In partial fulfillment of the requirement for a Bachelor of Engineering (HONS) (PETROLEUM ENGINEERING). DR MOHAMMED IDREES ALI AL-MOSSAWY). To meet the ever-increasing demand, current extraction techniques, especially laboratory experiments, need to be updated and improved to better understand reservoir conditions. The size of the composite core in the current WAG laboratory experiments has a significant impact on the laboratory experiments themselves.
One of the enhanced oil recovery techniques used by PETRONAS and other major oil operators to extract oil from a depleted reservoir is alternating gas injection into water. This improved oil recovery technique is an updated and improved version of current water injection and gas injection recovery processes. The core length is short due to the way the core is pulled out.
The implication of the short core is that capillary pressure has a significant impact on the calculation of relative permeability. A 3 inch core will be used in this study because the equipment to be used has a limitation on the length of the core.
OBJECTIVE
SCOPE OF STUDIES
LITERATURE REVIEW
- WATER ALTERNATING GAS
- PETROPHYSICAL PROPERTIES
- Porosity
- Permeability
- Saturation
- Wettability
- CAPILLARY END EFFECT
- KLINKENBERG GAS SLIPPAGE EFFECT
- Composite Core
- METHODOLOGY
- RESEARCH METHODOLOGY
- TOOLS, SOFTWARE, APPARATUS & MATERIALS REQUIRED
The communication between each formation layer did determine the effectiveness of the movement of oil that will be extracted from the reservoir [4]. The progression of the displacement front does not follow a regular pattern because the layers show a different value of permeability [4]. Porosity, permeability, saturation and wettability are some of the petrophysical properties that affect the improvement of the oil recovery process.
Porosity can also be defined as the ability of a rock formation to hold fluid or gas within its pore space. The higher the porosity value of the rock, the higher the ability of the rock to store oil [4]. The porosity value of the formation sediments is controlled by the degree of cementation, the degree of.
In any enhanced oil recovery process, the effectiveness of the program is highly dependent on the permeability of the formation. Saturation is a fraction or percentage of the pore volume occupied by a particular fluid (water, oil and gas) [7]. In the case of an oil-wet reservoir, it will be difficult to recover the oil [8].
So the pH of the brine used in these experiments is a constant value to ensure an optimal result. As the viscosity value decreases, the tendency of fluids to flow would be greater and vice versa. The capillary effect exists due to the break in capillarity during the wetting phase at the outlet end of the core sample [2].
As the pressure increases, the mean free path of the gas molecules becomes smaller and more molecules will collide with the wall. The laboratory experiment performed is the determination of the porosity and permeability by gas, the saturation of the nuclei by brine, and the determination of the permeability by liquid. The equipment is designed to determine the porosity of the core according to Boyle's Single Cell Method method, for direct measurement of the void volume.
The gas flow rate is determined based on the displacement experiment by Al-Mossawy & Demiral (2011). The output flow rate reading is measured to calculate brine recovery during brine injection and gas injection.
RESULT AND DISCUSSION
Quality check of the cores
- PoroPerm Experiment
- Saturation
In this experiment, Poroperm equipment is used to determine the permeability, porosity, pore volume, grain volume, and bulk volume of the core. The maximum pressure is set at 400 psig due to the maximum capacity of the equipment, while the minimum pressure is set for safety reasons that the core may not be fully enclosed in the core holder sleeve. The impact of a poorly contained core is that the core can become detached from the equipment and pose a hazard to the equipment operator.
Apart from that, approximately 150 psig pressure difference between confining pressure and injection pressure is set to ensure that the collected data is valid and not corrupted due to the gas seeping through the core casing holder that confined the core. So the hypothesis that 'the lighter the core, the higher the porous volume inside it'. R5 high permeability value is the highest may due to the connection of the pore space inside the core.
The sheath holding the core or the confining pressure will compress the core to ensure that no injection gas is released into the vicinity of the core. The compression of the core can affect the size of the porous space. 1990), caution should be exercised when comparing core analysis data generated under different stress conditions, especially at low voltage values. Thus, the effect of this variation needs to be addressed because in the next step of the project, the Benchtop Permeability System equipment will apply a trapping pressure of about 1000 psig to the core.
It is proven from the graph that there are changes in the pore space of the core when a differential confining pressure is applied. Although there are changes that occur in the pore space of the core, the changes are considered small and can be neglected. A biaxial stress state is a state where stresses are uniformly applied in two directions only by confining the core in a rubber sleeve.
The bubble produced is an indication that the brine solution is replacing the air within the pore space of the core. This method of holding the cores is essential to ensure that the brine within the pore space of the core does not evaporate into the surrounding environment thereby reducing the saturation value. Based on the porosity and permeability result from the PoroPerm equipment supported by the saturation result, it has been decided that the core to be selected for the WAG experiment is the B1 core.
Permeability Experiment Using BPS-850 before WAG
In Figure 4.5, the flow rates used to determine the fluid permeability are 1.5 cc/min, 2.5 cc/min, and 3.5 cc/min. Based on Figure 4.6, it has been determined that the permeability at liquid value for B1 core is 21.9 mD.
B1 PERMEABILITY DETERMINATION
- Water Alternating Gas Experiment: Single Core
- Water Alternating Gas Experiment : Composite Core
- Permeability Experiment Using BPS-850 After WAG
- Discussion
Figure 4.7 shows the graph of brine mass and pressure difference in relation to the time of brine injection before gas injection. From Figure 4.7 it can be seen that the core has become saturated with brine because the breakthrough of the first drop of brine from the outlet is in the early minutes. From Figure 4.8 we can observe that the core is saturated with brine because the breakthrough of the first drop of brine from the outlet is also in the early minutes.
The graph in Figure 4.8 also shows that the outflow rate gradually decreases at about 5 grams of brine. From Figure 4.9, we can see that the time required for the first drop of brine is about 5 minutes. Figure 4.10 is a plot of differential pressure versus time for brine injection prior to gas injection using a composite core.
Figure 4.10 also shows the brine mass recovery graph during brine injection when using a composite core. From the graph in Figure 4.10, we can see that the time required for the first drop of brine is longer compared to the graph in Figure 4.7. Figure 4.11 shows a graph of differential pressure versus time for gas injection into the composite core.
Figure 4.11 also shows the plot of mass of brine collected during gas injection for the composite core. Figure 4.12 shows the plot of differential pressure versus time during brine injection for the composite core. From figure 4.12, we can observe that the time taken for the first drop of brine is about 5 minutes.
From the figure 4.15 we can observe that for the composite core, the recovery flow rate of brine is slower compared to the single core. Based on figure 4.16, we could observe that the recovery for composite core yields a lower mass compared to single core. From the figure 4.17 we can note that for the composite core, the recovery flow rate of brine is slower compared to the single core.
Figure 4.18 shows the overall efficiency of each core in terms of brine recovery. It can be observed in Figure 4.18 that there is an overall stable brine recovery rate for brine injection before and after gas injection.
![Figure 2.1: WAG process in reservoir [15]](https://thumb-ap.123doks.com/thumbv2/azpdforg/10248793.0/12.892.172.783.337.708/figure-wag-process-in-reservoir.webp)
