Mariyamni Awang

Comparison of MMP Between Slim Tube Test and Vanishing Interfacial Tension Test

There are many tests used for determination of crude oil–CO2 MMP, but there is no test that is taken as the standard for MMP measurement. However, there are two tests that are widely used which are vanishing interfacial tension (VIT) test and slim tube test. VIT test is fast but it is not accurate while slim tube test is exactly vice versa, it takes a lot of time for one MMP point; however, the result is much more accurate. This paper is going to discuss the accuracy of the MMP measurement for both tests at various scenario and observe the trends. Both tests are found to have very different principle in measuring MMP, and their results vary quite a bit. However, they are both very useful in proving the effectiveness of additives in reducing MMP.

Palm Fatty Acid Methyl Ester in Reducing Interfacial Tension in CO 2 –Crude Oil Systems

The interfacial tension (IFT) is one of the most important parameters affecting the ability of CO2 to become miscible with crude oil. The high IFT difference between CO2 and crude oil resulted to more problems during the displacement such as fingering and segregation. Extensive research on chemicals to be used as additives in reducing the IFT between CO2 and crude oil has been done. However, large amounts of chemical are required with field application. This paper presents a preliminary study on the application of fatty acid methyl ester (FAME) from palm to reduce the IFT with crude oil and CO2. In this work, FAME is used as an additive in the mixture of CO2 and crude oil. Vanishing interfacial technique (VIT) was used to determine the effect of the additive on CO2–crude oil system. With this finding, an economical approach was obtained which is suitable for mass application in the reservoir.

Comparison of Liquid CO 2 Injection with a Common Tertiary Recovery Method Using Non-Isothermal Simulations

For the past decades, carbon dioxide injection has been used as a successful tertiary recovery method. The main advantage of CO2 can be referred as its miscibility with the crude oil which can lead to higher recovery. Generally, a large quantity of CO2 exploration can often be explored as gas or supercritical phase, but low-temperature CO2 is produced in some downstream facilities such as cryogenic separation units. This low-temperature CO2 opened a novel opportunity to evaluate the potential of low-temperature CO2 injection for enhanced oil recovery methods. Recent studies showed that usage of liquid CO2 instead of its supercritical form can increase the efficiency significantly. But its effectiveness in comparison with other tertiary methods is not investigated yet. In this paper, first, a non-isothermal compositional simulation is conducted by using a commercial simulator and by injecting low-temperature CO2. Then, the results are compared with an equivalent solvent injection scenario. The results show that, after 2 pore volumes of liquid CO2 injection, a total recovery of 75.79% is obtained, which shows 17.43% increase in comparison with solvent injection. The results of this study proved a significant advantage for low-temperature CO2 injection in comparison with common tertiary methods to improve oil recovery that can be implemented in the field.

Field-Scale Investigation of Miscible CO 2 Injection in a Heterogeneous Shaly Sand Reservoir

Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to improve oil recovery, and its applicability has grown significantly due to its availability, greenhouse effect, and easy achievement of miscibility relative to other gasses. Therefore, miscible CO2 injection is considered one of the most feasible methods worldwide. For long-term strategies in Iraq and the Middle East, most oil fields will need to improve oil recovery as oil reserves are falling. This paper presents a study of the effect of various miscible CO2 injection scenarios on the performance of the highly heterogeneous clastic reservoir in Iraq. An integrated field-scale reservoir simulation model of miscible CO2 flooding is accomplished. The compositional simulator, Eclipse-300, has been used to investigate the feasibility of miscible CO2 injection process. The process of the continuous CO2 injection was optimized to start in January 2056 as an improved oil recovery method after natural depletion and waterflooding processes have been performed, and it will continue until January 2063. The minimum miscibility pressure (MMP) for CO2 was determined using empirical correlation as a function of crude oil composition and its properties. Ten miscible CO2 injection options were undertaken to investigate the reservoir performance. These options included applying a wide range of the CO2 injection rates ranged between 1.25 and 50 MMScf/day. All development options were analyzed with respect to net present value (NPV) calculations to confirm the more feasible CO2 development strategy. The results showed that the application of CO2 injection option of a 20 MScf/day attained the highest recovery of 28% by January 2063 among the others. The recovery growth was so minor by increasing the CO2 injection rate above this level. Based on economic findings, the option of 20 MScf/day also attained the highest net present value. The results showed that after January 2063, the oil recovery attained by the different CO2 injection options are less than the one attained by the waterflooding process. Therefore, the miscible CO2 injection became unviable economically after January 2063.

System Identification Based Proxy Model of a Reservoir under Water Injection

Simulation of numerical reservoir models with thousands and millions of grid blocks may consume a significant amount of time and effort, even when high performance processors are used. In cases where the simulation runs are required for sensitivity analysis, dynamic control, and optimization, the act needs to be repeated several times by continuously changing parameters. This makes it even more time-consuming. Currently, proxy models that are based on response surface are being used to lessen the time required for running simulations during sensitivity analysis and optimization. Proxy models are lighter mathematical models that run faster and perform in place of heavier models that require large computations. Nevertheless, to acquire data for modeling and validation and develop the proxy model itself, hundreds of simulation runs are required. In this paper, a system identification based proxy model that requires only a single simulation run and a properly designed excitation signal was proposed and evaluated using a benchmark case study. The results show that, with proper design of excitation signal and proper selection of model structure, system identification based proxy models are found to be practical and efficient alternatives for mimicking the performance of numerical reservoir models. The resulting proxy models have potential applications for dynamic well control and optimization.

Use of Group Method of Data Handling Algorithms for Predicting Heated and Steamed Zone Volumes During Steam Flooding

The predictions of steamed and heated zone volumes are critical aspects of steam or hot water injection for enhanced oil recovery because they are used to calculate the expected oil recovery. There are a few models available to calculate steamed and heated zone volumes, but most of these models assume that the volumes of the steam and heat penetrated zones are the same. This assumption is incorrect in general. Furthermore, the available models are quite complex to use because of the difficulties in obtaining data for their required variables. In this study, new prediction models for calculating the steamed and heated zone volumes using regression analysis methods based on group method of data handling (GMDH) parametric and nonparametric algorithms are presented. The models are based on published experimental data. The GMDH algorithms considered to develop the new predictive models are full polynomials (FP) and polynomial neural networks (PNN). The new proposed and the existing models were evaluated and compared using rigorous statistical tools. The results show that both the FP- and PNN-based GMDH models have a better prediction performance compared to the existing models. In addition, the results show that the FP-based predictive model provides a better match with experimental data for the volume of heated zone than does the PNN-based predictive model. On the other hand, the PNN-based predictive model provides better match with the experimental data for the volume of steamed zone than the FP-based model. All these results suggest that the predictive methods based on the GMDH algorithms could be useful tools for determining the recoverable oil and analysis of thermal performance of a steam drive process.

Evaluation of Carbon Dioxide Adsorption on Malaysian Coals for Potential Sequestration

Adsorption experiments of carbon dioxide (CO2) were contacted on two coal samples from Sungai Buloh and Silantek mines in Malaysia. A fixed bed adsorption unit was used to determine CO2 adsorption capacity of the coal samples. The experiments were conducted at different pressure ranges (5-40 bar) and temperature at 25°C. The CO2 adsorption capacity of Silantek coal sample showed adsorption capacity of 4.178 mmol/g at 40 bars and 25 °C, which is higher than Sungai Buloh sample. Different adsorption isotherms were employed to examine the experimental results, Langmuir isotherm of Silantek coal sample illustrated better correlation than Freundlich isotherm for the same sample. In contrary, Freundlich isotherm of Sungai Buloh coal sample illustrated better fitting than Longmuir isotherm correlation for the same sample. This is related to the coal rank and moisture content and ash content.