No abstract

This paper proposes a new compositional simulation approach which has an implicit equation for the oil-phase pressure and water saturation, an explicit equation for the hydrocarbon saturation, and explicit equation for the overall composition of each hydrocarbon component that satisfies thermodynamic equilibrium. The proposed formulation uses an Equation of State for phase equilibrium and property calculations. Interfacial tension effects are included in this research to characterize the thermodynamically dynamic nature of the relative permeability. A two-dimensional relative permeability algorithm is included which handles lumped hydrocarbon phase hydrocarbon phase as well as individual phase flows. For each grid block two equations are required, namely total hydrocarbon and water-phase flow equations. These equations are highly non-linear and they are linearized by using Newton-Raphson method. The resulting set of equations are solved by an efficient Conjugate Gradient based iterative technique to obtain pressures and saturations simultaneously, and hydrocarbon-phase saturations are deduced from their respective equations. The new compositional simulation approach is validated through analytical and other numerical methods. lt is demonstrated in this present paper that the results are compared favourably with analytical techniques and published numerical results. They also confirm that the proposed codified formulation is unconditionally stable and it is as stable as the fully compositional model yet the computational cost reduction was substantial. Impact of sequence-based on correlation style on volatile oil recovery is modelled with this approach. Specifically, the effect of clino-formal permeability barriers on predicted displacement efficiency of oil by injected water and injected gas into volatile oil reservoirs is assessed. The results show that oil recovery factors are strongly affected by the combination of the structure of permeability and the transmissibility barriers between the layers. P. 281

Total global CO2 emissions from fossil-fuel will still increase in the next ten decades. These are attributed to the heavy reliance of human activities with fossil fuels. The uncontrolled CO2 emissions from combustion of fossil fuels cause the CO2 concentration alteration in the atmosphere. As the result, this phenomenon cause global warming and change the climate globally. In the future, CO2 emissions are predicted in range from 29 to 44 GtCO2/year in 2020. Therefore it is necessary to abate the CO2  missions to the level that would prevent dangerous anthropogenic interference to the global climate system. The growth of energy efficiency improvements, the switch to less-carbon intensive fuels and renewable resources employment is still low in the context CO2 emissions mitigation. Carbon Dioxide Capture and Storage (CCS) as a third option for these mitigation options might facilitate achieving CO2  missions stabilization goals. As a part of the commitment and participation on combating the global warming, Indonesia has signed the Kyoto Protocol in 1998 and ratified it in 2004 through Law No. 17/2004. On the other side, Indonesia oil production has been declining since in the last ten years but demand for this energy is still high. In this frame CCS-Enhanced Oil Recovery (EOR) by CO2 injection might answer the global warming challenges and alongside contribute to increase the oil production in the near future. This paper presents a preliminary study of CCS-EOR potential in Indonesia. A brief explanation of geological setting and reservoir screening for site selection also presented. Then some discussions about CCS-EOR global potential will be highlighted as well as the analysis. It is hoped that this study would provide a standard guideline for determining CCS- EOR potential in Indonesia.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIt has been known that the distribution of hydrocarbon components in a fluid column is affected of gravity. Many authors have shown the effect of composition variation within a hydrocarbon column due to gravity. In thick reservoirs as the depth increases, the mole fraction of the lighter hydrocarbon decreases, whereas the heavy fraction fraction increases. These variations may affect reservoir fluid properties considerably. In studying reservoir processes, especially with miscible displacements, it is essential to have of underlying mechanisms.In this paper, we investigate the effect of composition variation with depth on volatile oil under depletion and miscible gas processes. A ternary diagram was used to identify the process displacement mechanisms at different locations. A new efficient compositional simulation approach was used to model the volatile oil reservoir bahaviour.It was shown that the decreasing light component with depth caused different miscible displacement processes as the oil composition move toward limiting tie line in the ternary diagram. Saturation and reservoir pressures variation with depth were not linear in a thick reservoir. This non linearity increased with the increased in volatility of the oil. In the case of depletion, the concentration of light component decreased below its original composition in the produced layers. In vaporisinggas drive the light component gradually vaporized from the bottom to the top of reservoir, whereas the intermediate component decreased below its original composition from the bottom to the top of the reservoir.

In part II of this two-part paper series, a field permeability model for enhanced methane recovery and CO2 sequestration, incorporating the findings of the current laboratory tests presented in part I is presented. It has been reported that coal matrix swelling/shrinkage associated with CO2, adsorption/desorption are typically two to five times larger than that found for methane, yet there has been no direct measurements of this effect on permeability of coals to CO2. The feasibility of ECBM/CO2 sequestration technology depends very much on the magnitude of matrix swelling effect on permeability, especially in deep, low permeability coal seam reservoirs. The main objective of this research is to investigate and develop numerical models based on the the effects of coal matrix swelling induced by CO2 adsorption on the permeability of different coals which have been undergoing methane desorption under simulated reservoir conditions in the laboratory.