Measurement of Gas Diffusivity in Heavy Oils/Bitumens using Pressure-Decay Test

2014 ◽  
Author(s):  
Ram R Ratnakar ◽  
Birol Dindoruk
Keyword(s):  
Heavy Oils ◽  
Pressure Decay ◽  
Gas Diffusivity ◽  
Decay Test

Measurement of Gas Diffusivity in Heavy Oils and Bitumens by Use of Pressure-Decay Test and Establishment of Minimum Time Criteria for Experiments

SPE Journal ◽  
2015 ◽  
Vol 20 (05) ◽  
pp. 1167-1180 ◽  
Author(s):  
Ram R. Ratnakar ◽  
Birol Dindoruk
Keyword(s):  
Oil Recovery ◽  
Accurate Determination ◽  
Experimental Studies ◽  
Gas Solubility ◽  
Heavy Oils ◽  
Gas Oil ◽  
Pressure Decay ◽  
Molecular Diffusivity ◽  
Decay Test ◽  
Long Time

Summary Molecular diffusion plays a very important role in various reservoir processes, especially in the oil-recovery processes where convective forces are not dominant or when direct frontal contact and mixing are not possible. For example, in heavy-oil and bitumen recovery, injected light hydrocarbons can diffuse into the oil beyond the potential fronts and/or convective zones and promote the effectiveness of the displacement process, reducing in-situ viscosities and in turn enhancing the oil recovery. Similarly, diffusive mixing can also be a dominant mechanism in the gas-redissolution process, even in lighter-hydrocarbon systems. For example, it controls how much gas will be dissolved in oil and how long it will take to dissolve, in the absence of mechanical/convective mixing, as in the case of reservoir repressurization. The extent of dissolution of a gas into oil is governed by its solubility, but the rate is controlled by both molecular diffusivity and solubility. Thus, accurate determination of these parameters is essential to design and understand displacement processes. Despite the significance of diffusion in various aspects of oil recovery, there are very few experimental studies available in the literature addressing the diffusion of gas in heavy oils. Experimental work is most commonly based on the pressure-decay concept. However, the parameter inversion in these tests relies on an error-function solution that neglects the transient processes at the gas/oil interface and assumes constant-saturation concentration. This assumption is not appropriate when decay in pressure is large because pressure in the gas cap changes continuously as gas is dissolved in the oil, and hence the gas solubility varies with time. One of the major issues related to this experimental process is that it takes a long time (order of several days to several months) to achieve steady-state (converged) solution to determine diffusivity. In this work, we have Experimentally investigated the diffusion of methane in heavy oils as well as light oils by use of a pressure-decay test Captured properly the variation in gas concentration in oil at the gas/oil interface with time by expressing gas solubility in terms of Henry's constant in the mathematical model Developed the exact solution of the 1D pressure-decay (transient-diffusion) model with pressure-dependent gas/oil-interface concentration and shown that after a long time, pressure decays exponentially in time with an exponent that depends on diffusivity as well as solubility Presented the inversion technique to determine the diffusivity and other parameters from late-transient-pressure data, and shown the convergence in their estimates (Most importantly) developed a cutoff criterion permitting us to stop the experiments while still being able to extract the converged diffusivity values (this is important in situations when the experiment is stopped prematurely for technical or other reasons)

Monitoring and maintaining the integrity of immersed ultrafiltration membranes used for pathogen protection

2002 ◽  
Vol 2 (5-6) ◽  
pp. 307-311
Author(s):  
P. Côté ◽  
J. Cadera ◽  
N. Adams ◽  
G. Best
Keyword(s):  
Drinking Water ◽  
Membrane Filtration ◽  
Ultrafiltration Membranes ◽  
Vacuum Decay ◽  
Integrity Monitoring ◽  
Pressure Decay ◽  
Decay Test ◽  
Conventional Technology ◽  
Water Borne

Membrane filtration has become the preferred alternative to conventional technology to remove water-borne pathogens in the preparation of drinking water. This paper presents the integrity monitoring and maintenance options for the ZeeWeed® immersed membrane. Results from two versions of air-based tests, a pressure decay test and a vacuum decay test are presented and shown to be conservative when compared to challenge results from independent studies.

Measurement of Gas Diffusivity In Heavy Oils

10.2118/98-63 ◽  
1998 ◽  
Author(s):  
Y. Zhang ◽  
C.L. Hyndman ◽  
B. Maini
Keyword(s):  
Heavy Oils ◽  
Gas Diffusivity

Estimation of concentration-dependent diffusion coefficient in pressure-decay experiment of heavy oils and bitumen

2011 ◽  
Vol 305 (2) ◽  
pp. 132-144 ◽  
Author(s):  
Seyyed M. Ghaderi ◽  
S. Hamed Tabatabaie ◽  
Hassan Hassanzadeh ◽  
Mehran Pooladi-Darvish
Keyword(s):  
Diffusion Coefficient ◽  
Heavy Oils ◽  
Pressure Decay

Measurement of gas diffusivity in heavy oils

2000 ◽  
Vol 25 (1-2) ◽  
pp. 37-47 ◽  
Author(s):  
Y.P. Zhang ◽  
C.L. Hyndman ◽  
B.B. Maini
Keyword(s):  
Heavy Oils ◽  
Gas Diffusivity

scholarly journals A Novel Model of Pressure Decay in Pressure-Driven Membrane Integrity Tests Based on the Bubble Dynamic Process

2019 ◽  
Vol 9 (2) ◽  
pp. 273
Author(s):  
Songlin Wang ◽  
Jiaqi Ding ◽  
Han Xu ◽  
Pengchao Xie ◽  
Junfeng Wu ◽  
...  
Keyword(s):  
Dynamic Process ◽  
Accurate Determination ◽  
Membrane Integrity ◽  
Defect Size ◽  
Chamber Pressure ◽  
Bubble Dynamic ◽  
Pressure Decay ◽  
Chamber Volume ◽  
Decay Test ◽  
Gas Chamber

The membrane integrity is estimated using a pressure decay test based on the bubble dynamic process of membrane defects. The present work builds a schematic diagram for a bubble formation model of a pressure decay test, proposes a simulation model of pressure decay rate (PDR) in the membrane gas chamber by means of numerical simulation using microdefect bubble dynamic behavior, and tries to establish the main factors influencing the back-calculated defect size resolution. Results obtained from the variations in the membrane gas chamber pressure and the PDR allowed for accurate determination of the membrane defect size, and the PDR was found to be relatively dependent on the gas chamber volume and the initial applied test pressure. The measured data about PDR using controlled experimental parameters was in good agreement with the trend found in the prediction model, proving that the pressure decay test process is in essence a bubble dynamic process. Furthermore, the back-calculated defect size resolution was found to decrease with the increase in gas chamber volume and PDR as well as with the decrease in applied pressure.

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