油气藏数值模拟
•基本流动方程—多相流 •两相非混相流体
油相基本流动方程:
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数值模型的建立:微分方程的离散化 时间与空间离散
导数的差商逼近
五点差分格式
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Apply material balance equation for oil and water for each gridblock
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Water is Blue
Production decisions are more effective with simulation
History Match for Well, 2-14 (Water Cut & GOR)
Initial Sw
Year 12
Initial Sw
Waterflood Year 12
Large Indonesian field 4km x 8km Eight sands, faulted, several hundred feet thick 60 years of history Severe loss of production
Support Geological & Engineering Analysis
油藏研究方法
直接观察法
如钻观察井、井下测试、井下电视、岩心实验 、开辟生产实验区等)
模拟法
模拟法
模拟法
物模
数模
数学模 拟
数学模型求解方法
解析法
数值方法
数值模拟
油气藏数值模拟
—科学开发油气田的关键技术
利用计算机模型模拟仿真油气复杂开发过程,动态重现 开发历史,预测未来开发动态,可在计算机上“多次” 模拟开发过程,进行油田开发方案优选、产量和地层压 力动态预报、寻找开发中后期剩余油分布和采收率预测 、经济效益预测以及对整个油田开发的重大问题进行决 策的一门有效的工具。
production
2. Propane K-value adjusted to match bitumen-
propane saturation data. K pure C3 = 1.00 ; K
adjusted = 1.44
3. Heavy oil data chosen as average data for
一阶导数的 差商逼近
考察函数u(x), 其自变量的一阶导数可定义为 下面的各种极限:
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前差商 后差商 中心差商
二阶偏导数的差商逼近
混合二阶 差商逼近
Recommends work over for wells Each well goes from 4 BOPD to 400 BOPD Field now matches simulator forecast
Cut Away of Reservoir - See Inside
Oil is Red
油藏流体及其与岩石作用的复杂性
岩石非均质性及孔隙结构(孔道大小、孔隙之间关系) 油、气和水的组分各不相同,各组分间存在相间传质, 流体性质随温度、压力的变化很大 油层中的流体与岩石相互作用产生物理化学现象如扩散 、吸附等 各种提高采收率方法的使用,如热力采油、化学驱、混 相驱以及各种增产措施如酸化等
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网格系统
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•有限差分方程的建立 空间离散
考虑二维椭圆型微分方程:
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数值模拟的基本过程
建立数学模型
建立一套描述油藏流体渗流的偏微分方程组 。完整的数学模型包括定解条件(初始条件 和边界条件)。
建立数值模型
偏微分 方程组
非线性有限 差分方程组
线性代数 方程组
离散化
线性化
建立计算机模型 将各种数学模型的计算方法编制成计
算机程序,用计算机计算各种结果。
渗流数学模型的建立
Example Cases
Light Oil - Ecuador
Waterflood operation Identify poorly swept areas Value of additional oil $30 - 40 MM US Cost of study $250 M US Profitability ratio 140:1
实际上就是通过渗流微分方程方程,借用大型计算机, 计算数学的求解,结合油藏地质、油藏描述、油藏工程 、试井等学科再现油田开发的过程,由此来解决油田实 际问题。
Why Simulation ?
Evaluating Reservoir Management Strategies
Simulation: Why Oil Companies Buy
New well drilled without simulation produces only water Simulation determines what can be done - success or abandon Saves field, saves operator
Support Geological & Engineering Analysis
Only way that simulation will match performance of primary & waterflood is to use well damage factor in the simulator
Support Geological & Engineering Analysis
5. Straight lines rel perms
6. Temperature effects included
7. Diffusion of C3 into Oil D = .12 cm2/h
Additional Concepts
It is less expensive to add hydrocarbons from existing reservoirs than to find new ones. Simulation can increase recovery by at least 5% over the short term and even more over the longer term. Simulation provides a tool to evaluate field management strategies.
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计算传导率( Transmissibility)
Consists of two parts Geometric part (flow area) Saturation and pressure dependent part (mobility)
VAPEX – ATHABASCA OIL – LAB
ASSUMPTIONS:
1. The two step process: asphaltene
precipitation and heavy oil production, is
modeled as one step process: heavy oil
Design of processes Transfer of of laboratory process to the field Design of field pilots Design & optimization of new field operations
Correct Mistakes
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P ro d u c tio n w e ll In je c t io n w e ll
Aerial View of a Reservoir with Superimposed Grid