储层流体物性参数的确定及应用

The objectives of the differential test are to generate PVT data for conditions below the bubble point.
3. Gas-oil Separation
(3) Separator Tests
The object of these tests are to examine the influence of separator pressure and temperature on formation volume factor, gas/oil ratio, gas density and tank-oil density.
V2 , V1 = volume of the oil at reservoir temperature T2and T1
The manner of separation（油气分离方式）：
(i) the flash vaporisation or relative volume tests—闪蒸脱 气、接触分离 (ii) the differential test--微分分离. (iii) the separator tests--多级分离.
Bo
Vf Vsock tan k
Vf Bob Vb
Bo
Bt B oi
P<Pb:
Vf Bt Bob Vb
Pb
P
（3） The Coefficient of Isothermal Compressibility of oil (原油的等温压缩系数)
The compressibility of the oil phase above the bubble point can now be calculated from the graph.
• 2 components - solution gas and stock tank oil • Bo, Rs, etc. • Empirical correlations(经验公式)
Compositional Models
• N components based on paraffin series • Equation of state based calculations
3. Gas-oil Separation
(1) Flash Vaporization (Relative Volume Test)
The pressure on a liquid is reduced suddenly, causing a flash separation of gas from oil and an equilibrium between oil and gas is established immediately.
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Schematic of a Two Stage Separator Test
With the equipment available, a single test or a multiple separation test can be carried out.
Steps of Separator Tests:
Flash Vapourisation.
3. Gas-oil Separation
The steps of flash vaporization test:
（1）The PVT cell is filled with a certain quantity of reservoir liquid at a pressure above the estimated bubble point and room temperature. After the PVT cell has been filled (about 90 ml), it is immersed in a temperature bath and heated to reservoir temperature (p=constant). Thermal expansion:
2、parameters from flash vaporization test
(1)bubble point(地层油的泡点压力) Pb Bubble point(泡点 ) is the pressure when first bubble of gas forms in the liquids. (2) Formation volume factor (地层油体积系数): P>Pb :
R si
V1 V2 676 92 768(ft 3 / STB) L2
Bob Vres / L 2
2、parameters from flash vaporization test
Vf Vb
Pb
Bo
Vf Vsock tan k

Vf Vb
Bob
Vf Bt Bob Vb
第三节 储层流体按组分模型处理时物性参数 的确定及应用 1、储层流体密度的确定 2、凝析气藏体积系数、地下流体组 成、储量等参数的确定
第一节 储层流体的黑油模型与组分模型的区别；
In order to predict reservoir and well fluid behaviour, two approaches that are commonly used are the multicomponent compositional model and the two component black oil model. The latter simplistic approach has been used for many years to describe the composition and behaviour of reservoir fluids. It is called the “Black Oil Model”.
1 v2 v1 co v1 p1 p2
1 MPa
where: V2 = volume at pressure P2 （P1>P2）; V1 = volume at pressure P1.
The average compressibility of oil between the bubble-point pressure and the prevailing pressure (Pi~Pb)：
Gas Solubility and Formation Volume Factors are associated with the black oil model .
Figure 1 "Black Oil Model"
2、Comparison of Two Models Below gives a summary comparison of the two approaches. Black Oil Models
3. Gas-oil Separation
/The starting point is reservoir bubble point. /Fluid is displaced from the PVT cell ensuring that the PVT cell contents remain at bubble point pressure. /The gas and liquids are collected from the separation stage(s) and their respective properties measured. /The final stage is at stock tank conditions.The resulting fluid is termed stock tank oil.
By plotting the volume of the system versus pressure a break is obtained in the slope. This occurs at the Bubble Point pressure.
(2) Differential Vaporisation
3. Gas-oil Separation（油气分离）
The main purpose of separation is to get PVT data. main applications of the PVT data: •to provide data for reservoir calculations, • to provide physical property data for well flow calculations • for surface facility design. the
3. Gas-oil Separation
Equipment for the Study of Subsurface Samples
3. Gas-oil Separation
（2）Reduce the pressure and calculate the P~V relationship
At reservoir temperature
3. Gas-oil Separation
At each step below the bubble point， the liberated gas is removed from the cell stepwise(逐步地). At each step below
the bubble point the quantity of gas, oil volume are determined.
1、The black oil model The black oil model considers the fluid being made up
of two components – gas dissolved in oil and stock tank oil.
The compositional changes in the gas when changing pressure and temperature are ignored. To those appreciating thermodynamics this simplistic two component model is difficult to cope with.
1 Vob Vof 1 Bob Boi Co Vof Pb Pi Boi Pi Pb
Co=10-140 MPa-1 for reservoir oil
Vof—volume of oil at prevailing pressure p, m3;
（4）The thermal expansion factor
第二节 以黑油模型为基础的流体物性参数的确定 1、parameters from Separator test
Sep. P psi
50 0 100 0 200 0 300 0
Sep. Gas/oil T ˚F ft3/STB
75 75 75 75 75 75 75 75 737 41 676 92 602 178 549 246
Stock tank gravity ˚ API
40.5 40.7 40.4 40.1
Bob bbl/STB
1.481 1.474 1.485 1.495
(1) Initial gas oil ratio Rsi:
(2) Formation volume factor at bubble point Bob:
第一章 储层流体物性参数的确定及应用
第一节 储层流体的黑油模型与组分模型的区别； 1、黑油模型 2、黑油模型与组分模型 3、油气分离方式 第二节 以黑油模型为基础的流体物性参数的确定 1、多级脱气确定的物性参数 2、闪蒸脱气确定的物性参数 3、微分脱气确定的物性参数 4、地层油的密度 5、地层油的粘度