度概率分布图 Fig. 8 Probability distribution of flow field intensity

 图9 面通量分布曲线图 Fig. 9 Surface flux distribution graph

 图10 面通量与流场强度指数对应关系 Fig. 10 Correspondence between surface flux and flow field intensity index

4 流场分布特征及调整对策

 图11 枣Z断块流场强度分布图 Fig. 11 Distribution of flow field intensity of Block Zao Z

 图12 小层油藏流场分级分布图 Fig. 12 Distribution of flow field classification in each layer

 图13 不同类型流场调整技术对策图 Fig. 13 Technical schematic of different flow fields adjustment

 图14 井区调整前后含油饱和度对比图 Fig. 14 Comparison of oil saturation at well block before and after adjustment
5 结论

(1) 以研究区中孔、中渗储层建立的理论模型为基础，优选出渗透率、地层压力梯度、含油饱和度、面通量4个参数作为油藏流场的主要表征参数，结合层次分析法和模糊数学理论确定了油藏流场主要表征参数及各参数的权重值，建立了油藏流场定量表征的方法，实现了对复杂断块油藏高含水开发阶段油藏流场的定量描述。

(2) 以枣南孔一段枣Z断块数值模型为基础，运用流场强度表征方法，根据油藏流场强度$F_{{\rm s}}$概率分布结果确定0.25、0.45、0.55和0.65为流场强度划分的界限值。流场具体划分为强优势流场、优势流场Ⅰ类、优势流场Ⅱ类、弱势流场Ⅰ类、弱势流场Ⅱ类。单砂层上，各类流场呈区带分布，平面上强优势流场分布在动用程度较高的主体部位，而弱势流场主要在主控断层附近、断层夹持部位发育。

(3) 针对流场潜力分布特征，采用断流线、改流线、稳流线、引流线和造流线等技术对策开展流场调整，达到均衡驱替，现场实施效果良好。

(4) 枣Z断块流场调整实践结果表明，采用论文建立的油藏流场表征方法能够正确认识高含水期油藏流场特征。利于有效指导注采井网重构，进而改善油藏开发效果。

$\mathit{\boldsymbol{C}}$-参数矩阵；

$K$-渗透率，mD；

$i$-网格序号，无因次；

$M$-面通量，m；

${S_{\rm o}}$-含油饱和度，%；

$\Delta p$-压力梯度，kPa/m；

$\Delta p'$-标准化压力梯度，无因次；

$\Delta p_{\max }$-网格中压力梯度最高值，kPa/m；

$K'$-标准化渗透率，无因次；

${K_{\max }}$-网格中渗透率最高值，mD；

${S_{\rm o}'}$-标准化含油饱和度，无因次；

$M'$-标准化面通量，无因次；

$\mathit{\boldsymbol{A}}$-隶属度矩阵；

$\mathit{\boldsymbol{B}}$-权重向量；

$F_{\rm s }$-流场强度，无因次；

$a, b, c, d$-回归系数，无因次。

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